223 replies to this topic

[Rosssco]

Could poor calibration result in a misfire then? That may seem an obvious question..

 

I wondered if I should do an initial fuel and ignition learning session to see if it sorts my idle mis-fire out..

[CHILL Gone DUTCH]

Interesting...

 

I'm having similarish problems with my car (2.4 bottom, rebuilt head, external trigger wheel, 3.1" pulley, Siemens 630cc injectors, standard fuel pump etc.). They are more intermittent however, as sometimes there is no misfire, sometimes there is..

 

The misfire now seems to be restricted more to a lumpy idle, where it feels its running on 3-cylinder below 1k rpm.. Above that its ususlly pretty good (still on the base map - didn't want to calibrate fuel trims till I'd resolved the misfire issue), although occasionally (like today), I get a mis-fire around 2k rpm, which smoothes out about this, but is also load dependant (i.e. greater throttle demand increases it..)..

 

I've also had a few new sensors etc. and redone the injector clips.. I also get a P0141 error code which is odd as I thought OBD-Tuners deleted the 2nd lambda..

 

Your not the only person who has thought Obd tuner deleted the second lambda this is not the case it is fully required, you can disable the catalyst check but you need to remove the Cat for this, Obd does require the second lambda 

[DaveyC]

Yeah, I just had a look at that too. This isn't the map I am currently using. I've now got very similar values in that whole area but I'm still getting the stuttering.

[CHILL Gone DUTCH]

Could this misfire becoming  from some sort of exhaust gas recirculation

 

 

[DaveyC]

Valve is removed and blanking plate fitted.

[CHILL Gone DUTCH]

Valve is removed and blanking plate fitted.

 

Yes but you could be getting the exhaust gasses pulling back into the engine if the exhaust gas pressure is higher than the inlet pressure 

 

do you have CATs fitted to all with the issue ?

[DaveyC]

Got a brand new HJS cat from Tullett with full 3" system. Also had the issue on a milltec with cat completely removed from the pipe.

[CHILL Gone DUTCH]

ah ok 

it was just a thought 

 

[CHILL Gone DUTCH]

are you all on standard Cams 

 

[DaveyC]

I'm on comp cams blower cams. These were timed by Vocky. Had the same problem with standard cams in my old engine before it exploded, the timing chain was most recently replaced by Vocky on that one too.

[Hopegreen]

We are on the standard ones.

Edited by Hopegreen, 27 January 2016 - 05:52 PM.

[CHILL Gone DUTCH]

@Davey; I checked your mapping and in the area of that logged stuttering (just above 2000rpm and ~45KPa MAP) there is a big jump (around 10°) in your ignition values. The ecu interpolates between values,but I would blend that area more and see if that helps your issue there:

 

 

 

 

here is a stage 2 low end ignition setting i have worked with without the misfire 

[CHILL Gone DUTCH]

and also here is my perfect stage 3 ignition setting with saab and M62 and stage 2 zzp cams 

 

 

Edited by CHILL Gone DUTCH, 27 January 2016 - 06:10 PM.

[Exmantaa]

@Davey; I see the misfire check is disabled in your calibration.

Not sure if OBD only switches off the fault codes and they still show in the log (no misfires were logged), but maybe just switch that on to see if the ecu can detect any misfires in your problem area?

 

 

@Chill; those tables look at least much more smooth in the low load area's. You have mMore advance, but smoother transitions.

Edited by Exmantaa, 27 January 2016 - 06:21 PM.

[DaveyC]

I used to have it active (for a short while) and it didn't detect them most of the time. Had to disable misfire check after changing the pulley as it kept triggering the check engine light under boost when everything was running smoothly. I will give it another go with check enabled and see if it picks anything up.

[CHILL Gone DUTCH]

i have run my low end ignition as high as 34 but when balancing things out with the transient settings i ended up lower than 34 as you can see in the tables

[DaveyC]

Just went out to do a quick lock with misfire check enabled again. Battery is flat. Ooops.

[smiley]

Rosco, don´t forget map or transient screenshot please.

[DaveyC]

https://drive.google...iew?usp=sharing

 

Just been out and recorded a simple log with misfire check enabled and edited the ignition cells in the area of low-load 2000rpm to all be identical.

 

Note the misfire check does not pick up every misfire. The car is actually misfiring every time I am at a constant throttle around 2000rpm.

[Pollet]

This afternoon I changed the primary lambda for another one OEM replacement, and the car turn to go fine. No misfires and strange things. Probably this will be ypur problem, but how Peter says in the tutorial, ecu is too much sensible to lambda readings, so it has to be an VX original replacemet. Hope this info will help.