Has anyone log there AFR while running a M2 Stage III ecu? I just installed a used one and was shocked by how lean it ran.

On a third gear WOT pull, on a fairly warm day, I logged high 12s even topping at 13 A/F at about 6000 rpm at 11 psi. With the stock ecu I run mid 10s to low 11s.

Mod are D/P, C/B, modifyed stock airbox.

 

damn that's really lean.

 

When I spoke to M2 sometime in 2001, they said you shouldnt see AFRs over 11. I also had a wideband when I ran that ECU and would see AFRs in the 10.5-10.7 range.

 

might want to check your fuel system bc mine runs fairly rich and i have more mods.

 

Wow, that doesn't sound right at all, especially for an M2 ECU. If anything, they're on the conservative side.

 

Are you running a wideband AFR?

 

I second the recommendations that you check your fuel system. I blew an engine with the M2 when I made changes in the stock exhaust and it was the stock fuel pump that could not deliver enough gas at the higher boosts that the M2 delivers over the stock ECU. While the stock ECU runs 10 psi the M2 is around 12-13 psi, enough of a difference to draw a lot more fuel and make a big demand on the fuel pump. I would bet that there is nothing wrong with the M2 ECU but, the problem is your stock pump.

Albert

 

It may not be the fuel pump. It could be something as simple as a clogged fuel filter.

Boost pressure isn't the end-all in determining how much fuel you need. It's the volumetric efficiency of your engine, i.e., what mods you've done to the intake and exhaust. You can have two engines both running 12-13 psi, but they can have entirely different airflow and fueling needs. I've been running 12-13 psi with my stock fuel pump on a Pettit ECU for years, but I don't have a MP or single turbo.

 

His engine is fresh, maybe less than 1000 miles, and seems to be running very well. Pump may be cheap insurance. I put a supra pump in last year, it was an easy upgrade, and I've got a local guy that can get you one. I'd try that and the fuel filter and datalog again. If you need some help, let me know my lift would make the fuel filter job much easier.

 

Thanks for the replys.

The filter has about 3500mi on it ( same as the motor ) And although I'm not opposed to replacing the fuel pump, the static pressure of my existing pump is within spec and when I run my stock ecu at the same boost psi, same air flow mods, ( D/P C/B modded stock airbox, MBC ) my A/F are in the 10s/11s Wouldn't that eliminate fuel pressure/ volume problems?

Unfortunately I lost the log where I ran to redline with the M2 ecu when my laptop locked up, but I recababrated my wideband and tryed again, but I back out at about 5000 rpm when I was seeing High 12s Here's the log




And here's a log of a run to redline with the stock ecu about one hour later with no other changes.




Do you realy think replacing the pump would make a difference??

Thank's again for you help.

 

pump and fuel filter and check again

 

The stock fuel pump should be fine with your mods. After reading your first post, my thought was that maybe your new M2 ecu is in fact a stock ecu. However, if that were the case, you would likely be hitting fuel cut.

I think you got a bad ecu.

 

Ya, I popped the top and it is a rechipped M2 ecu.

 

mine remapped by FAM speed in Japan.... air fuel at 9.8 and below... ultra rich....

 

With your mods, you are probably around 250-260 rwhp at 12 psi. The stock fuel pump is reliable to at least 300 rwhp. The pump is not the problem.

Since things seem to be running well on the stock ECU, and the lean fuel ratios occur when replacing it with the M2, I don't see how it can be anything else.

 

If your testing was consistant with respect to the wideband (calibration) it sounds like the M2 chip or the computer it resides is bad... Why not pull the chip out and place it in the stock ECU and retest?

 

Found the problem, the circuit controlling the fuel pump speed relay is smoked. I wonder if the previce owner blew his motor with this ecu??

 

Good find. Looks like it should be easy enough to replace. Is that circuit readily available?

 

The burnt Inductor would be easy to find and replace but there is a totally fried IC right behind it that I can't identify. Besides who knows what other damage there might be. I don't think I'd trust the ecu.

 

^Yep. Once something has fried on a circuit board, it's a pretty sure bet that other components have suffered damage in one way or another.

 

Do Fritz's parts come with a warranty?

 

Paul,

I have a ecu that was supposed to be a M2 sitting in my shop. I've opened it up a couple of times and found no "piggyback" chip, or anything that looks like aftermarket. If you want to use it and compare it to yours, drop me a pm. I'm almost 90% sure it is a stocker though.

Matt

 

Attached is a pic of the M2 "daughter" board assembly, and the period-correct M2 labels.

:-) neil