The Project Pad

First off, I've scoured the FAQ and SJMAuto's ECU tech page, Motorgeek, QW and my CQ Bentley for ideas with no luck.

Just did a motor swap into a nice clean chassis owned by at least two enthusiasts before myself.

The motor, ECU and POS that I swapped were all in fine working order as I drove the donor car for a week or two prior with not a single issue to suggest the impeding hair puller.

Once the swap was completed I couldn't get the car to idle properly. Turns out it was the coolant after run pump and ISV wiring plugs were reversed. In the process, I diagnosed the following:

-- engine bay grounds have juice
-- MAF functions properly
-- boost hose --> ECU is solid
-- boost hoses are solid
-- car gets fuel and makes spark
-- N75 appears properly connected
-- TPS clicks when moved thru range of motion
-- unplugged positive battery terminal for 30s to reset codes


Current problem is that the car will idle strong but not make ANY power. Can't even attain 20 km/h. As such, I can't drive it home and (of course) my lease is up at the garage I'm renting this week.

Plan is to go today armed with a paperclip to see if there are any codes (CEL/MIL is not on while running). Triple check the N75 is attached properly.

Only other thing of note, is that after driving around the block to test the car, the oil pressure light comes on and beeps, but there is 5bar on the gauge. Not sure if this is MFTS or oil pressure sensor related, but shouldn't be the culprit.

Unfortunately I don't have a compressor to check for boost leaks. But in all reality the engine would make more power than what it has right now anyway. I know this from having daily driven a couple 7a coupes for the last six years.

It's like something is putting you in super limp mode if you can't even hit 20kph. That's messed up, I don't have much advice. The guys on QW and mg seem to have you covered.

Hard to say if you say maf and vacuum are ok. I'm no pro but did you swap the maf for a known working one just to make sure? Tps working correctly? Even tho it clicks, doesn't mean it works, did you test the resistances at pins? It could be saying to the ecu i'm in idle mode even tho throttle is open. Does it "freerev" high/normally? Does the rpm drop instantly on the tach while engine still revs allot or progressively? I had a problem on an old 20v where the engine would cut/choke at ~3000 rpm on the mac1x ecu, no one could figure it out. Turns out there were used/broken teeth on the flywheel making the ecu loose synch. Ignition would cut/rpm signal would also cut till it found synch again (so maybe vr sensor alignment/distance issues when you put it all together).
You could also have put the wrong or plugged the engine temp sensor wrong/mixed it up. May sound stupid but do you have the right injectors for the ecu you have? What's your fuel pressure like at the rail?

Oil pressure thing is probs because you have the secondary oil sensor wired wrong (goes off at around 2000rpm i think ).

Got it!

Had doubled up the chassis to motor mount ground on the passenger side. Removed one and properly routed the other... presto! She fired right up and drives great!

Thanks everyone for the advice.