Stutter/misfire on deceleration

87azsupra · 08-06-2019, 06:47 AM

Hey guys first post here.

Have an 87 base model na 7mge.

Had a bhg so I changed the head gasket and head for a newer head. Swapped old cams, lifters, and put in arp headstuds torqued at 90 ft lbs.

Block was hand scraped and cleaned. Apex headgasket with copper spray. Head was milled at unknown amount and pressure tested.

Put it all together checked the timing marks 10 times before I went to start the car. Wouldn’t start ended up being dizzy off one tooth. Got it started and it idles great and drove perfect for the first 100 miles.

I have since encountered a stutter/misfire after 3k depending on where I place the accelerator pedal. I get lots of pops and backfire on decel with a bit of blackish blue smoke when the stutter/pop happens. I can let off readjust the speed and it’ll be fine til I start to let off then it misfires and stutters.

Car doesn’t misfire on idle, it will free rev all the way up in WOT or neutral. Doesn’t misfire when holding the pedal down or at any rpm in neutral.

I have checked the timing at the cams and crank. Checked with a timing light set at 10*.
Checked the tps.
Changed plugs.
Checked plug wires.
Retorqued the head.
I don’t lose any water. I don’t have any oil or water leaking near the plug galley.

I’m stumped and annoyed as hell after all the hours I put in this car. Any help would be appreciated.

I can provide pics, whatever info needed as well.

08-06-2019, 06:47 AM	#1
87azsupra Stock Join Date: Aug 2019 Location: Mesa, Arizona Posts: 1	Stutter/misfire on deceleration Hey guys first post here. Have an 87 base model na 7mge. Had a bhg so I changed the head gasket and head for a newer head. Swapped old cams, lifters, and put in arp headstuds torqued at 90 ft lbs. Block was hand scraped and cleaned. Apex headgasket with copper spray. Head was milled at unknown amount and pressure tested. Put it all together checked the timing marks 10 times before I went to start the car. Wouldn’t start ended up being dizzy off one tooth. Got it started and it idles great and drove perfect for the first 100 miles. I have since encountered a stutter/misfire after 3k depending on where I place the accelerator pedal. I get lots of pops and backfire on decel with a bit of blackish blue smoke when the stutter/pop happens. I can let off readjust the speed and it’ll be fine til I start to let off then it misfires and stutters. Car doesn’t misfire on idle, it will free rev all the way up in WOT or neutral. Doesn’t misfire when holding the pedal down or at any rpm in neutral. I have checked the timing at the cams and crank. Checked with a timing light set at 10*. Checked the tps. Changed plugs. Checked plug wires. Retorqued the head. I don’t lose any water. I don’t have any oil or water leaking near the plug galley. I’m stumped and annoyed as hell after all the hours I put in this car. Any help would be appreciated. I can provide pics, whatever info needed as well.