Buick guys, I would really appreciate your advice and consel on this head scratcher of an issue. My car ('87 T-type, 131K, original motor, alky control, 60# injectors, 5931 turbo, TT chip, etc.) is running fine at part throttle, but falls on it's face as soon as it goes into boost. This just recently started happening and I felt pretty confident that it was the coil pack failing, so I picked up and installed a new coil pack, but it made no difference whatsoever. Watching the Scanmaster and datalogging it seem to show all of the sensors working just fine at part throttle. The O2 is switching fine, the MAF seems to be measuring airflow correctly, coolant temp sensor looks accurate as well as the IAT and throttle position sensor. I pulled the spark plugs and they all look very good and the plug wires (MSD) are less than a year old and all look good. Also, leaving the methanol injection on or turning it off makes no difference in the bog. The only other weird symptom I have noticed is that the O2's are extremely low after the car idles for a few minutes and it smells very rich. The O2's at idle are sometimes like 030 instead of 800 like they usually are.
The car has been running great in this configuration and nothing has been changed on the motor. The only recent change to the car was freshening up the transmission. The car goes mid to high 11's at the track like clockwork.
I've attached some screen shots from the Powerlogger of when the O2's drop like a rock to zero during WOT. This obviously coincides with the car falling on it's face, which is easy to see in the MAF readings. The dip in the MAF numbers are when it bogs. The O2 readings dropping to zero is slightly behind the MAF dip, which is not surprising to me since O2's are a downstream measurement. There is NO knock retard associated with the timing of the bog. I immediately get off the throttle when it bogs as I don't want to hurt it. The Powerlogger file is attached if it's easier to review it.
I don't believe it to be a fueling or fuel pump issue. At idle, the fuel pressure looks good, but I haven't checked it under a load yet with a gauge. However, if the fuel pressure was falling under a load, I don't believe the O2's would immediately drop to zero like that. Thanks in advance for the feedback.
What would cause O2's to immediately drop to zero like that?
The car has been running great in this configuration and nothing has been changed on the motor. The only recent change to the car was freshening up the transmission. The car goes mid to high 11's at the track like clockwork.
I've attached some screen shots from the Powerlogger of when the O2's drop like a rock to zero during WOT. This obviously coincides with the car falling on it's face, which is easy to see in the MAF readings. The dip in the MAF numbers are when it bogs. The O2 readings dropping to zero is slightly behind the MAF dip, which is not surprising to me since O2's are a downstream measurement. There is NO knock retard associated with the timing of the bog. I immediately get off the throttle when it bogs as I don't want to hurt it. The Powerlogger file is attached if it's easier to review it.
I don't believe it to be a fueling or fuel pump issue. At idle, the fuel pressure looks good, but I haven't checked it under a load yet with a gauge. However, if the fuel pressure was falling under a load, I don't believe the O2's would immediately drop to zero like that. Thanks in advance for the feedback.
What would cause O2's to immediately drop to zero like that?
