Computer issues-S.O.S. help

[kings-x59]

If the throttle plate is closing correctly, iac is working correctly, map sensor and tps working correctly, the throttle body / intake mods shouldn't make it idle high. Is there any possibility that the previous owner, in his porting efforts, created a vacuum leak in the throttle body? as in, burned a small hole through it somewhere?

One other thing just popped into my mind..I've read that the shaft on the throttle plate can wear the hole through the throttle body a bit and create a vacuum leak.

[GEJ]

If the throttle plate is closing correctly, iac is working correctly, map sensor and tps working correctly, the throttle body / intake mods shouldn't make it idle high. Is there any possibility that the previous owner, in his porting efforts, created a vacuum leak in the throttle body? as in, burned a small hole through it somewhere?

One other thing just popped into my mind..I've read that the shaft on the throttle plate can wear the hole through the throttle body a bit and create a vacuum leak.

Yeah,I am leaning towards a TBI issues myself.I'll let you know what I find tomorrow.

[NotDadsW41]

Gary - Again what RPM are we talking about for this high idle? And how long does it last?

All of the TBI equipped vehicles I have owned idled high at startup when operating in open loop mode. Once they warmed up past a certain temp, the idle would come down.

I think you may be chasing a problem that is not really a problem.

[GEJ]

I have seen a small change cold vs operating temp.Still abit high.I'll measure it and let ya know.

[kings-x59]

ditto on the high idle when cold. Mine runs rich and idles quite high until it hits operating temps.

[GEJ]

If it is idling at like 1500 to 1700-I think that is too high.Again,I have seen a slight difference cold to hot.The EGR,IAC,PVC,all seem to be working.Going to disconnect the temp sensor and see what that does.As I said,I will measure the RPM's and tell all of you what that is.

[Rebel]

I check to make sure the spring hasn't fallen off and if not, adjust the idle screw.


Good luck Gary

[GEJ]

As some know I have been chasing a high idle issue on my TBI 350.The engine is still in the donor van because I refuse to swap the problem into Ole Yellar.Recently I swapped the tilt sterring from the donor into Ole Yellar.Well I went back and swapped the Ole Yellar steering column back into the donor to continue to look for the high idle problem and started it up connecting all the wires to it.Damm,it idled normal. Now what in the world would effect that?????.Kind of lost on this one.

[GEJ]

We think the steering column swap and the normal idle was just a chance happening.I still can't get a snap-on scanner or paper clip to link up.If I disconnect the computer and reconnect it,it runs differently.I dropped the data link connector off the dash and looked at the wiring and it all appears to be good.The current thought is it is the computer that is bad.Next wk we are going to swap out the computer and see what that does.If not for nothing,at least I might be able to get some codes from it.

[GEJ]

Three computers and still can't get it to link up. Ck'ed the data connector and the wiring.All looked good. Well I bought this donor for it to be a running TBI 350.So much for that plan.Going to swap out the TBI in the next couple of days to see if that will lower the idle.

[Rebel]

I check to make sure the spring hasn't fallen off and if not, adjust the idle screw.

Ahhhhhhhh,,a carb,,so nice.
Good luck Gary,,wish I could help ya but ole school hear ain't going there. I'll just stick to my carb.

[LiftedAWDAstro]

So Gary, what are the actual RPM's it is idling at? Are you sure it's a high idle?

[GEJ]

So Gary, what are the actual RPM's it is idling at? Are you sure it's a high idle?

Yes Dean-three mechanics,Blazer and myself all agree on that count.After(as I said)the steering column swap,it ran normal and for some reason a check engine did come on.That lasted for only one start and slowly went back to the high ilde. That meant the link to the computer worked for a short time.Now what concerns me more than anything is that fact we can't scan the computer(s) and we put in three of them.Now the swap of a TBI "might" resolve the high idle,but what sensor would prevent scanning the computer??.I am leaning towards a wiring problem and I am going to look at the diagrams at which wire powers the computer.I need VU values if I where to check all the pins at the comupter connector and then at the data connector.I might be able to find if there is a break in the harness or something miss wired.The other thing that may or may not have anything to do with it is it does take alot of turns to start,but aside from the idle,it runs well.

[GEJ]

Here is a thought.If the TBI was preventing a normal idle,would that throw the computer(s) into open loop and prevent me from scanning??.Hummm...
What I am saying is of course with the engine not running and having a bad IAC,IAC motor,temp sensor throttle position sensor.

I guess I am asking at what RPM does the computer go to open loop??.W.O.T.???.

[LiftedAWDAstro]

Open loop is generally where the engine is cold and runs off a pre-programmed fuel map until the O2, coolant temp and other sensors take over control and it goes into closed loop. It is not based off RPM at all but is based on engine temp.

So, what is the actual idle? It has been asked by at least 3 people in this thread and you said 3 mechanics have looked at it...surely 1 of them hooked a tach up to see what it is at and if the mods made any change!