2G stuck in limp mode

[tschuhly]

Hey all,

I am trying to figure out what steps I should go through to figure out what is causing my issue.

Some background is that the car has been put together and running since about mid April. Towards the middle or end of May it started to act like it had a misfire or something. I replaced the spark plugs with the higher horsepower ones but that didn't do anything.

I decided to check for codes and I got the knock detection circuit fault code. I found that my sensor was loose so I tightened it up and no luck. I then was driving it and as I took off from a light, it sputtered a little and when I gave it slightly more gas it bucked hard once and then turned off. I got it towed and later found that my ECU 20amp fuse had "blown" or broke (I'm not sure if it was just old and brittle or if it legit blew). I replaced it and my knock sensor with a new one jic and my car started up except now it won't go over 4500rpms.

It doesn't have any codes but is still running a little weird and is still in limp mode. I tried to go into my ECU pinout settings to tamper with them to see if it was because of my AEM boost sensor being pinned to my MDP pin, but it is still in limp. I will say that for a little bit I had forgot to unplug my stock MDP so there were probably 2 conflicting signals going to the ECU so maybe that did something? I haven't driven it yet because I worried it will leave me stranded again.

I attached a log of it starting, idling and revving a little. Any guidance would be appreciated!

 

[99dsmer4g63]

The plastic cap with the black wire and “shield” wire are factory. There is a few ground connections like this buried in the harness in the nearby area.

https://stmtuned.com/collections/sheridan-engineering-products?srsltid=AfmBOorhrSQMgPVEucUBF-XE_tuT4j72W1TvpaZGJhDWsGoG6-lNHE8t

-Daniel

 

[tschuhly]

Also, I called a local Mitsu dealer and the parts guy gave me to seemingly useful links for terminals and connectors that I will put here for helping future people.

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connectorexperts.com

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findpigtails.com

 

[tschuhly]

The plastic cap with the black wire and “shield” wire are factory. There is a few ground connections like this buried in the harness in the nearby area.

https://stmtuned.com/collections/sheridan-engineering-products?srsltid=AfmBOorhrSQMgPVEucUBF-XE_tuT4j72W1TvpaZGJhDWsGoG6-lNHE8t

-Daniel

Do you think I should reroute an entire new wire from the ECU to the sensor? If so, what's the best way of doing this in your experience or is there anything to keep in mind? For instance, this is definitely a different wire than the rest, do you know what I should purchase if going this route?

I think I may also try to run a wire from the sensor to the ECU temporarily just to see if it makes the rough idle and throttle go away to see if this truly was the issue.

 

[tschuhly]

Final update...I think I've most certainly found the problem.
The wire on the harness side of the knock sensor plug, was apparently damaged enough to not be making a good connection with the plug pin but it hadn't pulled out of the connector completely which is why I didn't see it. I am going to attempt to repin that to see if that fixes things!