3.8/auto - ZERO codes - terrible idle - not driveable - backfires

Gdad45

New Member
Sep 3, 2020
3
0
1
64
Scott County Kentucky
Trying to get a friend's Mustang going. 1996 3.8 Auto

At idle the ignition advance usually is 6-8 degrees. Occasionally the idle smooths out and the advance reads 20-25.
Short term trims % for both banks are 10-12
All four O2 sensors are .1 - .8 volts
ST11 & ST12 are both 7-8 %
Fuel pressure at idle is 30psi
Manifold vacuum at idle is 15-17. I cannot find any leaking or broken vacuum lines or vacuum leaks.

I can't check the injectors as the bolts for the upper manifold are apparently seized and I do not want to snap them off
New plugs and wires. The pintle in EGR valve operates OK.
The vacuum hose to the canister is blocked off. I'll get that connected tomorrow.
Disconnecting the alternator results in the engine idling fairly well. A different alternator did not change anything.

Thoughts??
 
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Gdad45

New Member
Sep 3, 2020
3
0
1
64
Scott County Kentucky
Trying to get a friend's Mustang going. 1996 3.8 Auto

At idle the ignition advance usually is 6-8 degrees. Occasionally the idle smooths out and the advance reads 20-25.
Short term trims % for both banks are 10-12
All four O2 sensors are .1 - .8 volts
ST11 & ST12 are both 7-8 %
Fuel pressure at idle is 30psi
Manifold vacuum at idle is 15-17. I cannot find any leaking or broken vacuum lines or vacuum leaks.

I can't check the injectors as the bolts for the upper manifold are apparently seized and I do not want to snap them off
New plugs and wires. The pintle in EGR valve operates OK.
The vacuum hose to the canister is blocked off. I'll get that connected tomorrow.
Disconnecting the alternator results in the engine idling fairly well. A different alternator did not change anything.

Thoughts??
ANYBODY?