evo won't stay started, until warmed
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From: Alexandria, VA
Originally Posted by RichJ
Nastea, did your car just start doing this all of the sudden, or did you just add a mod? Does everything sound okay in the motor mechanically? One Evo friend of mine just had a lobe go bad on an HKS cam, so you can't completely rule out mechanical failure. The Walbro pumps also have been known to fail. Certainly what you are talking about could happen with a faltering fuel pump. The best way to track this down would probably be to start with an OBD II scan tool and see what's going on. I'd drive it easy until this is sorted out since a fueling issue could cause detonation in normal driving. Good luck.
because once the car comes out of open loop it runs completely fine, 100% fully functional..
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Originally Posted by nastea
there is not detonation, my AFR while driving is 11.5-11.6, just what i want it at, the only thing i did, was remove my SAFR, which was adding fuel at idle (8%) i just need to reprogram it and hook it back up..
because once the car comes out of open loop it runs completely fine, 100% fully functional..
because once the car comes out of open loop it runs completely fine, 100% fully functional..
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From: Alexandria, VA
no it was tuned without it... and the ecu was reset... so its just hte lack of vaccuum, i used the safr, to maintain good idle. before, but i took it off, but it seemed to run ok...until the last week, but like i said it runs fine once that bitch is warm
If you read what I wrote, I did say richer, not leaner.. HOWEVER, due to the fact that MAF pipes, and other intake mods can affect the MAF reading, it will directly effect the AFR in open loop since it will not generally compensate in open loop other than adjusting the Idle Air Bypass (Idle speed).. If the MAF reading at idle is too low, it will run lean, if its too high, it will run rich.. Generally though if you allow alot of unmetered air through, the car will end up lean, and that is what happens when you alter the characteristics of the MAF sensor.. Its pretty prevelant in closed loop operation also since the LTFT and STFT (Long term and short term fuel trims) need to learn about the new characteristics, and sometimes it gets confused because its outside of its "Area of comfort" and that is what the short term trims are used for, therefore Abhorrant MAF readings can cause stalling, simply it just cannot respond to a sudden lean condition fast enough to "catch" it before it stalls..
Ok.. so what I wrote in two portions seems to contridict itself.. However I'm talking about both MAF readings, and Unmetered Air, which are two different issues.. Unmetered air is when the ratio of air passing through the sensor in the unmetered portion is greater than the sample in the metered portion.. this results in a lean condition.. This is usually caused by turbulence in the MAF sensor, usually aftermarket open element filters are the culprit.. The other anomoly is "stalling" of the Mass air sensors airflow.. That can result in low or erratic readings in the metered portion of the MAF Sensor, that usually a result of a larger diameter MAF pipe.. Why? because the same air volume into the turbo with a larger pipe, lowers the velocity of air through the sensor.. Karmann sensors are sensitive to this and when it drops below the speed required to generate its vortex characteristics ("Karmann Street Principal"), you get erratic idle, and possible stalling.. (This is why when you get on it, and brake,clutch and stop, it can stall) a VTA Blowoff valve demonstrates similar characteristics, but for a different reason (basically the opposite) This leads to an interesting observation that the Blowoff from the Diverter valve with a 1G is causing the airflow to stall in the sensor.. But I'm still testing this theory and a possible (and unexpected) solution, I will have a suggestion for it when I can demonstrate it consistently.
Your lucky that your AFR's went right to 14.7:1 in cold start open loop.. Generally they will be really rich (if you have bigger injectors) or lean if you have intake mods and no fuel compensation. **HOWEVER** you may find that in really cold weather, you may need to make your mixture richer or it won't idle adequately until the engine warms up. (Long term fuel trims do have some effect on open loop idle however, which is a little contradictory but there's a reason, and thats climate related)
IF the engine is completely cold, and the coolant is less than a particular temp, the engine will run open loop for as long as 5 minutes (about how long it takes for the engine to get up to more or less operating temp)
IF the engine is already warmed up, then it basically runs in open loop for 15-30 seconds when first started. (even if its sitting for an hour or two)
But since you have the S-AFC tuned by buschur, and you have the 660's and 255 pump.. Its no surprise your readings go right to 14.7, thats what the package is designed and calibrated to do.
