1995 M3 Dinan Supercharged, Stg. 1, high RPM hesitation

[wsybert]

1995 M3 with a stage 1 (non-intercooled) supercharger. 5psi boost.

I took it to a dyno today to have the AFR checked. Running very lean at WOT and high loads. Couldn't get past 5k rpm without studdering and seeing 14-15+ AFR numbers at that point.
This shop is not a BMW tuning shop, they tune Mopar, but the guy was knowledgeable about what he was seeing. (Nothing else nearby)
I have very little history on the car. (Bought it with the issue.) I did talk to the PO, who didn't have it for very long, but said it started a few months after he got it.

The tune is Dinan. I pulled the DME and see the Dinan chip.

The fuel pressure is higher than what it was setup for... only because I was trying a few things. It is running at 60psi, instead of factory 49psi.
(I put in an adjustable FPR).

All the plugs are showing signs of detonation and lean mixture, so this is most definitely a fueling issue... just not sure why.

Anyone know where else to look or what else to check??

Thanks for any help.

Bill

[flyfishvt]

What injectors and maf are you running?

[wsybert]

Bosch 502 MAF
Lucas D1720BA injectors

[95AWM3]

How old is the fuel pump and fuel filter?

[wsybert]

How old is the fuel pump and fuel filter?

Not sure. I'm seeing 60psi at the rail under load and WOT, so I'm getting enough fuel.

- - - Updated - - -

Could the Turbotronics scaler be bad or MAF? Anyone have a way to check these?
Only other thing I can think of is the tune, but it's a Dinan chip and I doubt it would go bad in anyway.

[wsybert]

Any ideas?

[wsybert]

Could it be MAF scaling issue i.e. bad turbotronic module? Or Bad MAF?
I'm at a loss here. Help.

Everything to me is pointing towards lack of fuel of the top end.

[540-S3]

Hopefully this will help you - see page 2 of PDF: Tune Turbotronics 9.

[wsybert]

Hopefully this will help you - see page 2 of PDF: Tune Turbotronics 9.

Thanks!
Mine is a T10, but am guessing the output should be similar. I know it's not the same electronics.
I'll give that a shot.

[wsybert]

Dyno runs showing the AFR. LOOK AT THE ORANGE TRACE. (There are remnants of a green trace (AFR #2) on the one graph. I tired to erase as the sensor was failing and gave inaccurate readings, just to give some better clairity.)

The graph looks a little odd, as this is the way it records the data. START is the start of the run and it reverses when you let off the throttle, and ends up at the FINISH point.

You can see the the car adding fuel and then start to lean out around 4900-5000 RPM. It tried to recover but ends up hesitating and getting too lean. He let off just as that started to happen.

I did two back to back runs with similar results. The second graph is the second run. You can see that AFR #2 sensor is crapping out.

[wsybert]

Well, I found the issue. Bad MAF clamp. The T10 should be 3570 ohm and it was 2662 ohm. I got the 3570 number from Dinan tech support. I didn't check, but guess the voltage the DME was seeing was out of range at the top end.
I am seeing 5.57 volts after the clamp now at max RPM and WOT.
Still seems a little high. Opinions?

[1000hp]

How much timing at 5k RPM?
And what do those injectors flow?

[wsybert]

How much timing at 5k RPM?
And what do those injectors flow?

Not sure of timing. How could I check that at 5k under load?
Injectors are 28# per Dinan specs.
Not sure if you read my last post, but I think I solved the issue. Need to check AFR now to be sure.

[wsybert]

I miss measured the voltage. I took it before the resistor by mistake. Doh!
After the resistor it was 4.21 volts at max RPM and WOT.
Sounds more reasonable.

- - - Updated - - -

Also, for those wondering. The Dinan Turbotronics 10 is simply a resistor.
The one I took out was a 2660 ohm, but according to Dinan is should have been 3570 ohm.
Odd, as the T10 I took out was fine, as far as the resistor goes. Wrong value?!? The color bands matched up with what I measured. Odd...

[wsybert]

Put the car on the Dyno. Ran well. First run (solid line) was with the resistor value Dinan gave me. Second was a little less... About 150 ohms less. AFR looks better with the lower resistance number. That's where I left it. 300 HP on a mustang Dyno... I am happy for now. May do some custome tuning on it later.