1994 with idle issue (1 Viewer)

[Troy Nelson]

I have a 1994 80 series that runs great on this call as soon as it warms up it will not idle or only hold about 200 RPM and stutter back-and-forth until it finally dies,I have checked the idle air control and cleaned it and have smoked the vacuum system and have not found any vacuum leaks. I am at a loss as to what position could be... any ideas

 

[ppc]

Cracked intake tube is a possibility most likely on the underside ribs. What has been your recent repairs and maintenance?

 

[Troy Nelson]

Cracked intake tube is a possibility most likely on the underside ribs. What has been your recent repairs and maintenance?

I have checked the intake too. I have not found any cracks in it. I have just purchased the vehicle and It was having this issue. It also had a leaking valve cover gasket and replaced the valve cover gasket, replaced numerous vacuum lines that had cracks in them and still it is not fixed the problem. I have taken the idle air control out and cleaned it I have not tried to adjust or re-set the throttle position sensor. I have smoked the system and have not found any smoke leaks. I have sprayed brake cleaner over all the vacuum lines and was able to locate numerous vacuum line faults this way. When I spray brake cleaner under the plenum I seem to get a idle surge but am not finding any cracked lines. Maybe VSV?

 

[jbee]

I had loose wires at oxygen sensors that caused my weird idle on a 94.

 

[Troy Nelson]

H

I had loose wires at oxygen sensors that caused my weird idle on a 94.

hmmmm, I will try that

 

[fjbj40]

I know this much. If the AFM is not plugged in the engine runs fine till it warms up, as long as you apply no throttle, but once it warms up the rpm drops to about 400, then stutters and dies once 200rpm is reached. It will also stutter and die as you apply throttle. I found this out after all my intake RR and the only thing I forgot to hook up was the AFM and that is how it behaved.
So, have a look at the AFM as it may have issues?

 

[Troy Nelson]

I know this much. If the AFM is not plugged in the engine runs fine till it warms up, as long as you apply no throttle, but once it warms up the rpm drops to about 400, then stutters and dies once 200rpm is reached. It will also stutter and die as you apply throttle. I found this out after all my intake RR and the only thing I forgot to hook up was the AFM and that is how it behaved.
So, have a look at the AFM as it may have issues?

I know mine is plugged in but I will check all the connections and check it for leaks as well

 

[mudgudgeon]

I know mine is plugged in but I will check all the connections and check it for leaks as well

Do some reading about the AFM before you take tools to it.
Many have screwed up a good AFM by undoing screws that should not be touched

 

[Troy Nelson]

I know this much. If the AFM is not plugged in the engine runs fine till it warms up, as long as you apply no throttle, but once it warms up the rpm drops to about 400, then stutters and dies once 200rpm is reached. It will also stutter and die as you apply throttle. I found this out after all my intake RR and the only thing I forgot to hook up was the AFM and that is how it behaved.
So, have a look at the AFM as it may have issues?

If I apply throttle all is well. In fact the po seems to have bypassed this problem by simply adjusting the throttle cable to a higher idle

 

[Landseer]

Cracks in the intake tube are frequently not readily visible. I swore mine looked good but wrapping it in duck tape immediately solved a low idle problem, replacement intake tube solved it long term.

 

[Troy Nelson]

Cracks in the intake tube are frequently not readily visible. I swore mine looked good but wrapping it in duck tape immediately solved a low idle problem, replacement intake tube solved it long term.

I will try it. This point I’m at my wits end. I have seafoamed it, nothing, I’m wondering if it has something to do with the throttle position sensor?

 

[sogafarm]

I will try it. This point I’m at my wits end. I have seafoamed it, nothing, I’m wondering if it has something to do with the throttle position sensor?

Speaking of "wits end", they sell intake tubes.
www.absolute-wits-end.com

 

[sogafarm]

Do some reading about the AFM before you take tools to it.
Many have screwed up a good AFM by undoing screws that should not be touched

Ditto on this, do not do anything to the AFM sensor screws, you will break soldered connections on the inside which are critical. You can unplug the wiring harness but do not touch the two screws!!!! I know this personally.

 

[Troy Nelson]

Speaking of "wits end", they sell intake tubes.
www.absolute-wits-end.com

Bought one

 

[Troy Nelson]

I will try it. This point I’m at my wits end. I have seafoamed it, nothing, I’m wondering if it has something to do with the throttle position sensor?

I taped it and it made a huge difference but still stutters. Ordered a new one.

 

[Landseer]

It might take the ECU a few minutes to "relearn" now that you're not getting unmetered air.

 

[Tireguy87]

Good luck. I’ve been chasing an idle issue in my ‘94 for months now. I know it’s not good to just throw parts at it, but I’ve replaced just about everything I know of. First cold start up and it dies immediately. Second start it will idle and stumble. Give it gas and it wants to bog down until it’s good and warmed up.

 

[Troy Nelson]

Good luck. I’ve been chasing an idle issue in my ‘94 for months now. I know it’s not good to just throw parts at it, but I’ve replaced just about everything I know of. First cold start up and it dies immediately. Second start it will idle and stumble. Give it gas and it wants to bog down until it’s good and warmed up.

This one starts great but as soon as warms up idle gets a little spotty. I duct taped the intake and it got a lot better but still sketchy. Looking for other ideas. Also anyone have details on calibrating TPS?

 

[sogafarm]

Good luck. I’ve been chasing an idle issue in my ‘94 for months now. I know it’s not good to just throw parts at it, but I’ve replaced just about everything I know of. First cold start up and it dies immediately. Second start it will idle and stumble. Give it gas and it wants to bog down until it’s good and warmed up.

That sounds like what my '94 did when I pulled the AFM out stupidly. The first tab on the afm plug regulates the initial start up. If yours has ever been tampered with then the only way to fix it is to take off the sealed plastic cover and look inside to see if the contact is making proper connection. It looks like a wind up clock on the inside. I readjusted mine, and also resoldered the 2-4th pins to the board. I have pics and details here:
My first 80

 

[Troy Nelson]

That sounds like what my '94 did when I pulled the AFM out stupidly. The first tab on the afm plug regulates the initial start up. If yours has ever been tampered with then the only way to fix it is to take off the sealed plastic cover and look inside to see if the contact is making proper connection. It looks like a wind up clock on the inside. I readjusted mine, and also resoldered the 2-4th pins to the board. I have pics and details here:
My first 80

I am thinking the tps going into the intake and butterfly?