BTW, the stalling is directly related to the altered readings in the MAF sensor from their MAF pip.. Almost any MAF pipe that is larger in diameter than stock displays this problem, but its pretty minor and doesn't happen very often. What you describe about the AFRs after driving a bit and coming to a stop is also what I experience with similar mods.. They are also likely MAF related.. But they do stabilize and it would likely not cause stalling.. My experience is if you load the engine and immediately hit the brake and clutch, that is when the car could stall for me. (Same as you described)
The "Fuel cells" your referring to are closed loop operation, they do not use mapped cells, and in closed loop, the car will always attempt to maintain 14.7:1 fuel ratio, Closed loop operation is actually the only time the O2 sensors are really used.. This is the way the ECU operates and will switch to "Fuel enrichment" mode at throttle positions 30% or more (where federal regulations don't govern emissions in open loop fueling)
IDLE issues when the car is warm and operating in closed loop are generally a result of short term, and long term fuel trims.. So are drivability at part throttle (30% TPS or less) and of course, idle and part throttle compensation for load Alternator and A/C use since when you go into open loop, I am fairly sure the A/C system disengages the Compressor anyway.
When cruising, the S-AFC has no effect on fuel enrichment.. the ECU "Learns" it through long term and short term fuel trims and will compensate for the bigger injectors.. those LO-TH settings are used for open loop operation where the load cells in the ECU don't get AFR Feedback and cannot adjust on their own. So you need to manually "Trick" the IDLE mixture and other open loop features..
If the ECU were designed to use closed loop fuel control **ALL** The time, you could make injector modifications and any other modification you want, and it would make fuel and timing adjustments based on feedback from the knock sensor and O2 sensor, and you'd never need any tuning device to maintain its desired fuel ratio since it would learn on its own.. But the truth of the matter is that it only does that when the engine is warm and at idle through 30% throttle.
BTW, the increased fuel volume/pressure has been documented to increase fueling slightly.. Do a search on that, Its out there..
Anyway, you are otherwise describing basically the same things I discovered happening with my car with the Buschur pipes.. The only thing I can say at the moment is I have the stock injectors and pump currently installed, therefore I can tell you with 100% certainty that its the upgraded pipes influencing the MAF reading (which I have documented and logged)
Now.. Back to Nastea's problem.. I'll make some suggestions in the next post when I read the rest of the responses.
Ok.. so what I wrote in two portions seems to contridict itself.. However I'm talking about both MAF readings, and Unmetered Air, which are two different issues.. Unmetered air is when the ratio of air passing through the sensor in the unmetered portion is greater than the sample in the metered portion.. this results in a lean condition.. This is usually caused by turbulence in the MAF sensor, usually aftermarket open element filters are the culprit.. The other anomoly is "stalling" of the Mass air sensors airflow.. That can result in low or erratic readings in the metered portion of the MAF Sensor, that usually a result of a larger diameter MAF pipe.. Why? because the same air volume into the turbo with a larger pipe, lowers the velocity of air through the sensor.. Karmann sensors are sensitive to this and when it drops below the speed required to generate its vortex characteristics ("Karmann Street Principal"), you get erratic idle, and possible stalling.. (This is why when you get on it, and brake,clutch and stop, it can stall) a VTA Blowoff valve demonstrates similar characteristics, but for a different reason (basically the opposite) This leads to an interesting observation that the Blowoff from the Diverter valve with a 1G is causing the airflow to stall in the sensor.. But I'm still testing this theory and a possible (and unexpected) solution, I will have a suggestion for it when I can demonstrate it consistently.
