Rebuilding my tbi? Is it hard?

[Williebeaman]

so I’ve been having some idling issues and even had the truck die in me a few times when I come to a stop or reverse or even sitting in traffic occasionally. It’s a 89 jimmy 350 tbi 700r4. So I got the truck back in January and so far I’ve done ball joints,hubs,bearings, rod ends, oil/diff change, and I’m about to do the plugs and wires tonight. I was wondering what’s the difficulty level of this? It seems simple enough but one video I’ve seen says you have to hook a wire up inside and set my idle? The whole unit is super dirty and looks like it might be the culprit probable something gummed up inside. Also is the 20 dollar rebuild kit on amazon a good one? Got mostly good reviews. Thanks for any help and information!!

 

[dyeager535]

Dont know what you can get quality rebuilds for now, but if bone stock, you might be best off buying a rebuilt one.

Those units can get slop in the throttle shaft, that can create a vaccum leak and I assume also issues with the TPS.

That's also assuming the TBI or one of its components are the issue.

 

[nbrown2500]

Check out these guys https://throttlebodyinjection.com
I am going to order mine from them next month. They have been very helpful over the phone and have answered all my questions. I have looked into rebuilding mine but it is all a wash when you consider the cost of the new parts including having bushings installed for the butterfly and the time it takes to do the work yourself. They also test the units before they leave their shop. Just my two cents.

 

[Williebeaman]

Well dang I was hoping y’all would tell me it’s super easy and to go for it I watched a few YouTube videos it doesn’t seem SUpER difficult. Hmmmm what to do what to do ....

 

[dyeager535]

None of it is hard, except bushing the shaft. If that needs done, rebuilding the rest of it is pointless IMO. I mean there are plenty of things to go wrong/leak there, so the throttle shaft isn't the only possible issue, but if you are going to do it, do it right, no?

But it's also not guaranteed it needs bushed.

 

[nbrown2500]

Yes if your TBI doesn't need the bushings and your other components work and are fairly new then just rebuilding one is not hard at all.

 

[jtrux]

I have done a few. Easy. Now I will go ahead amd say that it's not likely your culprit. I would take a hard look at the wiring going to it. Recently had some issues and some of the wiring had grounded to a braket due to rubbing issues. Anyways, I would look hard elsewhere just to make sure that there's not another issue.

 

[jtrux]

Specifically the wires going to the TPS.

 

[Williebeaman]

Well I did it today, it for sure seems to respond better to my throttle and is running great but I still have my problems of occasionally stalling out when coming to a stop and idling at a red lightning and reverse stalls me out sometimes I’m gonna try replacing the egr and also my alternator is pretty dang loud I noticed today with the hood open and looks older than me.

 

[dyeager535]

Be careful with the egr. Dont toss yours. You may be able to reach under it while running (before it gets hot) and push up on the underside. Engine should run worse. Some operate the opposite way however, and sometimes the aftermarket will get you the wrong one. Most are "universal", but gm used hundreds...most are physical differences (position of vacuum line for instance) but some are how they operate. FWIW egr does not work at idle, when cold, decelerating, etc.

Anyway. Do a good check underhood. Wires. Hoses. Plugs/plug wires. Vacuum leaks dont help TBI. Any engine codes? Check engine light operates properly?

 

[wasted wages]

when it stalls, are you having to hold the brakes harder than normal? It could be a problem with the torque converter.. especially since it seems to be worse in reverse.. if the one-way sprag in the convertor is locking up it will drag down the engine and stall it.
My next door neighbors car was doing this so bad, he had to shut it off at stoplights and restart it when the light changed !!

 

[Williebeaman]

I’m not having to hold the brakes any more than usual. I’ve had it die before at stop lights and I’ll start it up and it’ll run like a champ. It doesn’t do it all the time.

 

[wasted wages]

You would definitely notice it,, my neighbors car was pulling pretty hard when he would stop. Almost like not pushing in the clutch on a manual transmission..

 

[Williebeaman]

Could it be my idle air control valve? I looked at it when I rebuilt the tbi but it looked good to me so I put it back in.

 

[imiceman44]

Could it be my idle air control valve? I looked at it when I rebuilt the tbi but it looked good to me so I put it back in.

You can't tell from looking at it.
The best way is to try another.
You could also remove it and see if it makes a difference.
They are not expensive enough not to change it and try to fix the problem

 

[Psymantis]

Could it be my idle air control valve? I looked at it when I rebuilt the tbi but it looked good to me so I put it back in.

My '87 occassionally stalls at red lights and putting it into reverse. The service engine light comes on when it stalls but it always starts right back up and runs fine after. I replaced the egr and iac and it's still stalled a couple times since replacing them.

 

[Williebeaman]

My '87 occassionally stalls at red lights and putting it into reverse. The service engine light comes on when it stalls but it always starts right back up and runs fine after. I replaced the egr and iac and it's still stalled a couple times since replacing them.

Well dang that sucks. Guess I’ll try anyways. It’s really annoying I wanna fix this.

 

[imiceman44]

My '87 occassionally stalls at red lights and putting it into reverse. The service engine light comes on when it stalls but it always starts right back up and runs fine after. I replaced the egr and iac and it's still stalled a couple times since replacing them.

Did you clean up the egr passages in the intake when you changed the egr?
Most of the time it is pretty plugged up

 

[imiceman44]

Also look for some vacuum leaks, mostly at the base of the throttle body

 

[Williebeaman]

Also look for some vacuum leaks, mostly at the base of the throttle body

I’m a total noob rock working on cars I’m learning as I go. How would I check for vacuum leaks? and if I find them is it as simple as a new hose? Thanks for any info!