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Old 02-19-2009   #126
LT5-Lee
 
Join Date: Jan 2009
Location: Houston, Tx.
Posts: 56
Wink Re: 91 ZR-1 Cutting Out Under Load

Quote:
Originally Posted by GregCrowe View Post
OK, in complete detail:

When the car is cold or even just warm and being driven for the 1st 15 minutes, no issues whatsoever, even with full throttle. After the car has been driven and has sat, heat synching the engine, the miss begins. Normal driving with light throttle, no issue. When a load is applied, the miss begins. The miss is very "electrical" feeling. It does not come and go under heavy fuel delivery situations. It's just a very quick electrical miss and shudder. The car never dies nor does it even come close to dying. Again, it's only under medium to heavy load. If you want to make it miss the absolute worst, let it heat synch and then bog it down in a high gear at low speed and floor the gas. Then the car will shudder and jerk. If you try to accelerate through the gears at full throttle, the car just plain misses like it has 2-3 bad plug wires arching.
Greg, I think I found my gremlin..=D>

and I can't believe what it turned out to be. I was wiggling everything while the engine was idling and for the hundredth time, I played with all the sensors and then the MAP sensor and the engine died? I swear I checked it out many times, but it seems the rubber accordion seal on the connector must have gotten twisted and was not quite snapped on tight. My scan tool showed the correct voltage readings, but I guess when the engine torqued just right it lost connection?

I can not believe it because it was one of the first things I suspected and always made sure it was tight, but I had to squeeze it so hard before I heard the plastic snap, I thought I was going to need some channel locks before I actually heard it snap on!!!

I maybe a little premature as I have only made a few hard runs for testing it out because of traffic, but knock on wood, I hope I got it!

After doing some data logging I probably have some other issues that made it worse, like a lazy LH o2 sensor with low cross counts (or a really slow scan tool "Auto X-ray"),but I am preying the MAP sensor connector was the major problem. My problem wasn't just heat related, but it chugged so bad it felt like it would throw you into the windshield just like you described so I thought I would just pass along my good fortune just in case?
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