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Severe hesitation at LOW rpm + bad mpg
Hey all, ik this forum isn't as active as it used to be but I'm hoping someone can help me out.
I've been struggling with exceptionally low mpg for quite a while now. No matter how I drive, city or highway, granny shifting or bouncing off the limiter, I cannot break 16mpg. BHR v2 coils, new wires and plugs approximately 10k miles ago. Both o2 sensors just a couple months ago. Always 93 octane w/ Idemitsu premix .5oz/gal + sohn. However, I've become increasingly more aware of another issue which I'm hoping is related. When the engine is cold, and especially if the ambient temp is cold, the car falls flat on its face FROM IDLE TO 4K, at which point it's like a lightswitch flips and the car immediately comes to life. Any amount of throttle from big toe to WOT presents this issue. Video of the issue, while not as severe as it sometimes is, linked here. I posted this on Facebook and reddit and literally everyone said SSV. Problem is, from my research, that's only an issue PAST 4k. Plus, I reached in with a long pair of pliers to move the SSV actuator arm and it moves flawlessly. Vid of that linked here. Lastly, I checked my 10k mile spark plugs and they looked awful. https://cimg2.ibsrv.net/gimg/www.rx8...e4df099810.jpg Does anyone have any idea what could be going on? The only things I can think of at this point are the solenoid that controls the SSV, the MAF, a vacuum leak, or maybe an injector issue. I'd be eternally grateful for any wisdom you can share! |
Are there any codes? Vac leak and solenoid issues should be diagnosable via OBD. On a warm idle you should have 0 furl trimd. If they're not 0, report back with numbers.
Those plugs look overfueled. What's the history of the car and engine? Any mods? |
Originally Posted by Loki
(Post 4987188)
Are there any codes? Vac leak and solenoid issues should be diagnosable via OBD. On a warm idle you should have 0 furl trimd. If they're not 0, report back with numbers.
Those plugs look overfueled. What's the history of the car and engine? Any mods? Hope that helps! |
Has the engine been out? It's easy to mix up primary and secondary injector wiring causing similar issues.
Clues should be in the idle fuel trims. |
Originally Posted by Loki
(Post 4987202)
Has the engine been out? It's easy to mix up primary and secondary injector wiring causing similar issues.
Clues should be in the idle fuel trims. Short of that, is there any way to get anywhere by simple visual inspection? |
You could check if the MAF is clean and if there is oil in the intake, and check for obvious vacuum leaks, loose hoses, etc.
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Originally Posted by Loki
(Post 4987209)
You could check if the MAF is clean and if there is oil in the intake, and check for obvious vacuum leaks, loose hoses, etc.
Anywhere in particular you'd recommend I test vacuum from? |
I'm not sure a vacuum pump will held with an intake leak, you need the fuel trim data from the computer to tell you if it's getting unmetered air.
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Originally Posted by Loki
(Post 4987216)
I'm not sure a vacuum pump will held with an intake leak, you need the fuel trim data from the computer to tell you if it's getting unmetered air.
I did happen to notice that my MAF felt a little loose when I pulled it out. I then noticed the O ring was super loose and looked like it had been pinched when it was reinstalled. The screw holes were also stripped out causing it to wiggle around in its hole. Fingers crossed that that could be part of it🤞🏻 |
Originally Posted by Nikonnate
(Post 4987224)
Gotcha. I need it anyway to test the intake solenoids behind the manifold.
I did happen to notice that my MAF felt a little loose when I pulled it out. I then noticed the O ring was super loose and looked like it had been pinched when it was reinstalled. The screw holes were also stripped out causing it to wiggle around in its hole. Fingers crossed that that could be part of it🤞🏻 Could easily be, at idle the car only pulls 5g/sec of air, so even tiny leaks could translate to a big % of unmetered air. At higher airflow, a tiny leak becomes less of a factor and the is able to compensate. |
Originally Posted by Loki
(Post 4987225)
Could easily be, at idle the car only pulls 5g/sec of air, so even tiny leaks could translate to a big % of unmetered air. At higher airflow, a tiny leak becomes less of a factor and the is able to compensate.
