07 Z06 Texas speed 25-LS7S cam *SURGE*

[Christian GM]

hi guys,

I already posted something before.
well, on late December I installed this camshaft with his springs and pushrod into one 2007 Corvette Z06 LS7, E38 ECU.
well, I've two issue and I'm fighting with them.
1) when I press the ignition switch to turn off the engine it runs a few. a couple of seconds.
2) cruising or part throttle driving between idle and about 2500 RPM it's a pain. Surge and bucking.

I spent two days on the car (Friday and Saturday) trying all I have learned.
I read (again!) the Tuning School Advanced book and applied all his trick for idle and part throttle tuning, I've read ALL the thread here about surge, bucking, dieseling, Z06 and E38 camshaft tuning, EVERYTHING I found here and on the web, I applied the BlueCat VE tuning program (AMAZING!) I found that my VE table were about 20% rich!.
At least I solved one of the issue I add, the smell on the exhaust.

I'm tuning with LC-1 wide band and the LATEST Beta available.
the Vette has also LG exhaust without cat and 160° thermo and CAI.

any help will be REALLY appreciated.
I'm going nuts ,
and NO I' don't have access to a dyno

the latest log I upload it's not so long because my laptop battery die.

thank you SO MUCH!

[edcmat-l1]

I hope you didn't learn that from the tuning school.

You can't zero out the over/underspeed tables. You won't have any timing control over idle speed.

The timing tables are pretty well jacked up in general.

There's more ugliness, but that's probably the worst of it.

[Christian GM]

Mumble!
I zeroed out the table to minimize the surge on December before I did the VE tuning.
in December it worked out a little bit, I had some result.
but now with the correct VE maybe they give to me the opposite effect?
(However I found that info here on the forum - someone had surging and timing spikes and zeroed out the table)

thank!

[edcmat-l1]

Mumble!
I zeroed out the table to minimize the surge on December before I did the VE tuning.
in December it worked out a little bit, I had some result.
but now with the correct VE maybe they give to me the opposite effect?
(However I found that info here on the forum - someone had surging and timing spikes and zeroed out the table)

thank!

Don't know where you got that, but it is totally the wrong approach to tuning out cam surge.

You can get some pretty bad surge from the timing jumping around, but zeroing these tables is not the answer.

[Christian GM]

glad to know it.
I found many opinion in many thread, but I never found a tutorial or step by step to cure cam surge... how do you approach the issue?
thank you

[02Ls1]

Not to hijack this thread but how you tune the VE on this cars (e38 ecu).
I see that you say you applied the bluecat VE tuning program
I would like to start learning on the e38's ecu...

[Christian GM]

Not to hijack this thread but how you tune the VE on this cars (e38 ecu).
I see that you say you applied the bluecat VE tuning program
I would like to start learning on the e38's ecu...

here you go:
http://www.hptuners.com/forum/showthread.php?t=26884

bye

[hymey]

There is a LOT of work in getting them right in all areas. They have to be all closely looked at. Once idle air is right look at VE, ignition timing should be stable (but this alone wont cure it). I usually tune cams in the 240s and 110 lsa's they come out nice, injector timing is a big thing, idle airflow, VE, timing and tune in open loop, Coast down timing should be up there to nearly matching the hi octane table then work on integral coast down airflow correction. There is a lot to it. ps dont zero the timing correction.

[Christian GM]

hi guys,

I followed your comment and I started from a blank sheet.
I redid the tune from zero, doing the idle before, the startup table (airflow, timing) then I zeroed all the control as well suggested from Greg DVD, put the vehicle in open loop mode, put all the lambda multiplier to one, and I carefully mapped the VE with the Bluecat program. then I did the same procedure for the MAF.
I pasted the value, and I drove the car.
the fueling is a lot better, the exhaust smell is also better.
I still have dieseling, no way to cure it, I try different value of timing, from 10 to 40.

but the worse, are again the timing spikes on steady throttle cruising, between 1200 and 2600 RPM or so.
looks like that the vehicle use the high octane spark table, then the coastdown (I matched them in the area where I have the issue) and then the idle spark table. WHY??? I can not raise up the idle spark table to match the HO, I will have worse idling!!!

any help will be appreciated.

thank!

[Sherminator]

Have you tried running straight MAF to see what happens?

[Christian GM]

I've tried both in SD only disabling the MAF and viceversa, in MAF only disabling the dynamic airflow.
it's about the same.
thank you

[wstaab]

Your stoich is 14.828125.
Way too lean for a cammed car.
Try 14.4 to 14.5.
Do yo have E10 in Italy now? If so try 14.3
You timing tables are real aggressive for a cammed LS7.
Copy the proportional idle airflow tables from a 2009 Z06 into your tune.
GM fixed some issues with them on 2009 and they help on a cammed 2006 through 2008 LS7.
Bump the idle up to 950 rpm at temp. Set the minimum idle to 875 rpm.
Disable M6 spark smoothing.
Go back to stock on your adaptive idle overspeed and underspeed tables.
You do not have enough adjustment range in gear and coast.
Biggest problem is stoich a/f ratio and your timing tables
Good luck
Chow

[DSteck]

Programmed stoich won't matter if it is closed loop. It is still 1 lambda.

Sometimes big cams buck and it is unavoidable. Pulling timing from the main spark tables in the problem area can help along with running open loop to run rich (low 13s).

[Christian GM]

hi guys, thanks for the replies!
to Wstaab, I downolad from the tune repository the 2009 Z06 stock file.
but, maybe I'm blind, where damn are the "proportional idle airflow tables"
to DSteck
how do you set up the tune to do it? running open loop to run rich (low 13s).

I'm a lot involved in this tune because the car is of the most famous BMW tuner in Italy.
and I want to give the car in PERFECT condition to him.
I already fixed one Pro-Charger Z06 to him, and he was impressed... no I have this challenge to win again - and I feel I'm close to the solution

thank you.

best regards

[Christian GM]

ok,
I did some modify to the file, and I tried different solution.
with wstaab suggestion I get some nice result!
timing spike are gone!
but surge are still there... it's boring in the traffic, also on uphill driving at low speed in the turns... you've to go always above the 2500 RPM.

I setup AFR at 14.4 that is the best in my opinion, because above I have more surging, and below the fuel smell is tedious... (there is however always fuel smell)

I noticed that when I'm at cruising or when I feel the surging, my WB read AFR above 14.5 near to 15! way lean...
there is some table that command the fueling lean in low load condition...
if I can change that table maybe I will fix it...

what you think? it's the correct way to do?

thank you!

[Christian GM]

MUMBLE MUMBLE...
I did the VE and MAF calibration with the "old" HO spark table...
I removed many degrees in the low load area (idle to 2500 RPM and below 0.48 g/cyl)
so, MAYBE, now I need to do the VE and MAF calibration again in that area to match the timing and have the correct fueling...
correct???

thank you!!!

[Christian GM]

ok,

I calibrated again the MAF and VE, some minor trimming in the spark table and give back the car to the customer.
it's not totally perfect between 1000 and 2500 RPM, but hey! it's a cammed car!
he put the car on a dyno yesterday... 598 CV.
I think he's overall satisfied now!

but since a cammed car is richer than a stock one, he will add high flow cats to reduce the fuel smell

thank you guy for the support to all.

bye!

[C6Z_sd]

Christian, if you don't mind, please post your final tune. I'm thinking of ordering the LS7S cam myself and would like to see what all you had to do to tame it.

[DSteck]

Delaying end if injection timing can help with the smell a great deal. Just don't delay it too far.

[Christian GM]

SURE, you're welcome.
this is the latest file I'm running now.
but as is write on the "tune repository":

Note: HP Tuners is not responsible for any damage done to your vehicle by using any of the tunes found in the Tune Repository. HP Tuners does not validate nor approve any tunes that have been uploaded to this repository. Use at your own risk!

this is the same for me! use at your own risk

bye