PORSCHE951

So I scoped the crank sensors and monitored them at idle and high rpm and did not see any drop outs.. had a problem uploading the scope data to the cpu so all I have is a lame pic of the triggers at idle. I did make a log and monitor it where I found the dwell time is cutting out when my misfire happens while trigger 1 and trigger 2 voltage and signals remain ok. also noticed a limits flags word 1024 which displays shortly before and after the misfire / ign cut event... no idea what that means. I tried to upload the log but it says the extension llg is not allowed?

The car uses 2 crank sensors and no cam sensor, but yes i will try and plot both on the screen... from my understanding trigger errors will only count if there is a problem with trigger 1 (crank, rpm sensor) ?

Yeah I can try. I'll take the car into my work Wednesday and scope the crank signal again with the Snap-on Modis. I'd like to make this work rather then using an alternate trigger wheel... especially since the wave form would remain flawless on the Modis screen even when errors were counting at ~4800 rpm and the engine was missing.

The problem happens when reving at idle or driving under load. Honestly cant remember the peak voltage of the signal however I know it was more then the arming voltage, constant strong signal that never dropped out. I also dropped the arming voltage to as low as 1.5v across all rpm range and the problem still existed... Should probably mention the crank sensor has been replaced and gapped properly due to the old one being damaged from previously touching the flywheel/ reluctor teeth. (The problem has existed before and after sensor replacement).

Hey guys, apologise for the late update...good thing I haven`t relied on this Porsche as a daily driver. I got the trigger figured out as far as starting goes. found some poor wiring at the crank sensor connectors so installing some new terminals and re pinning the connector did the trick. That solved my no start issue, I still have a very livable extended crank when cold which I cannot duplicate well as it has been summer and too warm outside. The main issue I am experiencing now is that the ignition is cutting out at 4800rpm.. at that time its as if it hits the rev limit and crank trigger errors count. My rev limit is set to 6600 rpm, with launch control etc all off. I have confirmed wire integrity from sensors to ecu and scoped the crank sensor signal right at the ecu connector to verify it is receiving a clean signal. Any ideas?... I see there is new firmware out, maybe I will give that a go..

I monitored the Trigger / Limit data while cranking, found that the rpm never left 0, Trig 1 showed YES for 1-2 seconds then went back to NO all while cranking. Trig 2 showed NO the whole time. I had the Trig 2 resolution set low at 1. I will try posting the log when I am back home.

I just saved another file while cranking, again no Trigger Errors or ECU codes however both Trig1 and Trig2 signal show "NO" and RPM reads 0.

Good to hear! No trigger errors or ECU codes... However under the trigger / limits tab it shows the Trig 1 signal YES, Trig 2 signal and ECCS signal as "NO". RPM also reads 0.

Sorry to hear that you are not doing well! Hope all goes well Wednesday! I am using an AEM AFR gauge. Looks like I'm having a trigger issue.. as I saved again while cranking and still did not get a RPM or dwell reading. Kind of odd this only happens when cold?.. I have not been pulling the plugs between cold starts for the past few days, but I have been letting the vehicle sit for 12+ hours in between.

Well.. it appears as though I'm back in the same boat these past few days as the temperature has cooled back down (10 deg ECT, 7 deg IAT). I have tried decreasing my ignition timing 5deg, taking away some fuel and then adding some fuel... and it just cranks away with no signs of fire. One thing I noticed in the cold crank pcl file I sent is that the RPM reads 0 and under ignition dwell it says 0. Is it normal to read 0 when cranking? I know the actual value should not be 0..

Well, I tried the file you sent me and noticed an improvement, it started!.. ambient temp was 25deg Celsius today which may have been a contributing factor. After cranking for approximately 3-4 seconds I touched the throttle, held it barely open, close to 5% as you suggested and it started 1-2 seconds later. Still not the ideal cold start up, but it appears to be a step in the right direction. I'd like to perform a cold start again when the ambient temp is a little cooler to see how it acts. I kind of overlooked ignition timing previously, but you make a good point. I was thinking of turning on ect ignition trim and pulling 5deg timing in 0-30 deg ect range to see if that would make a difference..

Plugs look lightly used, dry, gaps have not changed. It was warmer than most days here lately and it still didn't fire. I saved during cold crank.. 944 cold crankng.pcl

Thanks for the quick replies and suggestions Dave. I replaced the plugs a week ago as the old ones were quite fouled. The engine cranks over well, I have added a booster pack with no difference. I'll make the recommended changes and decrease the crank enrichment. I'll save a file while cranking cold tomorrow after work and post it up. -Andrew

The backfire was out of the exhaust

A few months ago I purchased a Porsche 944 turbo with a Vipec v44 ecu. Whenever the ECT is cooler then about 15 deg Celsius (60 F) I get an extremely extended crank (10, 15, or 30 seconds) sometimes creating a no start condition. I have played around with the cold start crank enrichment percentage, crank hold times etc to try and solve this problem without much success. The car was dyno tuned before my ownership, obviously when warm, and runs awesome when it warms up... (when it starts!!) Restart when warm is also fine as it fires instantly! I'd like to say the car is over fuelling when cold because of a backfire it had once during a cold start.. however that cold start was after I updated the firmware to the latest calibration and the fuel pump ran for the whole update time.. The car has 55# low impedance injectors, and a t4 turbo.. is there a better way to my guess and check "blind" method? Any help or pointing in the right direction would be awesome! I'm not very experienced in engine tuning however I am a licenced automotive technician for what its worth lol... Thanks, Andrew 944+ cold start trial.pcl