90 k5 help

[klowninc89]

ok.....i was messing with my truck this afternoon...started up but i had to give it a little gas. then it did a really hard idle looping big time. barly touch the gas and it runs normal no engine light or anything. i tested the computer on the truck came back as a code 12. looked in my book and it says computer normal or no distributor.....idk if it could be the distributor. the injectors seem a little dirty but it runs normal with little help from gas pedal. revs up just fine to just when its at a idle. i have a new idle air control in now and i was thinking could it be the throttle sensor? someone please im am so tired of not driving this truck.....i need to drive it..lol any other ideas or question?

 

[wheels87k5]

Code 12 tells you that the ECM is functioning properly.

If you have to give it a little help to keep it running smoothly, then there is a chance it is the TPS or throttle position sensor. That is what happened to mine about 3 years ago and a new TPS fixed it.

Doesn't mean that is your problem, just a possibility. Hope it helps

wheels

 

[smier]

Simple stuff first, don't just throw parts at it. Check for vacuum leaks, don't forget the throttle body base gasket is prone to leaking. Might be a good idea to clean the throttle body and put a rebuild/gasket set in it ($45). Clean your Idle Air Control (IAC) as they get gunked up and stick, or you can replace it if it's real bad. I was amazed by how much better mine ran after cleaning and rebuilding the throttle body itself. I honestly feel this is a great system, but most of them have never been touched in their 20 to 25 years on the road, and are due for some maintenance!!! There is a ton of little O-rings and gaskets in the TBI unit that have outlived their lifespan, and may need replaced... Mine took me about 2 to 3 hours and 2 cans of Throttle body cleaner, the rebuild kits come with a great exploded view of the throttle body. It looks daunting at first, but once you've finished, you'll be amazed how simple they are. I recommend getting the kits with the diaphragm for the fuel pressure regulator, just pay attention to how it goes together. Good time to change the fuel filter if you haven't already. Some good fuel and some fuel system cleaner wouldn't hurt, especially if this thing sat for awhile...

 

[klowninc89]

I took off the vacuum line to the egr and idle was good. Ideas?

 

[496truck]

Plug the line and leave it off. For now.

Replace the EGR solenoid and EGR valve later.

 

[smier]

Take the vacuum line off at the EGR solenoid and see what happens, could be the EGR valve or the EGR solenoid acting up... Basically becoming a giant vacuum leak. Be careful just plugging the line, mine runs terrible under load and pings without the EGR and turns the check engine light on soon after...