Your lucky that your AFR's went right to 14.7:1 in cold start open loop.. Generally they will be really rich (if you have bigger injectors) or lean if you have intake mods and no fuel compensation. **HOWEVER** you may find that in really cold weather, you may need to make your mixture richer or it won't idle adequately until the engine warms up. (Long term fuel trims do have some effect on open loop idle however, which is a little contradictory but there's a reason, and thats climate related)
IF the engine is completely cold, and the coolant is less than a particular temp, the engine will run open loop for as long as 5 minutes (about how long it takes for the engine to get up to more or less operating temp)
IF the engine is already warmed up, then it basically runs in open loop for 15-30 seconds when first started. (even if its sitting for an hour or two)
But since you have the S-AFC tuned by buschur, and you have the 660's and 255 pump.. Its no surprise your readings go right to 14.7, thats what the package is designed and calibrated to do.
BTW, the stalling is directly related to the altered readings in the MAF sensor from their MAF pip.. Almost any MAF pipe that is larger in diameter than stock displays this problem, but its pretty minor and doesn't happen very often. What you describe about the AFRs after driving a bit and coming to a stop is also what I experience with similar mods.. They are also likely MAF related.. But they do stabilize and it would likely not cause stalling.. My experience is if you load the engine and immediately hit the brake and clutch, that is when the car could stall for me. (Same as you described)
The "Fuel cells" your referring to are closed loop operation, they do not use mapped cells, and in closed loop, the car will always attempt to maintain 14.7:1 fuel ratio, Closed loop operation is actually the only time the O2 sensors are really used.. This is the way the ECU operates and will switch to "Fuel enrichment" mode at throttle positions 30% or more (where federal regulations don't govern emissions in open loop fueling)
IDLE issues when the car is warm and operating in closed loop are generally a result of short term, and long term fuel trims.. So are drivability at part throttle (30% TPS or less) and of course, idle and part throttle compensation for load Alternator and A/C use since when you go into open loop, I am fairly sure the A/C system disengages the Compressor anyway.
When cruising, the S-AFC has no effect on fuel enrichment.. the ECU "Learns" it through long term and short term fuel trims and will compensate for the bigger injectors.. those LO-TH settings are used for open loop operation where the load cells in the ECU don't get AFR Feedback and cannot adjust on their own. So you need to manually "Trick" the IDLE mixture and other open loop features..
If the ECU were designed to use closed loop fuel control **ALL** The time, you could make injector modifications and any other modification you want, and it would make fuel and timing adjustments based on feedback from the knock sensor and O2 sensor, and you'd never need any tuning device to maintain its desired fuel ratio since it would learn on its own.. But the truth of the matter is that it only does that when the engine is warm and at idle through 30% throttle.
BTW, the increased fuel volume/pressure has been documented to increase fueling slightly.. Do a search on that, Its out there..
Anyway, you are otherwise describing basically the same things I discovered happening with my car with the Buschur pipes.. The only thing I can say at the moment is I have the stock injectors and pump currently installed, therefore I can tell you with 100% certainty that its the upgraded pipes influencing the MAF reading (which I have documented and logged)
Now.. Back to Nastea's problem.. I'll make some suggestions in the next post when I read the rest of the responses.
Originally Posted by RichJ
The point of a choke was to make the car run richer, not leaner though. It would be very odd for Mitsu to set our cars up to run leaner than usual from the factory at startup. I just tested my car with my portable wideband for the first time yesterday. It has an SAFC (tuned by Buschur's shop), 660s and a 255 lph pump. With a cold start, idle AFR went right to 14.7:1 immediately. I do have some minor stalling issues, but they aren't too bad (only when I jump off the throttle and push in the clutch after abruptly moving the car forward). I did notice that when coming to a stop after sustained mid-RPM operation, when I sometimes get some idle stumbling, that the idle AFRs are lean at around the high 15s or low 16s. As the car sits in place at a stop light the idle AFRs return to about 14.7 and the idle smooths out, which I assume is the short term correction factors adjusting (need to verify that with a scan tool), so I must have the SAFC tuned too rich for cruising (where presumably the correction factors are pulling fuel to correct and causing the idle problem when I stop). I'm suprised that the factory computer has cruise RPMs and idle RPMs mapped into the same fuel trim cell though.
