Hey guys, I am a Newbie (atleast post wise) from the jeep tech board. I tow my jeeps with a 88 suburban with 350 TBI, 700R4.
I was towing two jeeps on a long car trailer in the Mts and blew a head gasket.
I got the heads done with 16 new valves and the hole works. Put it together and now it doesn't always idle. It runs great on the highway but in stop and go traffic it will idle really low and sometimes the SES light comes on. (I will get the code tomorrow)
It idles so low that the power brakes loose vacume. If you stomp on it it hessitates and then sets you back in your seat like it used to. There are times when you almost have to do a brake stand to keep it running at stop lights.
Any thoughts or should I shut up until I get that code?
Tanx, Nate

VACUUM leak

Either you got a vacuum hose outta place, or the intake did not get seated down all the way when it was put back on. Hopefully it will be something this easy. But, you may have warped the TBI mating surface. That would suck. You could have dirty/loose/bad connections on any of the fuel injection connections. Check all the little shyt first.

It may be a faulty engine coolant temp sensor, located next to the thermostat. If this is faulty it will send bad info to the computer. It usually ends up with a high idle rather than a low idle, as though the coolant is cold. Is this an intermittent low idle or is it continuous? I thought the temp coolant sensor may be something else to consider and they are about $10-$15. Also to check for a vaccum leak spray some carb cleaner around the intake gasket areas, if there is a leak the idle will speed up. Goodluck.

Originally posted by cj8scrambld
Also to check for a vaccum leak spray some carb cleaner around the intake gasket areas, if there is a leak the idle will speed up. Goodluck.


Make sure you spray around that TBI gasket too.


Just for shyts and grins....... have you checked your base timing? Checked the vacuum advance to see if it's working right?

I'd check the gasket between the intake and tbi. Most of the idle problems have been there with ours. Might also check the idle control motor.

Ok, I checked the temp sensor (new when I did the heads) and it is good. I checked my vacuum lines for tight fits and all electrical connections are tight.
The TBI gasket is not sucked in. I am still not satisfied that the hole intake gasket is good. Hard to get spray under the distributor and along the back of it.
How do I check the idle control motor?
Is that the Idle Air Controler they talk about in the manual?
I checked the base timing after I put the distributor in but I guess it could be worth checking to see if the distributor moved.
How do I check the vacume advance?
Thanx again guys
Nate

Originally posted by Nate97TJ
Ok, I checked the temp sensor (new when I did the heads) and it is good. I checked my vacuum lines for tight fits and all electrical connections are tight.
The TBI gasket is not sucked in. I am still not satisfied that the hole intake gasket is good. Hard to get spray under the distributor and along the back of it.
How do I check the idle control motor?
Is that the Idle Air Controler they talk about in the manual?
I checked the base timing after I put the distributor in but I guess it could be worth checking to see if the distributor moved.
How do I check the vacume advance?
Thanx again guys
Nate

There is no vacuum advance on a TBI motor. There is no idle control motor. The advance is controlled by the computer (ECM). Sounds to me like a vacuum leak. Good luck.

Advance your timing a little and triple check for vaccum leaks

I wasn't sure if TBI motors had vacuum advance, but at least it was a thought:D

sounds like a vac leak for sure, spray the carb cleaner and check for leaks, jsut be carefull when spraying by the dist. cap. if you idle doesnt change, fatten the fuel mixture up by spraying carb spray directly into the throttle body itself, if the idle evens out you have a lean condition, most of the time this is due to a leak,,

Ok, I checked the temp sensor (new when I did the heads) and it is good.

You're talking about the sensor in the intake, not the head, right? The one in the head is for your gauge, the intake sensor is for the fuel injection.

This thread is 5 years old guys...do you think this guy is still around?

1 was gonna say the same thing...........