Here's one for the L31 vortec guys

bbc-olds

Frequent Racer
Jun 7, 2008
542
2
18
Malin OR
Been working one a 98 chevy PU with a vortec 350. Rebuilt it to a 383. has shorty headers,cold air intake, and a LT1 corvette cam, and roller rockers. Stock ecm. Engine runs with good power but stumbles about 4200 rpm. Sometimes less but never more. Throws the P0339 code(intermittent sig, crank sensor) after about 3 times. Cked all the wiring(tested good) Put it on a scanner and showed normal on all systems except the tach shows over 7000. Dash tach shows mormal but does move around. Have built a new harness from the sensor to the ECM. No effect. Anybody had this problem??? Put this on FSC website but no answers(maybe they don't like new people).
 

Doober

Moderator
Jun 2, 2003
14,704
1
38
Catalina, AZ
www.cardomain.com
I've had similar experiences over there, I just stick to what I know mainly... it seems once you start getting more posts they'll start actually replying, but you also have a lot of kids over there that like to spout off random crap, or stuff that tells everyone else how much experience they really have. Has the computer been tuned at all? If not that could be part of the reason you're having issues. If you haven't adjusted anything to compensate for the extra air/fuel requirements it's probably running out of fuel at higher rpms. I'm afraid I'm not much help on the electronics, haven't really dealt with the OBDII stuff. Link?
 

Z-man

Dragway Regular
Aug 12, 2006
1,058
0
0
Barnesville MN/ Fargo ND
Just a shot in the dark , did you do the crank sensor relearn on it? Do you have the old style injectors or the upgraded mulit tec 2 injectors. BTW your not the only one that gets ignored on FSC. Like Doober said lots of young punks on there that know little or nothin but some guys realy know their stuff.
 

bbc-olds

Frequent Racer
Thread starter
Jun 7, 2008
542
2
18
Malin OR
After pulling out most of the hair I got left I decided after checking the wiring about ten time the problem must be mechanical. Pulled the front cover and took off the sensor wheel. No obvious problem but for 18 dollars I put in another. Assembled it and went for a drive. Ran great and pulled all the way to the 5000 rpm shift point. Didn't get to compare the two but something had to be different. Go figure.
 

MalibuRacing.com Gear

Stickers & Shirts!!