Loping idle
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5th Wheeling
Joined: Dec 2019
Posts: 43
Likes: 2
Loping idle
Hello all, I have a 93 f150 flareside with the 302 and M5od, I recently replaced the vacuum canister with the plastic one that I found in a junkyard, and after replacing noticed when I come to a stop at a stop light (clutch in put it out of gear and then have the clutch pushed in while in first waiting for the light) the rpm bounces from roughly 700rpm to a little over 1100 rpm. When I stop by taking the truck out of gear and using all break it won’t lope but after sitting for a few seconds it will begin to do the same thing where it lopes from 700-1100 rpm. Could it be a vacuum leak somehwere that I’m missing? Also thinking about getting the egr block off plate, would that help this? Thanks all.
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5th Wheeling
Joined: Dec 2019
Posts: 43
Likes: 2
before I did the canister swap it would lope but not as speratic as now, probably be within 200 rpm range that it’d lope. I’ve always had problems with my egr since I got the truck, the only codes I’ve ever gotten were that and a faulty temp sensor.
Hotshot
Joined: Jul 2020
Posts: 10,331
Likes: 2,585
From: Near Salt Lake City
The usual cause for idle surge or lope is an intake vacuum leak
It is not just the A/C compressor running in defrost causing the surge? right?
Leak test the intake gasket with some Brakleen or water and see if the idle changes (carb foam, propane or non flammable Brakleen) is what I use
93 302 check the upper plenum gasket too
sometimes just a good visual, inspection will reveal a bad plenum gasket (they crack and some of it will be sticking out that you can see)
You should find buy or rent a scan tool and perform key on engine off and key on engine running tests (KOEO and KOER) tests
The idle fluctuating (slight) when on and off the clutch is normal for some calibrations to keep the truck from falling on its face when shifting gears
Check the codes to see if the truck thinks there is something wrong with itself.
It is not just the A/C compressor running in defrost causing the surge? right?
Leak test the intake gasket with some Brakleen or water and see if the idle changes (carb foam, propane or non flammable Brakleen) is what I use
93 302 check the upper plenum gasket too
sometimes just a good visual, inspection will reveal a bad plenum gasket (they crack and some of it will be sticking out that you can see)
You should find buy or rent a scan tool and perform key on engine off and key on engine running tests (KOEO and KOER) tests
The idle fluctuating (slight) when on and off the clutch is normal for some calibrations to keep the truck from falling on its face when shifting gears
Check the codes to see if the truck thinks there is something wrong with itself.
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