a/f running too rich???

[sml]

Hi, so it looks like that after dynoing my car, a/f is running very rich (11:1). What could be some possible causes of this? It seems like to me that if I'm running too rich, it means that too little air or too much fuel. Too little air could be due to the CAI and too much fuel could be due to the ECU map. I just cleaned the CAI filter yesterday and reconnected(undid) my ECU mod. I have a 97 lude with 70kkm and 5sp. Mods include: AEM CAI, pulleys, OBDII ECU workaround mod. Any adivce would be appreciated.

[littledan]

i've heard that vtec hondas run rich at wot and while in vtec. maybe that's the problem? don't know cause i'm just talking out of my ass here

[atomic]

OBDII ECU workaround mod?

OBDII is a protocol on the diagnostic port to view engine codes and statistics . what does it mean to you honda guys?

ANYWAY,

what octane fuel are you running? run the recommended and try it again . if you're running 91 and the manual calls for 87 or 89 then that would explain the richness .

[w3apon]

Originally posted by atomic
OBDII ECU workaround mod?

OBDII is a protocol on the diagnostic port to view engine codes and statistics . what does it mean to you honda guys?

ANYWAY,

what octane fuel are you running? run the recommended and try it again . if you're running 91 and the manual calls for 87 or 89 then that would explain the richness .

[littledan]

Originally posted by atomic
OBDII ECU workaround mod?

OBDII is a protocol on the diagnostic port to view engine codes and statistics . what does it mean to you honda guys?

ANYWAY,

what octane fuel are you running? run the recommended and try it again . if you're running 91 and the manual calls for 87 or 89 then that would explain the richness .

the workaround is to keep the ecu from learning that you have made a mod and detuning the engine to get back to factory specs... there was a thread about this just a little while back, maybe try a search

[rage2]

Originally posted by sml
Hi, so it looks like that after dynoing my car, a/f is running very rich (11:1). What could be some possible causes of this? It seems like to me that if I'm running too rich, it means that too little air or too much fuel. Too little air could be due to the CAI and too much fuel could be due to the ECU map. I just cleaned the CAI filter yesterday and reconnected(undid) my ECU mod. I have a 97 lude with 70kkm and 5sp. Mods include: AEM CAI, pulleys, OBDII ECU workaround mod. Any adivce would be appreciated.

It's not too little air dude, the air is measured via MAP sensor in the intake manifold, so it's not leaking nowhere.

Undo that mod like I told u already, drive for a few days and redyno. It's that mod that's screwing you up. Does the car feel any faster after re-connecting that wire?

[rage2]

Originally posted by atomic
what octane fuel are you running? run the recommended and try it again . if you're running 91 and the manual calls for 87 or 89 then that would explain the richness .

No it won't. Octane has nothing to do with running richer.

[sml]

Originally posted by rage2

Undo that mod like I told u already, drive for a few days and redyno. It's that mod that's screwing you up. Does the car feel any faster after re-connecting that wire?

Well, the thing is that I never felt that the car was faster or slower even when I disconnected the wire. So, by reconnecting the wire, I still don't feel that it's any faster or slower. But anywho, the wire is reconnected now and will stay that way till I put in the vafc and redyno.

[Dr. Lightspeed]

"Octane does not affect AF "

Not totally true. Depends on the volatility of the fuel and the outside temperature. Higher octane fuels have a lower evaporation point and especially fuels with alot of ethanol in them. This can really throw the AF out. Unfinshed combustion can lead to AF levels going allover the place. Now not saying this is the problem but merely playing Devils Advocate.

It is my personal preferance to tune on 87 for several reasons.
a) the one stated above
b) even tho you buy premium lots of gas joints cut it and you end up with detonation.
Also it is my preferance in tuning to watch the CO level rather than using a wideband. Wideband has become a catch term in the last couple years because it is definately more portable easier to use than a five gas. However a five gas will give more acurate results.

[del-lude]

What's a five gas???

[Dr. Lightspeed]

A five gas analyzer is a tailpipe sniffer that can measure CO, CO2, HC, O2, NOx. Quite helpful for uncovering problems.

[rage2]

Originally posted by Dr. Lightspeed
"Octane does not affect AF "

Not totally true. Depends on the volatility of the fuel and the outside temperature. Higher octane fuels have a lower evaporation point and especially fuels with alot of ethanol in them. This can really throw the AF out.

Yes, additives from different fuel sources can throw off your A/F curve, but my original statement is correct, octane has nothing to do with A/F mixtures.

Originally posted by Dr. Lightspeed
It is my personal preferance to tune on 87 for several reasons.
a) the one stated above
b) even tho you buy premium lots of gas joints cut it and you end up with detonation.

And that is why they made knock sensors.