Have you verfied this with a wideband? I can't see how the bigger pump would affect fueling in offboost conditions. If it does then the fuel pressure regulator isn't doing its job.
Nastea, did your car just start doing this all of the sudden, or did you just add a mod? Does everything sound okay in the motor mechanically? One Evo friend of mine just had a lobe go bad on an HKS cam, so you can't completely rule out mechanical failure. The Walbro pumps also have been known to fail. Certainly what you are talking about could happen with a faltering fuel pump. The best way to track this down would probably be to start with an OBD II scan tool and see what's going on. I'd drive it easy until this is sorted out since a fueling issue could cause detonation in normal driving. Good luck.
Have you verfied this with a wideband? I can't see how the bigger pump would affect fueling in offboost conditions. If it does then the fuel pressure regulator isn't doing its job.
Nastea, did your car just start doing this all of the sudden, or did you just add a mod? Does everything sound okay in the motor mechanically? One Evo friend of mine just had a lobe go bad on an HKS cam, so you can't completely rule out mechanical failure. The Walbro pumps also have been known to fail. Certainly what you are talking about could happen with a faltering fuel pump. The best way to track this down would probably be to start with an OBD II scan tool and see what's going on. I'd drive it easy until this is sorted out since a fueling issue could cause detonation in normal driving. Good luck.
Originally Posted by nastea
naw, i took it out.. cuz it was running fine....for a day or so... then it got kindof rainy around here like it always does 
If your idle is real rich in open loop (when the car is cold) remove a little fuel using the S-AFC at 800-1500 rpm, if its lean, you'll have to add fuel.. It should be a little richer than the closed loop ratio (14.7:1) since when the car is cold, you want to "choke it" a bit.. so 13.9 or so is what you should target.. This is obviously only an idle recommendation in open loop..
with Piggyback fuel systems, you can figure out approx how much fuel to remove to scale for your injectors.. Figure out the % larger the injectors are, then remove basically that amount (less 1% from my experience.. so if its 10% larger, you can remove about 9%-10%, 680's would be around 20% larger, etc..) This is scaling for open loop to get you around where it would be *STOCK*.. then you need to tune for your modifications or idle characteristics due to cams, pipe upgrades.. and in open loop WOT which are the same things, plus boost and timing considerations.
So, if you removed your S-AFC, but the weather conditions have been fairly mild with low humidity, you may have found the car ran fine.. then the air density changed due to weather, humidity, etc.. and your idle got poorer.. Thats when you need to add a bit of fuel (as Rich described) and that is the need for the S-AFC. Remember, for part throttle highway driving, and idle after the engine is warmed up.. the S-AFC's settings do not have any influence on the ECU.. even if you set it up to alter mixture at TPS below 30%, the ECU would just tune it out..
Oh, also if you have bigger injectors, so at idle you could actually be dumping too much fuel without the S-AFC in open loop.. Idle would also suffer..
Ok.. I lost my train of thought.. If you want more insight, just PM me and I'll try to get you through it point by point..
