HELP!!! 95' GMC Jimmy 2wd Jerking BAD when slowing down

[lildudefl]

ok so ive been trying to get the truck together so i can get it sold and am having a problem. Now right before i was going to began the spider injecter replacement which i was pretty sure was the cause of my sluggish performance i started getting a rough running condition after the truck reached operating temperature.

Got worst during braking(alot worst). So I went ahead swapped the spider injector and my lost power was recovered, BUT the jerking problem still exists.

So I am leaning towards the MAP sensor. I am getting a SES light when driving for a while but when i turn the truck off it disappears and there are no codes in the computer (been read multiple times).

Any ideas would be great to lead me in the right direction

----After a bit of thought, im wondering could anything regarding the transmission cause any on these sysmptoms because after i replaced the upper intake gasket the truck idles fine when not under load (ie, in gear), but in gear acts funny and has a violent jerking when slowing down even when not on the brakes-----

 

[chevy2480]

Re: HELP!!! 95' GMC Jimmy 2wd Idle Issues!!!

Coolant temp sensor might be going out. When truck is warm temp sensor might be telling computer it running colder then it actually is. This will cause computer to dump more fuel which in turn is kinda flooding the motor and making it run like crap. Had this issue on my tahoe.

 

[lildudefl]

Re: HELP!!! 95' GMC Jimmy 2wd Idle Issues!!!

Coolant temp sensor might be going out. When truck is warm temp sensor might be telling computer it running colder then it actually is. This will cause computer to dump more fuel which in turn is kinda flooding the motor and making it run like crap. Had this issue on my tahoe.

Thanks for the response first off,

Now, if that was/is the case wouldn't the coolant temp gauge reflect that incorrect reading?

 

[chevy2480]

Re: HELP!!! 95' GMC Jimmy 2wd Idle Issues!!!

Coolant temp sensor might be going out. When truck is warm temp sensor might be telling computer it running colder then it actually is. This will cause computer to dump more fuel which in turn is kinda flooding the motor and making it run like crap. Had this issue on my tahoe.

Thanks for the response first off,

Now, if that was/is the case wouldn't the coolant temp gauge reflect that incorrect reading?

No it wont there are two temp sensors. The one im talking about is by the water neck this one is feed back to computer. I believe the other is a one wire sensor in drivers head. The one in the head is the temp gauge

 

[DRIVEN]

Re: HELP!!! 95' GMC Jimmy 2wd Idle Issues!!!

Brake booster vacuum leak?

 

[lildudefl]

Re: HELP!!! 95' GMC Jimmy 2wd Idle Issues!!!

Brake booster vacuum leak?

Will check it out. Thanks, MAP sensor not the cause by the way

I dont hear anything near the vacuum hose for the booster, if i just plug it for testing purposes that should let me know right?

 

[DRIVEN]

Re: HELP!!! 95' GMC Jimmy 2wd Idle Issues!!!

That will work. You could just pinch it with some vice-grips too.

 

[lildudefl]

After a bit of thought, im wondering could anything regarding the transmission cause any on these sysmptoms because after i replaced the upper intake gasket the truck idles fine when not under load (ie, in gear), but in gear acts funny and has a violent jerking when slowing down even when not on the brakes

I have tried all of the possible causes i could think of and what everyone on the forum and in my circle