Originally posted by Dr. Lightspeed
Also it is my preferance in tuning to watch the CO level rather than using a wideband. Wideband has become a catch term in the last couple years because it is definately more portable easier to use than a five gas. However a five gas will give more acurate results.

If one knows what they're doing in regards to setting up proper timing and proper a/f, how it affects power, etc. You can get a perfect tune using a combination of wideband o2 sensor, as well as an EGT meter.

There are some hardcore guys that can tune with just an EGT.

[Dr. Lightspeed]

OK agreed octane has nothing to do with af but higher octane fuels generally have more additives.

Not all vehicles have knock sensors. If they do they retard the timing getting an incomplete burn the wide band then says lean sot he tuner adds more fuel and the problem worsens. (in experianced tuner) Remeber we were talking someone just looking at af ratios from a dyno sheet.

When you have high compression or alot of cam overlap a wideband will not be accurate. An EGT will keep you close but never dead on. Just like I said a WB is good but not great. We are discussing best not what will work. Once again all things taken into perspective a pro knows his own equip.

[atomic]

yah that's what i meant .. the "more expensive" gas that everyone thinks will make their car faster . the additives in the premium gasoline . well and the fact it doesn't completely burn in a low compression engine with friendly timing

edited for this:

the huge discussion over octane is ridiculous which is why i suggested . knowing most of these ppl r running high octane in an engine timed for ~87 ..

[sml]

I don't think it's what octane gas I use cause I am using factory recommended for DOHC VTEC engines (91oct). But here's a hypothesis that someone came up with on preludeonline.com. It really made sense to me, lemme know if it makes any sense to you:

"Something to consider, I don't know if this is correct, but humor me for a moment. There is much less air up at 3000 feet, which would cause the stock fuel map to run richer. The ecu would accomodate for this over time, but with its memory disabled one would always be running on the stock fuel map. This might be why he is running so rich.
In any case, as stated above a VAFC is certianly in order, and if one was installed one would want to use the workaround anyway.
Like I said above, it would be a combination of the workaround and altitude. I doubt the stock fuel map was designed for 3000 feet elevation, it was most likely designed for sea level. The "learning" ability of the ecu should over time adjust for this to get the mixture near whatever it shoots for in open loop. However, if the memory is disabled (workaround) this learning process would never occur, resulting in a richer mixture as the ecu would be delivering more fuel than needed at the altitude. The big question, though, is whether the adjusted map in memory even affects open loop (WOT) operation. I've never heard a straight answer as to that."

[rage2]

They're wrong. The stock fuel map is a lookup between RPM and Absolute pressure in the intake manifold (MAP sensor). So at 3700ft elevation WOT, you'd be running on the 0.85bar portion of the fuel map (because there is less air pressure here). At sea level, you'd be running the 1.00bar portion of the fuel map (because there is 1bar of pressure there).

[Alpine Autowerks]

A fuel that uses alcohol for octane enhancement will skew a wideband sensor, as they are measuring exhaust gas oxygen.

A CO meter or 5 gas is also reading tail gasses to determine what is going on in the combustion chanber ( so they all are indirect ) so like an EGT is engine dependant ...CO to A/F is engine dependant and

F1 teams use UEGO (wideband O2 sensors for tuning) that should say something about their sutabilaty.

Some car builders run rich a WOT to jiggle HP & Torque numbers.GMC used to run 10:1 for 4.3 Vortecs..you couls sometimes see the black smoke from the tailpipe if you were slow enough to be behind one at WOT. Others like Benz never leave closed loop even at WOT on some sedans to keep their higher than average green conscience appeased.

Sorry for rambling and not answering and specific question

[sml]

Originally posted by rage2
They're wrong. The stock fuel map is a lookup between RPM and Absolute pressure in the intake manifold (MAP sensor). So at 3700ft elevation WOT, you'd be running on the 0.85bar portion of the fuel map (because there is less air pressure here). At sea level, you'd be running the 1.00bar portion of the fuel map (because there is 1bar of pressure there).

So, you're saying that all ECUs should be precalibrated from the factory to run a different fuel profile when it detects different pressure from being in different altitudes?

[rage2]

Originally posted by sml
So, you're saying that all ECUs should be precalibrated from the factory to run a different fuel profile when it detects different pressure from being in different altitudes?

Anything that uses MAP sensor for airflow measurement will automatically have elevation/ambient pressure correction. To the ECU, running 100% throttle in Calgary would look the same as running 90% throttle in Vancouver @ sea level.

[sml]

Hmm... I got another clue today...
I noticed that under WOT, I only get to -100mmHg for the intake pressure reading off the vafc? Idle is around -550mmHg. Talked to a couple of people online who said that they're seeing 0mmHg off their rides under WOT. I think I might have a leak in my intake piping or I'm leaking vaccum! arrrggghhhh!!!