CrazyJek

I just want to run this by you guys. Ive searched all over the forum and read dozens of similar issues but they were not entirely like mine...or at least i though.

First off... 2004, manual, 65K on original engine. Recently replaced clutch with OEM, pedal bracket with BHR's, has AEM CAI, seafoamed since last oil change, new MAF, new spark plugs (has about 1500 miles on them), and BHR ignition with 30K miles on coils.

When i accelerate, it gurgles between 4-5k rpms unless full throttle, pulls fine from 5-6K, and then mid 6K it hits a wall and struggles. I had suggestions that it was an intake issue. This only just started happened literally right after i cleaned the AEM filter. LIke i cleaned the horrible amount of dirt off the filter, put it back on, reset the fuel trims, turned the car on...and BAM. This started happening. So i bought a new MAF and reset fuel trims again and the problem went away....90% of it.

Fast forward a couple days and the problem returns. It comes back after driving for a bit. Exhaust tips are jet black and i here popping. I also have a gutted CAT. Was fine when i did it and drove fine for 3K miles after i did it.

I checked vacuum hoses and all seems to be in place. I also moved the VDI and SSV with my finger and it seemed fine. However i dont see how that would all of a sudden be an issue when it wasnt earlier. Thottle body is spotless.

The problem mostly goes away after fuel trim reset and then returns after a couple drives...and then gets progressively worse. Throttle response is terrible, idling becomes terrible, and it smells rich and then sometimes foul. It varies. After reading around, the only thing i can think of is the front and rear o2 sensors. The check engine light is on for lack of a CAT and the code it threw was downstream sensor (which should affect acceleration right). But im going to drive it around a little bit more and then get the codes pulled again.

This is sounding like a sensor issue right? Before i spend $200+...maybe you guys can point out something i missed.

Thanks.

RIWWP

iTrader: (2)

Moved to Troubleshooting. DIY is only for when you have a set of instructions to provide. The 5th time in the past day or so.


If you want to be sure, before you spend $250 on a front O2 sensor, spend $35 on a bluetooth OBD2 adapter and $5 on Torque for Android, or whatever for iphones. There are a number of things you can do to confirm. It could be a vacuum leak or a sensor failure, so it would be worth some testing.

CrazyJek

Crap I could have sworn this was in troubleshooting. Didn't realize I was browsing DIY when I made this. Thanks for the switch.

And I'll def pick up the Bluetooth thingy. But wouldn't a vacuum leak be an issue regardless of fuel trims? Or would that only be for the SSV and VDI actuators?

Posted From RX8Club.com Android App

RIWWP

iTrader: (2)

A vacuum leak by definition is when the engine is ingesting air that isn't going past the MAF. This means that the ECU isn't accounting for that air until the front O2 sensor sees it, showing a lean condition. The ECU will then keep building positive fuel trims trying to balance out the vacuum leak, but it will never really be able to do it, because there will always be unaccounted for air. Depending on the size and location of the vacuum leak, it could lead to run-away positive fuel trims, giving you similar symptoms.

CrazyJek

Ahhh that makes perfect sense. Im guessing that bluetooth obd2 adapter will let me know if there is a vacuum leak or not? Im looking on Amazon right now (got prime shipping). Any particular one that is great and reliable? BAFX, LYL, Vgate, etc... Im guessing you get what you pay for so the $25 is prolly better than the $10.

ANd thanks for your help. You have always been a great help to me on these forums over the years with my issues.

RIWWP

iTrader: (2)

Generally, yeah, you get what you pay for, though for this and basic code reading, any of them should work just fine. 5 years ago, I spent $150 on mine

A vacuum leak isn't specifically defined in the ECU, but you can see the results of it in the MAF and fuel trim data. You will also be able to check the mode 6 test data on the O2 sensor, see if it is sticking lean, etc...

