I just bought a 88 suburban 4x4 for 200.00. The fuel pump was out, and it has been sitting for a few years. We cleaned the tank out, and pump a new fuel filter. I pulled several spark plugs, and they are brand new. The wires and cap look fine as well. I cleaned the injectors and the TB and it seemed to run alot better. I let it cool off and then I started it again to show my dad. It was back to the up and down idle. Its getting to the point, that it wants to die. Once you start driving it and it gets warm, it runs better. I unplugged the IAC while it was running, and no change in the affect of it. Im thinking TPS, but I really dont want to just start throwing money out there. What do yall think? I know this has probly been asked a million times, but I did search and I cant come up with anything. Thanks Trey.
CK5
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New guy needs help. Up and down Idle.
- Thread starter 88burbano
- Start date
Search for vacuum leaks. Everywhere. Follow every vacuum line and replace as needed. Sometimes the base gasket for the TBI unit leaks too. Also doesn't hurt to remove the TBI and clean all the carbon out of the passages on the bottom of it. Remove the IAC and clean out the IAC passages and the PCV hose passages, you'll find them all gunked up with carbon and sludge. Use a tooth brush and some carb cleaner, no tools that will gall the IAC seating area but you can use small picks and screwdrivers to pick out the sludge from the PCV passage in the front.
There ya go, start with that.
There ya go, start with that.
I already checked for leaks and unplugged stuff. I found one, but it came off the smog pump tree on the passenger side and went to the EGR. The smog pump is dead, but I went ahead and plugged it up. How do I remove the IAC? I was going to clean it when I was doing the injectors and tb. Ill work on getting the rest of it cleaned. Its running really bad.
Just unscrew it. It's like a 1 1/8th or 1 1/4. Or just use a big adjustable wrench, not much torque on it. Try plugging the EGR vacuum port. My EGR solenoid was (still is) bad and kinda caused what you are describing, just not to that extent. I have it plugged off for now.
Is it possible that there was gunk in the fuel lines from it sitting and whenever you started it and then shut if off and started up again it worked its way to the tb and injectors? I dont know much bout tbi but just a thought
Its so bad that you have to give it gas to keep it going, but once it warms up, its levels off.
Is it possible that there was gunk in the fuel lines from it sitting and whenever you started it and then shut if off and started up again it worked its way to the tb and injectors? I dont know much bout tbi but just a thought
Possibly, I may need to go ahead and run that lucas injector cleaner through it.
Update:
I replaced the TPS, the map sensor and the cleaned the IAC. I had it running perfect, but then I restarted it later in the day, and it was right back to the same up and down idle again. Could it be a vacuum leak? This is really starting to get on my nerves. Does anyone have any vacuum diagrams I can use to hunt down the possible problem.
I replaced the TPS, the map sensor and the cleaned the IAC. I had it running perfect, but then I restarted it later in the day, and it was right back to the same up and down idle again. Could it be a vacuum leak? This is really starting to get on my nerves. Does anyone have any vacuum diagrams I can use to hunt down the possible problem.
There should be one on the radiator support or atleast there is on mine and my dads. Altho they arent the best diagrams and kinda confusing.
