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Varying Afr's On Dyno

jarrod83

By jarrod83,
in Engines & Forced Induction

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jeffworld2 Veteran

jeffworld2

Posted
Posted

coul dbe simply the way you are using the wideband... i'm assuming right down at the tailpipe? if so make certain you have no exhaust leaks etc. and if it is a stupidly big exhaust you may have accuracy issues anyway.

make sure its calibrated properly too

Sydneykid Grand Master

Sydneykid

Posted
Posted

My method;

Turn ther map trace on the Datalogit on the Injection screen

Watch closely what load cells are being used around the time of the A/F ratio issues

Check the consistency of the values, I have found the odd rouge single cell that isn't obvious until you look at that one cell specifically

You can do the same with the logging, but I find it quicker on the dyno to simply watch what's going on on the screen.

Cheers

Gary

jarrod83 Community Regular

jarrod83

Posted
  • Author
Posted

im using the wideband in the stock 02 sensor bung in the dump pipe n it also simulates the narrowband 02 for the ecu.. it pretty mcuh has to be recalibrated everytime i turn the car the car on since it loses calibration every time i turn the car off n just outputs 7.4 over n over.. which can be very frustrating when trying new things..

sydneykid: im a little unclear what you mean, pretty much i log the afr's using datalogit which is plotted N(revvs) Vs P(load) the cells that consitantly play up and differ between the max n mins are the cells that the map tracer follows when the car is coming on boost

i was thinking maybe the 02 sensor is not giving the most accurate readings since its outputting data instantly rather than a avg over a 1/12 sec period... everytime i change it to avg it out it needs to be recalibrated n every time i recalibrate it, it goes back to instant response..

ill add some of the different logged runs when i get the laptop online

Sydneykid Grand Master

Sydneykid

Posted
Posted

There is some knock there.

Have a look at the consistency of your ignition timing around 10/13 and 10/14, there are some anomalies

Have a look at the consistency of your injection around 12/14, there are some anomalies there as well.

Does it misfire when it knocks?

Cheers

Gary

jarrod83 Community Regular

jarrod83

Posted
  • Author
Posted

have had a fair bit of knockin but never heard it misfire, i had my own tune i done myself from scratch n had the varying afr issue making it hard to tune past 12psi... then i took it to a performance shop n they started from scratch and got it upto 9 psi and said it has a fuel issue.. they wouldnt change any settings n every run the afr line would be completely different.. and their map is a hell of alot richer n retarded than mine n still has the same sort of problems at the same spots.. i can upload both maps if you would like?

heavytrevy Explorer

heavytrevy

Posted
Posted
so has anyone else got any other ideas that could cause the afr's to vary so much? could it be the standard coil packs or the iriway7's im running?

U need to check things that affect AFR's (fuel and AIR)

Im guessin if ur fuel pressure is ok it must be a vac or boost leak somewhere.

Regards

Trev

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