'04 Vette 18:1 in CL, 14.5:1 in OL. Low dyno numbers.
12-13-2009, 08:03 PM
#1
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'04 Vette 18:1 in CL, 14.5:1 in OL. Low dyno numbers. Just trying to figure out what may be causing this. 2004 Corvette A4. Car bone stock only put down 248 whp on a Mustang dyno. A 98 A4 corvette that was stock put down 315 whp with only a tune. Just stating that to verify the dyno is reading numbers on a properly running car.
When the car is started, AFR starts at low 11's and creeps up to around 18:1. If you make the car run open loop, AFR is 14.3-14.7 the whole time. Coolant temp sensor, IAT, O2's all seem to be reading correctly. MAF is showing 6-7 gps and around 2700 hz.
Any clue what in the world is causing car to go so lean? This is on a stock tune and the 248 whp was 100% stock car.
This one is baffling me. Hopefully, someone can help. I've got a fresh 04 file on the way in case the flash is corrupt in the PCM. No engine lights. Not even if you unplug the MAF. The 04 has the MAF with IAT built in and it does not throw a code for either if you unplug MAF...
When the car is started, AFR starts at low 11's and creeps up to around 18:1. If you make the car run open loop, AFR is 14.3-14.7 the whole time. Coolant temp sensor, IAT, O2's all seem to be reading correctly. MAF is showing 6-7 gps and around 2700 hz.
Any clue what in the world is causing car to go so lean? This is on a stock tune and the 248 whp was 100% stock car.
This one is baffling me. Hopefully, someone can help. I've got a fresh 04 file on the way in case the flash is corrupt in the PCM. No engine lights. Not even if you unplug the MAF. The 04 has the MAF with IAT built in and it does not throw a code for either if you unplug MAF...
12-17-2009, 05:25 PM
#6
Just trying to figure out what may be causing this. 2004 Corvette A4. Car bone stock only put down 248 whp on a Mustang dyno. A 98 A4 corvette that was stock put down 315 whp with only a tune. Just stating that to verify the dyno is reading numbers on a properly running car.
When the car is started, AFR starts at low 11's and creeps up to around 18:1. If you make the car run open loop, AFR is 14.3-14.7 the whole time. Coolant temp sensor, IAT, O2's all seem to be reading correctly. MAF is showing 6-7 gps and around 2700 hz.
Any clue what in the world is causing car to go so lean? This is on a stock tune and the 248 whp was 100% stock car.
This one is baffling me. Hopefully, someone can help. I've got a fresh 04 file on the way in case the flash is corrupt in the PCM. No engine lights. Not even if you unplug the MAF. The 04 has the MAF with IAT built in and it does not throw a code for either if you unplug MAF...
When the car is started, AFR starts at low 11's and creeps up to around 18:1. If you make the car run open loop, AFR is 14.3-14.7 the whole time. Coolant temp sensor, IAT, O2's all seem to be reading correctly. MAF is showing 6-7 gps and around 2700 hz.
Any clue what in the world is causing car to go so lean? This is on a stock tune and the 248 whp was 100% stock car.
This one is baffling me. Hopefully, someone can help. I've got a fresh 04 file on the way in case the flash is corrupt in the PCM. No engine lights. Not even if you unplug the MAF. The 04 has the MAF with IAT built in and it does not throw a code for either if you unplug MAF...
12-20-2009, 09:25 AM
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To force open loop, I was changing the "minimum coolant temp for closed loop" table. That way, the engine never got to the temp the PCM wanted to see to allow closed loop. Unplugging a sensor is not the way to put a car in open loop, IMHO, as you are causing a problem at the same time.
Also wanted to update this. I got a new flash to put in the PCM and everything went perfect. Car was on the dyno for 50 minutes and it was finished. When a change was made, it was reflected on the graph like it should be.
Also wanted to update this. I got a new flash to put in the PCM and everything went perfect. Car was on the dyno for 50 minutes and it was finished. When a change was made, it was reflected on the graph like it should be.
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12-20-2009, 07:53 PM
#8
To force open loop, I was changing the "minimum coolant temp for closed loop" table. That way, the engine never got to the temp the PCM wanted to see to allow closed loop. Unplugging a sensor is not the way to put a car in open loop, IMHO, as you are causing a problem at the same time.