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Joined: Oct 2003
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From: Edmonds, Wa
Regarding your theory on Safc tuning
MalibuJack,
You are correct with your theory for those of us using bigger intercoolers and intercooler piping. I confirmed your theory the other day after I had a local shop here in Seattle read your post. First let me share my mods with you so you can duplicate what wev'e done. I have a 3 inch turbo back with hi-flow cats, MBC, Aem intake pipe, upper and lower intercooler piping with a FMIC. I have the boost set to around 21-22 psi through an SAFC2. I first believed like most of you that it is impossible to use a vta blowoff valve without the stalling issues. Reading the post by Malibujack I decided to challenge his theory and this is what we found out. Day 1 car would most definatley die when pushing in the clutch or quick stops or reving over 2000 rpm. Does it sound familiar anyone? This was bothersome for the longest time. Day 2 I attempted to play around with the SAFC. The first challenge is to find out if the car is dying because of a lean or rich condition. What you need to do is warm the car up until it is operating temp, change your NE points at the lowest NE1 to around 800 rpm where the car is normally idling. Like Malibujack mentioned, in my case, I leaned it out around 30 pct (-30) at 800 rpm. Next NE2 point I leaned it 5 pct (-5) so it wasn't running so dog rich with the Aftermarket intake pipe. I made these changes on the high throttle map and low. My car responded the best to changes on the hi map. You will have to play around with it and find the sweet spot. By leaning it out at idle, I was no longer running rich so it would stall. I will also mention I did raise the idle manually to around 950 to compensate for the idle drop. The result is when warm the car is almost impossible to stall now. I am venting to the atmosphere on my HKS ssqv and only have problems when cold start. I will figure something out how to get around to the choke problem. Result: The car is alot more responsive and you can feel the power and responsiveness. The only drawback that I can see is because of these changes, the car when cold is a little lean while warming up. So it appears that we have an answer for the stalling problems running a vta set up and intercooling piping. You will need to have an SAFC or some sort of piggy ecu to compensate for the stalling problems. Props to Malibujack for coming up with this theory.
Any one feel free to chime in with any feedback.
Evilmania
You are correct with your theory for those of us using bigger intercoolers and intercooler piping. I confirmed your theory the other day after I had a local shop here in Seattle read your post. First let me share my mods with you so you can duplicate what wev'e done. I have a 3 inch turbo back with hi-flow cats, MBC, Aem intake pipe, upper and lower intercooler piping with a FMIC. I have the boost set to around 21-22 psi through an SAFC2. I first believed like most of you that it is impossible to use a vta blowoff valve without the stalling issues. Reading the post by Malibujack I decided to challenge his theory and this is what we found out. Day 1 car would most definatley die when pushing in the clutch or quick stops or reving over 2000 rpm. Does it sound familiar anyone? This was bothersome for the longest time. Day 2 I attempted to play around with the SAFC. The first challenge is to find out if the car is dying because of a lean or rich condition. What you need to do is warm the car up until it is operating temp, change your NE points at the lowest NE1 to around 800 rpm where the car is normally idling. Like Malibujack mentioned, in my case, I leaned it out around 30 pct (-30) at 800 rpm. Next NE2 point I leaned it 5 pct (-5) so it wasn't running so dog rich with the Aftermarket intake pipe. I made these changes on the high throttle map and low. My car responded the best to changes on the hi map. You will have to play around with it and find the sweet spot. By leaning it out at idle, I was no longer running rich so it would stall. I will also mention I did raise the idle manually to around 950 to compensate for the idle drop. The result is when warm the car is almost impossible to stall now. I am venting to the atmosphere on my HKS ssqv and only have problems when cold start. I will figure something out how to get around to the choke problem. Result: The car is alot more responsive and you can feel the power and responsiveness. The only drawback that I can see is because of these changes, the car when cold is a little lean while warming up. So it appears that we have an answer for the stalling problems running a vta set up and intercooling piping. You will need to have an SAFC or some sort of piggy ecu to compensate for the stalling problems. Props to Malibujack for coming up with this theory.
Any one feel free to chime in with any feedback.
Evilmania
I read your thread about the cold start issue with your cams. I have the same mods basically (264's) and a Dynoflash. When I start the car in the morning I have to give it blips of gas for about one minute and then it is OK. Did this damage your car and was it ever fixed?
Thanks,
John
Thanks,
John
Originally Posted by 2Fast2Stupid
I would look at and make sure the cold idle pin on the ecu is not loose, that is what was wrong with my evo. It would not idle but if you kept the car revved up after a min or 2 it would be fine.
It only started after XEDE was installed so I'm leaning towards and electrical problem that may have happend.
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