Rough Idle When Cold

[Upstate]

'87 K5 350 all factory TBI with manual transmission. When starting the truck it will turn right over but you need to immediately give it gas to get it to run. To keep it running till it warms up you need to get the idle around 1k or higher which I do by just keeping my foot on the gas. The check engine light does not come on ( yes the light works) and it appears to have good spark. Fuel is older, say like late last fall. Ideas?

 

[eel757]

could be the temp sensor i had the same thing happen to mine

 

[Upstate]

could be the temp sensor i had the same thing happen to mine

So it thinks it is already warm? You are talking the sensor on the front of the intake, tight?

 

[eagle mark]

Manual transmission TBI wear the throttle shaft out at a much faster rate then an Auto. Just think of how you would drive either.

If all the air is coming in through the shaft, instead of over the blades? Then it does not mix the fuel and air properly.

You really need a scan tool or data log to post so I could see it.

A little cheat for right now would be to turn the throttle blade Min. Air Screw in 1/2 turn and see if it helps. Don't play with this otherwise, it does not adjust idle, it only sets minimum Air.

 

[Upstate]

Manual transmission TBI wear the throttle shaft out at a much faster rate then an Auto. Just think of how you would drive either.

If all the air is coming in through the shaft, instead of over the blades? Then it does not mix the fuel and air properly.

You really need a scan tool or data log to post so I could see it.

A little cheat for right now would be to turn the throttle blade Min. Air Screw in 1/2 turn and see if it helps. Don't play with this otherwise, it does not adjust idle, it only sets minimum Air.

What type of Scan Tool should I get? I was looking at a wide band for the bikes, but I realize that is not what you are talking about.

 

[eel757]

So it thinks it is already warm? You are talking the sensor on the front of the intake, tight?

That's the one mine threw a ses light when it went out tho

 

[Upstate]

That's the one mine threw a ses light when it went out tho

I have no check engine light on.

 

[dyeager535]

Got a laptop? Tunerpro RT and an ALDL cable will get you scanning.

There is a thread about ALDL Droid here, too.

 

[Upstate]

Got a laptop? Tunerpro RT and an ALDL cable will get you scanning.

There is a thread about ALDL Droid here, too.

I have both, it looks like most of the cables use a VGA end? Does summit or any of them have a USB?

 

[eagle mark]

Those are very old and a Serial Port which most laptops don't have anymore. Here's a link with a few choices:
http://coloradok5.com/forums/showpost.php?p=3196282&postcount=3

 

[Upstate]

I'll order one tonight. Anything thing else that would help?

 

[Upstate]

Go figure I order a cable from a place that back orders the cable. Anyways, I checked play of the rod. No play when completely closed, I have less than a 1/16 of vertical play at WOT.

 

[Upstate]

Good news for today, temperature sensor was bad. Never any check engine light, but once I replaced the the sensor it now idles. Bad news, it won't start without touching the gas pedal. ideas?

 

[eel757]

Iac?

 

[Upstate]

I have another one that I can put on easily enough, I'll give it a try. BTW still no engine light.

 

[Upstate]

Since the cable is backorder, should I buy a Moates?

 

[Russell]

I'd just make my own cable. Cheap and easy.

 

[jekquistk5]

Have you cleared the ECM and tried again? Check tps voltage?

 

[Upstate]

Have you cleared the ECM and tried again? Check tps voltage?

Yes sir.

 

[Upstate]

Iac?

Wouldn't respond to power, replaced and than the motor starts without input. Still takes a couple cranks.