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16 mpg for mixed city/hwy driving is around what I get, so just for that part, it wouldn't alarm me.
But then, I probably drive a little more aggressively than most. I'm on my 4th fuel pump in 11 years. I'd speculate because of premixing, they usually last about 3 years. I had the last one replaced by the rebuilder who did mine. He bought a cheap one off eBay and it went bad almost immediately. If you haven't had your fuel ring recall, you can get it replaced then. Maybe a stealership would install your store-bought pump, but I wouldn't bet on it. At this point, look at it as a preventive maintenance item if it doesn't fix your problem. It's worth a shot, imo. Also, if you don't have a proper RX8 fuel ring tool, you'll want to get one, especially if you have a new fuel ring. Those rental ones are a PITA & tear up the tabs on the ring. I have the BHR tool, worth every penny. https://cimg5.ibsrv.net/gimg/www.rx8...e87effc717.jpg |
Originally Posted by BigCajun
(Post 4987229)
16 mpg for mixed city/hwy driving is around what I get, so just for that part, it wouldn't alarm me.
But then, I probably drive a little more aggressively than most. I'm on my 4th fuel pump in 11 years. I'd speculate because of premixing, they usually last about 3 years. I had the last one replaced by the rebuilder who did mine. He bought a cheap one off eBay and it went bad almost immediately. If you haven't had your fuel ring recall, you can get it replaced then. Maybe a stealership would install your store-bought pump, but I wouldn't bet on it. At this point, look at it as a preventive maintenance item if it doesn't fix your problem. It's worth a shot, imo. Also, if you don't have a proper RX8 fuel ring tool, you'll want to get one, especially if you have a new fuel ring. Those rental ones are a PITA & tear up the tabs on the ring. I have the BHR tool, worth every penny. https://cimg5.ibsrv.net/gimg/www.rx8...e87effc717.jpg Just to play devils advocate, wouldn't the fuel pump be more of an issue at high rpm rather than low? I'll check into the recall. I'm pretty sure mine either had it done before I got it or it didn't apply to mine. |
My non-highway fuel consumption driving would be around 13-15mpg, so not getting more than 16mpg is pretty normal.
Rotaries are thirsty, that's why I don't ever-day drive it.... |
Originally Posted by Joeyjoiner
(Post 4987249)
My non-highway fuel consumption driving would be around 13-15mpg, so not getting more than 16mpg is pretty normal.
Rotaries are thirsty, that's why I don't ever-day drive it.... |
Internet car mechanic is already hard to play as it is. Without OBD2 data on a modern car, it's really just a crapshoot of what it can be.
Get the OBD2 reader before you throw parts at it. |
Originally Posted by UnknownJinX
(Post 4987278)
Internet car mechanic is already hard to play as it is. Without OBD2 data on a modern car, it's really just a crapshoot of what it can be.
Get the OBD2 reader before you throw parts at it. |
Originally Posted by Loki
(Post 4987225)
Could easily be, at idle the car only pulls 5g/sec of air, so even tiny leaks could translate to a big % of unmetered air. At higher airflow, a tiny leak becomes less of a factor and the is able to compensate.
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Originally Posted by Loki
(Post 4987216)
I'm not sure a vacuum pump will held with an intake leak, you need the fuel trim data from the computer to tell you if it's getting unmetered air.
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It's hard to confirm or discard any theory without OBD data. While it *could* be injector related, but injector staging is based on load not rpm, so it wouldn't have a clean cutover at 4000
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Originally Posted by Loki
(Post 4987457)
It's hard to confirm or discard any theory without OBD data. While it *could* be injector related, but injector staging is based on load not rpm, so it wouldn't have a clean cutover at 4000
I'll also be sure to get a photo of my injector wiring, somebody (maybe you?) said theres a small chance my injectors may have been reconnected wrong if anyone was ever in there for any reason. And of course will report back if I find anything going on with the solenoids once I'm back in there. Hoping it will be warm enough tomorrow to get to it. |
On a warm idle you'll want airflow g/sec, short term and long term fuel trim and rpm.
