Won't rev past 2k M/T

[TexasCrankwalkr]

Tonight my friend and I tried to fix the A/F gauge on my 95 GST that the previous owner completely screwed up on when trying to install it.

When we took the panels off under the steering wheel and driver side kick panel we saw that all the wires were completely hacked. Wires were spliced were they didn't need to be and some wires weren't even connected.

So we connected some wires that seemed to have fallen off and tied to connect the correct wires together to make the A/F gauge work properly.

We disconnect the bottom ECU clip and noticed that he had spliced into it. We also tried connecting a wire to another power wire from the A/F gauge and it almost killed the car.

Once we were ready to see if the A/F gauge would work we put the key into the ignition forgetting that we never put the ECU clip back into the ECU itself. Once I turned the key the ECU made a clicking noise. (I'm not sure if this hurt anything but I thought I would put it into the story in case it is critical)

Once we plugged it back in we started the car back up and it started fine but idled rough. Once I stepped on the gas it would not rev passed 2k. It would stop at 2k sounding exactly like an IC piping had popped off. We checked the piping and everything was fine.

While the car was still idling my friend unplugged the MAF and the car wasn't even fazed by it. The car was also running unbelievably rich.

Thanks in advance, Matt

 

[mini zilo]

So basically you messed with a bunch of ECU wires that you don't know where they go, and now you don't know why the car doesn't run right?










Obviously you need to retrace your steps and put the wires back the way they were.

 

[TexasCrankwalkr]

Im not stupid, thats what we did, but thanks

 

[Mr Peepers]

Side notes:

The spots where the previous owner spliced into the ECU plug connectors weren't actually spliced/making a connection. We fixed them and made a connection.

While the car was running we hooked up the last wire to the A/F gauge, the car seemed to jump in revs. After that was the first time we tried to rev it to see if it was reading anything. It would start stuttering as soon as the throttle was pressed, and sounded just like a 2 step/stutterbox and would even build boost.

The only thing done to the connectors on the ECU were wires spliced into them. No wires were cut. After this we reset the ECU by undoing the battery cables and let it sit for ~10 minutes. Same thing, so we took all the spliced wires off so it was hooked up exactly like the gauge had never been there and reset the ECU again. No change.

Edit: My mistake may have been trusting the previous owner had the correct wires spliced. I had a printout but wanted to see if it was just a loose wire. Apparently it worked fine before, but that is nearly impossible when the spliced wires were not making a connection.

 

[mini zilo]

Well if you re traced your steps then my guess would be that when you were splicing the wire for the o2 sensor, something happened to it, and now it is causing bad readings and you are running rich like you said. How does the wire you spliced for the o2 voltage look?

 

[Mr Peepers]

No, I was trying to reconnect what wasn't properly connected while seeing if the gauge started reading again, being dumb and not double checking it was hooked up right in the first place. Just curious, how would the O2 sensor readout wire have that affect? It would make it run rich yes as the failsafe, but not being able to rev? The symptoms are exactly like a bypassed or bad MAS, even though we did nothing under the hood.

 

[staticbrainwash]

I'd make sure everything is connected back to EXACTLY what it needs to be. Like get a pinout reading on vfaq and make sure everything is in check.

Then, honestly, if it's not wideband. Just ditch the gauge, and wire everything back in how it should be.

Also check the ecu for damage.

 

[Mr Peepers]

Swapped with a known working MAS and no change.

One of the wires the previous owners spliced into was the vehicle speed sensor... I'm still trying to figure that one out for an A/F gauge

Looking for a working ECU to swap tonight.

 

[Mr Peepers]

Sorry for the late update.

After swapping the ECU it ran perfect. I am still unsure of how the ECU was damaged, but I am assuming it was from the seemingly random spliced wires. After making a connection from the previously half assed splicing, it screwed up the ECU.

Lesson learned. DON'T trust other peoples' wiring

p.s. the "lightshow" narrowband o2 gauge has since been discarded.

 

[staticbrainwash]

Haha, yay for no more Christmas lights!