Tablet Disconnects with missfire

[DeanWs]

Hi looking for some help with weird FAULT I'm having with my G4+ Extreme, engine CA18DET 

Using R35 coilpacks,low impedance injectors and stock cas. Knock temps and boost solienoid ect.. all wired in. 

I car is tuned and configured by Garth at MGT in the uk. Everything was going great on the dyno as it is fresh forged engine running it in. After a few hours on the dyno car was misfiring at high rpm after many checks and logs we were conviced it was ignition related with no other faults with trigger nothing seen in scope (spare cas tested same FAULT) to add missfire was also only happening at running temp and wide open throttle and we thought that one of the new rb26 coilpacks were playing up so they were swapped out for spares same FAULT missfire when warm so we swapped to r35 Garth changed dwell to suit accordingly. Car ran a further 3 hours on dyno with r35 FAULT was gone or atleast I thought it was

So after road testing the car I'm using a windows tablet with Pclink, when car is upto temp and I do WOT pulls at around 5k I'm getting missfire or sometimes even worse what feels like shutdown momentary my tablet disconnects from the ecu an may sometimes reconnect. I've checked my grounds gone back through the obvious with my wiring I can not find anything at a miss. I made the loom about 3 years ago following link diagrams and helpfiles using link loom with all new plugs and connectors new loom. 

 

To add the car was mapped by Garth a year ago without FAULT I pulled the engine for a rebuild I have now gone back for tuning as now runs more boost. The only difference from the first time till now is injector size.

Am I suffering with grounding loop interference ect?. Any help appreciated if anyone could reccomend any one experienced In FAULT finding in the uk please let me know. 

[Adamw]

If it feels like it is shutting down, I would start by setting set up ECU logging, record battery voltage, a few other common variables as well as trigger stuff at 100Hz.  That should at least show if there is any shutdown going on due to lose power connection or if it is just a misfire.  

[DeanWs]

Thankyou for the reply Adam will do that, if I was to do a log could I send you the file to check over to see if you any irregular events? Appreciate your reply

[Adamw]

you can attach the file here.

[DeanWs]

missfire tablet dissconnect.llg garth map 316whp good.pclr

[DeanWs]

Logged with Laptop missfires 2 to 3 times without making rpm target of 7500 but no connection issue with a laptop

[Adamw]

Can you tell me were it misfired in that log. 

The first pull at 1:17 it goes straight to the rev limit at 7300, then you change gear but lift of at 5500RPM in the next gear. 

The next squirt is at 1:40 where again it goes straight to the rev limit, then looks like a gear change and lifted off.  

The next short pull is at 3:14 but only goes to 5400RPM, doesnt look like it is misfiring as Lambda is stable. 

Next one at 3:34 is a pull to about 6000, but again no obvious sign there is a misfire.  

The next pull at 4:11 is again straight to the rev limit at 7300.

The last pull is to about 6200RPM, again no obvious sign of a misfire.  

[BulletFactory]

Hi Adam,

I'm the OP friend, trying to help him resolve the issue. I've found a part of the log which is more accurate to look at. Its a pull where its 99% throttle, hits limiter at just over 7300 rpm, but the RPM drops to around 5000rpm due to the missfire even though the TPS is still showing 99%, so he still has his foot in. On the picture i attached, its picking up knock at this point, well CYL 1, 2, 3 all hit a counter for knock (although i'm not actually sure what this means, maybe just picking up knock from the missfire?) but there is a good 2 seconds of 100% throttle whilst only being able to reach 5000rpm after hitting the limiter (i would think its maybe limiter cut but it seems an excessive amount of time for that) . Hopefully this helps. I'm not a tuner by any means, more trying to learn haha

 

[Adamw]

That is just the RPM limit.  Another pic of the same area of the log that you are looking at.  You can see the RPM limit is active the whole time and the percentage ignition cut is very gradually removed.  This is because the tuner has set it up the limiter with a very slow decay rate (1%/20ms) so the limiter takes 1.38 seconds to decay from 69% to zero.  

A more typical decay would be something like 30%/20ms.  But I wouldnt suggest changing that without asking the tuner why he set it up that way. 

[BulletFactory]

Hi Adam, thanks for the reply

I had my 3uzfe V8 mapped by the same company and he did my limiter the same where by it was cutting for too long, which for a drifting application (which is what this car is used for) is not ideal as it will cut too much power away and thus lose wheel speed. I think he maps it safely, which isn't a bad thing, but just needs that tweeking for the application of the car.

So after that first limiter cut, the throttle is held at 99% for a couple of seconds, he then comes off throttle, then goes back to 100% TPS at 1:42.358 seconds which is achieved, but the rpm is then stuck at around 3000-3500rpm and this is when the missfire type scenario occurs and you can hear and feel it in the car, its almost like its stuck on a limiter. Is there any type of protection that is still active which means after the first time he hits the rpm limiter, it then inhibits being able to climb back up the rev range for example?

On the screenshot i attached you can see the point where TPS is back to 100% but the RPM is just stuck at around 3111rpm. So for example is it the knock global counter which now sits at 3 after that first limiter cut, is that an inhibit for example or is there something else still active which restricts RPM range

Many thanks