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I -may- have found my issue. There appears to be a gap at the top of my SSV, as though it isn't closing completely. This would be in line with my suspicion that the SSV wasn't closed when it should be. Does anyone know if that gap belongs there?
Otherwise the SSV moves smoothly and holds vacuum. Please tell me this is it! https://cimg7.ibsrv.net/gimg/www.rx8...1bdd29a509.jpg |
Has anyone had issues with BHR v2 coils? I am pulling my hair out trying to diag my issue and one of the only things I can come up with is that my BHR v2s with 10k miles on them are somehow no good. I emailed Charles but last time I emailed him with a problem he never replied to me...
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It could be your VFAD. If you take your bumper off, it's behind it. It takes in air at lower RPMS from one gate, then when you go higher, it takes it in from a much shorter gate, and therefore more power. Maybe it's faulty. Its regulated by a microswitch thats mounted behind the stock air intake- that could be faulty too. Do you have an aftermarket air intake?
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Originally Posted by cmaderia10
(Post 4987508)
It could be your VFAD. If you take your bumper off, it's behind it. It takes in air at lower RPMS from one gate, then when you go higher, it takes it in from a much shorter gate, and therefore more power. Maybe it's faulty. Its regulated by a microswitch thats mounted behind the stock air intake- that could be faulty too. Do you have an aftermarket air intake?
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Originally Posted by Nikonnate
(Post 4987499)
Has anyone had issues with BHR v2 coils? I am pulling my hair out trying to diag my issue and one of the only things I can come up with is that my BHR v2s with 10k miles on them are somehow no good. I emailed Charles but last time I emailed him with a problem he never replied to me...
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Originally Posted by cmaderia10
(Post 4987508)
It could be your VFAD. If you take your bumper off, it's behind it. It takes in air at lower RPMS from one gate, then when you go higher, it takes it in from a much shorter gate, and therefore more power. Maybe it's faulty. Its regulated by a microswitch thats mounted behind the stock air intake- that could be faulty too. Do you have an aftermarket air intake?
That being said, if it is deleted, the vacuum port has to be properly capped off. Otherwise, that could cause a vacuum leak. |
Need help. Open and closed stats..
OK so the biggest concern that I have, and with my experience trying to discuss these ideas with my diesel mechanic father little hesitant, but what I truly think I’m experiencing is and it is basically a daily occurrence because I do daily my rx8. But for the last few months, I have felt that my rotary just prefers cold weather. PHX cold that is. Which wasn’t something that stumped me because I could tell how much effort she was putting in this summer which by the way was the hottest summer I’ve ever experienced in my 30 years of life but I think by coincidence possibly right around the time the weather broke was the time I started experiencing my intermittent” power loss throughout the day, which was why I thought it was weather cold in the morning warm at night even considered changing oil weight. But i now treat my innovo tablet like my daily carry. I know that I see my own numbers in front of me. I am starting to better understand long term, fuel trim, and short-term fuel trim. Now, with that understanding, I have recorded my drive to work and also my drive home from work. Granted, there are multiple drive cycles in between. So for this first question, when I’m asking is what would cause morning fuel trims good but after multiple drive cycles, trims start to reach the double digits slightly which is I think, causing idle surge, almost a bogging out, feeling at low RPM, vfad is functional. I can hear it every morning. But uh that’s just the beginning. Scanners picking up what it thinks is misfire but after further exam I almost certain it’s blow by.
