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Loping issue

L

Lori Chasity

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Location
Spring Hill, Fl
I have a 1995 Chevy Silverado stepside with a 4.3l vortex motor, TBI, and 285k miles.
My issue is a couple days ago I was going to breakfast and she all of a sudden started "loping" when I have to stop and park. She's got great power otherwise.
I've checked the plugs, wires and all vacuum lines and everything is fine.
I had a high idle issue but replaced the IAC and now that's gone. I still have a slight hard shift going from first to second bit that's not all the time. I have the shift solenoids on order.
Anyways, can anyone tell me what's wrong with my truck on the "loping" situation. Idk crap about these electronic motors. I work on our race cars that have real motors lol thanks all
 
So you specialize in Race Car Starter Motors? Because otherwise non-electric things are called "Engines"... :wacky:

Yes, race cars do not have EGR let alone electronic EGR. I would inspect the EGR valve and see if it hangs up. Emissions equipment varies, but, I am pretty sure the 4.3L has an electronic EGR valve starting in 1994, 1993 on CA emissions. The EGR will bind up partially open sometimes bad enough to stall the engine. Vacuum and backpressure operated EGR is also just as random of a failure.
 
The egr is an old style valve on that one. Even if you put full vacuum to it, it won't open unless theres sufficient exhaust pressure to close the internal transducer. Those trucks have ALOT of issues with the TPS, and your trans shifting issue would support this. Tbi engines have issues with throttle body basa gaskets blowing out causing all kinds of issues, over time the map sensor port can get sludged over from oil getting in through the pcv and vent just above the iac. Also alot of issues with injector spray pattern as this is a low pressure injection system. It's about as simple of an efi system as you can get, just need to do the basic checks like vacuum leaks, cracked vacuum lines, and it's always nice to have a scanner so you can see what the ecm is seeing from the sensors(the good part is there isnt very many sensors on that engine. Tps, cts, 2 knock sensors, map sensor, O2 sensor, and the pickup in the distributor).
 
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