PE Eq ratio commanded but WB reads no erichment

[evolmotorsprt]

As title says. 2002 Corvette Stock tune. When logging, PE ratio is commanded to a lambda of ~.85, but the WB said lambda=~1.0 at WOT. Wideband was in tailpipe, but at 4000RPM+ should read lower than .98. Sensor was checked. For some reason the fuel isn't making it into the engine. I'm thinking this is a physical problem rather than software related.

A friend asked me to come look at this car to give him help. I noticed the car was pinging at WOT even on the stock tune. I've included a log to demonstrate the issue along with the stock tune. I lowered the PE torque threshold to see if that was the issue, but it didn't help. Any guidance would be appreciated.


No Erichment.hpl
Starting Point.Channels.xml
2002 Corvette C5 6MT Base Tune.hpt

[TCSS07]

The ecm is commanding the fuel change (PE) as it should so that's not the problem and you said that the wideband sensor was checked, how so? against another car and it read fine for that car? what size exhaust is being ran on both cars that the sensor is attempting to read? I've seen wideband sensors act weird if the exhaust is to big because it cant get a proper reading. I would recommend getting a wideband 02 installed in the exhaust tubing and see how the afr is that way or temporarily install one in a o2 location and check it that way.

02 sensor mv are pretty bouncy also - make sure no exhaust leaks

[Ben Charles]

Get WB in the exhaust and add 16% fuel and see if it changes

[evolmotorsprt]

The ecm is commanding the fuel change (PE) as it should so that's not the problem and you said that the wideband sensor was checked, how so? against another car and it read fine for that car? what size exhaust is being ran on both cars that the sensor is attempting to read? I've seen wideband sensors act weird if the exhaust is to big because it cant get a proper reading. I would recommend getting a wideband 02 installed in the exhaust tubing and see how the afr is that way or temporarily install one in a o2 location and check it that way.

02 sensor mv are pretty bouncy also - make sure no exhaust leaks

Yes, the WB was checked against another C5 Corvette that entered PE correctly. The car above has 2.5" dual exhaust, and I put an extension on the innovate clamp to get it another 10" into the tailpipe. If I get time to go back I'll replace one of the narrow bands with the WB. Meanwhile I told him to replace his fuel filter.

I also tried commanding an EQ of 1.3 at idle (OL with MAF failed, and verified in scanner) to try to get the car to stutter and die being too rich. The car idled just fine. I'm wondering if the fuel system is passing enough fuel for idle and normal driving, but it's being bottle necked somewhere as it's pushed, or if the pump isn't maintaining pressure at higher flow rates. Is there a way to log fuel pressure vs RPM?

[TCSS07]

Sure search the pid list in the scanner for fuel pressure if it allows it to be logged and make a histogram plotting fuel pressure vs rpm and or get a fuel pressure guage and connect it to the shrader valve of the fuel rail and see since your on the dyno much safer then taping it to the windshield lol

[evolmotorsprt]

Sure search the pid list in the scanner for fuel pressure if it allows it to be logged and make a histogram plotting fuel pressure vs rpm and or get a fuel pressure guage and connect it to the shrader valve of the fuel rail and see since your on the dyno much safer then taping it to the windshield lol

Taping it to the windshield, lol. That?s the same thing I told him earlier today.

[TCSS07]

You gotta do what you gotta do am I right lol - but yeah do the fuel system checks and wideband into the actual exhaust and if everything checks out ok with fuel pressure and the wideband still reads lean like it does then id have to say the airflow model is off and id add like 30% to the maf in the wot hz cells and see how the afr reacts to that - again make sure you have no exhaust leaks though

what mods are done to the vehicle because your injectors were working around 60% so keep an eye on that because if the tune is off you might run out of injectors by the time the afr gets inline if there isnt any outside factors of course like fuel pressure and shit like we discussed

[evolmotorsprt]

You gotta do what you gotta do am I right lol - but yeah do the fuel system checks and wideband into the actual exhaust and if everything checks out ok with fuel pressure and the wideband still reads lean like it does then id have to say the airflow model is off and id add like 30% to the maf in the wot hz cells and see how the afr reacts to that - again make sure you have no exhaust leaks though

what mods are done to the vehicle because your injectors were working around 60% so keep an eye on that because if the tune is off you might run out of injectors by the time the afr gets inline if there isnt any outside factors of course like fuel pressure and shit like we discussed

The crazy thing is he only has an intake and catback. I thought this would be an easy: check the VE, fix the MAF here, add a little timing here type of thing. But, the car wouldn't go below .98 lambda no matter what I changed. I will say when I selected the purge evap on in the scanner, the car instantly went rich to what I was commanding (evap problem?). I'm wondering if this should tell me something, but I have no idea lol.

[TCSS07]

Any dtcs? A stuck open purge valve would set a lean condition and or a driveability concern and any type of vac leak would cause your lean condition so but usually youd get some afr change when you enter pe since its dumping fuel .... the only issue you have is at wot right? Like idle and part throttle are ok?

[evolmotorsprt]

Any dtcs? A stuck open purge valve would set a lean condition and or a driveability concern and any type of vac leak would cause your lean condition so but usually youd get some afr change when you enter pe since its dumping fuel .... the only issue you have is at wot right? Like idle and part throttle are ok?

No DTCs. I checked to computer before I read it.

Yes, no problems driving normally. Only when at WOT the car isn?t getting the fuel. It's showing like 9* of kr past 4000RPM on the GM OEM tune. Needless to say I only did one full pull on the car.

[anniversaryss]

Seems similar to when my fuel pump was either dying or not getting enough voltage for higher rpm.
Car would run fine but no matter how much fuel id put in it it would always lean out up top.
New pump and a hotwire kit and all good now.

[TCSS07]

Yeah do those fuel system checks and repair as necessary

[evolmotorsprt]

Just an update for those interested... My buddy replaced his fuel filter and the rail pressure went from 52-62psi at idle. Maybe it was the problem? I'll find out this weekend when I go to look at his car again. It would be great if the fuel filter was the only issue.

[evolmotorsprt]

So I went back and looked at his car again. It looks like his fuel filter may have been part of the problem. I was able to get the fueling in line tuning the MAF (OL, Trims Disabled, with WB), but the flow rate seems high for a car that only has intake and exhaust. Maybe his MAF is going bad? This may explain some of the lean issues he had with the stock tune in conjunction with the clogged fuel filter.

Also, I don't know if it was the winter gas or something else, but it doesn't like any more than 20deg of timing on the top end.