https://cimg1.ibsrv.net/gimg/www.rx8...9588f101c8.jpg Morning fuel trim https://cimg3.ibsrv.net/gimg/www.rx8...08bb15e856.jpg Morning https://cimg7.ibsrv.net/gimg/www.rx8...071cbf590f.jpg Morning Now for my drive home. And remember there are a few in between. I guess I could best describe them, as not good for her. Typically a day consist of at least an hour or two of traffic, not standstill, but might as well be for her definitely under 4K but I make sure after traffic has cleared. She definitely gets opened up. I understand that there are things happening in between these two drive cycles but if she really learning that fast? Or could possibly my connection to the battery be failing at night forcing to relearn every morning? Things I’ve done in the last few months have been basically maintence. Oil change every 3k depending on smell, cuz I can. Cleaning and greasing connections and grounds keep in mind I haven’t done all of them, but I’m probably about to because I am getting a an eps communication, bus fault, and instrument cluster bus fault receive error which I’ll be doing as soon as time is kind to me. Ummmm tranny oil about 5 k ago. Coolant flush over the weekend. Oh and also know that my tablet is bringing up the communication errors. I have been experiencing some very strange electrical stuff lately. Drove home in a rainstorm wasn’t a choice. Got home and shit went haywire lost power steering. I still think something is wrong with coolant temp sensor, but no signs pointing to that Besides my own observations, but other than the coolant temp being a conspiracy, I’m creating a little creepy sometimes without the keys in my pocket in the car in the garage I’ll be digging into the car and I’ll just randomly start here the doors locking multiple times on their own when no one has access to them. So can someone help me diagnose. Oh and btw yes I am new to rx8 club and still in infancy owner ship so I’m deemed unfit, uneducated, and apparently that adopted nephew people like to hide under the stairs until they buy a piano or chalkboard lol. But for real country of origin? cuz this no post rule is kinda dictator adjacent. so what I’m trying to do is apologize to the creator of this post as I am not trying to take over but I do think we share similar issues and my motivation to see all the shit talkers faces in 5 years is borderline. Oh I’m also seeing something about a small leak to chase down. |
Originally Posted by My_daily-rx8
(Post 4988757)
OK so the biggest concern that I have, and with my experience trying to discuss these ideas with my diesel mechanic father little hesitant, but what I truly think I’m experiencing is and it is basically a daily occurrence because I do daily my rx8. But for the last few months, I have felt that my rotary just prefers cold weather. PHX cold that is. Which wasn’t something that stumped me because I could tell how much effort she was putting in this summer which by the way was the hottest summer I’ve ever experienced in my 30 years of life but I think by coincidence possibly right around the time the weather broke was the time I started experiencing my intermittent” power loss throughout the day, which was why I thought it was weather cold in the morning warm at night even considered changing oil weight. But i now treat my innovo tablet like my daily carry. I know that I see my own numbers in front of me. I am starting to better understand long term, fuel trim, and short-term fuel trim. Now, with that understanding, I have recorded my drive to work and also my drive home from work. Granted, there are multiple drive cycles in between. So for this first question, when I’m asking is what would cause morning fuel trims good but after multiple drive cycles, trims start to reach the double digits slightly which is I think, causing idle surge, almost a bogging out, feeling at low RPM, vfad is functional. I can hear it every morning. But uh that’s just the beginning. Scanners picking up what it thinks is misfire but after further exam I almost certain it’s blow by.
