Tuning Help - L76

[Shelby]

Hi All,

Hoping you can help me out with my tuner.

I have a L76 in a AC Cobra, was running a stock tune in a stock engine up until late last year. Put in a small cam (See attached) and contacted my tuner for an updated tune.

Taking the car for a run with the stock tune the car "felt" vey strong - obvious lift in torque in the mid range with the new cam and apart from running rich at idle ran well. Was advised I would need an updated tune as it would be lean under load so opted for a mail order upgrade.

The car ran horribly after the mail order tune. So bad I convinced myself after lots of research I had installed the cam one tooth off. Pulled it all apart and degreed the cam - was within 1 deg of spec. Car was hard to start at times, breaking up in the mid rpm range and headers really hot - obviously the timing was way off.

Tuner advised I would need to then upgrade to a remote tune to try and sort my issues and sent me the autocal with a fresh tune. The new tune fixed the obvious signs of poor running. Took a few back and forths with log files and tunes to get things like the fans running right and speedo signal in the ECU (stuff I thought should have been bread and butter for a decent tuner) - I was having to do the research and tell him what to change.

Car has been off the road for a while with some other upgrades and Im back into it now trying to get the tune sorted. I dont think Im getting the most out of the new cam. Its not huge so didnt expect too much but 1/4 times are no better than with the stock cam. Car does not feel as good as it did when I first swapped int he new cam and ran the stock tune. Other small issues with drivability as well (too fast idle when cold, throttle "holding" at low speed as approaching intersection etc). The engine bay also feels hotter than it used to so I suspect maybe the timing is still a bit off.

Any advice you could give me on what to tell the "tuner" would be great. He is well known and well mostly well respected so I thought getting this tune right would be a no brainer.

Cheers,

2127121272

[joecar]

L76 cam = 200/208 116.5

new cam = 214/222 117

the new cam will run fairly ok on the stock tune (will even idle ok)... should be able to easily tune for it (it still has sufficient negative overlap).

[Shelby]

L76 cam = 200/208 116.5

new cam = 214/222 117

the new cam will run fairly ok on the stock tune (will even idle ok)... should be able to easily tune for it (it still has sufficient negative overlap).

Thanks Joe, is there anything you can tell from the log file that is obviously wrong? At the moment I've spent $900 to basically get the fans and speedo fixed which should gave been right when he sent me the original tune years ago.

Should I tell him just to put it back to stock and start again?

Cheers

[joecar]

Log looks to be ok, STFT are good, not far from zero, O2V show suitably rich at higher throttle.


Try logging SAE.LONGFT1/2, GM.HO2S11/21, SAE.LAMBDA.

Do you have a wideband...?

[statesman]

I've spent $900 to basically get the fans and speedo fixed

You could have bought yourself a V2 flashscan for around that money. :shock:

[Shelby]

You could have bought yourself a V2 flashscan for around that money. :shock:

Yeah....unfortunately it snowballed a bit after what I thought would be an easy update via mail order.

I have an updated tune and the car is running much better already.

[Shelby]

Joe - I have another question that hope you can help me with.....

I have never been able to get the reverse lockout to operate correctly. The ecu should be grounding out one side of the solenoid, but it does not. I logged revinhibiton and it is reading yes at idle - does this mean it is inhibiting reverse? ie, not grounding out the solenoid? - I am not getting ground on that wire. I would expct it should be "no" (ie. not inhibiting reverse) and the wire should be reading ground. Are there any settings that adjust how the reverse lock out work?

[joecar]

See B3322-3.

I need to look at a wiring diagram for and E38 with MT.

Which pid did you log (attach log)...?

If revinhibit says on, then reverse is inhibited... this should not do this at idle, see B3322,3.

[Shelby]

See B3322-3.

I need to look at a wiring diagram for and E38 with MT.

Which pid did you log (attach log)...?

If revinhibit says on, then reverse is inhibited... this should not do this at idle, see B3322,3.

I have the rev lockout one side wired to +12v in run\start, other side grounded out by x2-11.

I dont have a clutch position switch, but the diagram I have indicates this is just used for clutch in to start and cruise control cancel.

Im going to test it tomorrow and take a log and wire up a dummy clutch pedal input to see if that makes a dofference.

[Shelby]

I have the rev lockout one side wired to +12v in run\start, other side grounded out by x2-11.

I dont have a clutch position switch, but the diagram I have indicates this is just used for clutch in to start and cruise control cancel.

Im going to test it tomorrow and take a log and wire up a dummy clutch pedal input to see if that makes a dofference.

Logged some data and it looks as though the "Reverse Inhibit Commanded On" is changing values over 5km/h'ish. It is the opposite to what I thought, Yes means reverse is allowed (ie. the solenoid is energised) and No means No reverse.

The values I am getting on the pin X2-11 do not change at all though. Getting a pretty constant 0.5v - had the multimeter hooked up to the wire and checked while driving. I did start with a stock harness and added the x1 connector etc, however the wiring for the reverse lockout is as per VZ 6lt - no changes to that part were needed.

I can only speculate that the tuner started with a different model or auto tune? Is that possible?

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