Questions and Answers
Blazer Rough Idle
Q. I've owned this truck, 1987 Chevy S-10 Blazer, for about a year and a half. It has a fuel injected 2.8 liter V-6, 4WD, A/C, Auto and about 160,000 miles. It does not have ABS. This problem has been developing for about a year now. At first I just blew it off because it happened so infrequently, but now it's getting annoying (and dangerous). I have not been able to ascertain what factors cause this to happen.
Sometimes when I put my foot on the brake pedal to stop, the pedal is very stiff and I have to push very hard to bring the truck to a stop (the dangerous part). When I do come to a stop the truck idles very rough and sometimes stalls (the annoying part). These events never happen independently of each other. As the problem got worse it would stall more frequently. I've had it in to my mechanic and the Chevy dealer and no one can figure out what is wrong. Part of the problem is, of course, that it won't do this within a mile of a mechanic.
I got it back from the Chevy Dealer a couple weeks ago at which time they, and I quote from the my receipt: "Removed throttle body to service vacuum ports & clean reset TPS voltage & replaced gasket. Replaced broken knock sensor & pigtail reset timing. Replaced fuel filter." Prior to that I had the power brake booster replaced and a front and rear brake job, neither of which seemed to make a difference. It is better than it was as it hasn't stalled since I got it back from the dealer, but I'm still having the same problem. Any help would be appreciated!
Thank you,
BrianA. Well brian, it seems your Dealer and I are thinking along the same lines, there is a vacuum problem. The rough idle, stalling and hard brake pedal are all indications of low or no vacuum.
GM Issued a TSB about this in July, 1987. I quote from the bulletin:
DATE:
July, 1987NUMBER:
765002SUBJECT:
HARD BRAKE PEDAL FEELMODELS:
1986-87 S/T MODELS WITH 2.8L V-6 ENGINES
A condition described as an intermittent hard brake pedal feel may be caused by reduced vacuum at the brake booster. A power brake kit has been developed to resolve this concern.The bulletin also mentions the Throttle Position Sensor and idle speed need to be readjusted to help alleviate the problem.
Additional Information provided courtesy of ALLDATA