https://cimg1.ibsrv.net/gimg/www.rx8...9588f101c8.jpg Morning fuel trim https://cimg3.ibsrv.net/gimg/www.rx8...08bb15e856.jpg Morning https://cimg7.ibsrv.net/gimg/www.rx8...071cbf590f.jpg Morning Now for my drive home. And remember there are a few in between. I guess I could best describe them, as not good for her. Typically a day consist of at least an hour or two of traffic, not standstill, but might as well be for her definitely under 4K but I make sure after traffic has cleared. She definitely gets opened up. I understand that there are things happening in between these two drive cycles but if she really learning that fast? Or could possibly my connection to the battery be failing at night forcing to relearn every morning? Things I’ve done in the last few months have been basically maintence. Oil change every 3k depending on smell, cuz I can. Cleaning and greasing connections and grounds keep in mind I haven’t done all of them, but I’m probably about to because I am getting a an eps communication, bus fault, and instrument cluster bus fault receive error which I’ll be doing as soon as time is kind to me. Ummmm tranny oil about 5 k ago. Coolant flush over the weekend. Oh and also know that my tablet is bringing up the communication errors. I have been experiencing some very strange electrical stuff lately. Drove home in a rainstorm wasn’t a choice. Got home and shit went haywire lost power steering. I still think something is wrong with coolant temp sensor, but no signs pointing to that Besides my own observations, but other than the coolant temp being a conspiracy, I’m creating a little creepy sometimes without the keys in my pocket in the car in the garage I’ll be digging into the car and I’ll just randomly start here the doors locking multiple times on their own when no one has access to them. So can someone help me diagnose. Oh and btw yes I am new to rx8 club and still in infancy owner ship so I’m deemed unfit, uneducated, and apparently that adopted nephew people like to hide under the stairs until they buy a piano or chalkboard lol. But for real country of origin? cuz this no post rule is kinda dictator adjacent. so what I’m trying to do is apologize to the creator of this post as I am not trying to take over but I do think we share similar issues and my motivation to see all the shit talkers faces in 5 years is borderline. Oh I’m also seeing something about a small leak to chase down. In the screenshots your fuel trims are normal, do you have a screenshot of when the problem is occuring? Is there oil in your intake? |
Originally Posted by cmaderia10
(Post 4987508)
It could be your VFAD. If you take your bumper off, it's behind it. It takes in air at lower RPMS from one gate, then when you go higher, it takes it in from a much shorter gate, and therefore more power. Maybe it's faulty. Its regulated by a microswitch thats mounted behind the stock air intake- that could be faulty too. Do you have an aftermarket air intake?
The was oil yes. Cleaned everything up to but not past TB. I’m pretty certain the previous owner just overfilled the oil because I haven’t had a problem since and I haven’t Installed a catch can. https://cimg7.ibsrv.net/gimg/www.rx8...fc49a3117.jpeg Vfad had no oil and tbh if it did I’d be very confused but I did clear a small rock from the flaps joint. And whoever says vfad Ain’t shit never rode rode a street bike. My r6 had the vfi I think they call it. Same concept of creating One of my favorite things in the world power band https://cimg8.ibsrv.net/gimg/www.rx8...fe870ecdb.jpeg Like I said, I love the VF. I think it does great I only run stock box no oil on filters https://cimg0.ibsrv.net/gimg/www.rx8...e413093d6.jpeg Battery was replaced a week ago and someone on a different forum, convinced me of the high CCA, Walmart battery Solely based on the fact that I test them regularly and could catch it before it fails which means a free new battery at Walmart as long as I can kill it within two years https://cimg1.ibsrv.net/gimg/www.rx8...2065915af.jpeg Also had A weird paranoia in the back of my head that maybe The past owners Thai wire job maybe had the oil constricted by the angle it was at so while I had the bumper off, I rig this little contraption https://cimg2.ibsrv.net/gimg/www.rx8...5efb04e9c.jpeg https://cimg4.ibsrv.net/gimg/www.rx8...d04432e81.jpeg Mounted with rubber spacers for that no ratttle redline https://cimg9.ibsrv.net/gimg/www.rx8...303764c3a.jpeg Also a coolant flush. Green With water wetter https://cimg8.ibsrv.net/gimg/www.rx8...f009d3765.jpeg https://cimg7.ibsrv.net/gimg/www.rx8...d69047656.jpeg https://cimg9.ibsrv.net/gimg/www.rx8...866e8af69.jpeg https://cimg0.ibsrv.net/gimg/www.rx8...0f094e497.jpeg https://cimg1.ibsrv.net/gimg/www.rx8...42416b0f4.jpeg https://cimg2.ibsrv.net/gimg/www.rx8...68ebc0091.jpeg https://cimg3.ibsrv.net/gimg/www.rx8...8d3ca4d42.jpeg https://cimg4.ibsrv.net/gimg/www.rx8...3f5a89950.jpeg https://cimg5.ibsrv.net/gimg/www.rx8...f010c1ce5.jpeg https://cimg7.ibsrv.net/gimg/www.rx8...04da37e9a.jpeg |
