911 SC 3.0 Tuned KJETRONIC issue to work

[florent78]

Hi

I open this post cause I start to de totally depress waiting this car for years

it's an Eropean model

to sum up it's a 3.0 SC engine totally rebuild
- forged pistons and con rod , gt3 oil pump ..
- Compression Ratio is 10.5 now
- twin plug head
- Schrick camshaft
- heavy dual spring etc ..
- XDI electromotive to manage ignition
- Digital WUR
- rebuild Kjetronic head with slight increase (tested and works perfectly)

so everything is nice to do a great engine ....

car is with a reputable tuner and ..... after issues and hours of dyne to tune properly he is also dispointed cause he cannot made the car works well


to explain the car is perfect regarding AFR, etc, ... you can drive it

and you don't know why 2 days after the car is terrific with surge and bad idle etc .....

we do mods to remove the additional air pipe on TB to get a good idle return, it works but still issue

my tuner consider we are at the limits of the Kjectronic and with the camshaft we do not have enough depress to manage engine tune properly.

I know Kjectronic is extremely sensitive to overlap.

My shrink camshaft are this version:
0005L1880-02
0005R1880-02

schrick told me they works perfectly for a kjectronic


I see many guys having 964 regrind and even 3.2l engine with Kjetronic and no issues

so I cannot understand why my engine is so strange

again it can works perfectly a day ....

and 1 week after you take the car and issue (tuner told me about weather pressure etc ...)

for me it's an engine / it's mechanical not ... biological

so if it works it works ;-)


what would be your advice to investigate on ??


Regards
Florent

[jac1976]

Plenty of people on here will be able to lend advice. I’d reach out to William Knight, Henry Schmidt, among others.

[florent78]

Thanks

I will see if they answer directly on the post

If not i will pm them

[timmy2]

Digital WUR may not be consistently working correctly.

[florent78]

well it's the unwired wur

it's suppose to be tested and works fine

and the tuner has all the tools to check ....

that 's why I ask you perhaps we miss something very simple witch is putting the mess ...

[florent78]

Hi again

here is the schrick AAC diagram

compared to the 964 regrind ..... do you consider it's similar ?
better ?
worse ?




what is strange is the valve clearance

first doc and info from schrick expert is 0.2 mm

but on this diagram you can read 0.1mm ...

pretty strange