CrazyJek

Gotcha. Yea i generally dont like to skimp on parts for this car. Amazing what 5 years can do huh?lol



Also... i checked this awesome diagram out https://www.rx8club.com/series-i-tec...iagram-214910/ and checked most of those hoses. All attached securely and seem fine (the ones i could eaily reach). But the one color coded in blue... i can easily blow and suck air into it from the air pump side. The other end is impossible to get to without pulling the UIM off. Is it supposed to do that? Im not too familiar with the vacuum hoses on this car. I have tomorrow off so im going to do some more inspecting. Maybe i can just pick up a bluetooth OBD2 from a local place so i dont have to wait. I hate when my car is running like crap.

EDIT: This part.

Karack

it's worth checking the ignition when the problem is occurring, most of these popping/gurgling issues in the mid range are due to weak ignition or fouled spark plugs. even though they may not be due, they have dealt with a seafoam and that is fairly rough on the ignition.

the downstream O2 sensor is also only really used to determine cat condition and OBDII emissions readiness test pass/fail conditions, replacing it won't affect your issue. if the upstream O2 sensor is switching from .00-.7v under varying conditions then it likely isn't the issue either.

checking codes is also worth a shot, a faulty crank position sensor could be causing erratic misfires(which usually aren't picked up by the ECU. i don't know why because i've run cars through obvious misfires and the ECU gives the thumbs up like everything is peachy, it has to be REALLY bad to pick them up).


i lean towards ignition because most of the time when i see the issue all other readings on the car check out fine. ignition is one thing that is very difficult to actually monitor.

RIWWP

iTrader: (2)

Keep in mind that a vacuum leak can be remarkably small. The only vacuum leak I ran into with my 8 was a tiny pinched gasket between the upper and lower intake manifolds, at the rear auxiliary runner against the firewall. Maybe a millimeter wide.

There are a number of ways to find a vacuum leak, but the only really good one is to have the intake system smoked at a shop. But that is still getting ahead of yourself. Wait to see what the OBD2 data is like. It might not be a vacuum leak and you might be right about the O2 sensor.

CrazyJek

I prolly should have made it clearer...i did the seafoam on the old plugs. Soon as it was done and it was run through and cleared out...car ran amazing. Then i changed the plugs and it was even better. They could be fouled though...that's possible with all this happening. And the ESP sensor has been reset multiple times. Im getting no misfires though.

Ok sounds good. Ill wait for the OBD2 stuff and then go from there. Thanks again.

Karack

then you can pick up the OBDII adapter and check the front O2 voltages to make sure it is switching and for any other codes that may have come up. and if you have a timing light, when it's running like *** simply clip the lead onto each wire and be sure all 4 are giving signs of spark. a vacuum leak is possible but i guess i'd have trouble imagining one would pop up out of the blue like this and come and go like the wind.

CrazyJek

Yea i just ordered one off Amazon right now. Ill run the car until tuesday when i get it and that should be enough time for it to start running like crap again. Then ill check the codes and tech info. The timing light idea is a good one. I dont have one but i may know some people who do. Ill ask around. Thank you.

nycgps

iTrader: (1)

you don't need to spend 250 bux on stock O2 sensor, there are cheaper ones that's exactly the same

gtown_htx

I've heard nothing but bad things about aftermarket o2 sensors, more specifically the upstream. Which do you reccommend?

RIWWP

iTrader: (2)

I generally have that impression too. Upstream is a 4 wire WIDEBAND sensor, downstream is a 4-wire NARROWBAND sensor. Most cheap sensors are narrowband. I haven't seen any really convincing success stories on replacing the factory wideband with an aftermarket one, and several that just introduce new problems. For such a critical sensor, I always recommend an OEM one. If replacing the narrowband downstream in the cat, anything should work fine. That one can't really screw anything up and narrowbands tend to be more consistent anyway.

gtown_htx

Agreed. And speaking of downstream, I'm currently not using one and haven't for a while (hole is plugged) due to being catless. Is there any reason why I should put it back in?