Ok so a few things:
- no water wetter in these engines. It creates more problems than benefits. You want Mazda FL22 and nothing else, to be safe. Some coolants eat the seals and water wetter ends up being water clogger. - ignore STFT while driving. It's responding to what you're doing in the moment, not the engine condition. LTFT is what matters. High LTFT indicates a vacuum leak, and it's not continuously variable, it only has 3 bands: idle, low load, high load. You're most likely to see high ltft due to a small vacuum leak at idle - vfad isn't a power band aid, it's to quieten the car at medium load. The powerband is done with the intake valves. See if oil in the intake comes back after a high rpm run. If it does, it's being forced up by blowby and causing your stumbling. Might have less to do with the time of fay than you opening it up after traffic. |
Originally Posted by Loki
(Post 4988763)
Ok so a few things:
- no water wetter in these engines. It creates more problems than benefits. You want Mazda FL22 and nothing else, to be safe. Some coolants eat the seals and water wetter ends up being water clogger. - ignore STFT while driving. It's responding to what you're doing in the moment, not the engine condition. LTFT is what matters. High LTFT indicates a vacuum leak, and it's not continuously variable, it only has 3 bands: idle, low load, high load. You're most likely to see high ltft due to a small vacuum leak at idle - vfad isn't a power band aid, it's to quieten the car at medium load. The powerband is done with the intake valves. See if oil in the intake comes back after a high rpm run. If it does, it's being forced up by blowby and causing your stumbling. Might have less to do with the time of fay than you opening it up after traffic. straight up respectful answers without eggshells. I like it. I obviously am not educated in mechanics. Just been around it forever. So what I can take away from that is. Study before, you panic. Because I truthfully am, not because I can’t survive what I now believe to be a rebuild only option. Which after is all said and done will be super stoked but still. It’s the constant I told you so. so listen it only got worse today. 100% believe it’s what you’ve already said now. Water clogger. After I flushed it I noticed a type of scaling in the reservoir. And also I used some green shit from a reputable company who claims is for all Mazda. But I used a screened funnel and after about half the coolant drained took about 30 seconds to drain 4oz because it was straining a crystalline like substance. so with that said I think I’ll say it. She’s about out the door 😔 unless by some kind of unrealistic miracle. The stumbling is horrible I had no other option but to get her home park it and figure out how to go about what come next. It started with me noticing what you’re saying is a vacuum leak “ small” which has to be accurate because after some carb cleaning investigation nothing was found. But now I’m pretty sure it’s the coolant seal. But please by all any mean necessary prove I’m wrong. She’s not dieing at idle yet but so close idk how she clings to life. The fake gauges aren’t hitting a concering mark but they are both fidgeting at a matched pace. Like back and forth between normal and +1 and -1 off normal. I cannot for the life of me find the source of coolant smell but got a new cap on the way home because she never left normal temp range but was building up pressure like a lot. I can’t be to sure but I swear I saw that bottle expanding on warm up and undeniably contracting immediately after cool down. Pressure seemed too dissipate in system faster then I’m used too notice while waiting to put on cap. Still no visible source of coolant smell tho. But she reeks of it. Like over power the decat stank lol. Anyways here I am unwilling to accept reality and hoping someone has a different diagnoses that I can tackle sometime after work this week? Oh and white smoke is noticeable on little nuetral revs. And maybe while driving but idk I drive lol. Any way thanks for your time so far. |
Since you messed with the VFAD, possible the VFAD nipple under the throttle body was left open? That would certain lead to issues with unmetered air.
