gf261

After re-installing the intake on the 87, it now idles at about 1300-1400 rpms. Anything that I could have bumped during the reinstall that would cause this? The one thing about it that does make me feel better is that it is consistant and does not bob up and down. Any insight on where to start looking or how to adjust idle would be great. Thanks in advance.

Jim bailey - 928 International

There is no idle adjustment on any 1987 or newer 928 ...none zero .The actual speed is computer controlled by the LH brain which opens and closes the idle stabilizer valve under the intake multiple times per second to hold a constant 675 plus 25 RPM for the 87-89 S-4 and when you turn on the A/C etc. it compensates .

worf928

Check the cable from the firewall (goes to the pedal in the cabin) to the cable assembly on the side of the intake. Make sure it hasn't pulled away from the firewall and is correctly seated at the firewall. Make sure the three levers are not binding and move freely.

Did you disturb the adjustment of the cables during the intake R&R?

EDIT: Also make sure that the throttle cable is routed correctly around the pulley.

Your constant incorrect idle points to a mechanical issue as the likely culprit.

Chris

You have an air leak somewhere south of the MAF or you have a vacuum leak.

Idle stabalizer electrical wires hooked up ?

Chris

gf261

Jim, thanks for the brain info. Since it is a constant figure, I am in line with Dave on the mechanical thing. I know that the pully arrangement is fine, checked it four or five times at least. The under intake valve looked good, although there is a chance that my five way splitter might be the culprit if that is where its vacuum line goes in. (if memory serves)
Dave, I think that you are probably correct. It is just a matter of running down the mechanical part. I don't think that the cables are an issue since they were wire tied together and out of the way as soon as they were removed. The levers are fine as well. I will check the portion at the firewall.
Chris, I feel good about the idle stabilizer wire. I am going to re-check the MAF for a leak. Wouldn't this cause other problems as well though? Everything else runs like a top. The idle is the only problem.

Thanks again guys for the help, it is truly invaluable.

the flyin' scotsman

Had a similar high idle condition when I removed the MAF and disturbed the throttle cable on the pulley. You could start by disconnecting the cable to the gas pedal and determine if the idle returns to normal. If the issue remains then perhaps the cable to throttle plate.

An air leak would cause the idle to stay high for a short period of time before settling to a more regular level, also may cause a backfire when releasing the go pedal.

worf928

Garrett, Malcolm's suggestion was going to be my next suggestion.

But, do the check at the firewall first. With the cable assembly disconnected and flopped back and forth during the intake R&R the pedal cable is disturbed. On older 928s the plastic part at the fire wall is usually broken due to age and thus when the pedal cable is flopped around the plastic part slips out of its 'socket' on the fire wall. The result is that when you bolt the assembly back to the intake the pedal cable is pulled out a little further and results in a 1200-1600 rpm idle.

One guess on how I know this?

If you are certain that the pedal cable is not the culprit after disconnecting the cable as Malcolm suggests then you have a LARGE intake leak. Check the y-connector on the passenger side of the MAS elbow. If the elbow is not new then the y-connector can easily get pulled out during the installation of the intake.

gf261

Dave, that may very well be what has happened. I will check on that first since my cable was pivoted out of the way in just such a fashion that would allow that to happen. Hopefully that is it. I don't think its a MAF problem, all the seals were very pliable and it all looked tight when re-assembled. Anyway, I'll start at the firewall and see how it goes. Thanks again!

lorenolson888

My car did the same thing... it was the cable housing near the firewall.. my car is an 86 but I am sure if the cable goes thru the firewall in a smilar way it could be overlooked easily.. I pulled on it and the tension was released... idle went back to normal...
LO

KAmey1970

Idiot newbie question....(I have had my shark for 3 weeks and have just finished the TB/WP)

What is correct idle.

I am at about 700.

Kevin

Jim bailey - 928 International

Kevin that depends on what year and model 928 you have.

KAmey1970

1983 US

gf261

Found it guys. The cable that runs from the bottom outisde of the pulleys to the driver side fender was slightly bent. I straightened it and it idles like a charm. All suggestions were checked and found to be fine though. Thanks for the help again everyone.