AEM Ultimate Resource Thread>>>>

[Heikki]

While tuning for pump gas afr I noticed something strange on my fueling and hope experts here could point out what might be causing it.

Attached is internal log file on short 1-2 gear acceleration. As you can see my afr is dialed to be on the safe side, but there is a strange "lean bump" just as the boost controller achives the set boost, in this case ~1.2 Kg/cm2. As you can see the fuel corrects itself immediately after the boost stabilizes, but I definately would not like to see such a lean bumps when I really start cranking up the boost.

Also strange how there are knock spikes on first gear near redline, and nothing on second gear.

Opinions?

Heikki

EDIT: This is with boost compensated fuel map.

[Heikki]

And here's 3rd gear pull to ~1.05 Kg/cm2. No lean spots whatsoever.

Heikki

[BAdAzZV8]

Is it simply a boost spike and you don't have the fuel tuned at the higher boost level? Does it correct itself if you add fuel to the upper region?

[Heikki]

Sorry no, I should have clarified from start that I am running a boost comp fuel map, therefore any boost spikes should not matter.

Heikki

[BAdAzZV8]

Even with boost comp, you still have to setup your fuel map at the higher boost level. I have my fuel adjusted cell by cell in some places even with a boost comp setup. It won't magically be the exact same number everywhere, it may differ by 1 or 2 points here or there. Try adding fuel in your fuel map at the boost level that you're getting the lean AFR.

[Heikki]

Ok well that clarifies it then, I thought that linear boost compensation would take care of all load levels once a safe baseline is set, which in my case was 1Kg/cm2.

So basically I can either fine tune higher load rows as you suggested or go back to boost comp graph and adjust the gain accordingly.

Thanks for you help.

Heikki

[mjannusch]

Your best bet is to use the boost compensation to get your tune somewhat near where you want it to be (using just a straight-line boost compensation) and then tune the high load cells to really dial-in the tune to perfection.

I don't recommend adjusting the boost comp curve to try to tweak the fuelling because volumetric efficiency changes at different RPMs, but the boost comp curve only adjusts load compensation. So if you adjust the boost comp curve, you are shifting a whole row of load values in the fuel map versus just the area that you really need to change.

[Heikki]

Thanks mjannusch, I agree the best way is to tweak the high load cells as oppose to adjusting the boost comp curve.

I did some 1.5Kg/cm2 runs yesterday with a blend of 93/100 octane and AFR was in the high 11's. I think I have collected enough data now that I will be able to get my fuel map dialed in pretty well.

One thing I noticed that my brake booster line is bleeding manifold pressure into the master cylinder. My brake pedal got rock hard whenever I was on boost.

I just bought some C16 and plan on going to the dyno later this week to tune the timing. What I have gathered, with AFR at low 12's I should be able to run at least 25 degrees, perhaps even 30 degrees of timing with 2Kg/cm2 of boost.

Heikki

[mehlosTT]

Wrong section posted by accident_ sorry

[1veryfastvr4]

been forgetting but here is the AEM 3.5 bar map sensor holder i was talkin bout long time ago