Wicked99

I have a 99 6-speed with a 413 ci. with a 251/257 dur.@600 Lift 114 LSA cam,Stage 3 ported heads, oz700 clutch, LS6 MAF, LS2 ported intake, LS2 ported 90mm TB, 42# inj., SLP long tubes, X-pipe and borla cat-back. I just dyno tuned the car today. The problem im having is a low RPM surge around 2600 rpm and lower, in all gears. The problem was present before the tune and is still there, the tuner did all he could to fix the problem with no luck. Could it be something other then cam surge? After 2600 rpm the car is a beast and runs great. Any help would be great.

Plus the car has a really hard time starting up. It threw up a cam position sensor code. any ideas? And were is it located?

tblu92

YES---You must do a Crank position Re-Learn procedure after a cam change---EFILIVE has this procedure included in their software--not sure about HP Tuners---It is a simple thing but causes fits if not done--Ask your tuner if they did it--
Other than that it can be a host of other issues--I'm sure he's tried everything to correct the surging---It would be almost impossible to diagnose with having the car here or without doing some data logging-
I would also point to the LS6 MAF---Using other that the Stock MAF than the car came with will always cause problems---The entire MAF table has to be re-calibrated--This can take hours--sometimes days --as you have to hit every cell--can't be done on a dyno--but driven all different ways on the street However it can be done---
If you continue to have trouble and it seems hopeless--With your cubes and hds/cam set-up-----you may consider a "speed density" tune (MAF less)-- your type of combination is a prime candidate for it---You can also get a custom callibrated tune

Wicked99

He spent several hours messing with the MAF tables, driveablity, and WOT. But in the end he said that the O2s were not acting right and may need to be replaced. along with the hard starting, plus i had to drive two hours to get to the tuner. So I had lots of time to play with the car on the way home and see were it was acting up. But if i change the MAF out now it will need to be retuned for it. But i guess if it fixs the problem then it will be worth it.

tblu92

What about the Crank Position sensor relearn procedure ????

Ask If he did this--It is a MUST with a new cam---

lar66BB

What type of CAI do you have. When I put a Vararam on my Z I would
get a low RPM surge. The PCM wasn't reacting quick enough a low
speed. I put a screened MAF on it and solved the problem.

bayarea

you have a big cam man its not gonna drive like stock.

Wicked99

I know the car is not going to drive like stock. I have had cammed motors in the past and have never had this problem. A friend of mine thinks the heads are to big for the cam. They have 2.08 intake and I think 1.65 exhaust as far as the air intake goes its is a cone filter. I bought the car from a member here on the board. So im just trying to work out the issues without having to take the motor apart.

Wicked99

I will ask him If he did the procedure, but im sure he did not. Would it have any to do with the way it runs?

Wicked99

Here is my last dyno run. And i found two bad plug wires today. But problem still there.

bayarea

definetly a problem with power there.

Wicked99

fixed the start up issue. The cam position sensor was disconnected. Me and the tuner are getting together on the 8th to do the drive tune.