1994 C1500 350 Idle adjustment? Help???

[LoveTrain59]

Hi, I Have a 1994 c1500, with a 5.7 350 TBI. I decided to try to repair my head gasket, and mid way through was told by a mechanic that I should just put it back together before I mess it up, So I did.

Long story shot, I have it back together, and it runs and starts, but it idles at like 1500 RPM, and sounds way louder and different then it did before. There is one plug that I cant find where it goes to

Heres a pic of it: http://imgur.com/a/F4ExU

Any help would be amazing, Thanks.

I also accidentally adjusted my Kick down cable by screwing it a few times one way, So how would I adjust that to where it needs to be?

Thanks for any help.

[sntrym95]

After you started it, did you disconnect the timing connector and set the base timing to 0*, then turn the engine off and reconnect the timing wire?

[sntrym95]

That connector may be the underhood light connector.

[LoveTrain59]

Originally Posted by sntrym95

That connector may be the underhood light connector.

So the under hood light that turns on when you open the hood? I didn't work, but It's still connected. I didn't set the timing to top dead center, I just replaced the rotor and cap.

[sntrym95]

Ok. I have a couple questions. Why were you replacing a head gasket? How far did you get? What did you disconnect?

[harricanfloyd]

MAF?? did you have the intake tube apart

[LoveTrain59]

I was under the impression I had a blown head gasket, and decided to replace it, since it was spring break and I thought I'd have time to do most of it.

I took off the hood, air cleaner, air filter, throttle body, and computer box things. I unplugged most of the wires in the way.

[sntrym95]

High idle can be caused by a number of things:

1. Coolant temp sensor (wiring, connection, the sensor is bad). Check your connection on the CTS wiring.
2. IAC valve. If the IAC is operating incorrectly, or not at all, it will cause high idle, no idle, etc. Check the connection to the IAC, make sure you plugged it back it correctly and all the way in.
3. The throttle cable you adjusted. Screw it in until there is slack in the cable, and make sure the arm is against the stop. Adjust the cable until there is very little slack, and the arm does not move forward while you are adjusting it. You can also disconnect the cable for the time being to see if that fixes the idle. If it does, that's your issue. If it doesn't, it's something else.
4. Vacuum leak. This could be any number of things - throttle body gasket, vacuum line from EGR, vapor recovery switch, PCV valve, heater bypass (if equipped). Check all the vacuum lines to make sure you put them back where they should be. If you need pics, just ask and I can get you some.

[LoveTrain59]

I just started my truck again since last weekend, and the idle goes to about 1000 rpms. The IAC doesn't snap in, but I pushed it in as far as it would go.


Heres a pic of the cable that I adjusted (circled in red), and also one of the connector that I cant find where it goes. The colors of the wires that go to the connector are Purple and Blue, and the connector itself says 'PED 26'

http://imgur.com/a/UflF7

Just want to make sure we're talking about the same things since I honestly dont know much when it comes to engines.

[LoveTrain59]

I went crawling through other forums and Chevy sites, to find out that the cable is for cruise control, and the connector is some assessory, that no one really know a that it goes to, and it doesn't affect anything.

If I'm not right, please tell me. Otherwise, thanks for the help guys!!

[LoveTrain59]

The idle is still at around 1,500 rpms, and its quite loud, sounds like the belts or something, but its not a loose belt. so that's my last problem.

[95 S_Trucker]

My guess is you have a vacuum leak. Did the throttle body gasket beak when you removed it? Brake booster vacuum line?

[sntrym95]

What you adjusted was the throttle cable. The cruise cable is the other connector on that lever. Try disconnecting the throttle cable and see if the idle returns to normal. 1000 RPM is normal on initial startup, but should come down to 700-800 in Park after a minute or so. Use number 3 in my post above to adjust the throttle cable if it returns to normal when the connector is disconnected.

[LoveTrain59]

Yea the gasket broke when I removed it, I had to buy a new one.

I drove it for about 5-10 min yesterday, and it got down to 1000 rpms after driving it but when I park it the idle goes back up.

I'll try that Sntrym95. Thanks

[LoveTrain59]

#3 didn't help. I screwed the piece on the throttle cable until there's no slack, and it doesn't help. Still idles at around 1500 rpms.

Here's a pic of it. https://imgur.com/eKxEtgY

[sntrym95]

Sounds like a vacuum leak if the throttle cable is adjusted correctly. Check all the vacuum lines to make sure they are tight and in the right spots.