I have finally found the root of my performance problems. And it is no surprise. When my truck gets warmed up (which is easy in Texas) or if I drive farther than 30 miles in a trip, My truck gets hesitating bad and it throws a P0701 code on the 95 GMC Jimmy. It is OBDII. I got the code with the scanner. The scanner says Map sensor low voltage input. But online it is listed as transmission performance issues. I know my tranny is ganked. I'm pretty much not messing with it as I know I'm going to end up needing a replacement probably next year. I'm wondering is there any way to bypass the map sensor, as this is causing it to cut out the fuel. I know I'm going to keep getting P0701 codes if I bypass it, but I at least want to be able to drive it without the hesitate. The tranny itself is workable but whatever it is is causing the low map sensor reading and causing a fuel cutoff. So other than replace the tranny (which is in the plans next spring) what are my options?

 

Do you have a Junkyard around? If so, go there and pull a map sensor off a 95 or older, I believe that after 95 they eliminated the map sensor

 

Already done that. It's not the map sensor. I definitely have tranny issues. I've wrote about some of it here. But I know it's bad. I'm just trying to make it hold off until spring when I'm going to have it replaced. I've checked the wiring diagrams and see that the voltage goes from the input through the map sensor to the egr and the tranny. EGR is new. But I check the voltage and it only gives 1.5 of the 5 volts going into the map. And this gets sent to the pcm. That tells the motor how much fuel to send through the injector. If I can get the full voltage at least it won't throttle my fuel flow. And it's not a fuel issue. I have full fuel pressure and a new FPR. It's been getting worse since December. And now I see how the wiring is (from the chilton's diagram) I can see if I bypass the map sensor it will bypass this issue. And Since I know the tranny is a mess anyhow I can just let that go until I replace it.

 

Well I think I might have actually found it. Well I know the tranny is worn and it's going to need replacing. But today I took the intake off. I was doing some checking. **** me off. I found the egr valve was cracked at the base. I mean the damn thing was new just last year. And it's physically broken! Cripes for $100. So now I gotta replace THAT!

 

well glad you found the problem, hope that was it. let us know if that fixed it

 

That really ticks me off. It's been getting progressively worse for the past two months. To the point where it would almost totally bog down buck and chuck on a long drive. Come to find out the egr valve was actually broken at the base. **** me off because there was no reason for it. It was new last year. And actually the side that was broken off that mounting bolt wasn't even tight. DOn't know. I picked a used one up at pick a part $13 and it is fine again. Already took it for a run to the store, no problem. The big test will be taking the kids home tonight. Had one code. The evap solinoid was plugged in backwards. No biggie. But the P0701 code is gone.

 

At least you got another egr for cheap and it fixed it... would **** me off to especially after I spent 100 bux for a new 1 and it broke. Glad to hear you got it fixed tho

 

Yep. It runs great now. That really pissed me off. I kept trying to trouble shoot everything EXCEPT the EGR as it was new last year. But it runs like it was new now. Now I can concentrate on getting the Tranny fixed up. But I suspect that's going to need a replacement anyhow next year. But at least it is running smooth again.

 

Glad to hear its running great

 

Yep. Its fine now. Acutally, now it runs better with the USED egr valve then it did when I put the new one in last year. It just seems to idle and run a little smoother. The thing that was confusing is the P0701 said low map sensor input voltage. Looking at the schematics in the book, there are 4 things plugged into that circuit. One being the egr valve. Last year I knew the egr valve was bad because it threw up it's own code (something about the pindle bad position or something) but this time it didnt' throw up it's own code. And I did searches here and there were no threads on this code. So if someone else has this code come up and sees my post, even though it says MAP sensor, don't forget to check the egr valve.