madmax Posted July 11, 2011 Share Posted July 11, 2011 I just swapped motors from a 290k vg30i to 150k same thing. I drove the donor truck for some time before I rolled it and it developed this issue a long time ago. The motor that came out did not have this particular problem so I know I have a good part, I just don't know what it is. Anywho it runs great until about 3500rpm then it starts to misFire or not get enough fuel. I'm leaning towards misfire though. Maybe MAF? Link to comment Share on other sites More sharing options...
Kingman Posted July 12, 2011 Share Posted July 12, 2011 There's next to zero information here to go off of man. So here's what I'll throw out there while basically knowing nothing. Run the codes from the ECU. Do a full tune up. Replace fuel filter. Clean injectors. Clean MAF and harness. Check timing. Check/replace O2 sensor. Check/ replace CHTS. Clean the contacts on the TPS. Etc etc etc. Link to comment Share on other sites More sharing options...
Tungsten Posted July 12, 2011 Share Posted July 12, 2011 Fuel pressure regulator? Get the codes! It's so easy just turn the key to the ON position, you can even start the engine if you like, and turn that screw on the ECU to diagnostic, count 3 lights, turn the screw back and count the flashes. Link to comment Share on other sites More sharing options...
madmax Posted July 13, 2011 Author Share Posted July 13, 2011 (edited) Sorry about the little info. Replaced MAF today, reset the ecu problem solved instinct wins again! I think this is the first time I've seen a 55 code. Just so the post isn't a waste it was running just a little rough at idle this morning and misfired ALOT at WOT over 3500 RPM. Timing wasn't advancing far enough maybe? The old MAF was cleaner than the one I replaced it with so it wasn't just dirty. Edited July 13, 2011 by madmax Link to comment Share on other sites More sharing options...
WarehouseRat Posted July 13, 2011 Share Posted July 13, 2011 run a fuel pressure check under load, if the ecu sees a lean condidtion it will momentarly kill the ignition to prevent detonation, maf shouldn't cause a misfire but would effect drivability and mileage Link to comment Share on other sites More sharing options...
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