Engine misfires only slightly?

WJBARNICKOL

MEMBER
1995 FORD F-250
7.5L
V8
4WD
MANUAL
72,000 MILES

95 ford 460 engine has injector fire pulse of 5us but with a 0.2 us flicker. Engine misfires only slightly. Does not change with RPM. Drivability is very good. Wont quite pass smog of less than 1 percent CO have replaced plugs, wires, ICM, coil. Have tested fuel pressure, MAP, EGR idle air control. TPS.

Saturday, April 18th, 2026 AT 4:56 PM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
55,469 POSTS

So there are a few things that can cause this issue.

1. Leaking or dirty injectors
2. Fuel pressure regulator
3. Engine coolant temperature sensor
4. O2 sensor lazy or biased rich
5. Exhaust leak ahead of O2
6. Compression issue on one cylinder
7. Base engine timing / distributor issue

Here is a guide to help fix the problem

https://www.2carpros.com/articles/why-an-automotive-engine-will-run-rich

Have you run the codes? This guide will show you how

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

Also, please go over this video to help check the compression. If we have a problem here nothing above will fix it.

https://www.youtube.com/watch?v=KOxIm1F8AW0

Please go over these guides and get back to us.

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Sunday, April 19th, 2026 AT 8:48 AM