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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 5783
Experience:  GM Grand Master Technician 2007. 14 years experience.
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GM Buick LeSabre: 2000 LeSabre - 3.8 - Hot soak rough start

Customer Question

2000 LeSabre - 3.8 - Hot soak rough start idle. I replaced CPS last year for a jumping tach issue. I replaced MAF sensor because it was throwing a code. It ran ok for a month or two. Then when restarting hot one day it jumped to about 1200rpm then over 4 seconds it slowly went down and stalled. I restarted 6 times before it stayed running at 800rpm or so. Fuel pressure was fine, and holds at 48psi or so for 8 hours. I changed Fuel Pressure reg, had my injectors cleaned and serviced, and replaced Idle Control Solenoid. Still doing the hot soak rough idle stallout. Now, if I gun the throttle to about 2K every time I see the tach drop down, it will idle properly after the 4th or 5th rev and not stall anymore. Any Ideas?
Submitted: 6 months ago.
Category: GM
Customer: replied 6 months ago.
If I restart hot within a minute, it idles fine. If I let it sit for an hour it restarts fine. I checked my TPS numbers and O2 Up stream and Downstream activity with a scan tool. The MAF freq looks normal too. This has had me going for 6 months. I have a 2nd MAF sensor which I got from a junkyard which I did not try yet.
Customer: replied 6 months ago.
I just put in the MAF I got from the junkyard. It was for a 2001 instead of a 2000. No more hot soak rough idle start. However it does idle a little rougher than it used to, and it bucks one time after about 40 seconds when accelerating. It runs fine after that. I am going to Advance Auto to get another one. It is a Spectra Premium lifetime warranty. I am still open to your recommendation for what brand of MAF sensor to get. I thought Spectra Premium was a good brand.
Expert:  Roy Belding replied 6 months ago.
good afternoon my name is ***** ***** I will assist do you still have any codes??? as far as the fuel pressure, you are at the bare minimum of the scale. it is 48-55 lbs. it should be in the 50,s at a minimum. I suspect when it is hot, the pressure drops. have you checked the pressure when it is hot and is acting up???? Roy
Customer: replied 6 months ago.
Let me get back to you if I need help. I think I solved it myself.
Expert:  Roy Belding replied 6 months ago.