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Dave Nova
Dave Nova, Buick Technician
Category: Buick
Satisfied Customers: 1808
Experience:  ASE Master Certification. GM World Class Certification
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Buick Rendezvous CX: I have a 2005 Buick Rendezvous, 3.4L that

Customer Question

I have a 2005 Buick Rendezvous, 3.4L that is acting exactly as described in this post http://www.justanswer.com/buick/7drfu-buick-rendezvous-cxl-05-buick-rendezvous-3-4e-awd-sent.html At exactly quarter throttle continuously, vehicle falls into open loop, spark advance negatives, has no power. I've checked this vehicle from top to bottom, and seem to be coming up empty handed. Thought's?
Submitted: 1 year ago.
Category: Buick
Customer: replied 1 year ago.
The problem can only be re-created during a road test at quarter throttle or more continuously. This issue can't be recreated statically in the garage under a no load or torque load condition. Fuel PSI and fuel integrity are ok. When the problem is happening, all scan data is normal (coolant temp, O2 voltages, MAF, MAP, TPS). What I observe is the spark advance going negative, Loop is open, and injector pulse shoots to the 20.0's mark. If you back off the throttle, closed loop resumes and the vehicle runs normally until the quarter throttle mark is hit again. Aside from testing, I've even substituted a MAF, and ignition module with no change in operation. Harness and connectors look good ( aside from some corrosion in the ignition module connector) PCM internal inspection looks good as well. What makes this odd is the quarter throttle mark is the catalyst for the issue
Expert:  FIXITMAN replied 1 year ago.
Hello, my name is***** for the question. If I am not online when you return please give me some time to get back to you. Can you tell me how many miles are on the vehicle and if the check engine light is on?
Customer: replied 1 year ago.
I'm not in the shop today, unfortunately I don't recall the mileage offhand. No check engine light illuminated but it did have a stored trans code for long shift adapt stored originally. I did initiate a few codes along the way as a result of eliminating a few active sensors to allow the pcm to compensate with a default value to observe results.