4.0 swap running issues

Swaping 258 to 4.0, 4.0 parts to 258 etc!
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Posts: 579
Joined: May 22nd, 2008, 11:57 pm
Stroker Displacement: 4.6L
Vehicle Year: 1980
Vehicle Make: AMC
Vehicle Model: Spirit
Location: Red Deer, AB, Can

4.0 swap running issues

Post by amcinstaller »

Ok so it's been a minute since I've been around, but I finally got around to getting my AMC Spirit running with a 4.0 swap. Overall it seems great but I have a couple issues I'm having trouble working out. I have tried searching for days, some people having kinda the same issues, and they post their results but I try those and they don't fix mine. Here is my troubles:
Random sputters, sometimes a miss at speed or sometimes just stumbly at a light
Hard 3500ish redline (like fuel cutting or spark cutting)

What is has in it:
-93 4.0, with SBEC from an auto, TCM stuff trimmed out. AX15 trans, Ford 8.8
-NSS was grounded initially to let it start but in troubleshooting I cut it. Starts because the SBEC does not control start out
-no VSS (currently pulling speed signal to my autometer gauge from the tone wheel in my 8.8 axle)
-delco 10/12SI alternator to 175 amps
-Taurus electric fan setup, no engine driven fan, runs around 195-200F
-99+ intake with 39PSI rail
-new 3/8 fuel lines, 3 inch intake, 2.5 inch exhaust no cat
-CCV venting to atmosphere, not into intake
-Autometer sport comp tach (8k, set to 6cyl, triggered from the SBEC tach output)

What I've tried/replaced:
-injectors are new remans, had a couple that were dribbling
-fuel pump replaced
-Fuel rail regulator replaced, has 40PSI at idle with the reg unplugged, plug it in and it drops to 30ish at idle
-new plugs/wires/cap/rotor, gapped to .035
-when it was going into the car, I took the time to do the rear main seal, pan gasket and head gasket. Went with a felpro MLS, retorqued head bolts, leakdown test shows all cylinders around 70% (in the green on my tester)
-cleaned throttlebody, replaced TPS
-Didn't get an o2 sensor with the engine so that is new
-if I kink the vacuum line to the MAP sensor, it dies if you give it throttle
-put a new thermostat before installing engine

My codes:
12 (batt disconnected, never seems to go away)
33 (no fan relay)
35 (no cruise) could have these two backwards
42 (I think? the alternator code, I have an SI unit)
55 end of codes

The only thing left I can think of is the coil is questionable, but I measured it with multimeter and it seemed ok? The CPS is mounted to the factory spot on the AX15 bell, and the distributor is all lined up nicely (even checked the hole underneath for the trigger wheel). Other than that, does the SBEC put out a 6cyl tach signal for a 4.0 and 4cyl signal for the 2.5? I really doubt they wouldn't match
1980 AMC Spirit Restomod in Progress
SilverXJ wrote:Roller rockers won't help that mess you have created. Nor will God for that matter.
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