Hey guys,
I have been looking threw the posts for about 2 days now to see if i could find anything to help me out lots of ideas but no luck yet. So i wanted to put my specific problem out to see if i can get some help. I just bought a 96 gmc jimmy got it cheap cause it had this problem. It has the 4.3 vortec and i can get it started and it idles like a champ but when you throtle up quickly it will bog out and if you hold it open it will die. From the other posts i have cleaned the egr valve and iac valve and the mass air flow valve. i changed the tps but it didn't help at all so i took it back and put the origanal back on. now the guy that i bought it off of change the cap, rotor, wires and plugs. I am stumped i took the cat out and checked it. its not plugged even ran it with out the cat hooked up and same thing so the exaust is no plugged. I checked the fuel pressure and with the key on it goes up to about 55 and then stops and losses about 1 psi in about a minute maybe it may not even loss a full psi. When the engine is runing pressure is about 50psi. Now for the fun stuff if i start it and smash the throtle till it dies it will not start unless i shut the key off and turn it back on again. If i don't it will just crank and try to start almost wants to but won't. An ideas??? I know how to use a voltmeter so if any one could tell me how to test the tps, mas, iac, egr and the values they are supposed to be i would love to do that so i'm not just replaceing stuff till i accidently get the right part. Sorry so long.

Thankyou,
Jonathan

 

Replace the ICM (ignition control module).

 

Wow, that explained a lot. Care to tell us why he needs to swap a possible un-needed part again?

 

Sorry, was heading to bed when I saw his post last night. This will explain:
https://blazerforum.com/forum/2nd-generation-s-series-1995-2005-tech-41/jimmy-warms-up-then-chokes-36543/

 

Ok thank you for the response. Our problem sounds almost the same. Is there anyway i can test it before i go and spend money on it? I'm on a budget and if that doesn't fix it the parts store may not let me return it. I was also wondering if anyone new how to test the mass air flow sensor? I was fooling around with the truck last night and i had the air box open and blew air from my air compressor into the MAF and the truck did the same thing as if you hit the gas too quickly. Is there a chance that could be bad instead? I cleaned it already but i didn't know how to test it.

Thanks again,
Jonathan

 

The ICM and coil can and should be tested. Most autoparts stores have the proper diagnostic equipment. Have them test each item at least 10 times in rapid succession. This will get the components up to operating temperature where they are more likely to show faults.

 

Thanks for all the input this thing is still winning. I had to go out of town this past weekend but i just had the ignition control module tested. It tested bad the first time and had it test two more times just for the heck of it. It came out bad all three times. So i went ahead and bought a new one. Now i should have had them test the new one but it didn't. I replaced it and the truck is acting exactly the same. I will be taking the new one back tomorrow to have it tested and see what the machine says. I did not test the coil the parts store said that they couldn't test coils. Any other thoughts as to what it could be? Is there anyway to test the MAF?