Idle surging and no power in drive,,, please help!!!

[dirttracker11x]

1990 2500 suburban 2wd auto with a 350 tbi.

Ok, recently my buddy and I replaced head gaskets and intake gaskets along with throttle body gasket. Since we put it all back together and I set timing with computer unhooked, it will not run right.


At idle the rpm's surge up and down, crappy throttle response and cant get any higher rpms out of it, in drive it just dies. We thoughr it was timing so we checked and triple checked, its all good, then we changed iac valve, helped a little but still does it.

The only possible way I can get it to idle decent and good throttle response with computer unhooked is at 20 to 28 degrees timing!!! When u plug computer up it advances it to 38 or so, but still no power in drive when u hit the gas.

Things we have changed are: Head gasket, intake manifold gasket, coolant temp sensor, idle air controll valve, map sensor, plugs, wires, cap, rotor, fuel pressure regulator, fuel filter and cleaned injectors and throttle body.

Please help wth is going on lol

 

[Gatorboy]

That really kind of sounds like a vacuum problem somewhere. Check the small vacuum connection behind injectors right in front of the distributor. I've seen similar problems from a vehicle that did not have the line hooked up.

 

[Horns]

I would have to agree with Rob. You have a Vacuum leak somewhere. Use carb cleaner to start spraying around the engine where a vacuum leak could be. When you hear a change in the idle you've found your leak.

Make sure to check all the vacuum lines, the brake booster, the mating surface between the manifold and the TB, and the mating surfaces between the manifold and the block/heads.

 

[dirttracker11x]

My buddy said he already checked for leaks but I will do it again, would a vacum leak cause it to run like crap when its at 0 or 4 advanced timing and run alot better at idle at 20 plus advanced??

 

[Gatorboy]

It could. Vacuum leaks are very strange. Depending on where the leak is completely changes the way it runs. Also changing the timing that much may just hide the leak symptoms to a certain extent.

 

[dirttracker11x]

Ok, if all checks well with vacum leaks what else could it be? Distributor??

 

[Gatorboy]

It's possible but I'm leading more towards the vacuum issue. But I'd pull the distributor and check it out only if all else fails.

 

[dirttracker11x]

Ok well he is gonna check again for leaks tonight

 

[sewlow]

Have you checked the fuel pressure, pump, filter? Might be something to look into before pulling the dist.
If this was my truck, & with my luck, the probs would be something totally unrelated to what I just worked on. Lol!

 

[Gatorboy]

Have you checked the fuel pressure, pump, filter? Might be something to look into before pulling the dist.
If this was my truck, & with my luck, the probs would be something totally unrelated to what I just worked on. Lol!

Story of my life haha