| Go back to previous topic | | Forum name | Turbo/Nitrous Tech | | Topic subject | Problems w/ idle. Need some input. | | Topic URL | https://forums.2gnt.com/dcboard.php?az=show_topic&forum=i8&topic_id=85017 |
85017, Problems w/ idle. Need some input. Posted by Axewhlder, Apr-18-05 10:47 AM
Alright, this has been an on-going thing for my car.
When it's not run for a few days and I start it I'll get a rough idle until it's at operating temp. If I give it a little gas it'll bog, sputter and smoke as well as blow mass amounts of black shit out the tailpipe. Once it's at operating temp it's just fine. No problems, boosts well and idles like a champ.
I get a CEL sometimes. When I check it tells me that bank 1 is too lean. I reset it and everything it peachy.
I have the EGR blocked off, 30#ers and running 10psi of boost. I have the idle fuel pressure at 22psi and havent had this problem since I installed the injectors and such. It just started happening reacently.
Oh yea, I also kill my plugs every few hundred miles because I'm running so rich.
All me and some friends could figure is the computer is trying to compensate for something at warm up and dumping crazy fuel in my engine causing it to bog. Cant figure out why though.
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85023, RE: Problems w/ idle. Need some input. Posted by BlackMagic, Apr-18-05 11:58 AM
so you're computer tells you that you're running lean, and your spark plugs foul because you think you're running too rich, interesting
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85026, RE: Problems w/ idle. Need some input. Posted by Axewhlder, Apr-18-05 12:11 PM
Originally posted by BlackMagic so you're computer tells you that you're running lean, and your spark plugs foul because you think you're running too rich, interesting
Yup.
Now I'm being told that it could be the o2. I noticed the one on my D/P is a bit frayed. Not severed though.
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85027, RE: Problems w/ idle. Need some input. Posted by DarkOne, Apr-18-05 12:19 PM
I've seen O2's do stranger things on their way out. If you frayed a heater wire, the sensor could be failing to reach its operating temp (~700*F) and failing to read free oxygen until sometime near the motor's operating tempeature. The ECU can't trim fuel if the O2 is cold, because it reads way, way low.
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85028, RE: Problems w/ idle. Need some input. Posted by BlackMagic, Apr-18-05 12:48 PM
well try replacing it and see what happens, but when your cars heating up, isn't the ECU just running off of stored data, so it's not even reading anything from the o2 sensors yet
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85029, RE: Problems w/ idle. Need some input. Posted by DarkOne, Apr-18-05 12:57 PM
It's running off a preconfigured enrichment map, until such time it thinks it should be getting info from the sensor. O2 sensors have a stable warmup time. When it starts looking at the sensor for feedback as to where it should be and the sensor is reading low, it starts adding fuel expecting it to come up (increases the short term fuel trim). The O2 reading changes little (because the exhaust is warming it up, not he internal heater circuit) so it thinks it need to add more. Eventually, it runs out of positive trim, throws a bank lean code, and continues on its merry way until the sensor reaches its operating temperature and starts to read as it should. At that point, the ECU will be able to determine it is rich and start backing down the trim.
make sense?
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85030, RE: Problems w/ idle. Need some input. Posted by Axewhlder, Apr-18-05 01:13 PM
Originally posted by DarkOne It's running off a preconfigured enrichment map, until such time it thinks it should be getting info from the sensor. O2 sensors have a stable warmup time. When it starts looking at the sensor for feedback as to where it should be and the sensor is reading low, it starts adding fuel expecting it to come up (increases the short term fuel trim). The O2 reading changes little (because the exhaust is warming it up, not he internal heater circuit) so it thinks it need to add more. Eventually, it runs out of positive trim, throws a bank lean code, and continues on its merry way until the sensor reaches its operating temperature and starts to read as it should. At that point, the ECU will be able to determine it is rich and start backing down the trim. make sense?
That makes sense to me. Thanks for the input dude. I appreciate it. I'll swap out the 02 when I get a chance.
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85032, RE: Problems w/ idle. Need some input. Posted by BlackMagic, Apr-18-05 01:35 PM
Originally posted by DarkOne It's running off a preconfigured enrichment map, until such time it thinks it should be getting info from the sensor. O2 sensors have a stable warmup time. When it starts looking at the sensor for feedback as to where it should be and the sensor is reading low, it starts adding fuel expecting it to come up (increases the short term fuel trim). The O2 reading changes little (because the exhaust is warming it up, not he internal heater circuit) so it thinks it need to add more. Eventually, it runs out of positive trim, throws a bank lean code, and continues on its merry way until the sensor reaches its operating temperature and starts to read as it should. At that point, the ECU will be able to determine it is rich and start backing down the trim. make sense?
yep sounds good to me
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85036, RE: Problems w/ idle. Need some input. Posted by Axewhlder, Apr-18-05 02:27 PM
Side question..
Would the ever present DP exhaust leak have anything to do with it as well? I've been told that a pre-o2 leak would suck in cooler air making the o2 read differently as well.
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