For the coolant smell, there's always the overflow tank drain under the battery. Check from underneath the car or the underside of the hood, engine cover and other things you wouldn't normally look at for coolant splatter. Might be a clue. Building pressure in the coolant system is normal, its supposed to do that. What would be a bad sign is bubbles in the overflow or coolant on the spark plugs. You can always do a chemical block test (exhaust in coolant) if you suspect a coolant leak. Rebuild is generally last resort, once you've proven the engine core itself is damaged. You don't want to rebuild only to find out that the problem is still in the car and now affecting your new engine. |
Originally Posted by Loki
(Post 4988774)
Since you messed with the VFAD, possible the VFAD nipple under the throttle body was left open? That would certain lead to issues with unmetered air.
For the coolant smell, there's always the overflow tank drain under the battery. Check from underneath the car or the underside of the hood, engine cover and other things you wouldn't normally look at for coolant splatter. Might be a clue. Building pressure in the coolant system is normal, its supposed to do that. What would be a bad sign is bubbles in the overflow or coolant on the spark plugs. You can always do a chemical block test (exhaust in coolant) if you suspect a coolant leak. Rebuild is generally last resort, once you've proven the engine core itself is damaged. You don't want to rebuild only to find out that the problem is still in the car and now affecting your new engine. https://cimg2.ibsrv.net/gimg/www.rx8...85d38fe35.jpeg |
Finally bringing this thread back to life
Sorry to leave you all who have been trying to help hanging. Ended up parking the car for the winter shortly after my last post.
I finally got it to misbehave in a quantifiable way. Gave it the beans when still cold (ik, not smart, just a quick stab to shoot a gap) and got a flashing CEL which obviously means misfire. Attached are some photos of the data Loki asked for a while back. Hope this tells you something, I'd really like to grt this thing back on the road. https://cimg1.ibsrv.net/gimg/www.rx8...79f5ff644d.jpg https://cimg2.ibsrv.net/gimg/www.rx8...a50ea13bef.jpg https://cimg3.ibsrv.net/gimg/www.rx8...38834e5f18.jpg |
All I see there is you have a smallish vacuum leak. Airflow is under 5 g/sec at 800+ rpm and fuel trims are +5-7. Something small, like a cracked hose. Probably not the reason for the misfires, but that data is at idle, not when the issue is happening so not much to go on.
It's been a while so sorry if it was asked already but are the intake air straightening screens still present and undamaged? Really need those. |
Are you talking about the two black slats that go inside the airbox? My buddy told me to delete those but I still have them so they can go back in. What is the implication of those not being in there? I was told they actually free up airflow or something like that, my buddy ran his 8 for 275k miles with no issues (that he knew of) without them. If those aren't what you're talking about, what exactly should I be looking for?
Regarding the vacuum leak, what would you suggest as being the best way to go about finding that? I might be able to borrow a smoke tester from someone. I do have a hand pump I can use to confirm a leak if you tell me where the best place to test from would be. I used it to test the vacuum tank and all three intake solenoids, and they all checked out. It is definitely running rich somewhere. Plugs are gross at 10k miles, and it coughs out a noticeable black cloud under load at low revs. I did get myself a new bluetooth scanner for Christmas, so if you need any data I can get that for you pretty quickly. Potentially unrelated, I also had a pending P0420 when I checked the misfire. The code randomly throws once in a blue moon but doesn't come on after I clear it. BHR hi-flow, brand new front and rear O2 sensors. |
Originally Posted by Loki
(Post 4990601)
It's been a while so sorry if it was asked already but are the intake air straightening screens still present and undamaged? Really need those.
https://cimg8.ibsrv.net/gimg/www.rx8...ff2a845bfd.jpg |
Originally Posted by Loki
(Post 4990601)
All I see there is you have a smallish vacuum leak. Airflow is under 5 g/sec at 800+ rpm and fuel trims are +5-7. Something small, like a cracked hose. Probably not the reason for the misfires, but that data is at idle, not when the issue is happening so not much to go on.
