Putter

I reset the timing on my 90 vert to 6* BTDC. After hooking up all items, the idle has jumped up to about 1,000 r.p.m. I would appreciate input as to what needs to be adjusted. It was about 800 r.p.m prior to me re-setting the timing. The idle control screw on the throttle body is adjusted out to the point it does not touch the accelerator plate.

Thanks in advance for any ideas

A couple of years ago, I replaced the fuel pump, injectors, manifold gaskets (upper & lower), just additional information.

CFI-EFI

The spec for the timing is 6° BTDC. The idle speed is programmed into your chip, or prom and is not user serviceable. Changing the timing should not change the idle speed. It sounds as though you have a vacuum leak that needs to be taken care of. There is no "idle control screw". As I said the idle is controlled by the ECM. With your FSM at hand, from the tech tips, or one of the various members personal sites, follow the steps to set your minimum air adjustment and TPS voltage. With those properly set, you can see if you have a vacuum leak to chase or possibly an IAC problem.

RACE ON!!!

vinnies87

Bound Throttle cable
Issue with trottle blades
IAC
vacume issue

AGENT 86

Did you unplug the EST wire before attempting to reset timing ??
Have you messed with the min idle screw on throttle body ??

Putter

I disconnected the EST as directed for setting timing. The screw on the throttle body does not even touch the butterfly plate.

The throttle body seems to functioning just fine.

I am going to inspect for throttle cable binding / adjustment, tonight.

CFI-EFI

The butterfly plates are inside of the throttle bores. There is no screw on the throttle body that could possibly touch either one of them. There are two screws through each butterfly plate to retain them to the throttle shaft, inside of the throttle bores. Are you referring to the throttle stop screw used for setting the minimum air adjustment? Are the butterfly plates tightly closed in the throttle bores? If so, air is entering the engine from other than the minimum air setting. That means either an IAC issue or a vacuum leak. If the butterfly plates are tightly closed in the bores, don't waste time checking linkage or cables. Also, there are no throttle cable adjustments.

RACE ON!!!

mikey whipreck

On my '85 there is a mess of vacuum tubes near the hold down bolt for the distributer. I had to move those tubes around a lot to get to that bolt to adjust my timing.

Assuming that your idle changed, and all you did was adjust timing, I would check those vacuum tubes in that area..

Putter

Yes, I meant the throttle stop screw. I did not literally mean the butterfly plates themselves, just the connecting plate lever that actuates the butterfly plates.

I will check all of the vacuum lines around the distibutor.

NT Vettman

I would at this point do a minimum air set.This set of adjustments sets a base timing and a base idle speed not controlled by the ECM. I have the minimum air set adjustment instructions giving out by Gorden Kilabrew. If you want it PM me with you email address

CFI-EFI

There seems to be some resistance to that idea. See post #2.

RACE ON!!!

SunCr

How the idle changed with a timing adjustment eludes me. Why did you adjust the timing in the first place?

The idle stop screw should be touching the linkage. Minimum air is just that - a minimum amount of air flowing pass the butterfly which is necessary for the IAC to do it's job. The only way to open the butterfly is with the screw. Something ain't right - would prefer to know why you made the adjustment in the first place rather than suggest you do something that might make it worse.

NT Vettman

I agree that it would be nice to know why he reset the timing in the first place. But now if he or some one had adjusted something other than the timing the IAC is not function right because it doesn't have the base setting to start with. I learned the hard way when I replaced my throttle body and adjusted the idle screw out of ignorance. I still say at this point it's the way to go to get every thing back to the basics then if it still idles high then trouble shoot farther.

xflagz51

If the throttle body is dirty then you may not be able to adjust any of it. If there is schmegma between the butterflies and the throttle bores, then the butterflies will never close to where they should be. The IAC can get jammed up with crud as well. This condition happens slowly over time, and it may not be what is causing your problem. But it's something that is worth checking if nothing else works.

vader86

You need to take the TB off and clean it, then do the IAC reset. Procedure is on my site.

mikey whipreck

While I agree with you guys that cleaning the throttle body and adjusting the min air (even though I disagree with how to adjust it) will improve the idle... Why would it help the guy in this case?

His idle was fine, he screwed with the timing, now his idle is off. My first assumption would be that he knocked something loose while changing the timing. He messed with the idle stop screw, but I still don't see how that has any bearing on idle.

Maybe I just dont know that much about this system though. If I'm wrong, please point out where I'm wrong.

Putter

To all of those that I now have pondering as to why I reset the timing on my 90 vert. As I mentioned, I changed the intake manifold gasket due to an oil leak. When I pulled the distributor out, I had marked the back of the manifold as to where #1 plug wire. When I put the parts back together, I forgot to take a screwdriver and turn the oil drive gear back a little so that the distributor would drop in in the correct tooth alignment. I don't drive the vehicle much (16,000 miles in 7 years), so I decided to check everything out. I pulled the distributor, moved the oil drive gear and reinstalled the distributor. I disconnected the EST, loosened the distributor, set the timng to 6* BTDC, and reconnected the EST. The idle speed is now about 1,00o rpm and thus, my thread.

Rich

xflagz51

Hey Mikey, you're absolutely right. That's why I said, "this may not fix your problem". You can correct me if I am wrong, but the #1 problem with the idle on these cars is dirt and filth building up over time and opening up the butterflies to the point of increasing the idle speed. It's also the most basic check and if you don't do it then you will be chasing your tail with the rest of the adjustments, better to make sure of that before you waste a lot of time.

Putter

I will clean the throttle body, vist Vadar's site for the IAC adjustment, and follow up with everyone.

I did clean the throttle body when I pulled the mainifold off to replace the gasket and have only put about 5,500 miles on the vehicle since that time. I performed a little porting on the plenum housing just behind the throttle body (the two bumps at the bottom and around the edges, nothing elaborate.

I have inspected all of the vacuum lines for leaks, but everything appears to be connected.

Other than the idle, the vehicle runs strong.