Wide band question

[larrym]

Ok I just installed an AEM wide band.
I did a couple of test runs when I cruse under light throttle I get a reading close to 13.0 to 14.0 it fluctuates
At idle with my TT chip it sits around 11.0
Wide open throttle I getting around 11.0 also according to the tables that came with the wide band that's rich should I subtract fuel ?

Pressure is set to 42lbs with the vacuum line off, I can take it out at the chip because the readings while cruising seem good.

The install was easy, I had the bung install just before the test pipe pointing down as per instruction about 3 feet from the turbo.


http://www.aempower.com/ViewProduct.aspx?ProductID=939

[Royal-T]

WOT - you want kinda rich.... get too lean AND BOOM:duh:

Cruise and light throttle should be closer to 14.7... so you are a little rich there... TT chips are open loop so you are kinda rich there as well.... mine idles at 14.7 +/- .1 and at a constant cruise or light acceleration it is at 14.7 also... at WOT i am shooting for 10.8 [but i spray meth] HTH

Not sure but at WOT you probably could gain HP by leaning out a lil' maybe closer to 11.5 or so... do some searching for optimal AFR for Forced Induction applications on gasoline

[kenmosher]

What I've found on the engine dyno is that around 11.7:1 at WOT and high boost is about optimum for best power without spiking the EGTs. You can go a touch leaner if your heads flow well and you have enough octane, but it becomes a diminishing return equation ... and runs the risk of hurting stuff.

Safe is about 11.5:1 and makes almost the same power. 11:1 is a bit rich and is probably starting to rob HP.

[larrym]

Thanks!

I purchased the wideband as a tuning tool and a safety feature.
I did back off the regulator abit and it idles at around 13 now and cruises at 14.5
Still around 11. at WOT

Looks like my fuel pressure is good.
I did check it when I installed the pressure regulator it would rise 1lb for each pound of boost.
I have a automotive test gauge that is ment for diagnostics.

[larrym]

More tuning and I have some issues, I was a little off on my readings.

I gave it a bit of a run and at WOT wideband read 10.0 came on to that at part throttle as the boost starts to come on. I tried leaning the chip 8% no change.
The cruise and idle readings seem good 14.0 or so.

I use an AutoXray it seems to work well, Block Learn is around 132 at Idle and 126 while crusing.
That seems good to me I have confirmed these readings with my buddies scan master and the scan tool seems very acurate. I do get the odd enomolus reading that quickly resets back to what it should be.


This morning I set the base on my translator to 10% lean and pulled out 20% fuel on the chip.
I ended up with about 11.0 on the wideband with a hard pull through first and second. I lowered the boost to about 12lbs and still getting knock. It still spikes to 10.0 on part throttle pulls.

I'll lean out the translator and see what happens next.

I don't hear audible knock, which I have heard while over boosting(hooked up my external gate backwards )

Thats peringnition correct?

Detonation is unburnt fuel knock?

[Keller]

Thats peringnition (sic) correct?
Detonation is unburnt fuel knock?
Detonation is usually from just being too damn lean from too much air (boost, usually, in these cars) and having it thus detonate. It is possible to have too much timing from a race chip or a chip that is too aggressive for today's fuels give too much timing. You can get knock from too muck fuel, but it usually has to be very fat. Your O2 data would indicate that.

Since this is a feedback closed loop system, I fear you are twiddling knobs as fast as I read your sentences. The system does not have time to adjust to your changes. It can not react quite so fast, and your changes need some time to show up and be absorbed into the feedback loop fully. Not to mention you are changing the Translator and the chip. Maybe more test time in the seat and not changing the adjustments quite so frequently would let them stabilize a little.

[kenmosher]

Detonation

Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

Mild or occasional detonation can occur in almost any engine and usually causes no harm. But prolonged or heavy detonation can be very damaging. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem.

Detonation can be from too much cylinder pressure (static compression too high, low octane fuel, too lean, or too much boost) or too much spark advance.

Preignition

Another condition that is sometimes confused with detonation is "preignition." This occurs when a point within the combustion chamber becomes so hot that it becomes a source of ignition and causes the fuel to ignite before the spark plug fires. This, in turn, may contribute to or cause a detonation problem.

Instead of the fuel igniting at the right instant to give the crankshaft a smooth kick in the right direction, the fuel ignites prematurely (early) causing a momentarily backlash as the piston tries to turn the crank in the wrong direction. This can be very damaging because of the stresses it creates. It can also localize heat to such an extent that it can partially melt or burn a hole through the top of a piston!

Preignition can also make itself known when a hot engine is shut off. The engine may continue to run even though the ignition has been turned off because the combustion chamber is hot enough for spontaneous ignition. The engine may continue to run-on or "diesel" and chug erratically for several minutes.

To prevent this from happening, some engines have a "fuel cutoff solenoid" on the carburetor to stop the flow of fuel to the engine once the ignition is turned off. Others use an "idle stop solenoid" that closes the throttle completely to shut of the engine's air supply. If either of these devices is misadjusted or inoperative, run-on can be a problem. Engines with electronic fuel injection don't have this problem because the injectors stop spraying fuel as soon as the ignition is turned off.

[larrym]

Thanks for the education. This site is a great resource! I spent most of the day and evening tuning. (good thing I had a bit of driving to do today at work)

I 'm happy with the results too!
With 8% fuel trimed from the the chip and the Maf translator set at 10% lean on both the base and WOT settings. The wide band is reading around 11.5 at WOT with 15lbs of boost I only saw 1 degree of retard.
:drive:

[Royal-T]

Thanks for the education. This site is a great resource! I spent most of the day and evening tuning. (good thing I had a bit of driving to do today at work)

I 'm happy with the results too!
With 8% fuel trimed from the the chip and the Maf translator set at 10% lean on both the base and WOT settings. The wide band is reading around 11.5 at WOT with 15lbs of boost I only saw 1 degree of retard.
:drive:

GREAT NEWS!!! Now get some alky and have some fun:woot:

[PaCemkr86]

sounds like you got it dialed in...

get an alky system and start cranking up the boost

[larrym]

hehehehe thats my next investment, I did some research and felt that a wideband was in order first and get the tune right before I started to add alky.

[PaCemkr86]

i agree. good job, and please keep us updated on your progress..