Newbie here with some tuning questions

[Gianelli280]

Did a cam swap and looking for some tuning help - I'll post a pass and my boogered tune, and have a feeling I'm WAY off with the tune because factory cam and tune was quicker in the 1/8.

Here's the lowdown:
Truck is an 85 gmc 1500 with an lq9, headers, comp springs and a howard's cam https://www.summitracing.com/parts/crn-1449041 ~2200 stall (factory 2000's ss camaro) 3.73 gears and trans-go hd2 shift kit.

Did some SD tuning to dial in main VE, and pasted that into the factory tune and reverted to MAF. I haven't tuned in the MAF yet, but the cam seemed to not really need that much? Again, total newbie here.

Here's the 1/8 times:
Factory cam and tune did a best of 9.128 @ 80.02
New cam and booger tune did a best of 9.237 @ 78.98

Obviously i did something wrong, or this cam is garbage? I have a feeling it's my tune. I'd be less shocked if the slower time came after the shift kit (which is definitely shifting quicker).

I'm pretty sure that histogram is of the same tune, but the only thing that would have changed is <1* of timing and some shift points. I realize the KR during the burnout and probably should address that too?

Thanks in advance

[5FDP]

You're losing out because power enrichment is not even being enabled with the settings it has currently.

It won't drop down into PE because you still have the 5,500rpm and you left the enable torque value at 100% while disabling all the engine torque mngt.

Lower the enable torque to 50%, lower the hot/cold pedal enables to like 50-60%, remove the 5,500rpm and set the enrichment ramp in rate to 2.000. This way it will drop into PE and stop the fuel trims from freaking out and going way positive just to try and catch up. You'll want to disable COT so it does not cause the commanded AFR to go even richer if it thinks the cats are too hot.

Tire size and gear ratio need to be updated as well. It still says it's running 27in tires and 3.42 gearing. The gear tire wizard is under the edit tab. You can have it auto scale the transmission settings on your 4L60e as well.


Work the VE and MAF more. Make sure you are doing them separate. The VE must be tuned with the MAF turned off and the tune put into speed density. Currently it kinda just looks like you added 15% to the VE and the stock curve/peak to the table is still there. Once the airflow model is corrected you for sure can add more timing so long as the fueling is correct. A mild cam should totally be able to support 23-25 degrees of timing at WOT, should pick up some nice power over the 15-18 that it's running now.

See where it gets you with doing that. I do have a feeling once everything is gone over that you'll be close to the fuel limts on the injectors or you may already be over once PE is setup correctly. Larger injectors should be in the back of your mind, then you'll also be able to rev it out more. Something like 6,000rpm shift points instead of 5,500.

[Gianelli280]

Very much appreciated - I?ll run through the tune over the weekend.

[Gianelli280]

Revisited the VE tune in SD mode, and have reworked my table quite a bit - found out STFT's were still enabled during my SD runs which explains the factory model only with 15% more fuel, whoops. However, after dialing in the table below 4000 rpm and 50kPa, I started to see knock on some harder pulls, all while staying under 50% throttle.

It seems like it is either too far advanced on pulls around 40% TPS, or I need to be adding fuel. Should I enable PE as I get into these higher ranges, or do I not need to worry so much about the VE table as it approaches a PE condition? I'm using the stock Main Spark Advance tables (which I've copied the high to the low as per guides), so I would expect they should be conservative enough to prevent any knock.

I need to run a few more times in SD before I'm comfortable with the table, but seeing 3* of KR on a meager pull is disconcerting.

[Gianelli280]

Here's a scan of what I'm seeing. Log and tune should be attached.

[5FDP]

The upgraded OS do not require the timing tables to be the same. The OS change allows them to stay like factory where one is higher and the other is lower.

If you're using an AFR or lambda error to calibrate the VE there is no need to take out or add in random amounts of fuel. The error will do the work for you and correct the table when you apply the changes. Manual editing can still be done here and there but no need to randomly try to fix it.

Don't forget to set the min LTFT temp to 284 so that's not active either and reset the trims so everything is zero'd and it's open loop only.

13.00 maybe a little lean on a truck engine, 12.5ish is perfectly fine for PE.

[Gianelli280]

Sounds good - should I also have PE kick in a little earlier to avoid the knock?

[5FDP]

The knock is minimal right now, could even be something that is not there the next time you drive it.

Fuel grade could also be a cause, 89+ octane at a minimum should be ran in this thing as 87 just is not very good keeping knock away.

Work with what you have, get the VE and MAF done and see how it drives. Adjusting timing in area's where knock may still be present is still something you can do.

[Gianelli280]

Ok, I won't let it hinder progress. The old boy only drinks premium, though arco is my go to - just filled up with premium at chevron, so I'll keep an eye on it. Seems like I should only really worry about multiple hits at heavy pedal, or is that a pitfall?

I'll see what it looks like after VE and MAF tuning. Thanks again for the knowledge, I really appreciate the help!