I recently installed a Vortech SC, M50 manifold, and tubular headers. It was time to lean out this thing to make more power and get my mileage back to where it should be. So I was out and about tonight tuning my 97 M3 using the PLX R-500 wideband that can now monitor boost, EGT, and AFR as well as my fully hooked up Apexi SAFC2 that has had the TPS signal replaced with a GM 3bar MAP sensor. I was testing the car at partial and WOT and noticed that when in partial throttle AKA a TPS value of ~25%, that the AFR's would either peg the richest setting of 9.99 or would be around 12.5. I thought closed loop would get the AFR to be around 14.7? This doesn't seem to be case. I thought the readings were wrong so I tested by lifting off throttle numerous times and the AFR immediately jumps to the leanest setting of 19.99. WOT AFR's were in the low 10's as well. EGT's never peaked past 480C which is also more evidence the car is running super rich.

Does E36's even use closed loop? If so, under what conditions does it stay under it and when does the car transition to open loop? Perhaps the Dinan tune has something to do with the lower than normal AFR's? Something seems amiss here.

what about injector pulse, maybe its still pulsing that for the smaller injector. any way to check this with the equipment you have.
good luck....i have little experience just getting some ideas for you.

A little more background might be helpful. Is this a stock ECU with stock software and non-stock injectors? stock or non-stock MAF?

The ECU is in closed loop for idle and part throttle assuming the car is up to operating temperature.

Being that you have the S-AFC in there that complicates things big time. I hate those things - they plain don't work well on our cars consistently.

Whoops! More info guys. Stock Siemens DME with Dinan tune. ~32lb injectors that come with the Dinan SC kit. Stock 3in MAF. I know the SAFC is trouble, but I had it lying around so I wanted to play around with it :) I will be checking my LTFT and STFT tomorrow and seeing what numbers I pull.

EDIT: Fuel trim is interesting to say the least. Was getting -24% on both banks at idle. I had to pull 18% fuel at 1k RPM just to get back to stoich and get the fuel trims in check. Had to remove 34% at 2k RPM. I'm scared to tune the rest of the range since I'm limited to 50% in both directions and I have a feeling that I will quickly approach that. I wish I got some fuel trim numbers with just the SC kit installed and none of the manifolds, but I didn't. Now I'm curious to know if others had to remove similar amounts of fuel to account for these two additional mods?

Sounds like you have a stock calibration in the DME if you really need to remove that much fuel.

Are you saying that my "Dinan DME" that that came with the T9 unit that I bought off Ebay really is in fact just a stock DME? Maybe the T9 unit is malfunctioning? Any way that I can verify it myself? Nick, I might need to send you the DME if this is the case for verification and possibly to give me a proper tune.

That's exactly what I'm saying.

Does the DME have a paper label on it from Dinan indicating the date it was programmed, along with the software version?

I'll have to double check, but I don't recall seeing one. Just your standard VIN label. Let me PM you the details.

sounds like a stock dme with a "dinan" chip stuck in it. sorry.
what DME is it?

What do you mean by "Dinan chip stuck in it?" It was the same exact kind that came out of my stock 97 M3, a Siemens 41.1. This kind of sucks to know :( but more testing is required to know for sure. Oh, you betcha there will be some charge-backs involved.

I mean "dinan" as in "fake" ebay style. Someone bumps up the rev limiter, adds a little timing or fuel, and bam, its a "dinan". Don't know how easy it is for that to happen for you odb2 guys.

Well, it looks like the DME could be on the stock programming! I am getting around 10AFR while cruising on the highway which must be way too rich if it is indeed Dinan programming. You guys sure that the M50 manifold and tubular headers wouldn't cause the car to run super pig rich all across the rev band?

UPDATE: I spoke with BimmerWorld and was reassured that the image they pulled was indeed the Dinan programming. Now I'm getting conflicting explanations. Of course I trust Nick's judgment on issues such as this. I will be sending my DME to pull the programming again to check what is truly on there.

The other possibility is that you piggyback is way out of wack and is causing problems. Maybe you can try putting the MAF signal wire back to stock to see if it gets "closer".

Good suggestion Shuasha. One thing I will try is pull the MAF plug off, because I've heard of people's cars running better with it unplugged which I believe means their MAF is bad. Taking the SAFC out of the equation is the next logical step. If none of these things cause any changes I will try disconnecting the T9 unit after jumpering the airflow in/out pins so that the DME still gets the proper signal. This will prove if it is doing its job or not.

Also are you massaging the signal before or after the T9 does its thing with the MAF signal?

Definitely after the T9 which I believe is where it should be placed. Now that I think about it, I am going to try to remove the SAFC2 first since the car it previously came out of ran like crap with it on, but then after I removed it ran fine. Weird... but possibly related. Before removing it though, I will try to reinitialize the device and see if that if that fixes anything.

Well, it looks like the DME could be on the stock programming! I am getting around 10AFR while cruising on the highway which must be way too rich if it is indeed Dinan programming. You guys sure that the M50 manifold and tubular headers wouldn't cause the car to run super pig rich all across the rev band?

UPDATE: I spoke with BimmerWorld and was reassured that the image they pulled was indeed the Dinan programming. Now I'm getting conflicting explanations. Of course I trust Nick's judgment on issues such as this. I will be sending my DME to pull the programming again to check what is truly on there.

Dinan software for a Naturally Aspirated car or Dinan software for a Supercharged car? There might be some confusion there.

Silex, just curious.. does the ecu have the Dinan Turbotronics scaler attached and hooked up? Also, curious what the obdii fuel trim values read? And, have you verified that its running in closed loop mode after it warms up?

Dinan software for a Naturally Aspirated car or Dinan software for a Supercharged car? There might be some confusion there.
Like I mentioned in my OP, for a Vortech supercharger since that's the kit I installed.

Silex, just curious.. does the ecu have the Dinan Turbotronics scaler attached and hooked up? Also, curious what the obdii fuel trim values read? And, have you verified that its running in closed loop mode after it warms up?
Yes it is indeed. Trims with the SAFC2 installed were around -24 on both banks at idle. It was very erratic though.

Removed the SAFC last night and the car seems to idle at stoich once it warms up! Once in closed loop mode I took it for a drive. Through first gear it was pretty consistent and ran at stoich. Once I hit second up to fifth to cruise on the freeway, my AFR's stayed around 12.2. A bit better than when the SAFC2 was connected. As I noted earlier, the car this came from had idling and fuel delivery issues with the unit installed as well which was fixed when it was removed. There appears to be something wrong with the unit itself or perhaps the connection (with the use of t-taps) was too loose.

After doing some thinking of the correct way to hook up the unit, I believe having the SAFC2 before the T9 makes sense. Since I'm on stock MAF, the SAFC2 will be set up as a Hot Wire with the default 1 in, 1 out settings. With the T9 before the SAFC2, it scales in a manner that is unknown so I would have to have the SAFC2 set up with the proper MAF scaling as well. I have no idea how SAFC2 settings alter its characteristic curves nor the static setup for the T9 so it's just a blind shot in the dark.

I have since contacted Apexi and they are mailing me a copy of their SAFC Select manual. I can now put to rest the exact connections I need I tap into as well as the proper settings for my car! I will try hooking it again this weekend. This time... with the proper connectors...