Yoda31
Probationary Member
- 18
- 14
- Mar 17, 2023
-
Colorado Springs,
Colorado
Guys I’m at a loss for what could possibly be causing this stumble and am praying someone can rid me of this gremlin.
Short backstory:
6bolt early 92’ Talon rebuilt just about everything from the bottom up. Dialed in idle/cruise tune and had been running fantastic for several weeks. Went out one day to start tuning WOT and before I could start, car started acting up. Got it home and pulling into garage it died and would not restart. Fuel pump was not coming on and I found the Hotwire between the relay and fuel pump (rewired) had fried at the connector off of the pump hanger. Rewired that section and pump kicked on. Fired right back up.
Then the stumble began and I’m convinced it is coincidence as I have gone through everything I can imagine fuel related with no change.
I’m convinced it is somehow timing related as I don’t recall in link seeing ignition timing make large jumps like it does. I believe as it fluctuates it typically “runs” up and down instead of jumping from low to high, but I am not sure.
Things tested/checked/replaced:
Fuel - Fuel pump tested & replaced, all lines cleaned/cleared, both filters cleaned/tested, injectors cleaned and tested both on & off vehicle, connectors to injectors replaced, fpr checked/diaphram good/holding steady psi while running, mpi replaced, replaced fuel (e85)
Air - blt multiple times no leaks, compression test both hot & cold throttle open comes back fine. No change from when running great. Does not leak down.
Spark - 2 sets of plugs tested at different gaps, plug wires ohm-tested and replaced, coil packs replaced, ptu replaced, tried 4 different CAS (making sure it’s not 180* out), ecu link v3 tested & replaced.
Other sensors/misc:
Disconnected or replaced coolant temp/iat/isc (fiav deleted), tps, MAP, no change. Mechanical timing components all new, mechanical timing verified, timing tensioner replaced, voltage at battery while running steady low 14s, lifters/rockers pass visual inspection, oil clarity and pressure look great, throttle cable/biss/open-close sensor functioning properly,
I’m sure I’ll be adding more that I’m not thinking of atm.
The stutter is very consistent as if missing on one cylinder. It revs fairly clean, but seems to be just a fraction slower to rev than normal. With throttle held at any percentage, the stutter happens and is consistent with the rotation of the motor.
I’ve noticed the timing in logs on link seems odd but not sure as I never noticed before how it fluctuated. Spark test seemed a bit inconsistent, but got spark from all four plugs. I attributed the inconsistency to bad grounding during the test on my part but may be related to the issue.
I’ve got no idea where to look from here and would seriously appreciate any suggestions for things I may have missed. At this point, I’m just retesting things I’ve already checked several times.
Short backstory:
6bolt early 92’ Talon rebuilt just about everything from the bottom up. Dialed in idle/cruise tune and had been running fantastic for several weeks. Went out one day to start tuning WOT and before I could start, car started acting up. Got it home and pulling into garage it died and would not restart. Fuel pump was not coming on and I found the Hotwire between the relay and fuel pump (rewired) had fried at the connector off of the pump hanger. Rewired that section and pump kicked on. Fired right back up.
Then the stumble began and I’m convinced it is coincidence as I have gone through everything I can imagine fuel related with no change.
I’m convinced it is somehow timing related as I don’t recall in link seeing ignition timing make large jumps like it does. I believe as it fluctuates it typically “runs” up and down instead of jumping from low to high, but I am not sure.
Things tested/checked/replaced:
Fuel - Fuel pump tested & replaced, all lines cleaned/cleared, both filters cleaned/tested, injectors cleaned and tested both on & off vehicle, connectors to injectors replaced, fpr checked/diaphram good/holding steady psi while running, mpi replaced, replaced fuel (e85)
Air - blt multiple times no leaks, compression test both hot & cold throttle open comes back fine. No change from when running great. Does not leak down.
Spark - 2 sets of plugs tested at different gaps, plug wires ohm-tested and replaced, coil packs replaced, ptu replaced, tried 4 different CAS (making sure it’s not 180* out), ecu link v3 tested & replaced.
Other sensors/misc:
Disconnected or replaced coolant temp/iat/isc (fiav deleted), tps, MAP, no change. Mechanical timing components all new, mechanical timing verified, timing tensioner replaced, voltage at battery while running steady low 14s, lifters/rockers pass visual inspection, oil clarity and pressure look great, throttle cable/biss/open-close sensor functioning properly,
I’m sure I’ll be adding more that I’m not thinking of atm.
The stutter is very consistent as if missing on one cylinder. It revs fairly clean, but seems to be just a fraction slower to rev than normal. With throttle held at any percentage, the stutter happens and is consistent with the rotation of the motor.
I’ve noticed the timing in logs on link seems odd but not sure as I never noticed before how it fluctuated. Spark test seemed a bit inconsistent, but got spark from all four plugs. I attributed the inconsistency to bad grounding during the test on my part but may be related to the issue.
I’ve got no idea where to look from here and would seriously appreciate any suggestions for things I may have missed. At this point, I’m just retesting things I’ve already checked several times.
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