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So, as in my other thread, I'm still having the same problems with my rx8, 2009 with a new (probably rebuilt engine 8k miles ago under warranty, car has 70k now) anyhow now I've bought a bluetooth obd2 scanner and I'm noticing my LTFT qt idle is around 11.7-15ish and my maf flow is at 4.3 grams, at wot it only goes up to around 150, which I'm hearing is pretty low (should be 200 or more?) Here are some screenshots from torque, not sure about timing, or if it's even accurate but -5 at idle with 30-35 at wot
also when decelerating (foot off gas) a/f is over 20 and accelerating it goes down to 10-11 Right after startup After warming up Cruising
AFR doesn't really mean much here. The car is supposed to run pretty rich when you floor it and it will be lean as you let off the gas as you aren't injecting fuel.
Most OBD2 can only pick up the ignition timing of the trailing plug. -5 degrees BTDC at idle is within the specs.
AFR doesn't really mean much here. The car is supposed to run pretty rich when you floor it and it will be lean as you let off the gas as you aren't injecting fuel.
I have not I will be doing that tomorrow (fair amount of junk around it) that's the first thing I thought of,
the reason I was asking about a/f was because the commanded is around 13 ish and measured is 10-23 depending on what I do
In the cruise picture you're off the throttle, so commanded AFR is meaningless, the fuel injectors are completely off. Whenever you are off the throttle the injectors are off.
Low MAF and high LTFT sounds like pretty classic vacuum leak. Poke around. One common place is under the throttle body where the VFAD connects, or the other end of the VFAD line.
In the cruise picture you're off the throttle, so commanded AFR is meaningless, the fuel injectors are completely off. Whenever you are off the throttle the injectors are off.
Low MAF and high LTFT sounds like pretty classic vacuum leak. Poke around. One common place is under the throttle body where the VFAD connects, or the other end of the VFAD line.
Do you have an aftermarket intake?
everything is stock, not sure how I'd even test for a vacuum leak short of a smoke test but that's what my next plan was...
In the cruise picture you're off the throttle, so commanded AFR is meaningless, the fuel injectors are completely off. Whenever you are off the throttle the injectors are off.
Low MAF and high LTFT sounds like pretty classic vacuum leak. Poke around. One common place is under the throttle body where the VFAD connects, or the other end of the VFAD line.
Do you have an aftermarket intake?
I was gonna say vacuum leak, but since they are having trouble with high RPM air flow, I was thinking the MAF sensor itself first. Doesn't hurt to just check, though.
Originally Posted by micvite
I have not I will be doing that tomorrow (fair amount of junk around it) that's the first thing I thought of,
the reason I was asking about a/f was because the commanded is around 13 ish and measured is 10-23 depending on what I do
yeah no clue what the timing reading was
Again, AFR is meaningless outside of the steady state(cruising at a set speed and RPM). When you floor it, it goes into open loop and purely relies on the ECU map. AFR sensor reading will be ignored.
I was gonna say vacuum leak, but since they are having trouble with high RPM air flow, I was thinking the MAF sensor itself first. Doesn't hurt to just check, though.
Again, AFR is meaningless outside of the steady state(cruising at a set speed and RPM). When you floor it, it goes into open loop and purely relies on the ECU map. AFR sensor reading will be ignored.
would the maf explain the misfire at wot after 7500 rpm and bucking as opposed to smooth operation after 7500 rpm at low throttle? Is there an easy way to tell if the maf is just completely shot as opposed to just dirty? As in say after cleaning problem doesnt go away how do I tell if the maf is still good? This is what cruis contr at 45 looks like
It could, but that could also very easily be coils or cat. You want to be really sure those are in good shape, because if not, you will be shopping for a new engine.
A quick primer on how hot-wire MAFs work: There's a wire that has an electrical current passing through it and a temperature sensor. The current heats the wire up. As air passes over the wire, the wire is cooled and more current is required to heat it up. The more air passing over it, the more current is required to maintain a given temperature. The ECU monitors this and that's how it determines the amount of air is being drawn in.
Now, what happens if you have a coating of oil, grease or other schmoo on the MAF? It changes the thermal capacity and conductivity of the hot wire.
Similarly, if you have a craptacular intake (*cough*K&NTyphoon*cough*), the air across the MAF isn't smooth and the flow pattern may change significantly at different flow rates. This causes wacky and unreliable measurements.
