Tuning woes, running waaay to rich

[Navybluesubaru]

I have an 02 wrx with the latest ecu revision for the model (AF426). I have modded injectors, the ecu set to 672 and the maf table left alone. The car idles fine and the fuel trims hover around zero. When I go full throttle from around 2k-3k up to around 5k, the afr's dip into the low 10's and high 9's. It runs so rich the engine refuses to accelerate anymore, typically around 5k it just stops revving and sputters. I took the fuel maps and put 13.5 in the higher load columns and the car still runs mid to low 10s AFR. The load gets as high as 5~ish, even at only 6psi and 4500rpm. The maf voltages are being logged as high as 4.2, while a similar utec log under the same rpm and boost reports only 3.7 maf volts. It appears as though the ecu is seeing a lot more maf voltage than the utec sees. Note, I am logging the stock ecu with the UTEC totally disabled and I was comparing semi-recent utec logs for comparison. I know the stock ecu simply passes the value on to the utec so how could they be different?

Anyhow, my main problem is that the stock ecu runs 10:1 even though the map contains values of 13 and 13.5. I would like to somehow get the car to run 13 when I say 13 and to run 11 when I say 11. Any suggestions? All I have thought of is to modify the maf table and reduce the air quantity so the ecu registers it as less air, thus less fuel.

Jeff

[Jon [in CT]]

Remove the piggyback.

[Ultimate CC]

well one thing to note is that the values for afr's in the table only apply to stock cars, once you modify them they then become just a value hence the reason for having a wideband o2...as for your problem I am not sure how to help you...

[Jon [in CT]]

The load gets as high as 5~ish, even at only 6psi and 4500rpm. The maf voltages are being logged as high as 4.2, while a similar utec log under the same rpm and boost reports only 3.7 maf volts. It appears as though the ecu is seeing a lot more maf voltage than the utec sees. Note, I am logging the stock ecu with the UTEC totally disabled and I was comparing semi-recent utec logs for comparison. I know the stock ecu simply passes the value on to the utec so how could they be different?

Yes, the UTEC does poll the ECU using SSM protocol in order to log MAF voltage from the ECU. However, the actual MAF voltage passes through the UTEC before it arrives at the ECU. The first UTEC implementations modified that MAF voltage in order to trick the ECU into supplying leaner or richer A/F mixtures in openloop. That capability is still present on all UTECs, I think. It seems clear that your UTEC is NOT totally disabled, given the large differences in logged MAF voltage. Remove it.

[ride5000]

Yes, the UTEC does poll the ECU using SSM protocol in order to log MAF voltage from the ECU.

the utec has never done this, nor do i think it ever will.

[MRF582]

I have an 02 wrx with the latest ecu revision for the model (AF426). I have modded injectors, the ecu set to 672 and the maf table left alone.

Wow. With modified stock injectors and stock fuel pressure, your injector scalar value if using Enginuity 0.3.2 or above is WAY way too rich.

http://forums.nasioc.com/forums/showthr ... ?t=1114228

Prerequisites - stock intake, stock fuel pressue, modified stock injectors.
Even if your intake is not stock, you should be able to fine tune it a bit. Try the values I posted in that thread and see if they work for you. So far everyone that has modified stockers who has used those values has reported success.

[Navybluesubaru]

The utec does not do any SSM, it mearly intercepts the signal before the stock ecu ever sees it. I have no plans of removing it(the utec) so thats out of the question.

I followed the advice of MRF582 and rescaled the maf table and adjusted the injector size as he stated. It works great and the car idles and cruises great. Under full throttle though the car still nose-dives super rich, richer than 9:1. The richest value in my stock ecu is 11:1 and my intake is stock size, although not the stock setup; its a perrin short-ram.

I dont really need the car to be drivable without the utec but I at least thought it would be nice to have the stock ecu semi-tuned in the b/g as well.

btw, the utecs own 'open-loop fueling' has its own internal mafv/air lookup table that mimicks the stock ecu one; when I set it up to 850cc and a fuel map with all zeros the car will run great right around 10.5-11:1, so the utec has no problems with my intake or anything else being out of whack so I would think that the stock ecu would also recognize the values as being within tolerance to perform proper fueling calculations.

Jeff

[Jon [in CT]]

Yes, the UTEC does poll the ECU using SSM protocol in order to log MAF voltage from the ECU.

the utec has never done this, nor do i think it ever will.

Of course the UTEC uses SSM protocol. How do you think it is able to log the A/F ratio from the front A/F sensor? If the UTEC could interpret that sensor's signal itself, it would be able to do closed-loop fueling.

[Jon [in CT]]

I have no plans of removing it(the utec) so thats out of the question.

How hard could it be to temporarily remove the UTEC to guarantee that it isn't screwing up the MAF signal seen by the ECU?

[xswrex]

Yes, the UTEC does poll the ECU using SSM protocol in order to log MAF voltage from the ECU.

the utec has never done this, nor do i think it ever will.

Of course the UTEC uses SSM protocol. How do you think it is able to log the A/F ratio from the front A/F sensor? If the UTEC could interpret that sensor's signal itself, it would be able to do closed-loop fueling.

An apexi turbo timer can also display the A/F ratio reading from the front o2 sensor. It uses SSM as well

Seriously now, do you know how UTEC looks like set aside how it works? It uses directly the car cable harness, so it reads the signals and then passes them on to the factory ecu (modified or unmodified). That simple

[Jon [in CT]]

An apexi turbo timer can also display the A/F ratio reading from the front o2 sensor. It uses SSM as well

Seriously now, do you know how UTEC looks like set aside how it works? It uses directly the car cable harness, so it reads the signals and then passes them on to the factory ecu (modified or unmodified). That simple

Hook up an Apexi turbo timer to the front A/F sensor on any New Age WRX and it will either fry or always stay pegged at the richest value because it is detecting a voltage that is always greater than 2.5V instead of the 0-1V it was designed to expect.

The UTEC can modify the MAF voltage before it is detected by the ECU. Why not remove it while scaling new injectors to eliminate any chance that the ECU is seeing an incorrect MAF voltage?

[xswrex]

The UTEC can modify the MAF voltage before it is detected by the ECU. Why not remove it while scaling new injectors to eliminate any chance that the ECU is seeing an incorrect MAF voltage?

you dont have to remove it to find this out. The UTEC reports and logs both unmodified/modified MAF volts

[ride5000]

Yes, the UTEC does poll the ECU using SSM protocol in order to log MAF voltage from the ECU.

the utec has never done this, nor do i think it ever will.

Of course the UTEC uses SSM protocol. How do you think it is able to log the A/F ratio from the front A/F sensor? If the UTEC could interpret that sensor's signal itself, it would be able to do closed-loop fueling.

jon, seriously--it does NOT currently, nor has it ever had in the past, any capacity whatsoever for ssm communications.

now, while i think that is "stupid," due to the level of functionality that could be unlocked, i am 100% certain that this is in fact the case.

i do agree that while troubleshooting ANY system, removing extraneous components is generally the first step.

[cdvma]

The UTEC doesn't do SSM. It doesn't even know what SSM is. The ECU only has one UART for SSM so if the UTEC was using it nobody would be able to use DeltaDash or any logging software.

It gets the AFR by doing a current sence and translating the value...just like the stock ECU does.