Z'mnypit

iTrader: (58)

I recently did an engine swap for a guy for a 347 forged LME motor. Well everything is perfect except for the fact the tach will only rev to about 2800rpm then it will go to 0 and sit until the car reachs back idle where it will then pick back up. I figured no problem, its a bad ground. Ive redone/checked every ground on the motor and its still doing the same thing.

Ive scanned the car with HPtuners and get two cam postion sensor malfunction codes. I pull the intake swap out the sensor clear the codes and it comes right back with the same codes. None of the wiring is pinched in the bellhousing, ive checked that. Ive checked everything I know to check and its still not right.

I was told that maybe the reluctor ring on the crank is bent or out of place. I guess its possible beings the crank is a stock crank that was reused but machined 1st. Or maybe the shipping knocked it out a tad. I was told that if its off or bent it would do exactly as I described. It seems to run a little rich at idle but not bad, its hard to start, you can turn it over a couple secs before it will actually fire, then sometimes it want fire and acts like its flooded. Its got a bad surge/miss 4500rpm and up almost like its starving for fuel, but according to my logs its dead on the money with the AFR.

After I completed the install, I tired to do a crank relearn but as soon as the tach would stop it would give me an error message so i was unable to do the relearn. I tried I know 50 times or more.

It just doesnt make sense, can anyone else think of anything that I could try, or check before I start pulling the motor back out? I know it prolly want work but Im going to pull the crank position sensor out and swap it just a try. If you have any suggestions postem up.

Z'mnypit

iTrader: (58)

Anybody?

John02SS

iTrader: (47)

I've had a similiar problem and the cam sensor was bad. I've seen them not complete the relearn if the code was stored in teh pcm for the crank or cam sensor. Clear the codes and then immediately try the relearn. Hope that helps.

Z'mnypit

iTrader: (58)

Ill give it a shot but Ive swapped the sensors and cleared the codes with no luck. Im going to try the crank sensor soon.

Z'mnypit

iTrader: (58)

need more suggestions

STKN1STGEAR

iTrader: (1)

I have a similar problem With an LS2 swap. I can read the RPM's with EFILive but the tack doesn't work at all. Also I get the cam sensor error. When I turn on the ignition, all the gages but the tack go to full and back, as a self test I assume. I was told that the wiring is wrong and to swap the wires til I get it to work. did that but no go.
HELP!!!!!!!!!!!!!!!
Al

Z'mnypit

iTrader: (58)

Well this was an LS1 swap, the cam sensor wiring wasnt messed with at all. Ive got a crank sensor on order just to check it. I have a feeling its not the problem, but its worth a shot so I can rule that out.

STKN1STGEAR

iTrader: (1)

you said that you scanned the car with hptunner, Did you read the RPM through the software? I can read the RPM on mine through EFILive just not with the tach on the dash.
Al

Z'mnypit

iTrader: (58)

Yep, I can read the RPMs all the way to the limiter at 6600rpm with my laptop. I can read the rpm on the tach up to 2800rpm, thats whats frustrating me.

GuitsBoy

iTrader: (4)

Careful your timing set hasnt come loose... I had this happen. With a loose timing set the cam can walk around a bit. At idle it might sit with the reluctor groove lined up with the sensor, but when you give it gas, it might pull forward or push back out of line. Its worth doublechecking before it eats the motor.

Slowhawk

iTrader: (12)

I've seen crank sensors do your problem. If the Cam sensor is new then I would go to the crank sensor. Also a loose timing set can do this.

Z'mnypit

iTrader: (58)

I had the front cover off the other day swapping the gasket and everything seemed real tight. Ive ordered the crank sensor and it will be here Wed so Ill swap that out then, and it that doesnt work Ill pull the front cover back off and recheck everything. Ill pull the timing gear, chain and all off and try reinstalling it. Ill even pull the cam.

Now that mentioned above about the Hptuners reading it, it has me wondering. If the cam was walking or the sensor was bad, or the ring was bent then why would the Scanner still pick up the RPM's but not the tach?

GuitsBoy

iTrader: (4)

The HPTuners scanner reads from the crank sensor. The tach is driven by the cam sensor. FWIW, When my cam walked I had a cam sensor high signal error.

Z'mnypit

iTrader: (58)

Ahhh, well looks like Ill be pulling the cam this week or weekend. If the crank sensor can pull the RPM then its obviously not bad. I do get two SES lights for the cam sensor, Cant remember what they were right off hand. Why and how did your cam walk? Did it do any damage?

GuitsBoy

iTrader: (4)

Cam walked because I had used old loctite. My guess is that it wasnt properly sealed or had a leak and the tube of red loctite catalyzed somewhat before application. I made sure to clean the bolts and holes with brake cleaner andthen torqued to spec. After a couple hundred miles the bolts loosened up and backed out about 1/8 - 1/4 inch. It threw the cam code and the tach stopped working. I took it apart the next day and luckily caught it before the lifters rolled off the lobes. I tightened the bolts back up with new loctite and they were fine for 20K miles until the next cam swap.

Z'mnypit

iTrader: (58)

Interesting. Ill give it a shot this weekend. Only thing that kinda worries me is that the tach hasnt worked since day one of the new motor install. I guess it would be different if it had worked then stoped. But it never started working right at all.

GuitsBoy

iTrader: (4)

You did check for any garbage stuck to teh magnetic tip of the cam sensor, no? Maybe the reluctor was ground incorrectly? Match it up to the stock cam to make sure it wasnt ground off target.

Z'mnypit

iTrader: (58)

Yep, plus it has a brandnew sensor now so its clean and good. The reluctor worked on the other motor but not this one. Only difference is this is the new style LS1 block with the short head bolts, not the long ones like the older style LS1 block.

RooRnZ28

iTrader: (14)

if you have a double roller timing chain, then that is your problem..

i had an SLP double roller and it was installed wrong. my tach didnt work at all and it was a bitch to fire up, wouldnt want to crank over... then i swapped out to an LS2 chain, and all the problems disappeard!

Z'mnypit

iTrader: (58)

Yep the car has a double roller. I have a stock timing set laying around I could throw on there to check it out. Just out of curiosity how can it be installed wrong?