OK, so my FI car (99 NI Maggie) was running lean on the Dyno. Installed a Kenne Bell boost a pump to keep the FP up around 58 or so PSI. No difference. Then for grins I disconnected the MAF and bamm!! MY AFRs come down from 13.5 to 12.1 to 11.8, perfect. sooo, what the heck is wrong with the MAF? Do I have a bad MAF or are the settings in the VE table incorrect? More importantly, how the heck does one go about troubleshooting this issue?
Try cleaning the maf with some brake cleaner and take some a/f readings again. A dirty and/or oily maf will cause irratic readings.
Also, was this at WOT or across the rpm range? I'd work on the injector flow rates and the VE table to get your LTFT's (long term fuel trim cells) in line (0 to around -8). If it was lean with a Wideband O2 at WOT then I'd also work on the PE Multiplier table along with the above (and timing) as a starting point.
Sounds like you need to adjust the PE table and add some fuel at WOT and see if it changes first. Was this an out of the box tune or is your tuner having problems with making changes and nothing happening??
Sounds like you need to adjust the PE table and add some fuel at WOT and see if it changes first. Was this an out of the box tune or is your tuner having problems with making changes and nothing happening??
This was an out of the box Magnuson tune. Prior to the mag install my AFRs were around 12.2-12.5 with the stock motor at WOT on the Dyno. With the MAF on (and the Maggie on) I wasn't able to get below 13.5 AFR at WOT on the Dyno. I installed the BAP, no change. Disconnect the MAF, and was getting 11.8-12.2 at WOT. The upper RPM ranges in the PE table are something like 1.13 to 1.11.
I don't have access to a good tuner package so I'm basically changing things one at a time and taking it to the dyno to see what happens. This is getting kinda expensive so I've got the MAF disconnected right now until I get the money for HP Tuners.
Ok, I've got a few questions for you:
1. What size injectors are you running and what were the injector duty cycles on the dyno?
2. Do you know what parameters the Maggy tune altered?
3. Is your MAF an untouched stock unit? (no porting, descreening, etc)
4. Was fuel pressure monitored on the dyno?
The PE values you listed above, 1.13 - 1.11, do not correspond to 11.8 - 12.2. They calculate out to be 13.0 - 13.2 (14.7/1.11 and 14.7/1.13). These #s look more like a standard tune to lean out the stock settings for some extra hp. If no changes were made to the PE or OLFA tables then this is why AFR wouldn't lower (assuming fueling is adequate).
here is my PE table. I am at 11.3-11.5 at WOT
1.207 1.207 1.207 1.207 1.206 1.228 1.241 1.244 1.261 1.265 1.275 1.279 1.284 1.281 1.29 1.301 1.301 1.301 1.301
This was an out of the box Magnuson tune. Prior to the mag install my AFRs were around 12.2-12.5 with the stock motor at WOT on the Dyno. With the MAF on (and the Maggie on) I wasn't able to get below 13.5 AFR at WOT on the Dyno. I installed the BAP, no change. Disconnect the MAF, and was getting 11.8-12.2 at WOT. The upper RPM ranges in the PE table are something like 1.13 to 1.11.
The first thing you should do is to have your PE values set around 1.2x, this will ensure that you will run a safe AFR.
It sounds to me that your VE table is too lean. This skews your fuel trims positive under part throttle conditions (+ trims = pcm adds fuel). When you go wot with positive fuel trims, the pcm will add extra fuel to prevent a perceived lean condition. The fact that it only goes rich with the MAF disconnected would make me look at VE first. Once the VE table is adjusted to go slightly rich under part throttle (negative fuel trims), then the MAF table will need to be readjusted.
Here is a link to a good maggy tune that either you or your tuner can use as a starting point for your car: http://www.horist.com/hptuner/search.asp?action=exe
I guess I need to take the plunge and pick up HP Tuners so I can see what's going on inside my motor. I'll post, either more questios, or the solution, once I get the tuner in my hands.
I love my HP tuners. I have the optional EIO cable and the LM1 wideband oxgen sensor. HP tuners can log the data from the wideband. Its really a fantastic feature...
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MAF and Lean condition question
so I've got the MAF disconnected right now until I get the money for HP Tuners.
