GrampasBuick

I'm working on a coworker's Vette and it's being weird.
He had a (now former) friend install a cam, headers, a FAST 92 mm intake, throttle body, injectors, and some other small stuff. About 500 miles later it was throwing the 343 code, cam position sensor. Ohming it at the computer shows it working. Could be cam bolts backing out. While troubleshooting they reversed the wires on the cam sensor.
Car has not been tuned yet due to Check Engine light. It runs crappy as a result.

So then I get the car. I pulled the intake and put in a new pigtail for the cam sensor because a wire fell out in my hand on the old one. Was hoping that was the problem. But I had to reverse the wires to make them correct.

I fire it up, it starts hard, but starts and runs like it has been. After 10 minutes or so of running, I was about to test drive it, when all the sudden it starts running really really bad. There are about 10 codes, most of which say Throttle Position, and the dash display says reduced engine power. It won't go over 2000 rpm and it sounds like it is missing cylinders.

WTF!!!

All this stuff is new. Live data on my obd2 scanner shows the car thinks the throttle is at 100%.

I don't know what this guy did to this poor car.

Any ideas?
P.s. The 343 code came right back, so looks like I gotta pull the timing cover, which involves pulling the steering rack.
Should I just bow out and not get involved?

Old Geezer

iTrader: (3)

wrong forum, grandpa...

vettenuts

iTrader: (4)

I have seen cam sensor issues when the bolts in the cam plate loosen and the cam starts moving back and forth. Normally, I wouldn't suggest this being the issue but since a cam was installed it could very well be. Also, was the original plate installed or the new design, which uses different bolts than the original. I would not drive the car or start the motor until you can confirm the cam is not moving.

You need to find out more about how that cam was installed.

GrampasBuick

That's what I was thinking, it made sense that it took about 500 miles for the code to come up. Took some time for the bolts to loosen.

As far as finding out more, that's not gonna be an option unfortunately. The owner isn't very technical with cars and the former friend is, well, a FORMER friend.

GrampasBuick

It's a 97-06 LS1 that I'm working on. I put it in the 97-06 LS1 forum.

vettenuts

iTrader: (4)

I hope I am wrong on this, but not sure I would run the motor until to can eliminate the cam walking as the issue.

GrampasBuick

So I took it all apart and the cam bolts are tight. Good that it's not that and we don't have a mechanical problem.

That doesn't explain the car going into limp mode.
It also doesn't explain the cam sensor code. Cam sensor is also new.
I talked to the owner and it turns out that it is an LS2 throttle body and the mechanic messed with the computer to get it to work. It's a new TB, only like 500 miles on it. The owner said the car freaked out and went into limp mode a couple times and he clears the computer to "fix" it.
I can't get it out of limp mode. No TPS signal. And I can't put the original TB because it's different from the LS1.
(grumbling)

jcvett56

So when the key is and in the ON position can you press on the throttle pedal and hear/visually see, with intake off of course, the throttle body move?

Since they put a 6-pin LS2 Throttle Body in lieu of the LS1 DBW 2-Pin,6-Pin some other wiring has to be moved around since 2 wires are being absorbed.
This may explain your no TPS signal.

GrampasBuick

I just came in for the night, so I'll have to check tomorrow after work. Thing is, it was working. It was running, sitting in my driveway idling, and then all of the sudden it just started this crap.

How do I ohm a TPS? I feel like if OBD2 is telling me it's a bad TPS, I should at least give it the benefit of the doubt and check it.

RonSSNova

iTrader: (3)

There should be an adapter harness for the new TB that is installed. Two orig plugs from the car to one plug for the TB.
Check and clean those connections.

The TB actually has two tps inside it. You can't replace them.
If either messes up, you get reduced engine power.

You can clear the C5 codes from the dash. Press options, while holding it down , press fuel four times. That will put you in diagnostic mode. It will scroll through the modules and show codes. Once done it goes to manual mode. I think options lets you scroll manually. Push reset to clear codes.

That new TB could be the issue. But more likely a wiring issue.

GrampasBuick

The TPS codes won't clear. Basically the car freaked out and gave me engine codes, HVAC codes and stability control codes, and they all clear out fine. But the TPS codes don't go away and it stays in limp mode.

The adapter for the TB is new, only 500 miles.

The owner was talking about excessive heat from the headers, and it's on the passenger side where the harness goes to the computer. I wonder if something is shorting out.