General Maintenance & Repairs - LS1 problem starting up and runs very poorly..

Newbie here to LS1Tech, glad to be apart of the community. :burn:

LS1 went down south on me 2 days ago driving down the highway and now the car drives and sounds like a go-kart. Motor is out of a 99 Camaro SS. Everytime I try to fire it up it takes a few cranks to get it started, once it starts I wanna say it idles at around 100 or less and I have to keep the RPMs up or else it will die! Right now it has very rough idle, wants to stall when it's under load, backfires like crazy, and it has lack of power when you try to accelerate.

Checked all the fluids and they are still good, noticed my Oil Catch was broke though.. went on to run a OBDII and it threw out some eye brow raising codes..

P0108 Manifold MAP Sensor High Voltage
P0134 02 Sensor Activity
P0342 Camshaft Position Sensor A Circuit Low Input (Bank 1 or Single Sensor)
P0412 Secondary Air Injection Switching Valve A Circuit
P0418 Secondary Air Injection System Relay A Control Circuit

I went ahead and tried to run a compression test and all I got was 1 cylinder giving me a reading and that was 120. All the other cylinders weren't giving me any reading what so ever! I took off the covers and there was no damage inside..

Can't figure out what it could be, any help would be much appreciated, thanks!

Are you blowing an smoke out of the exhaust, and if so, what color is it?

It's blowing out smoke but not out the exhaust, it's coming from the intake and it's black.

Sounds like your map sensor is bad and causing a vacuum leak.

You should pull the intake manifold off but be careful of getting the brake booster hose caught on the oil pressure sending unit. After you pull the manifold you can acess the cam position sensor.

I would also replace your 02 sensors. Make a day out of doing maintenace

Sorry for not updating, haven't got around to it quite yet but gonna take a crack at it first thing tomorrow. Chrysler kid, going to clear out the codes and go from there.

However I did run a OHM meter to the MAP sensor and it was reading 1.00? Don't know if that is the right amount?

I would scan it, see what the 02 sensors are doing. Might just need to replace one of them and all will be good.

Clean the MAF too.

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Most likely replacing your front o2(s) will fix your issue. AIR codes are nothing to worry about at this point.

But the engine does not have any compression in the driver side of the engine, and the other side I only got to test 2 out of the 4 and only 1 cylinder was producing compression.. I don't see how changing sensors would fix this problem when it's a mechanical side that's causing a compression issue?

I did however took off the timing cover to inspect if it may have skipped a tooth and causing no compression but I was surprised that it was in fact not off. I even manually cranked the motor with the intake manifold off and inspected the valves and no bent valves and only heard that 1 cylinder compressing air. Swapping sensors would fix this?..

But the engine does not have any compression in the driver side of the engine, and the other side I only got to test 2 out of the 4 and only 1 cylinder was producing compression.. I don't see how changing sensors would fix this problem when it's a mechanical side that's causing a compression issue?

That was some pretty important info you left out......don't you think.

Swapping sensors would fix this?..

No.


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That was some pretty important info you left out......don't you think.
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I didn't leave out anything if you read my first post..

"I went ahead and tried to run a compression test and all I got was 1 cylinder giving me a reading and that was 120. All the other cylinders weren't giving me any reading what so ever! I took off the covers and there was no damage inside.."

Just a quick update, I pulled off the heads and saw light scuffs on all 4 of the driver side pistons, the valves are indeed bent.

I'm in So Cal, if any of you guys have a local machine shop you go to that has fair prices it would be appreciated. I'll be ordering the parts tomorrow. Just want to get her back on the road again soon. :drive: