2010 Corvette famous spinmonster 230/234 cam surging

[zchrisz1986]

hi everyone.

i've been driving around trying to tune this cam it surges at light throttle pretty much at any rpm range. can someone see if i'm missing something?

it's currently MAF only. surging happens in closed or open loop.

cam is a 230/234 .600/.615 114 +2
kooks 1 3/4" long tube headers

maf closed loop v12.hplcorvette cam swap VVE v20 closed loop MAF Only DFCO disabled idle ovr undr adjust v12.hpt

[LS ROB]

Stock injectors i assume? Couple of things.. Log Volumetric efficiency and put the High rpm re-enable to 0 instead of 8000 under the AIRFLOW-DYNAMIC tab.

[obthomas]

Only because I am going through this same scenario I have a couple of suggestions.
Try to smooth out your high octane timing advance table in the idle areas, same with the idle timing advance table. The goal would be to eliminate big jumps in the tables and from one table to the other. Next half the idle over and under correction tables to sort of dampen the corrective values. Your over correction table is removing what appears to me to be a large amount of timing and does not help with the surge. Good luck.

[kelvinberroa]

4th

[zchrisz1986]

i will log the VE and change the enable point. i did attempt making the timing the same. no change with that.

[blindsquirrel]

4th

What's the opposite of Impostor Syndrome?

[zchrisz1986]

i changed the dynamic airflow value and added two ve airflow pids not sure which are helpful

car is all stock except the cam, headers and cold air intake.

ran beautifully before the cam.

see attached. surging seems to be at any rpm on steady throttle.

maf closed loop v12 ve.hpl
corvette cam swap VVE v20 closed loop MAF Only DFCO disabled idle ovr undr adjust v12.hpt

[LS ROB]

Id suggest taking some timing out of the High and low octane tables to start with. Looks like you get spark retard anytime you part throttle or more. Dialing in the VVE and MAF can help with that some. Log Injector pulse width and injector duty cycle as well.

[LS ROB]

If you are naturally aspirated, you can give this a go if you want. I took 6* from the High octane table then copy/pasted it to the low octane and took out an additional 3* there. That should help with reducing knock. I also changed PE,MAF & VVE settings. If you are not familiar with it, read up on "rich after flash." Basically, you will want to drive around for about 15min. before starting to log data. Once you are satisfied with your tuning, you can open your original tune file as a compare file and copy/paste the timing tables back over.

corvette cam swap VVE v20 closed loop MAF Only DFCO disabled idle ovr undr adjust v12-1.hpt

[zchrisz1986]

If you are naturally aspirated, you can give this a go if you want. I took 6* from the High octane table then copy/pasted it to the low octane and took out an additional 3* there. That should help with reducing knock. I also changed PE,MAF & VVE settings. If you are not familiar with it, read up on "rich after flash." Basically, you will want to drive around for about 15min. before starting to log data. Once you are satisfied with your tuning, you can open your original tune file as a compare file and copy/paste the timing tables back over.

corvette cam swap VVE v20 closed loop MAF Only DFCO disabled idle ovr undr adjust v12-1.hpt

thanks Rob i'll give it a try, was raining and thundering all day yesterday. i'm going to go over the car as well to rule out mechanical.

[Alvin]

I know you said the surging happens in OL too but this looks like the o2's are overly sensitive to me. The swing is too drastic. While driving use the scanner to force it into open loop and see if the problem settles out.

Also VVE tuning is very important. Its hard to tell how close you are on it.

[zchrisz1986]

I know you said the surging happens in OL too but this looks like the o2's are overly sensitive to me. The swing is too drastic. While driving use the scanner to force it into open loop and see if the problem settles out.

Also VVE tuning is very important. Its hard to tell how close you are on it.

yes the switching seems fast. i added 20 percent to the integrator delay today. i have no idea what is going on with this thing, it feels almost like it's misfiring at all these rpm's you floor it and it hauls. i'm trying to dial in the MAF. i just cruised around today in 100 degree weather and made no progress at all same surging at various rpms 1500-2300.

i've tuned a hotcam in my 6.0 camaro and didn't have this issue.

do you guys do crank re learns after a cam swap? i have not done this. there are no codes

[GHuggins]

Give this one a try. Hopefully got enough data from the log to get your VE close.

Are you still running stock injectors? You have some pretty significant timing cuts less than 2000 rpms so tried to address that and your surge both.

[zchrisz1986]

Give this one a try. Hopefully got enough data from the log to get your VE close.

Are you still running stock injectors? You have some pretty significant timing cuts less than 2000 rpms so tried to address that and your surge both.

thanks, i'll give it a try tomorrow. i did perform the crank relearn and took the car out it felt smoother but then started the same thing. wondering if it's a table related to temp doing something.

yes, stock injectors.

[zchrisz1986]

Greg, you are the MAN! i may have to enlist your talents further

this thing drove the best it has since i started. i still feel a little of that surge at around ~2100 rpm but i have to really feel for it. i ran open loop and have to adjust the MAF a little bit. i did notice that all my lovely exhaust music is gone letting off the gas and when i shift. is that due to the spark table modifications?

interesting about the drop off in the spark tables. that was from the factory.


i'll update soon once i adjust the MAF.

thanks!

[GHuggins]

No problem. Glad I could help you out. A lot of people don't realize a lot of thing cause this that all have to be addressed at the same time so not just one thing causes it. With those O2 corrections it should make dialing in your fueling a little easier too as you won't have to chase it around as bad.

Personally I don't like to adjust fueling in open loop. I like to adjust it how the ecm is going to use it. Closed loop for normal everything driving and then open loop for PE and then blend the two if need be. Everybody has their own methods, that's just how I like to do it.

I blended you main and idle spark tables for the timing dips. Just remember to not have the same timing in both as the main timing table will always need to be higher than the idle tables as the main is a limiter for the idle tables.

[zchrisz1986]

i noticed my wideband where it's at it's in the kooks x pipe just before the cat on the pass side. it seems i need the wideband to be around 13.5 if i make the wb 14.0 it's lean i can feel/hear it. i'll dial it in with the o2's to match the wb.

i meant to say. nice signature! you have a couple pieces of nice equipment.

[GHuggins]

Those were customers cars. I don't own anything that fancy. Just a truck and an old jeep for me

[zchrisz1986]

Those were customers cars. I don't own anything that fancy. Just a truck and an old jeep for me

ah ok! nice builds either way.

i took your advice for closed loop tuning. when i enable it the car tries to achieve stoich and the LT fuel trims and MAF show ~-10 but my wideband is saying 14.8-15.xx and it stutters i can feel it lean.

do the switch points on the o2 affect that? i guess what i'm trying to do is bring the NB o2's in line where the wideband reads 13.5 or there about.

[GHuggins]

You probably won't be able to do that with O2 settings alone. Only way I've ever accomplished that was with stoichiometric, O2 and transient tables combined and then you open a different can of worms.

What you're after with the O2's is a good slowish switch where peaks both low and high aren't shifting around that much. A 3 to 4 percent error from a lambda 1 setting is doing good.