It's tough to directly troubleshoot the MAF without having a Mazda VDS. Does your OBD-II app allow you to access MAF voltage (or allow you to specify custom PIDs? See here: https://www.rx8club.com/series-i-tec...e-pids-250627/). For S1 cars, the MAF voltage at idle should be 1.16 - 1.23 V and at 2500 RPM it should be 1.49 - 1.64 V. I don't know if it's the same for S2 cars but I doubt they changed the MAF. Log MAFv and RPM as you slowly increase RPM in neutral. Then plot MAFv as a function of RPM in Excel and see if you're in the right range. The slower you increase RPM, the higher resolution your data will be.
I'm going to add to the chorus of likely vacuum leak. A bad or dirty MAF could possibly also cause this but don't just throw parts at the problem. Cleaning the MAF is cheap; about $10 for a can of MAF cleaner at any auto parts store. Start there.
Simply spray the inside of the MAF tube (do not spray the little wires inside directly) and let it air dry. Do not blow on it to help it dry faster. MAF cleaner is pretty volatile and it should only take a minute in open air to dry completely.
If that doesn't solve your problem, search for vacuum leaks. If you have access to a smoke machine, use that. Pull the air filter, wrap it in a grocery bag, re-install it. Then pull the brake booster hose from the UIM and blow smoke into the UIM through that port. There's also another method of using intake/throttle body cleaner to find the leak but I've never tried it (I have a buddy with a smoke machine).
You can build your own smoke machine fairly easily. They just superheat baby oil to turn it into smoke (note: baby oil is not like whale oil. Do not harpoon babies to get it). So, get a paint can, add baby oil, add a resistance wire, heat the wire to make smoke. Install a schrader valve and a barbed hose fitting on the paint can. Connect a tire inflator to the schrader valve and a vacuum hose to the barbed fitting. Cannibalize the pressure regulator from a gas grill and something to control the current going into the wire. https://www.ericthecarguy.com/kunena...ke-evap-tester
If you don't find it that way, it's possible for one or more of the vacuum solenoids to leak but still work well enough to not throw a code. Pull the solenoids from the back of the UIM (pay attention to which electrical connectors correspond to which vacuum lines). Connect a Mityvac hand pump (or similar) to port "A" from the diagrams on this page and pull a vacuum. It should hold steady for a while.
Last edited by NotAPreppie; 11-02-2018 at 07:43 AM.
It could, but that could also very easily be coils or cat. You want to be really sure those are in good shape, because if not, you will be shopping for a new engine.
I checked coils (mostly visually) and they all looked brand new (like literally out of the box brand new), I'm guessing they were replaced with the engine or possibly right before it? I'm checking the cat out on monday probably (need a lift or some Jack's and stands which I don't have and a friend might let me use theirs).
Originally Posted by NotAPreppie
A quick primer on how hot-wire MAFs work: There's a wire that has an electrical current passing through it and a temperature sensor. The current heats the wire up. As air passes over the wire, the wire is cooled and more current is required to heat it up. The more air passing over it, the more current is required to maintain a given temperature. The ECU monitors this and that's how it determines the amount of air is being drawn in.
Now, what happens if you have a coating of oil, grease or other schmoo on the MAF? It changes the thermal capacity and conductivity of the hot wire.
Similarly, if you have a craptacular intake (*cough*K&NTyphoon*cough*), the air across the MAF isn't smooth and the flow pattern may change significantly at different flow rates. This causes wacky and unreliable measurements.
It's tough to directly troubleshoot the MAF without having a Mazda VDS. Does your OBD-II app allow you to access MAF voltage (or allow you to specify custom PIDs? See here: https://www.rx8club.com/series-i-tec...e-pids-250627/). For S1 cars, the MAF voltage at idle should be 1.16 - 1.23 V and at 2500 RPM it should be 1.49 - 1.64 V. I don't know if it's the same for S2 cars but I doubt they changed the MAF. Log MAFv and RPM as you slowly increase RPM in neutral. Then plot MAFv as a function of RPM in Excel and see if you're in the right range. The slower you increase RPM, the higher resolution your data will be.
I'm going to add to the chorus of likely vacuum leak. A bad or dirty MAF could possibly also cause this but don't just throw parts at the problem. Cleaning the MAF is cheap; about $10 for a can of MAF cleaner at any auto parts store. Start there.
Simply spray the inside of the MAF tube (do not spray the little wires inside directly) and let it air dry. Do not blow on it to help it dry faster. MAF cleaner is pretty volatile and it should only take a minute in open air to dry completely.
If that doesn't solve your problem, search for vacuum leaks. If you have access to a smoke machine, use that. Pull the air filter, wrap it in a grocery bag, re-install it. Then pull the brake booster hose from the UIM and blow smoke into the UIM through that port. There's also another method of using intake/throttle body cleaner to find the leak but I've never tried it (I have a buddy with a smoke machine).
