Strange misfire after downshifting

Cort · Sep 16, 2019

Hello everyone!

So when I start my car (95 SN95 5.0 5spd intake, gt40 heads mild comp cam) it runs and drives fine. If I downshift and coast in that gear for a few seconds it drops a cylinder. Stays that way until I turn it off and let it sit for 10 minutes or so. Turn it back on and everything is fine again until I downshift. If I don’t downshift and just coast in neutral it’s fine. ECM appears to be untouched. I recently purchased the car with all of the bolt ons in place already. I don’t believe it’s ever been tuned. Any thoughts?!? Thanks!

General karthief · Sep 16, 2019

#1 thing to do is check for codes.
there are instructions on this on the technical, how to thread.

Electrical - How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it... Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on. Dumping the computer diagnostic codes on 86-95 Mustangs Revised 26-July-2011. Added need to make sure the clutch is...

www.stangnet.com

Cort · Sep 16, 2019

General karthief said:
#1 thing to do is check for codes.
there are instructions on this on the technical, how to thread.

Electrical - How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it... Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on. Dumping the computer diagnostic codes on 86-95 Mustangs Revised 26-July-2011. Added need to make sure the clutch is...

www.stangnet.com

So please forgive my ignorance, but from what I read from the link you attached the dump code procedure is for the diagnostic plug under the hood. Mine is under the dash and looks different than what is pictured. Do the 94-95’s have an obd2?

96pushrod · Sep 16, 2019

Cort said:
So please forgive my ignorance, but from what I read from the link you attached the dump code procedure is for the diagnostic plug under the hood. Mine is under the dash and looks different than what is pictured. Do the 94-95’s have an obd2?

It also has one under the hood if it’s a 5.0. The one inside isn’t used to read codes.

Cort · Sep 16, 2019

I must be looking in the wrong area. Not seeing anything that resembles a diagnostic plug in the same area thats in the thread. Again, I apologize for my ignorance. I know you guys are always trying to help noobes like me.

General karthief · Sep 16, 2019

I'm thinking the 94-5 is located on the passenger side in the corner of the firewall.

Cort · Sep 16, 2019

Ok thanks. I’ll check there

Cort · Sep 21, 2019

So, I checked all the basics. Replaced the cap, rotor and plugs. All were worn pretty good. Plugs looked like it’s been running lean and one was cracked. All of them were .060 at the least. Ran a little better after changing them. Still not 100% right though. Vibrated a lot still. Glanced at the harmonic balancer while it was running and it didn’t look right. Kinda wobbled, but the pulley was true. Ordered a new one and installed it tonight. Night and day difference!!! Runs like a raped ape and very smooth. I’m sure it still needs to have the ecm tuned, but for now it’s way better.

Strange misfire after downshifting

Cort

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General karthief

wonder how much it would cost to ship you a pair

Electrical - How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs

Cort

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Electrical - How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs

96pushrod

I think they're a little easier to get off

Cort

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General karthief

wonder how much it would cost to ship you a pair

Cort

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Cort

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Strange misfire after downshifting

Member

wonder how much it would cost to ship you a pair

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I think they're a little easier to get off

Member

wonder how much it would cost to ship you a pair

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