Found: reason for my surging idle
fuzzypuppy
11-18-2007, 08:29 PM
I have seen many post's in the past regarding the pesky surging/searching idle problem on the TBI model GM trucks, in the past I too have been frustrated by this intermitant problem though hopfully never more.
The problem that I found on my truck (91 2500, 5.7 4l80e), was with the TPS sensor connector, though the plastic connections at the TPS seem tight and proper the problem is with the metal male and female pins inside the plastic connector, (at least on my truck), the female pins are spring loaded to assure a good connection because the male side of the connection are small round pins, with a close look at the male plastic side of the connector (female metal inside) I saw that only one of the spring legs was positioned to work as intended (though weak) it would pinch the small round male pin, the other two (supposed to be bowed) spring legs were layed flat for unknown reasons causing a loose connection.
Hard to explain.
I, for a short term fix I jammed some small stranded copper wire into the female hole to ensure a good connection between the male pin and female socket, cut the copper strands flush with the face of the connector to avoid the copper strands from one connection touching the others.
This has worked now for a couple of months, no more idle problems at all!!
Now I need to find a replacment connector, junk yards wont due since I figure that those in the yard will have weakened as mine have.
One odd thing though is my connector does not match with what my Haynes book says it should be, they show a flat connector up to 95 then a round connector up to 02, though my truck is a 91 I have a 95 through 02 round connector, I don't see any splices for at least a foot back on the harness so it seems original. I guess the book could be wrong.
Just thought I'd let those who might have the same problem know what I found, hope this helps others perplexed by this common problem.
The problem that I found on my truck (91 2500, 5.7 4l80e), was with the TPS sensor connector, though the plastic connections at the TPS seem tight and proper the problem is with the metal male and female pins inside the plastic connector, (at least on my truck), the female pins are spring loaded to assure a good connection because the male side of the connection are small round pins, with a close look at the male plastic side of the connector (female metal inside) I saw that only one of the spring legs was positioned to work as intended (though weak) it would pinch the small round male pin, the other two (supposed to be bowed) spring legs were layed flat for unknown reasons causing a loose connection.
Hard to explain.
I, for a short term fix I jammed some small stranded copper wire into the female hole to ensure a good connection between the male pin and female socket, cut the copper strands flush with the face of the connector to avoid the copper strands from one connection touching the others.
This has worked now for a couple of months, no more idle problems at all!!
Now I need to find a replacment connector, junk yards wont due since I figure that those in the yard will have weakened as mine have.
One odd thing though is my connector does not match with what my Haynes book says it should be, they show a flat connector up to 95 then a round connector up to 02, though my truck is a 91 I have a 95 through 02 round connector, I don't see any splices for at least a foot back on the harness so it seems original. I guess the book could be wrong.
Just thought I'd let those who might have the same problem know what I found, hope this helps others perplexed by this common problem.
ttrackerman
11-19-2007, 07:38 PM
:banghead: Hi was your problem just at idle, or was it also at low rpm travel around town. I am having the same problem with bad stumbling at low rpm driving. the only thing about my truck is that it runs very well at startup and will stay good for about 20 min's, then it will start stumbling.could this be the same problem. I have changed alot of parts with no change.
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