You can build your own smoke machine fairly easily. They just superheat baby oil to turn it into smoke (note: baby oil is not like whale oil. Do not harpoon babies to get it). So, get a paint can, add baby oil, add a resistance wire, heat the wire to make smoke. Install a schrader valve and a barbed hose fitting on the paint can. Connect a tire inflator to the schrader valve and a vacuum hose to the barbed fitting. Cannibalize the pressure regulator from a gas grill and something to control the current going into the wire. https://www.ericthecarguy.com/kunena...ke-evap-tester
If you don't find it that way, it's possible for one or more of the vacuum solenoids to leak but still work well enough to not throw a code. Pull the solenoids from the back of the UIM (pay attention to which electrical connectors correspond to which vacuum lines). Connect a Mityvac hand pump (or similar) to port "A" from the diagrams on this page and pull a vacuum. It should hold steady for a while.
so I pulled the maf, looks brand new haha, no oil dirt or anything, still hosed it down with a whole bottle of cleaner just to be sure (had some dirt on the outside of the maf, the part you see when you look at it in the engine bay) that did absolutely nothing, well my idle maf reading went up around .2 and I managed to get it to 170 at wot so I guess it did help a bit, and the Ltft came down to around 7-9%.
the maf voltage at idle is around 1.25-1.31 and at 2500 rpm it was around 1.5 (the rpms surge when I try to keep it at 2500 or 1500 or 1250 (will go down then back up to the rpm I was holding the car at every few seconds)
now... my brake booster line (i think it's the brake booster? The line that goes into the round plastic cover on the drivers side of the engine bay that's mounted vertically behind a tank with brownish liquid) has a lot(and I mean a lot!!!) Of yellow goop around it (silicon glue maybe?) And I'm pretty sure that's a vacuum line, do you think that might be the problem and I need a new intake now?
heres the fun part, after trying to redline it some more way later in the day (2 engine cycles after cleaning the maf) I now got a p0111 IAT performance code (that's a maf code right?) Do you think I should invest in a new maf and see if that fixes everything after I check out the cat? I'm going to see if the code comes back and I'll provide pictures of the ghetto rigged vacuum line when it's not raining anymore.
Yellow goop sounds like somebody tried to fix something. Review all your vac lines carefully and look for cracks or open connections. This is free. If that gets you nothing, then think about buying parts. Buying a new MAF is a good way to find out the MAF was not the problem.
As for the IAT code, clear it and see if it comes back. That's a bit of an odd one.
Yellow goop sounds like somebody tried to fix something. Review all your vac lines carefully and look for cracks or open connections. This is free. If that gets you nothing, then think about buying parts. Buying a new MAF is a good way to find out the MAF was not the problem.
As for the IAT code, clear it and see if it comes back. That's a bit of an odd one.
IAT never came back, I'm checking the cat tonight (will run car without it and see if the problem persists)
as far as checking vac lines, I've checked where they plug into the intake and those look fine (except goopy down below), but I can't seem to find where they end up though. Also, the coolant jar, is that supposed to have a little piece of tubing that goes nowhere?
now this might seem crazy and it probably is, but what are the chances mazda screwed up and put a 4 port in the car? Is there any way to tell aside from taking everything off and counting the intake ports on the housing? The reason this came to mind is all the problems always happen at 7500 rpm which is the "redline" for the 4 port or I should say where it loses power due to not enough air flow.
from the looks of this I need a new manifold... grrrr.
I don't think Mazda would have screwed up, 4-ports were no longer in production for North America in 2009. However, the previous owner could have cut some corners and used the wrong engine after his original one died. Although... he wouldn't have been able to wire it up properly without a lot of effort. So I'm pretty confident you still have your 6-port and either the cat is plugged or there's an airflow measurement issue.
The good news is you should be able to find a used UIM at a wrecker or from someone parting out a car pretty easily.
I don't think Mazda would have screwed up, 4-ports were no longer in production for North America in 2009. However, the previous owner could have cut some corners and used the wrong engine after his original one died. Although... he wouldn't have been able to wire it up properly without a lot of effort. So I'm pretty confident you still have your 6-port and either the cat is plugged or there's an airflow measurement issue.
The good news is you should be able to find a used UIM at a wrecker or from someone parting out a car pretty easily.
yeah... so new upper intake, might as well get a lower and all the valves and just replace everything at once I suppose....
it was a mazda warranty claim, all work done by mazda under the extended warranty last year before it expired. Just a thought lol.
btw, i went through like 2 qt or oil in around 500 miles or less to the point where the oil light came on and was flashing at beeping (car was really slanted not really that low) after an oil change done at the dealership... it looks like the oil filler neck is sort of wet (need one of those too I guess lol) and when I rev the car in neutral up high it smells like burnt oil/gas with a tinge of metal (not really sure how to explain it, but it seems to be from the exhaust so hopefully it's just the cat lol)
and this car makes so many noises that I'm not used to (like it sounds like water is trickling if you rev over 2-3k, when winding down from 4k rpm at around 3500 it sounds like an electrical whirring for a sec or 2 like a valve closing maybe? And the engine in general sounds like a giant turbine when engine braking)
If it's beeping and flashing that's not oil level, that's oil pressure. Bearing damage is next.
