help strange problem!
help strange problem! my car runs perfect over 3500 rpm, but under that rpm it bogs and misfires like crazy, anyone know what this could be? i changed my 02 sensors and it worked for about 2 minutes then it went back to doin the same thing again. im throwin a mass air code, but ive been throwin that code for over a year and it never mattered before
no he hasnt had it tuned..He went from a custom smaller cam to an MS3...i helped him change the front 2 o2 sensors..thats it...The thing is that he has been throwing that mass air code even when he had the custom cam. With the custom cam he had 0 problems. Just a hp tuners street tune. Not a real dyno/tune. It feels like its o2 sensors..At first the car is fine. Then at low rpms it will just randomly bog and sputter as if an o2 is out. Sometimes it fixes itself and then sputters again.
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Dont mean to be rude. But a MAF sensor matters at all points in the RPM ranges. Not just above 4000 rpms. The information is completely incorrect. To start try cleaning the MAF sensor. If that doesnt work. Replace it. Your problem should go away.
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Verdad Gallardo the screen in the mass air is out..Nothing really to clean..And new plugs as well as new o2's..wtf can it be!!
he said that code hasnt mattered before..but is it possible that the degree to which that sensor has been working has been diminishing and is now possibly not working at all? if that was the case, then the comp would throw the code at the first start of it not functioning properly but as the whole thing deteriorates to not working at all the car wouldn't run properly.
not sure, i dont know much about tuning. the fact it has no tune or a stock tune prolly doesn't help matters at all. if its bogging and backfiring all the time why would it ever see 3500 anyways
not sure, i dont know much about tuning. the fact it has no tune or a stock tune prolly doesn't help matters at all. if its bogging and backfiring all the time why would it ever see 3500 anyways
Here is an easy test, disconnect the MAF and see how it runs. You will get a check engine light but ignore it. If it runs fine (using just the VE table) then its a MAF issue. If it still behaves the same way its not the MAF.
Don't know the specs on the custom cam but any significant change in duration, lsa or lift will require a retune of the VE and MAF tables.
Does the car behave differently in open loop (when its cold and not using the O2's)
Does the issue arise only when the car is warm?
What are the O2's reading when warm?
I had a problem w/ my fuel pump when stuff like this was happening. Replaced it and its been good (knock on wood)
Might want to post/search the exact code. (unless I missed it)
Is this at WOT over/under 3500 or 1/2 acelerating decelerating.
Might want to post/search the exact code. (unless I missed it)
Is this at WOT over/under 3500 or 1/2 acelerating decelerating.
i have figured out that the maf is not the problem because i swapped it out with a friends and it still misfired and sputtered like a bitch. everytime i swap mafs i get a few minutes of normal driving and then it goes to **** again, it does this when the car is cold or warmed up it doesnt make a difference. so my maf is fine but its still throwin the the code for it, thats the only code im getting. im thinking maybe its a problem with the wiring to the maf? maybe a bad ground or something like that?
could be a bad map sensor. The PCM uses the map sensor to check the MAF sensors performance. I have seen a couple of cars w/ bad map sensors list a trouble code for the maf. If you have access to a scanner, make sure the map is working properly. Also if the map sensor is bad the car will run poorly with the MAF unplugged. Normally as stated above the car will run fine without the airflow sensor, unless the map is bad.
If you read the troubleshooting procedures for MAF DTCs you'll find it doesn't stop at just swapping the MAF. You have to know if your reference voltage and sense lines are OK. You need to backprobe the MAF and examine the MAF connector and wiring harness associated with the MAF or use a scan tool to monitor its' activity. It doesn't help to just start throwing parts at a problem like this. The parts dealer is good with it, but does it solve the problem? Not in this case nor in most. Why not first look at the O2 output on a scan tool like EASE or AutoTap. That way you would have no doubt in your mind if the sensor is switching at the correct frequency. You could even display Bank1 and Bank 2 side by side and see them switch simultaneously to detect a problem with one of the O2s(they don't go bad in matching pairs). The MAF can be cleaned. If the air filter isn't cleaned regularly the MAF and IAT sense lines can get covered with crud over time. Don't touch them during the cleaning process and treat the MAF with kid gloves. Those thin wires can't take a lot of abuse. I'd monitor the MAF after cleaning with a scan tool, but you can backprobe it using a DVOM if you don't have a good scan tool(not handheld).
