01 Silverado New Engine - Problem HELP!

Zembonez · January 5, 2006

My 2001 Silverado 4.3V6 AT Reg Cab developed an intake water leak at 80K so I decided to swap for a new engine rather than repair the old one. The install was a no brainer. I used every sensor, distributor, fuel injector spider, and other bolt-on parts from my old engine (which had been running perfectly but had the water leak) I of course installed new plugs / wires / cap / rotor / hoses, etc. everything went smoothly.

I plan on keeping the truck so this seemed like a good plan - UNTIL - On my first drive, I got the dreaded P0300 random misfire code. All cylinders fire perfectly except for #3 and #6 which misfire randomly (according to the computer and my Matco scan tool) I do not feel a miss or have any other dirveability problems. Fuel economy is about normal.

Is there a programming issue with the computer when installing a new engine? I did read in my shop manual that there is a learn procedure for the crank and cam sensors that needs to be done in the event they are changed. All I did was remove them from the old engine and install them on the new one. Can this result in a phantom P0300 code?

I took this to two nice shops recommemded by friends as "really good" and both could not find anything wrong but admit that the code is reoccuring. Neither shop seemed to interested in looking into the problem. The funny thing is that this truck has been perfect up to the point of swapping the engine and never had any codes or driveability issues period. The first problem was the intake leak.

Can anybody help or suggest anything constructive about where to go from here?

GM-Tech · January 6, 2006

You need to do a crankshaft variation relearn. This definitely can cause a P0300 when there's no actual misfire.

The computer can pick up a miss you may not even feel, but if it's enough to set a P0300, I'd say you should feel something. Do the relearn before spending a lot of time trying to find a problem that may not exist. It takes all of 30 seconds to do.

Zembonez · January 6, 2006

You need to do a crankshaft variation relearn. This definitely can cause a P0300 when there's no actual misfire.

I'm all over doing that. Does it need to go to my dealer for it or can it be done in my shop? Sorry for the ignorance here but I don't know what the procedure includes. Thanks

GM-Tech · January 6, 2006

I'm all over doing that. Does it need to go to my dealer for it or can it be done in my shop? Sorry for the ignorance here but I don't know what the procedure includes. Thanks

There's a crankshaft relearn function in our Tech 2 scanner. If you have a scanner capable of performing that function, it is easy to do. If you don't have the scanner capability, you'll have to go to someone that does... most likely only a dealer.

Zembonez · January 6, 2006

I really appreciate the help. Hopefully that will solve it.

Zembonez · January 19, 2006

You need to do a crankshaft variation relearn. This definitely can cause a P0300 when there's no actual misfire.

I'm all over doing that. Does it need to go to my dealer for it or can it be done in my shop? Sorry for the ignorance here but I don't know what the procedure includes. Thanks

<{POST_SNAPBACK}>

Well... a little while later (week or so) and I am back from having the "relearn procedure" done at my dealer.

WOO HOO!

It runs better than ever and all is good! Best 90 bucks I ever spent I believe...I really thank you for that bit of advice once more.

billcar9999 · January 19, 2006

That's a lot for a crank relearn. I pulled into the checkin area. Asked for it, had the why do you want that discussion. The mechanic got his tech2 and did it on the spot. It took about 20 seconds. I drove out. No charge.

Bill

Zembonez · February 1, 2006

UPDATE

1000 Miles later and still no problems... Runs better than ever. The relearn procedure fixed it. Goes to show you that really good advice can be had in here!

My truck went to 2 really well respected shops in Austin, Texas before I took it to my local Chevy store... BOTH of them could not find the problem, I was out $400 and two tows!

Had I only known! Should have come in here first.

WOO HOO!