Yesterday I installed a square top manifold on my 99 n/a NB. The install went smoothly, the biggest pain was when I decided to re-reroute my MAP line to my MS2E ecu. Everything started right up, and after some putting around and auto-tuning the car is was running better than it ever had before.

I took the wife out and about today to run some errands - everything was running great, but after the 3rd stop the car started was really hard to start. Once it got it turned over it went way rich and ran like complete garbage, I limped it over to my parents and plugged in my tuning laptop.

Just switching on the ECU and reading my gauges in turner studio my issue was obvious. My TPS is stuck at 143%. Touching the pedal didn't produce any change. I went to calibrate the TPS and the "get current" was ~1400. (regular settings are ~300 closed ~800 open) No change with pedal movement.

Also, without the car running the CLT sensor reading is jumping erratically between 0 and 45. It's 85 degrees out.

I'm thinking bad ground or bad ECU to Harness connection? Did I fray something during my IM install that went bad gradually? Did I screw up the TPS while the throttle body was off the IM yesterday (I never unhooked it)? Has anyone experienced anything similar? Thanks for any help, wife is already pushing for part-out

 

Looks like the TPS VREF and signal wires are shorted together. Also check the CLT wiring for continuity.

 

and/or bad grounds.

 

Do you think it's more likely that I jacked something up under the hood, or something shook loose under the dash? It's just odd to me that everything was fine immediately after re-assembly, then after a few hours it all went to ****.

I had the throttle body zip-tied to the upper radiator hose during the installation, but I wonder if I still managed to torque the wiring of the still connected TPS? But that wouldn't explain the CLT issue.

I'm going to go back and re-address my grounds - the ones on top of the TB and under it, attached to the vibration dampener, were cleaned before re-assembly. The first thing I did was check to make sure they didn't come loose, but I'll go back through them all.

Thanks for the responses guys.

 

if the tps was disconnected i could see this maybe happened. but the clt seems like a loose connection or sorts. id start digging there.

 

So I spent several hours rooting around my harness and don't have much to show for it. This is my first real attempt at troubleshooting a wiring issue, so if I come across as not knowing what the hell I'm talking about it's not a ruse.

I dug up a wiring diagram, and found a circuit (BLK/RED) that's shared between the TPS, CLT, IAT, old O2 sensor, Fuel tank pressure, and EGR boost sensor. This seems like the culprit, because I've now discovered that my IAT is also messed up (stuck reading at 70*).





I checked between all the connectors under the hood for blk/red continuity, they seem fine. No obvious breaks in the harness, I took the top chamber off the intake manifold and looked around in there too. Re-cleaned my grounds, they seem fine. I haven't crawled under and checked the fuel tank pressure connector yet.

I removed all the EGR crap a while ago, and put block-off plates on the back of the squaretop when I installed it. Also, as you can see in the below pic, I capped the tank purge line because I had seen other people on a returnless system do this without issues. With the 100* weather last weekend when my sensors went kaput, do you think I had excessive tank pressure or something related to EGR removal that could have caused a short in this circuit?



That's it for now. Wiring issues are soul-destroying so I had to come inside and pet cats.

 

PROBLEM SOLVED

I pulled the MS unit and found the soldered joint holding together a bunch of grounds in the harness had a connection broken off. Surprise, surprise, this was the ground supposed to be attached to blk/rd sensor circuit.

 

good show, old chappy.