90 sububarn 4x4 problem need help

**ssdjoey** · 02-16-2008, 04:29 PM

ok i just bought a 90 suburban 2500 4x4 from my unlce and it has a few issues my biggest concern is that when you start the car on a regular day(i live in san diego so no major weather problems) i have to revv the motor to keep it running once it gets warm(about 7-10mins of revving) it will stay running after that when i try to put it in any gear other than neutral it will shut off and i have to put it back into park and restart the only way i can get it to move is to put in gear and at the same time stay on the gas while putting in gear.Also when the car is really warm (after i drive for about 30min) i can put into park and shift to any other gear and it will not die. I have heard alot of different things to do 1 being to replace the idle control valve and also the computer any suggestions would be great,thanks for the help

**Pete95Sierra** · 02-16-2008, 06:12 PM

getting your idle checked out is a good start.... your air/fuel mixture is prob not right either so get that checked out as well

**ssdjoey** · 02-16-2008, 06:53 PM

will try that,any other suggestions?

**dwill3015** · 02-16-2008, 07:35 PM

Could your catalytic converter be plugged? I once had a car that had a plugged cat and I even had to resort to pull-starting it to get it running and then after it was warmed up, it would run like normal but seeing that thing glowing red when it was dark outside was what lead me to realize what the problem was. It's worth checking into.

**tbplus10** · 02-16-2008, 08:51 PM

This really sounds like the Idle Control Valve.
At cold start the Idle Control Valve acts like a choke to make the engine run richer, on some engines the Idle Control Valve even shoots extra fuel into the manifold during start up.
Even in warm areas engines need to be choked a little at start up. This isnt as obvious now a days with all the electronic controls running things for us.
Whens the last time you saw a manual choke knob on a car?

**ssdjoey** · 02-17-2008, 11:10 AM

haha havent seena manulka choke for a while i think my 81 toyota starlet had 1 it was pretty funny to see it haha, i guess i will try the icv, i dont think the cat converter is bad though but will takea look at night to see if it glows red,thanks for the advice guys

**Big6ft6** · 02-27-2008, 09:44 AM

You may also want to check all of your vacuum connections, check the hose to brake booster etc. An open vacuum line would mess things up. Otherwise I agree withe the IAC, idle control valve. This little valve is responsible for maintaining your engine idle any time you aren't on the gas (stoplights, parked, starting etc). Not sure where it is on the burb, probably near or attached to the throttle body.

choke and fuel mixture is all controlled by the ECU...so there isn't anything to "adjust" in that area. However if you had an open vacuum line it would in essense lean out your fuel mixture.