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weird lope/ rough idle ( out of ideas)

metalneverdies

metalneverdies

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I had a high idle but it was smooth before I fixed my leaking intake manifold.

I had a bunch of carbon built up in the EGR port. It was 100% blocked. I chipped that all out and cleaned everything up and the truck sounded much better ran better over all but now I have a weird lope / rough idle. once I give it the smallest tap of the gas in neutral or drive it goes away.

I re-did the timing. I checked for vacuum leaks. I even replaced my cap and rotor ( cap had a small amount of corrosion on the terminals inside). I used felpro gaskets and ACDELCO cap and rotor. It has new plugs.

Could this be caused by my EGR being able to work again? It also smells a bit rich.
 
When you "re-did" your timing did you disconnect the EST wire?
 
4X4HIGH said:
When you "re-did" your timing did you disconnect the EST wire?
Click to expand...

Yes I did. I then set the timing right at or a hair off from 0* using my timing light. Tightened up my distributor lock down bolt and re-verified my timing. Then connected the EST wire by the brake booster
 
You may be having issues then with the EST module just to the right (passenger side) of the TBI unit.
 
4X4HIGH said:
You may be having issues then with the EST module just to the right (passenger side) of the TBI unit.
Click to expand...

Is there any tests to verify that is the issue? I hate to throw parts at the problem.

The EST module is the flat "box" attached on the little riser bracket over the passenger valve cover right?
 
metalneverdies said:
Is there any tests to verify that is the issue? I hate to throw parts at the problem.

The EST module is the flat "box" attached on the little riser bracket over the passenger valve cover right?
Click to expand...

Yes that is it, it has a connector with about 4-5 wires.
 
Did it run fine when you timed it?

You sure the EGR valve is working right? Pintle is seating?
 
dyeager535 said:
Did it run fine when you timed it?

You sure the EGR valve is working right? Pintle is seating?
Click to expand...

It ran great before I did the intake manifold. I had timed it and done a tune up and it ran great. Noticed the manifold was leaking and then 2 weeks or so later i did the manifold and then when i was finished retimed it.

Thats what makes me think it was something with the egr. But it only does it at idle. From my understanding one cant test the egr in neutral you have to be driving dor it to actuate
 
Does it have any error codes? Is the IAC valve working correctly? Try unhooking the battery for a minute or so and connecting it again, or pull the ECM fuses. Sometimes mine does nonsense like that and that will cure it. If your lucky.

And you can test the EGR, with the engine running and your neck not getting caught in the fan. Grab the EGR and push the diaphragm "up" into the housing, it will only move one way, and the idle should change instantly. If not, the EGR or the EGR controller thingy are not operating correctly.
 
454Sub said:
Does it have any error codes? Is the IAC valve working correctly? Try unhooking the battery for a minute or so and connecting it again, or pull the ECM fuses. Sometimes mine does nonsense like that and that will cure it. If your lucky.

And you can test the EGR, with the engine running and your neck not getting caught in the fan. Grab the EGR and push the diaphragm "up" into the housing, it will only move one way, and the idle should change instantly. If not, the EGR or the EGR controller thingy are not operating correctly.
Click to expand...


no error codes. not much of a surprise with the super insensitive OBD 1 :mad1:

I have tried the battery deal. No luck.

I pulled the vacuum off of the EGR verified it gets vacuum when engine rpm increases. When the egr had the vacuum like pulled there was no change in idle.

It almost stalls out and looses all vacuum if you let it sit at idle stopped. I cant find any vacuum leaks. I went down to the o reilly's there are a couple helpful guys there. The one dude thinks its either a vacuum leak type deal or maybe the EST(?) module in the distributor. He was also wondering about my coolant temp sensor. It seems to work ok though because my dash gauge acts the exact same as before.

checked the EST module and looked at the wiring it all looks ok and the connector lock is still good.

:thinking: :confused:
 
metalneverdies said:
no error codes. not much of a surprise with the super insensitive OBD 1 :mad1:

I have tried the battery deal. No luck.

I pulled the vacuum off of the EGR verified it gets vacuum when engine rpm increases. When the egr had the vacuum like pulled there was no change in idle.

It almost stalls out and looses all vacuum if you let it sit at idle stopped. I cant find any vacuum leaks. I went down to the o reilly's there are a couple helpful guys there. The one dude thinks its either a vacuum leak type deal or maybe the EST(?) module in the distributor. He was also wondering about my coolant temp sensor. It seems to work ok though because my dash gauge acts the exact same as before.

checked the EST module and looked at the wiring it all looks ok and the connector lock is still good.

:thinking: :confused:
Click to expand...

The coolant temp sensor is for the ECM and NOT your temp gauge.
 
Drivers side head, single connector, green wire. Highly doubt it's the coolant sensor, does it start hard, run rich all the time, etc? If not, probably not a CTS issue.

I'd still lean towards a vacuum leak. You double checked tightness on all intake/TBI bolts? EGR bolts?

Electrical issues are never fun, but I would *think* ESC would be a consistent issue. Engine is under ECM timing control once it exceeds 400RPM, if the problem exists at idle you'd expect to feel it at light cruise too, if it was a spark issue.
 
All bolts are torqued to factory spec with a torque wrench. I re-used metal egr gasket but made sure to tighten down the gasket really well.

I figured my weird missing and terrible idle to continue under cruise as well if it was some type of est or timing issue. I have sprayed carb cleaner all around the vacuum lines and intake trying to find
A vacuum leak and have had no luck.
 
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