Check if your intake is full of oil. If it is, that explains the high rpm problems: you're barfing oil into the intake. Usually that's caused by excess blowby, meaning serious engine damage. Get a compression test. I'd pay a visit to the dealer who did the work, if you say it was just done last year.
And there is still the matter of the vacuum leak... did you check for open ports under the throttle body?
If it's beeping and flashing that's not oil level, that's oil pressure. Bearing damage is next.
Check if your intake is full of oil. If it is, that explains the high rpm problems: you're barfing oil into the intake. Usually that's caused by excess blowby, meaning serious engine damage. Get a compression test. I'd pay a visit to the dealer who did the work, if you say it was just done last year.
And there is still the matter of the vacuum leak... did you check for open ports under the throttle body?
So it was flashing as soon as I turned car on, it beeped once so not sure if it was flashing and beeping I immediately shut the car off, after restarting the car it never came on (I started driving it right away and I was 2qt short) but like I said I was parked at a fairly steep angle. So it might not have been pulling oil at all (hence loss of pressure)
intake (around maf and and throttle body) clean, no oil.
open ports? I'm not sure exactly what you mean but i'll look.
just undid cat, no change after taking it off. Didnt manage to see inside but left it hanging. Same problem.
The oil consumption is a bit weird. Are your spark plugs oily? It's going somewhere...
Open ports: open vacuum nipples
did not check plugs yet, will be replacing whole ignition next week, seems like after filling it yesterday I'm still at full after driving it around for 200 miles or so (do you think dealership didn't fill it all the way??? Lol)
no open vacuum nipples as far as I can tell except for goopy over there which well... I'll ne replacing that too... I checked my logs just now from torque (it seems the room never registered over 8500 rpm, even though I have been at over 9k before, torque error or do you think it could be the ECU not registering rpms right?)
If I found a blob like that and had issues with high LTFT and low MAF, I'd just smoke the intake system for leaks. If there's one sketchy repair there could be many.
The tach is about 500 rpm ahead of actual rpm at redline. So 9000 is actually 8500. That's why the difference.
that makes so much more sense now!
I was looking at the logs from the rings where it misses and nothing seems to spike or anything, seems very progressive all the way up...
Originally Posted by NotAPreppie
If I found a blob like that and had issues with high LTFT and low MAF, I'd just smoke the intake system for leaks. If there's one sketchy repair there could be many.
yeah I plan to do that as soon as I have the free time.
The tach is about 500 rpm ahead of actual rpm at redline. So 9000 is actually 8500. That's why the difference.
Originally Posted by NotAPreppie
If I found a blob like that and had issues with high LTFT and low MAF, I'd just smoke the intake system for leaks. If there's one sketchy repair there could be many.
so, I have not had time to diagnose the issue properly, however i did break off 2 studs on the exhaust flange in front of the cat (between the 2 sensors), having those tapped out and refitted has somehow eliminated the problem almost altogether, i can now freely(99% of the time) rev up to 9k rpm, i feel the valves opening at around 6500-7k rpm (you feel the extra power come on strong, "V-TECH KICKED IN YO!" lol). sometimes at most i feel a slight hesitation, where it feels like fuel cuts for a split second i guess right around 7500-8k rpm and then it goes strong from 8-9 again, so maybe the cat was the problem even though it looked fine and the banging just loosened up some stuff? no more flashing cel, no more p2004-2005 which i heard was the APV valve sticking open, so i guess I'm good for now and just need to replace the cat?
P.S. I called mazda and told them about what happened and the fact that the engine was new, they told me to take it to the dealership for diagnostic, and if it turns out the engine was the problem they would replace it for me for the cost of an "insurance deductible" which ranges from 100-250 for claims.
That's... unusual, but glad it's better. It should be smooth all the way to redline, there isn't really a "vtak just kicked in" point or dip anywhere.
I guess Italian tune ups do work eh? But yeah I'm guessing the cat is the culprit since that's the only thing that was tampered with. I guess at 6-7k you get pushed back into the seat a bit more like a super small shot of NOS is the best way I can explain it. Or maybe like a small turbo that comes on at 6-7k rpm
11-01-2018, 07:18 PM
