Dinosaurs In Space

SOLVED: for anyone who cares...

Noticed 0.05 VAC on the +5 VDC sensor line and slowly disconnected sensors trying to find the issue.

Took it all the way to the ECU trying to find the 5 VDC regulator circuit.. No luck

I installed an LM1 in the secondary O2 location in my 3" downpipe for tuning.. Apparently this guy had crept over to the heat shield and cut the wiring to where when the downpipe shook, it shorted out the +12v line which caused the ECU to stumble...

Disconnected the sensor and it runs good as new. What a ******* nightmare.

Hopefully this post helps some one in the future.. and hopefully it isnt me.

Bump

Car will run 100% fine in idle. Monitoring the 'idle mode sw' in cobb, as soon as it turns to OFF the car starts stumbing, no matter how much pedal is applied.

-New Pedal

-New Engine wiring Harness

-Replaced (used) throttle body

Next step is compression test I guess..

i had hesitations/stumbles on accelaration on most occasions till my crankshaft position sensor gave up the ghost>P0335 dtc.

 

I did a r/r routine on the sensor (cheap & easy), been running fine, no more code no more symptoms. 89000 miles ago.

Sorry, that was one sensor I forgot to list in the original post that was also changed.. Edited original post.

Look through the stumble thread for more ideas like the sti fpr setup and longer fuel line but I think the best solution is to reroute the fpr vacuum line from the #4 intake runner to the bpv vacuum source line. Try that and get back.

Sorry, this is not the typical fuel stumble issue. I've already dealt with that problem on this vehicle years ago and found a solution that works for me.

Hi All, I'm at my wit's end with this. Long read ahead

I've been having a low load stumble at all RPMs with driving for a few months now. I can get it to replicate the stumble by sitting in neutral and revving to 2000 -3000 RPMs trying to hold constant throttle input.

The AFR is reading 14.7 perfectly then the car 'burps' and the AFR jumps to 13.5ish, the RPMs jump then the car recovers. This happens about once every 1-2 seconds. This DOES NOT happen at idle.

When I force the car into open loop using AP, it still happens in open loop.

I'm not getting ANY codes.. and I am getting some roughness on all cylinders (but not much)

Thing's I've tried: All new parts are OEM

*New Air Filter

*New MAF

*New Front O2

*New Coil Packs

*New NGK LFR7AIX plugs (same as it had)

*New DW65C fuel pump (with new OEM in tank filter)

*New Battery

*New Crank Sensor

*Cleaned all ground straps

*Tore apart fuel system to look for debris, all new Orings + gaskets

*Disabled AVCS (in tune)

*Changed Tunes (have been running same tune for over a year with no problems)

*Cleaned throttle body

*Intake leak test @ 5psi - no leaks

05 LGT Wagon 5-spd

Mods are as follows: ~30k on engine / parts since rebuild

*IAG Stg1 block

*EFR 6758

*ID1000 with top feed fuel rails + plumbing

*Tomei FPR

*Stock Airbox + Perrin Inlet pipe

*Stock header + Custom UP pipe

*3" TBE

Log attached - You can even see the AFR change in the LM-1 data (installed in factory 2nd O2 location)

Any help is greatly appreciated! I haven't driven this car in a few months!

AFR Issues.csv