5.0 missing at idle, but runs fine otherwise

69 Rustang · Sep 20, 2006

I have a 302 in my 86 Ford F150 that runs great under load and at speed, but has a miss while idling. The motor is in excellent condition with about 10,000 miles on a complete overhaul. Here is what I have done so far:

New plug wires
New plugs
new cap and rotor
stock rebuild other than mild porting to remove emission humps
shorty headers
Added heat shields to plug boots due to headers (misses with and without the shields)
Scanned for codes, but found none

This is a speed density, dual plenum truck manifold fuel injected system. It barely passed smog last time.

Anyone have any ideas?

HISSIN50 · Sep 20, 2006

If it's SD, you can run a cylinder balance test to help narrow down the source of the miss. With the puter being able to note even the faintest of inconsistancies (what we cant do), it helps a lot.

The CBT is part of the self-diagnostics (you do it after KOER code retrieval). The test wont tell you what component is at fault, but it can tell which cylinder(s) are not pulling their weight, and to what degree.

Good luck.

5.0 missing at idle, but runs fine otherwise

69 Rustang

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HISSIN50

"How long does it take to get help in here?

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5.0 missing at idle, but runs fine otherwise

69 Rustang

Member

HISSIN50

"How long does it take to get help in here?

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