A couple of Tech Questions

[c2turbo]

Hey Guys I am having some very weird issues and looking for some ideas

I have an S80 on an early 911 twin plug NA with COPs / 42lb High ipm injectors /running full sequential / 60-2 no errors any where

so currently the car starts and runs in sequential I have set the injector deadtime

the car does not run smooth at idle it is rough ( it smooths out mostly at around 2000 rpms )

I am running one coil per plug so no wasted spark when I put the timing light on the car it jumps around every few seconds if I have the timing set at 15deg it will show 15 then jump up to 30-40 deg randomly just for a split second

also if i use the knobs and dial in a bunch of timing on the course setting, the more timing I add the RPM increases and the engine smooths out
the car will idle at 1500rpms with 26-30deg of timing. normally I would have a smooth idle around 10deg

my fueling is decent between 12.6 to 14 so not excessively rich or lean ( i am running map vs rpm and have most all compensations turned off or zeroed out for timing and fuel )

I have been going in circles for weeks I have replaced coils / Map sensor / AIT / wideband

I am wondering if I have wiring issues ( diag shows very few crank or cam errors mostly just one or two on startup )

just to clarify on "runs rough" it seems like it has a slight misfire and i believe it correlates to the jump i see with the timing light

I have validated the firing order on injectors and coils and they are wired per the firing order I have toned the wires end to end on all injectors and coils.

Any thoughts on other things I can try for troubleshooting?
thanks in advance Dave

I am attaching my base map

[katana]

Just because you have 6 cop's doesn't preclude the use of wasted spark. I don't know the settings but its in the manual - it may point to a problem? It does seem a lot of timing for low rpm - is the crank trigger secure? and TDC correctly indentified? Thats the limit of my diagnostic skills!

[c2turbo]

Hey Katana thanks for the response,I am running coil per cylinder check box and full sequential for injection and ignition.

1. The crank and cam sensors are new and mounting and wiring have been checked and tested many times
2. I have confirmed TDC physically on #1 cylinder vs timing marks on the crank pully

[stevieturbo]

At what engine speed does this 15/30 behaviour happen ?

You have sequential/COP active only above 1000rpm....so if you're hovering around this, it could be going batch/seq off and on.

This would also account for timing on a dial back light appearing normal/double.

IMO, change that crossover far below idle, or far above idle.

And verify base timing at a few fixed positions and rpm. 0deg ideally, as that rules out any light oddities. But test at say 10deg at a few different rpms. then 20 etc.

When running sequential, ( check diagnostic display to see if it is active or not ), dial back lights should always read normally.

[c2turbo]

Steve the Seq is set at 1000rpms the issue tends to happen any where from 1500 to 3000 rpms it seems to happen faster with more RPM's

Also the lower the timing the rougher the engine runs. To me it seems like noise on the crank sensor but shows no errors in the diag screen and the shielded wire ohms out. I also replaced the sensor just for good measure but no change.

The Timing is what is throwing me off, i have given it as much as 35-40 deg and the engine still revs quickly with throttle blip

I have also played with the crank position setting in general setup from 60 deg to 86 deg and very little change in the way it runs

[stevieturbo]

stop playing with things.

Baseline it properly, and then confirm timing is as expected when running as described.

If there are problems after that, perhaps there are mechanical issues like valve timing, or general tuning

[c2turbo]

I have baselined twice /checked cam timing, valve lash / really any Senaro that I can come up with that is why i am asking for ideas, I have vehicles with Motec / Vipec / AEM and one with a Haltech I have a 2 wheel drive dynojet at my house this is not my first rodeo
I have had this DTA for 15 years on 2 different cars and have been happy with the results , I am just really stuck on this.

Thanks again for the advice I will set the timing again, zero it out confirm with a light check at different RPM's and with 10 and 20 degs settings and see what happens .


I am not being sarcastic just frustrated

[stevieturbo]

I get it, but if it really is running that bad, and more timing helps....more timing that would seem normal. Then that shouts that timing is not where you think it is.
or else there is another issue somewhere.

Does anything change if you try and run it on one coil per cylinder ?