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Misfire

Tiny
JAYMOE76
  • MEMBER
  • 1995 FORD RANGER
  • 2.3L
  • 4 CYL
  • 2WD
  • MANUAL
  • 250,000 MILES
After changing plugs and wires and coil packs I still have a had misfire. It shakes and the check engine light flashes at full throttle. It shows cylinder 3 misfire code. Timing is good and seems to be getting enough fuel. When I changed plugs I noticed a lot of build up in the plenum. Crank and cam sensors are both new if that makes any difference.
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Friday, August 14th, 2020 AT 7:57 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Does this only happen at full throttle? Is the mileage you listed accurate for the engine? If it is, you may have a compression issue.

Let me know if you have already checked that. Also, here is a link that shows how to test compression. You may want to consider it.

https://www.2carpros.com/articles/how-to-test-engine-compression

Let me know if the only code you are getting is a P0303. If there are others, let me know what they are. One last thing. 1995 was the first year for OBD2 diagnostics, but some still used OBD1. Let me know which this vehicle has.

I will watch for your reply.

Joe

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Friday, August 14th, 2020 AT 9:02 PM
Tiny
JAYMOE76
  • MEMBER
  • 4 POSTS
Yes the miles are correct. When the issue first started it would run perfectly fine unless I ran it over 80 for a long period of time it would start losing speed and the check engine light would flash. If I pulled over and let it sit for 10 minutes it would go again and be fine. Then one day I was getting on the highway and it started misfiring like a tractor (its straight piped) its ran rough every since and I have changed plugs and wires twice and gaped them at.042. Also, I can unplug injectors and throttle positioning sensor and it will run the same. I'm just really lost with it at this point. I thought maybe a valve was sticking or might be bad and a guy told me about an old trick of dumping transmission fluid in it to clean valves but that made no difference either. At first it was showing codes for cylinder 1 misfire, EGR and o2 sensor but after doing all the other things to it without messing with EGR or o2 sensor those codes went away and I was left with 1 code for misfire on cylinder 3.
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Monday, August 17th, 2020 AT 1:14 PM
Tiny
JAYMOE76
  • MEMBER
  • 4 POSTS
It was originally only at full throttle but now it idles with a bad misfire and the motor shakes.
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Monday, August 17th, 2020 AT 1:17 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
If you pull the number three spark plug, what does it look like? Have you checked to make sure there isn't a partially plugged catalytic converter? If you remove an upstream O2 sensor, see if it runs any better.

Let me know.

Joe
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Monday, August 17th, 2020 AT 2:25 PM
Tiny
JAYMOE76
  • MEMBER
  • 4 POSTS
Yes, I just changed plugs a week ago they looked fine.
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Monday, August 17th, 2020 AT 4:01 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
If the plugs weren't oil filed or showing indication for a misfire, check engine compression. Also, was the timing belt replaced recently? It could be stretched and causing a timing issue.

Let me know, but honestly I would start with compression.

Joe
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Monday, August 17th, 2020 AT 9:05 PM

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