383 build / Tune

[79Firebird_99TA]

Greetings! Been a while since I've been over here.

Basically I stroked the LS and added a cam, headers ....etc... and there are still a few issues that the builder needs to work out. For one, it revs to close to 2k when I cold crank it .... and then slowly comes down to 1k. When driving it, it has what i've heard called the "cruise control" effect where the engine RPM is too high and will almost drive itself. What I am concerned with is a PO300 and PO327 that is popping up. The tuner isn't done and I'm curious if those issues could be tune related? Here's a short clip of a cold start.

[SMWS6TA]

Check you throttle body blade screw on the throttle body. It is located where the cable connects to the throttle body. It may need to be turn a few to close the blade some. Take off the airlid so you can see the adjustments you make on the screw. I've flipped mine so I don't have to take the throttle body off to turn it or have a stubby screwdriver.

Auto's should idle around 900-1100 rpm and Manuals 700-900.


You could also pull the idle air controller and see if it's gummed up with oil. (very common because of the POS PCV system GM threw on the LS1. You can try to clean it or just throw in a new one. If it is the original I would chose the later. Electronic components get weaker and go bad with age and heat cycles. There is a few ways you can address the PCV issues that will help in cleaning up the intake form the oil blow by of the pcv. Most are inexpensive and not difficult to do with one exception. 99-00 blocks will need an area address that will make most ppl uncomfortable to do because you have to clearance a spot inside the valley tray. It is messy and if not done properly you end up pulling the motor and having to break it all down and flush it to get all the shavings out or you risk killing you rod bearings or worse. 01-02 LS1's that have the LS6 block do not need to do this, you can just install the LS6 Valley Cover tray. There are some very helpful how to threads in the General Help section that address this.


P0300 Random misfire
P0327 Knock Sensor.

Both can be related, have you replaced the knock sensors before? If they're original it's long, long past time to replaced. If the intake has ever come off it could also be a pinched wire harness between the intake and cylinder. (ask me how I know) I use tape to hold it in place when ever I install my intake so it doesn't slide.

[79Firebird_99TA]

I'll check those things. This engine is a new build. The knock sensors are new. The PVC lines and hoses are all new and the EGR has been deleted and a catch can is in it's place.
I too think those codes may be tune related as the codes will set and reset themselves.