light load misfire

jerrah · Postby **jerrah** » Fri Aug 24, 2012 4:54 pm

My AEM gauge is offset to the analog as per the link posted above but doesn't affect the accuracy of the unit as long as you apply the correct offsets in tunerstudio. That said it still would need to be wired in correctly.

It would see strange that bad injectors/plugs or wires would run fine but just have a miss at 3000rpm.

Obvious things: Have you checked your base timing on the motor?

Could you warm up the car and take a log and post the current tune you're using? I've never found the 'autotune' in tunerstudio to work 100% without some thinking of the operator to ignore the faulty tuning. Make sure you go through and ensure all your sensors are calibrated including o2.

Having a working MAP sensor will help tremendously when you get it dyno'ed again.

gslender · Postby **gslender** » Fri Aug 24, 2012 4:56 pm

Further diagnosis....

When free revving, can you determine which cylinder is causing the miss?

In which case, you can track it by swapping either spark plug, lead, or fuel injector to see if it follows the move.

G

ozi_milhouse · Postby **ozi_milhouse** » Fri Aug 24, 2012 5:13 pm

Well guys, will take your advice on the free rev, but am afraid am off to melb this weekend so will be another week before i can report back......

The joys of a modified car hey

hey atleast it keeps me off the streets. boom boom.

And ouch. Just been quoted $500 for a retune...... I could always tune around the miss then extrapolate the cells around the 3000 cell for a smooth curve. that will more or less get me a close enought tune..

report back in a week.

thanks

ozi_milhouse · Postby **ozi_milhouse** » Wed Aug 29, 2012 9:45 am

Hey All,

Tried new plugs and another new set of leads. Definitely not either of these. taking you advice and I have booked in some dyno time on the 17th to sought out the MAP issue. So after the 17th i'll be reading true kpa values and using the entire map table rather than just the bottom half of the table. But i am 99% sure that this has nothing to do with my miss. So i will update once i have had the retune, reload a new log after that and see if we can track this miss down.

Cheers
Justin

ozi_milhouse · Postby **ozi_milhouse** » Tue Sep 18, 2012 8:17 am

Hi all. Thanks for your help. All sorted now. The miss had nothing to do with the incorrect map sensor settings. The AEM wide band was reading 1 full ADR richer than it actually was and only between 2000 and 4000 rpm. At other ranges the wide band was within .3 of an afr value.

The miss was a lean miss at about 3000 revs.

I also fixed the map sensor and retuned the entire table. Got 150kw. So happy with that.

Thanks again

J