Andrew 825SM

When my car warms up, it starts getting a horrible idle due to excessive fuel drowning the engine. I believe the excessive fuel causes the misfiring. When I rev the engine up, I can hear it misfiring sporadically. I checked my plugs and they are fouled. I am thinking it might be a malfunctioning Engine Coolant Temperature Sensor; the ecu might be thinking the car is still cold so it runs the car very rich. But I am not throwing any codes for a failure in that sensor. I am getting horrible gas mileage. Anyone seem to know what the problem is?

vtec.dc2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Andrew 825SM &raquo;</TD></TR><TR><TD CLASS="quote">When my car warms up, it starts getting a horrible idle due to excessive fuel drowning the engine. I believe the excessive fuel causes the misfiring. When I rev the engine up, I can hear it misfiring sporadically. I checked my plugs and they are fouled. I am thinking it might be a malfunctioning Engine Coolant Temperature Sensor; the ecu might be thinking the car is still cold so it runs the car very rich. But I am not throwing any codes for a failure in that sensor. I am getting horrible gas mileage. Anyone seem to know what the problem is? </TD></TR></TABLE>

are you running stock ecu? what fuel mods do you have? is this obd1/ibd2.. give more details.. says turbo gsr in your sig, is that the car you're talking about?

Andrew 825SM

It's a stock ecu and it is a GSR with a Greddy turbo kit on it. My fuel setup consists of a vafc, 450cc injectors, 4:1 fmu, inline pump and intank pump. And don't say I am running too rich with those mods cause I tuned it at the dyno last week and had a 14.5 A/F at idle and partial throttle. It only started running super rich about 2 days ago. I lost nearly a half tank of gas on a 40 mile trip and also at idle it puffs out black smoke.

I have already tried taking out the inline pump, cleaning my missing link, checking injectors, seeing if the fmu disk was stuck, cap & rotor, cleaned iac valve, changed spark plugs, and checked compression (which is fine). Nothing really helped. I am narrowing it down to a bad ECT sensor or maybe a bad primary o2 sensor, but I am not throwing any codes. Could a sensor be bad and not throw any codes? Again, any suggestions would be appreciated.


Modified by Andrew 825SM at 10:12 PM 10/19/2004

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Andrew 825SM &raquo;</TD></TR><TR><TD CLASS="quote">It's a stock ecu and it is a GSR with a Greddy turbo kit on it. My fuel setup consists of a vafc, 450cc injectors, 4:1 fmu, inline pump and intank pump. And don't say I am running too rich with those mods cause I tuned it at the dyno last week and had a 14.5 A/F at idle and partial throttle. It only started running super rich about 2 days ago. I lost nearly a half tank of gas on a 40 mile trip and also at idle it puffs out black smoke.

I have already tried taking out the inline pump, cleaning my missing link, checking injectors, seeing if the fmu disk was stuck, cap & rotor, cleaned iac valve, changed spark plugs, and checked compression (which is fine). Nothing really helped. I am narrowing it down to a bad EGT sensor or maybe a bad primary o2 sensor, but I am not throwing any codes. Could a sensor be bad and not throw any codes? Again, any suggestions would be appreciated. </TD></TR></TABLE>

You think you MIGHT have mentioned that you have a turbo before posting? Why post this in the ITR forum, anyway?

O2 Sensor might do it, but I thought you'd get a code. That would explain car running "OK" in open loop, and then sucking in closed loop.

What about vacuum line to the FPR? Check all of those.

Also, Umm, there's not a stock EGT sensor? What are you talking about?

vtec.dc2

what about fuel pressure? is it still same as it was? if you have obd 2, switch secondary o2 with primary to test if its o2 sensor causing problem (if secondary is long enough).. what about spark plug gap, and spark plug wires..

Andrew 825SM

I posted in the forced induction forum, unfortunately no response. The ITR forum seems pretty knowledgeable, that's why I posted here.


Sorry, I meant ECT (Engine Coolant Temperature) Sensor. I was thinking if it was faulty, the ecu would think that the car would be running cold and therefore would run rich. Is there anyway to test if the sensor is malfunctioning?

Checked plug gap and wire resistance, they seem to be ok. I will try switching O2 sensor tomorrow. Also I am running a test pipe, and my secondary o2 sensor is zip tied to my sway bar. I know it was raining on sunday, could getting the secondary o2 sensor wet cause a problem?

PureTeg420

you could cut the second o2 completely off and it wouldn't make a difference. Only the primary o2 sensor affects the fuel map

Andrew 825SM

All of a sudden, my car is running fine again. Maybe its a lazy O2 sensor.