Strange misfire after downshifting

Cort

Member
Sep 15, 2019
20
3
13
42
Colorado
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!
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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#1 thing to do is check for codes.
there are instructions on this on the technical, how to thread.
 

Cort

Member
Sep 15, 2019
20
3
13
42
Colorado
#1 thing to do is check for codes.
there are instructions on this on the technical, how to thread.
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

Advanced Member
May 15, 2018
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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

Member
Sep 15, 2019
20
3
13
42
Colorado
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.
 

Cort

Member
Sep 15, 2019
20
3
13
42
Colorado
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.
 
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