PORSCHE951 Posted April 29, 2014 Report Share Posted April 29, 2014 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 Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted April 29, 2014 Report Share Posted April 29, 2014 Hi, I will download your PCL and have a look. When you say you tried to start it , you mentioned it backfired. Was the backfire out of the exhaust or out through the intake. Regards Dave. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted April 29, 2014 Author Report Share Posted April 29, 2014 The backfire was out of the exhaust Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted April 29, 2014 Report Share Posted April 29, 2014 OK, cool. Regards Dave. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted April 29, 2014 Report Share Posted April 29, 2014 Hi Andrew, couple of things to try. Firstly try changing the Prime mode to Ignition On instead of Ignition Start position, this will fire the injectors prior to cranking which will wet the manifold runners and or inlet port with fuel before cranking. Back firing out the tailpipe is normally a good indication of excessive unburnt fuel in the exhaust when first starting, or ignition timing issues. Try reducing your First Crank Enrichment value down from 40%. All of your crank enrichment values seem to be quite high. Your IAT fuel trim is adding 2.5 % extra fuel trim at 9 deg c, which going by your runtime values, is what your IAT was at. However this is with the engine running, at 37 deg c. PLEASE MAKE SURE YOU HAVE CLEAN FRESH SPARKPLUGS IN THE ENGINE FOR THIS TEST, WET OR CARBON FOULED PLUGS WILL EXAGERATE STARTING ISSUES, It would be good to get the engine dead cold, crank the engine cold without touching the throttle, while the engine is cranking hit F2 key on the laptop and save the file as COLD CRANKING PCL. Post this file up, from this info I can calculate how much extra fuel trim is being added to your Main fuel table value. Also does the engine crank properly when cold, does it labour to crank over hot or cold. Regards Dave. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted April 29, 2014 Author Report Share Posted April 29, 2014 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 Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted April 29, 2014 Report Share Posted April 29, 2014 Hi Andrew, I see you have replaced the plugs a week ago, but please do us both a favour and check the plug gap and make sure there is definitely no fouling build up over the last week of use. Regards Dave. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted April 30, 2014 Author Report Share Posted April 30, 2014 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 Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted April 30, 2014 Report Share Posted April 30, 2014 Hi Andrew, try the attached file and let me know how it goes. If it doesn't start easily, crank the engine over with a small throttle opening example 5 %, DO NOT PUMP THE THROTTLE, JUST DEPRESS IT TO 5 % AND HOLDIT THERE AND CRANK THE ENGINE, see if it wants to fire. Also the cranking ignition timing would be around 19 deg BTDC, cold the engine may only want 12 or 15 degrees. Just something else to consider. In this attached file I have set the primer back to cranking mode and reduced the cranking fuel enrichment tables. Adjust the values when cranking at the highlighted table I have attached around the 10, 20 and 30 degree cells. Regards Dave.PORSCHE 944 COLD CRANK FUEL MODS VER 1.pcl Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted May 1, 2014 Author Report Share Posted May 1, 2014 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.. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted May 1, 2014 Report Share Posted May 1, 2014 Hi, well that's great news. The reason I suggested holding the throttle open approx. 5% is sometimes there is insufficient air bypassing the throttle blade or idle bypass solenoid. The starting issues can be a fine delicate combination of throttle blade air gap adjustment, or air bypass valve settings, fuel trims and ignition cranking timing. So keep adjusting. Try to keep my file as it is. When you make any new changes save that file with a new name. Make small adjustments on as few settings as possible. Most times people get what I call TUNING HUNGRY and want to make big value changes and change lots of parameters at one time. This makes it hard to figure what made it better or worse. Small steps, you will get there. If all goes pear shaped revert back to my original file and start over again. Good luck, Regards Dave. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted May 4, 2014 Author Report Share Posted May 4, 2014 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.. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted May 4, 2014 Report Share Posted May 4, 2014 Hi, If the RPM and dwell etc read 0 that means you haven't saved the file while cranking or you have a trigger issue, arming voltage set to high if Mag reluctor sensor etc. I am not very well at present, going in for surgery on Wednesday, so I will have another look at your PCL file and see if I can make some more changes for you, now with the new cold weather temps. Try to reload my file I sent you, see if it starts an easier as it did before. Are you using an AFR meter while trying to start, are you pulling the plugs to check for excess fuel, wet plugs etc. Regards Dave Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted May 4, 2014 Author Report Share Posted May 4, 2014 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. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted May 4, 2014 Report Share Posted May 4, 2014 Hi, I will be fine. I can't let all you good people down. Can you hit the F12 key and look under triggers and limits tab and look for trigger error counts etc. Also look under the ECU tab for ERROR CODES or counts. Regards Dave. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted May 4, 2014 Report Share Posted May 4, 2014 Hi, Ok so you leave the plugs for 12 hours. You still really need to have a look at them. When they are wet, fuel can form between the porcelean of the plug centre and the threaded housing, All fuels have additives mixed in them, conditioners etc, all fuel companies use these additives, the additives can form a coating on the centre electrode or ground strap. This works like an insulator, the more raw fuel deposited the more these waxes and gums form. Then of course there is the dreaded carbon fouling, where the plugs are black and sooty. The spark travels from the centre electrode to the base of the plug via the porcelean , (sorry don't know how to spell it). We need to see if the plugs are dry when cold cranking, or wet or at least smell of fuel after trying to start. Do you get any form of change in the AFR value while trying to start the engine during partial fire. Regards Dave. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted May 5, 2014 Author Report Share Posted May 5, 2014 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. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted May 5, 2014 Author Report Share Posted May 5, 2014 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. Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted May 5, 2014 Report Share Posted May 5, 2014 Hi, don't worry about trying to save the file while cranking. With the ECU Online and with runtimes value page open F12, with the triggers tab open and cranking you should see trigger 1 and 2 OK or YES and you should see an RPM signal. I just had a look at your last file and see a trigger 1 no trigger 2 and no rpm. Can you change your trigger 2 filter level from 3 down to 1 please. Setup your PC logger as per my screen shot and check the runtime values while you are cranking the engine capturing the data log info. Regards Dave. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted May 5, 2014 Author Report Share Posted May 5, 2014 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. Quote Link to comment Share on other sites More sharing options...
Gsab Posted June 16, 2014 Report Share Posted June 16, 2014 Any further progress here guys ? This is invaluable fault finding here.. Quote Link to comment Share on other sites More sharing options...
Simon Posted June 16, 2014 Report Share Posted June 16, 2014 Given the lack of trigger signals I would be also checking the arming voltages. Try lower than 0.5 it could be that due to the slightly slower cranking speed it is failing to pick up the triggers. Quote Link to comment Share on other sites More sharing options...
PORSCHE951 Posted August 28, 2014 Author Report Share Posted August 28, 2014 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.. Quote Link to comment Share on other sites More sharing options...
Simon Posted August 28, 2014 Report Share Posted August 28, 2014 Check the peak voltage of the signal at that RPM . It could be you need to lower the arming voltage above 4000 rpm. Arming voltage should be roughly half the measured peak voltage at the given RPM. Quote Link to comment Share on other sites More sharing options...
Simon Posted August 28, 2014 Report Share Posted August 28, 2014 Should also ask if it does it free revving or only while under load? Quote Link to comment Share on other sites More sharing options...
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