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im at my wits end with my 89 k2500 need some help.

topumpchump

By topumpchump
in Ask A GM Technician

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topumpchump Enthusiast

topumpchump

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I'm pretty positive that signal is getting to it. If I unplug the thing the ses light comes on and stays on and the truck won't even idle correctly. As soon as I plug it back in the light shuts off and all is back to normal.

 

I've got a complete intake from another working truck today. Has all the sensors and the truck ran perfect that it came from. So I'm gonna pull those and replace to see what happens. The other truck was the same year and everything but the body was toast so it became a donor for a few rigs.

 

I'll post back if anything changes and the status of the beast

 

Also picked up a new o2 sensor, couldn't hurt.

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tkat1000 Enthusiast

tkat1000

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there comes a point that you have to decist with the shotgun repair. it only serves to waste hard earned money and build frustration. proper diagnosis is the first step. the money you wasted on parts should have been spent on plugging a scan tool into the system to read the data.i know p.i.a. but theses day you really have to have one to do the job right.

 

common failures in the tbi map system: rotted broken vacuum hose, green groody connectors, carbon plugged vacuum ports. cracked blown out tbi base gasket and intake gasket vacuum leaks. when it gets real bad you'll have a high idle speed. as mentioned, the grounding terminals for this system suck. the crimps get corroded. look fine, but make lousy connection. the wire breaks inside the insulation. usually near the terminal ends. my make contact till some vibration causes it to separate. been a long time but if I remember correctly the ecm sensors ground through the thermo housing stud. which is steel bolt into a aluminum thread, again with the corrosion problem. there are also grounds on the back of the heads near the firewall on some of these.

 

I would suggest, you inspect the vacuum port feeding the map sensor for blockage and while your there clean out the pcv port on the throttle body also. I've also seen aftermarket pcv's do some weird things to the system. pull the ground terminals and replace anyone the even shows any sign of rott. use a back up wrench on the thermo stud so as to not break it off it the intake. give the wirring on the grounds and map connector a good tug. feel for anything that streachs signaling a break inside the insulation. common problem because there subjected to vibration. have someone sit inside the truck with it in drive foot on the brake. give the whole harness a good shaking and see if it farts out. trace it from there. make sure you replaced the map with the proper unit there was a couple different ones used for this model..

 

the injector may look like the spray pattern is good but you can,t measure flow rate with your eyes, fuel filter on backwards? and here's a good one for ya. if the injector connectors are clipped on the oppsite injector it will idle fine till you shift it into drive. it'll fall on it's face. banged my head to find that one....a fixed rich (-30) coolant temp sensor will cause a fart out under load but won't set a map code.

topumpchump Enthusiast

topumpchump

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UPDATE

 

I replaced the idle air valve, o2 sensor and the temperature sensor, reset the computer and drove it, parked shut it down an re ran the codes.

 

The computer isn't throwing any codes as of right now. Gonna throw a timing light on it tonight and be sure its not that. But again no codes are thrown.

topumpchump Enthusiast

topumpchump

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Fuel filter on backwards? You've got to be kidding me? They only flow one direction and if you screw that up. You shouldn't be allowed to drive let alone work on a vehicle. For the last time I've checked grounds, vacuums and harness. Its no longer throwing any codes yet still have the issue. I'm thinking its timing or possibly a sensor I've missed.

 

Any legitimate help would be appreciated. Read the post and replies and I'm sure you'll see what I've don't on countless occasions.

 

Thank you.

DaveH71 Enthusiast

DaveH71

Posted
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Calm down there hoss, people are just trying to help you. From all that i've read this just started happening out of the blue? Were you doing any work to the truck a month ago when this started happening or did you change anything? I know you said you checked for vacuum leaks but take some carb cleaner or starter fluid and mist around any gaskets or seals like the intake manifold/valve covers/TB/etc. If the idle changes at all during this you found your leak.

 

Are you sure the hoses are routed correctly? Get some sensor safe electrical cleaner and clean all the sensor connectors. Can you keep the truck in park and raise the idle without it cutting out like you said it does while driving? Do the cheap things first man.

ChevyTech77 Senior Enthusiast

ChevyTech77

Posted
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Fuel filter on backwards? You've got to be kidding me? They only flow one direction and if you screw that up. You shouldn't be allowed to drive let alone work on a vehicle. For the last time I've checked grounds, vacuums and harness. Its no longer throwing any codes yet still have the issue. I'm thinking its timing or possibly a sensor I've missed.

 

Any legitimate help would be appreciated. Read the post and replies and I'm sure you'll see what I've don't on countless occasions.

 

Thank you.

 

You're kidding me, right? There has been PLENTY of legitimate help in this thread yet you continue to just shotgun parts at this truck and then go off about people not knowing how to work on a vehicle and giving you bs help?

topumpchump Enthusiast

topumpchump

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Yes there has been a lot of help. But shotgunning parts is quite an understatement. Do you really think this is the only forum I've posted to? No would be the answer.

Assuming that making such a rookie mistake as the fuel filter or a ground that I've been over about a dozen times is quite insulting, not to mention annoying.

The legitimate help has and is well appreciated and had made a difference in the overall operation of the truck. Your snide remarks however, have not.

topumpchump Enthusiast

topumpchump

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Yes the truck runs great while in neutral. Idles great. Can ouch the throttle with no stumble. Just when in gear and under load does it act up.

 

Punch the throttle *

txab Senior Enthusiast

txab

Posted
Posted

top,

 

Lose the attitude. You'd be surprised how many people make simple mistakes or overlook obvious things when trying to track down a problem. We have no idea what your level of experience is. So quit getting bent out of shape, unless you want people to start ignoring you because of your 'tude. :)

topumpchump Enthusiast

topumpchump

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**UPDATE**

 

The problem has been solved. Turned out the ignition control module was fried. Replaced it and in runs like a champ again.

Jsdirt Senior Enthusiast

Jsdirt

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A prime example of why internet diagnosis is fickle at best.

 

Glad you got it fixed. :cheers:

gmtech4 Senior Enthusiast

gmtech4

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A prime example of why internet diagnosis is fickle at best.

 

Glad you got it fixed. :cheers:

 

 

amen brother

bossier62guy Senior Enthusiast

bossier62guy

Posted
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This is all cute and all but am I the only one that finds it hard to believe that a fried ignition module caused this problem? I'm no ex GM tech like govtech4 but I don't see how it was running at all. Nonetheless it's nice that it's fixed and you have a slew of brand new parts in it. Cheers and I'm done.

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