It's been a while so sorry if it was asked already but are the intake air straightening screens still present and undamaged? Really need those. Also I see what you meant now abt the screens. You meant inside the airbox right in front of the MAF. There's a little crinkle on one side but otherwise it's fine. Is there another one in there somewhere I should be looking for as well? The car is back from winter storage now so I can get you any info you need pretty quickly. I seafoamed it when I got it out and now it feels like it's running worse. Super unsteady at idle. Bucking and lurching under low rpm load when cold. Could this all just be bad plugs? Ik seafoam can finish off plugs that are already on their way out. https://cimg1.ibsrv.net/gimg/www.rx8...6dd5841901.jpg https://cimg0.ibsrv.net/gimg/www.rx8...f280d4d329.jpg https://cimg7.ibsrv.net/gimg/www.rx8...21eae202f4.jpg |
Yep you still have unmetered air getting in somewhere. 800rpm should be over 5g/secand you have +14% ltft, so... yep. Keep looking. Unfortunately there's no easy way to find small leaks. It could be hoses, it could be a pinched gasket in the UIM mating surfaces...
Spark plugs could also be a problem but that won't affect how much air is getting in, so you might have 2 problems. |
Originally Posted by Loki
(Post 4991056)
Yep you still have unmetered air getting in somewhere. 800rpm should be over 5g/secand you have +14% ltft, so... yep. Keep looking. Unfortunately there's no easy way to find small leaks. It could be hoses, it could be a pinched gasket in the UIM mating surfaces...
Spark plugs could also be a problem but that won't affect how much air is getting in, so you might have 2 problems. |
Originally Posted by Nikonnate
(Post 4987187)
Hey all, ik this forum isn't as active as it used to be but I'm hoping someone can help me out.
I've been struggling with exceptionally low mpg for quite a while now. No matter how I drive, city or highway, granny shifting or bouncing off the limiter, I cannot break 16mpg. BHR v2 coils, new wires and plugs approximately 10k miles ago. Both o2 sensors just a couple months ago. Always 93 octane w/ Idemitsu premix .5oz/gal + sohn. However, I've become increasingly more aware of another issue which I'm hoping is related. When the engine is cold, and especially if the ambient temp is cold, the car falls flat on its face FROM IDLE TO 4K, at which point it's like a lightswitch flips and the car immediately comes to life. Any amount of throttle from big toe to WOT presents this issue. Video of the issue, while not as severe as it sometimes is, linked here. I posted this on Facebook and reddit and literally everyone said SSV. Problem is, from my research, that's only an issue PAST 4k. Plus, I reached in with a long pair of pliers to move the SSV actuator arm and it moves flawlessly. Vid of that linked here. Lastly, I checked my 10k mile spark plugs and they looked awful. https://cimg2.ibsrv.net/gimg/www.rx8...e4df099810.jpg Does anyone have any idea what could be going on? The only things I can think of at this point are the solenoid that controls the SSV, the MAF, a vacuum leak, or maybe an injector issue. I'd be eternally grateful for any wisdom you can share! Hey I’ve got it pretty much the same issues but with one other big one that I’m wondering if you have. My rx8 with Bennettbuilt coils and SOHN is getting some sort of dilution in the oil about a quart every 1000 miles. I’m guessing it’s fuel based on the smell and runny lack of thickness to it (I’ve already sent out a sample to blackstone labs). I would like to know if you are having the same problem or if our problems could be related somehow? |
I haven't noticed any fuel dilution. Best course of action is to wait and see what Blackstone says. That was a good call reaching out to them right away.
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