BLO BY U - TA

iTrader: (28)

I had a 228/228 tuned and installed for about 4 weeks and no problems. Well that cam wasn't enough for me. I pulled it out and went with the Trex thunder racing cam last Tuesday. I ran a mixture of 112 and 93 and it was running great until Friday (about 20 miles). SES light came on so figured it was the O2's. I bought denso O2 and installed them but that seems not be to be the problem. Took it to the part store and they scanned it...throwing p0300(multi misfires). But it anly does it from 2k-3.5k then clears up. It run great WOT or part throttle.

I know the computer needs more work for this cam 242/246, but would that be the cause from the misfires?? Do you have any ideas?? I searched LS1techs forums and found out it could be abunch of things(bad wires, broken valve spings, ect). Some people deleted that code completely out of there computer with no more problems. But my tuner thinks theres more to it than that. He seems to think it igniton related and doesn't think deleting it will solve anything.

When I installed the first cam, I relocated the coil packs under the cowl with Thunders kit. I have ohm'd out the wires and they are all between .089-.184..seems ok to me. Next I took out the plugs, which were new TR55's when i installed the first cam 4 weeks ago and 1,3,5,7 are black. 2,4,6,8 are clean...maybe alittle lean. I also have the valve covers off and the springs look good with the quick once over i gave them.

What do you think it could be??????? Car's a 98Z M6 btw.

Alan

Blo-byu@sc.rr.com

ncd1966

iTrader: (2)

sounds like u need a good tune to me

Armageddon

iTrader: (41)

a tune should fix you right up

BLO BY U - TA

iTrader: (28)

So why do you think it didn't do that at first start?

Why did it wait till after i drove it around awhile?

I'm only asking because the guy who tuned the computer wasn't convinced that the tune was the problem....yes it still needs a tune for the cam but he's thinking it something else!

Alan

HAUS1

Isn't it with most codes, it takes some driving to register as a "problem"?

ss rally red

iTrader: (8)

You need to "detune" your misfire codes and have them report around 3K rpm & above,this is VERY common with larger cams.

GuitsBoy

iTrader: (4)

Yeah, on hot days with the A/C on, ive even set the p0300 code with my baby f13 cam. It only happens to me rarely, and only because I havnt detuned the misfire detection sensitivity. With a t-rex, you should definately be setting this code off left and right.

Josh

iTrader: (9)

I struggled with the P0300 code for more than a year with my T-ReX. Even after desensitizing it I couldn't get it to go away. I eventually just turned the code off.

Josh

BLO BY U - TA

iTrader: (28)

Well, I'm going to put it all back together and see...If its still there, the computer goes back

Alan

jay_99z

iTrader: (5)

Your car isn't the first car that your tuner has sent out with P300 problems. The two others I've seen tuned by him also had this. Can't say that on SCFYB but he needs to fix it.......that is all you have wrong.

BLO BY U - TA

iTrader: (28)

Well...

thats funny He was all but helpful over the phone!

Blown 98 Z

iTrader: (2)

The car needs a bit more tuning....

Missfire Max Time Between Events - Medium RPM table needs to be adjusted.

SmokingWS6

iTrader: (1)

Or save the trouble and disable misfire detection.

Misfire detection was designed for the characteristics of a bone stock motor. When you start changing factors such as rotating mass, say flywheel and under drive pulley, and the addition of a cam and stiff valvetrain will make detection and misfire rates invalid.

You can always raise the detection rates. For example, any reading below 3000, raise it to 3000. However on most large h/c ls1's I tune I disable it. Max misfire detection is usually set at 266*, raise the min up to 265* to disable. If there's a true misfire problem you'll feel it anyway.

MrDude_1

iTrader: (4)

all but helpful? so he didnt help? im confused



anyhoo, on a large cam LS1, if YOU have HPtuners, YOU know what you're doing, then a minor misfire code is nothing, and YOU can spend the hours/days tweaking the misfire detection so that it doesnt go off when its not supposed to....

but if you're getting a 'professional' to tune it with a large cam, they normally just turn it off... professionals dont have time to spend days with minor things like misfire control, part throttle tweaking, ect.. its just not the way they can do business.

go there, have him turn it off, and you'll be set... or you can chase your tail sending it back 80 times as he tries to get it to not show false counts....

BLO BY U - TA

iTrader: (28)

[QUOTE=MrDude_1]all but helpful? so he didnt help? im confused


Wasn't helpful....said it wasn't the computers problem, its ignition related. Go though the plug wires, ohm them because they are Taylors...Burnt wire (new, not burnt I said)

But at the same time would turn it off if I wanted him too. Just wasn't thrilled about doing that!

Alan

BLO BY U - TA

iTrader: (28)

Its going back Monday to get the code deleted out.