RIWWP

iTrader: (2)

Nope, not really. It does have some AFR refinement impact right around 14.7 when in cruise, trying to optimize more closely than the much more granular wideband can, so there can be some nearly imperceptible mileage improvements with it. Not enough to recover the cost of the sensor though, and rear O2 sensors tend to fail easily when you run catless. It's obviously pointless for the emissions side. I never got around to buying a plug for the sensor hole in the cat, so I just had a dead sensor plugged into the midpipe for years, a working sensor left plugged into the cat in the basement.

gtown_htx

Cool, that makes sense. Thanks for the info sir

CrazyJek

This is good to know...since i was wondering if a rear o2 sensor would be worth buying now that im catless. Ill just leave the current one in there.

I got my OBD2 adapter in the mail yesterday and im going to hook it up once i get out of work. But check this...

Im not exactly having the problem anymore... After i first made this post i went back under the hood to check for easily spotted vacuum leaks (disconnected hoses). Didnt find anything. SO i go to start the car and it doesnt start. I checked the battery terminal and the negative wire was very loose. Barely making a connection. So decided to reset fuel trims (4th time since these issues) since im already practically disconnected and then really tighten the link. Start the car and ive been driving this for 3 days now. I have no more gurggling between 4 and 5K RPMS and i dont hit a wall anymore at 6K. It struggled at 8K and made some popping noises but that sort of stopped too. I guess that makes sense since i wasnt able to hit that rev range for weeks.

My question is....is a loose battery connection an issue for fuel trims? Sometimes it would smell really rich and other times it would smell foul and burn my eyes. Like it was running rich and then lean. Like the readings were all over the place.

Im gonna see what the OBD2 puts out but im stumped. I truly dont understand lol.

RIWWP

iTrader: (2)

A loose connection at the battery terminal is the culprit for so many odd electrical problems, and in your case it could easily have been screwing with the ignition and/or fuel delivery and/or sensor profiles.

I would disconnect that connection, clean the clamps and terminal, and instead of cranking on the tightening bolt, ensure a firm seat before tightening. Corrosion on the terminal can eat away at the surfaces, making the current orientation hard to maintain a good connection, especially if the tightening bolt on the clamp is just really clamping on itself, rather than the battery post, or just a ridge on the battery post that will corrode through quickly again.

CrazyJek

Go figure... Well either way at least i got a cool new gadget out of this that will be useful. Im under the impression these things can clear a check engine light? Curious if that will work on an inspection. And ill keep driving some more and keep an eye on things.

What ill do is when i get out of work in a few hours, on my way home ill stop at Advanced Auto Parts and pick up some new connections. The ones i have are in bad shape. And ill clean up the terminals themselves. It's been a harsh winter.

Thanks RIWPP. You always come through.

RIWWP

iTrader: (2)

The device is just a communication tool. Think of it like the plug on the end of a shop's OBD2 scanner. The cable is now wireless or bluetooth (Whichever one you got), and the scanner itself is now your phone. So whatever OBD2 app you go with have various features available.

If you have an Android based platform, I highly recommend buying the paid version of Torque. The free version is entirely capable, but the $5 for the paid version is COMPLETELY worth it. And think of it as if you just bought an OBD2 adapter that is $5 higher than what you did.

Torque can clear codes, see system readiness status, return any of the ECU data PIDs live (along with any data points available from your phone or tablet like GPS, baro, angle, gs, etc...) via any one of a number of different gauge types (graph, sweep gauge, fill gauge, dial, numeric, etc...), graph data points against each other, run mode 6 tests, add plugins, etc...

CrazyJek

Yea i got a bluetooth one and i already bought the $5 Torque version. I was reading about it and it seems like an awesome app to have...should have done this a while back.

RIWWP

iTrader: (2)

I personally think everyone that owns a car could have one.

5p3nc3

Although u might have found the cause of your problem, I would still check your AEM intake, its possible to over tighten the worm clamps and crush the air straighners thus having unstable air over the MAF. Also check that all the piece's are sealed together, had this problem recently when I was in a rush putting my intake back together. Was experiencing hesitation around the 3-5k rpm mark and the P0172 system too rich code. Just double checked all the fittings and took the time to check if the sealed and didnt have any more problems