Hey gents,

I´m currently tuning my B20Vtec with BRE.
Car is running absolutely good so far, except there is an AFR drop from 12 to 14 happening in a short time frame somewhere around 7500rpm.
When we found out that this seems to be full related, I gapped down my spark plugs and installed a new Walbro fuel pump.
AFR at WOT is 12, except the above mentioned rpms.
Any suggestions or hints what I should look at?

Specs:

B20VTEC
13:1 compression
Denso Iridium B18C6 spark plugs gapped down
Wahlbüro 255l fuel pump
H22 injectors running at 12ms on WOT

Thanks in advance from Germany

 

Hallo daffy

Warum verkleinert ihr den elektrodenabstand? Bei Verdichtungheraufsetzung vergrößert man eigentlich den Abstand. Mit was wird abgestimmt?

 

So you are tuning, and I assume have tried increasing fuel at the problem rpm and it still has an increase in AFR?

What is your injector duty cycle at when this happens? If that's not an issue try hooking up a fuel pressure gauge to the rail and watch what happens when the AFR rises.

 

Nein, bei Verdichtungserhöhung wird der Spalt verkleinert.
Bre, steht im Text

 

@2x0

Duty cycle is somewhere around 11 with my 345cc injectors.
Will install a gauge for checking fuel pressure

 

was ist bre?
Bei turboaufgeladenen Motoren wird der elektrodenabstand verkleinert und bei Motoren mit erhöhter Kompression vergrößert. Dadurch hat der zündfunken mehr Stärke und Energie.

 

Bre is a tool for Tuning OBD0 cars.
And again, you Need to REDUCE the gap for FI and high comp cars. ( The reason for that is, that because of FI or high comp the spark can be blown out during Operation.
Increasing the gap reduces the spark power, because the way it Needs to pass is longer.
And if you read the diagram you posted in, ou will see that it is a fault from translating Inch into mm.
BEcause the incha values given Show, that you Need to REDUCE the gap. Only the mm values are messed up

Information from NGK:
Another consideration that should be taken into account is the extent of any modifications that you may have made to the engine. As an example, when you raise compression or add forced induction (a turbo system, nitrous or supercharger kit) you must reduce the gap (about .004" for every 50 hp you add). However, when you add a high power ignition system (such as those offered by MSD, Crane, Nology) you can open the gap from .002-.005".

 

Remove or change fuel filter and put an adjustable fpr to raise pressure to 50psi at idle, that solve the problem.

 

yeah ive read only the mm measurements. ure right