383 LS1 Tuning Help

[South Lakes Speed Shop]

Hi guys, I'm new to tuning but trying to learn as I'd like to be able to offer it as a service in the future and also I wanted to get my own car running with a tune I created......so first off my HP tuners has turned up and I'm trying to get the car to run for more than a few seconds so I can do some proper data logging!

I've got an MS3 camshaft in it which is 238/242 @ 0.600

The engine is a 383 LS1 at 11.3:1 CR with forged pistons

Ported stock casting heads

Innovate LM-2 AFR is fitted and I'm logging around 11.6 on the AFR

Stock injectors LS2 Throttle Body - ETC was changed to 0.0190 for this according to the Excel sheet found on here

So far I've managed to get it to go from not wanting to start to starting instantly, having 7 seconds of run time and then dying. So it's moving in the right direction but I could use some pointers

Both LTFT and STFT are turned off. The dying issue and not being able to stay running to get proper logs is the problem which I'd like to try and solve.

I reduced VE by 10% and increased Base Idle Air by 7g/s to try and help, timing has also been bumped up to 30? in the idle areas which it definitely liked! At 22 which was the stock number it didn't like starting


However I think I have reached the limits of my knowledge on this front, I am used to carbs and whilst I get the principles are the same the set up is not!

If someone could give me some pointers to get it idling long enough to datalog it would be appreciated. I am trying to put together a few tunes to flash onto the car and try different variables in order to log, mainly VE and Air Flow changes

[RDF1]

Read over this.


https://forum.hptuners.com/showthrea...8776#post78776

[5FDP]

It probably needed more fuel with a bigger camshaft and you have to make changes to both the MAF and VE if you are running both.

Without the tune I can't see how you have the idle timing and the spark corrections tables setup. If the over/underspeed spark correction is too aggressive it won't want to idle that well either. You should still be able to run around 20ish degrees of timing at idle.

Also make sure fuel pressure is good and that your corrected the cylinder volume for the larger engine size.

[South Lakes Speed Shop]

Read over this.


https://forum.hptuners.com/showthrea...8776#post78776

I did try that, unfortunately it wont stay running

I am not sure if it could be a fuel pressure issue or a base tune but I think it is most probably base tune, this thing has been fighting me since the day I took it in on trade and at this point I'm about ready to kill it

[South Lakes Speed Shop]

It probably needed more fuel with a bigger camshaft and you have to make changes to both the MAF and VE if you are running both.

Without the tune I can't see how you have the idle timing and the spark corrections tables setup. If the over/underspeed spark correction is too aggressive it won't want to idle that well either. You should still be able to run around 20ish degrees of timing at idle.

Also make sure fuel pressure is good and that your corrected the cylinder volume for the larger engine size.

I corrected the cylinder volume up to 0.78750

With regards to the timing I took the notes off this forum saying the MS3 wants 30 degrees in the idle areas and inputted them

AFR is coming back as running super rich so I didn't think it needed more fuel, hence reducing the VE but I did increase the RAF and have just done another tune file to try tomorrow with an additional few grams

[kingtal0n]

The most idle timing I would use is around 18* ...

pretty much with any engine at such low rpm its a bad idea to push a bunch of timing. It will make the engine more difficult to tune and stress out the fuel and rod bearings at such low rpms as you come on and off the throttle

[South Lakes Speed Shop]

OK! So I'm a freaking idiot.................


Turns out I was being tricked by the car. It primed but had intermittent (mainly not) pressure in the run position because the ground on the relay was bad. I put a jumper wire in and its idling at 12.2 ish AFR and 1200RPM so I can now actually do some proper logging and get this damn thing out the shop


Pleae see attached log and tune I used to get it running, any pointers would be great as I am also struggling to get the scanner to log everything required even with using the GRG Histogram package. The LM-2 will also not log but I believe this could be down to me running log works at the same time as VCM




Corvette C5 - It Runs! 900rpm idle.hplC5 - It runs!.hpt