installed MAFia, engine cutting out around 4500rpms

[recharged95]

95 Mustang 331 stroker with T-trim S/C at 14psi with a Lightning MAF. I was hitting 5Volts on the MAF at 5300-5400rpms (datalogged). It was smooth acceleration upto that point.

Now after installing the MAFia, on setting 2 and rescaling my MAF tables according to the directions (EEC tuner), the car starts cutting at 4400-4500, like I'm running out of fuel (sputtering). I'll let off at that point. Funny thing is the A/F looks fine (13.25:1) up to that point.

Now I have the 36" interface, and I spliced/solder it in right at the MAF (4pin), hence adding 36"of cable the stock length--could that be a problem? Should I splice the MAFia cable and solder(make it a shorter length)? Could there be something wrong with the MAFIa?

[mikel]

Have you logged the MAF V again to make sure it is not pegging?

[recharged95]

Yep. It's consistent around 4.04-4.07V. Once in awhile at lower rpms I get a spike in 16:1, but believe that's the logger (LM-1). I have the Mafia on setting 2.

I checked the front 2 spark plugs in case I was getting spark blow-out, both gapped at 0.038.

[recharged95]

Well, I did conclude I was getting spark blowout from the blower & switched to a CD ignition + new coil/plug gapped at 0.034. It cleanly pulls through that rpm range now--all the way upto 6200rpms.

(Jun23) EDIT-CLARIFY: the following pics are using the MAFia on setting 2, added 24% to MAF curve in tune

BUT, I lose power above 5400 rpms. The MAF is flat-lining at 4.68-4.7 volts consistently:

Run 1:

Run 2 (blower heat soak):

Cool down, tighten blower belt to make sure it's not slip):


Before installing the MAFia, I was hitting a max of 4.983V, shifting at 5500-5600rpms and it did not flat line. Installed MAFia & set to 2. Only ECU change from my old tune was I increased the MAF table by 24% as recommended.

I'm going to try some pulls w/o the MAFIa to double check, but I suspect the MAFia is faulty. Any ideas? Is there a way to self-test the MAFia?

=== edit new attachment to compliment the above graphs ===

Here's my MAFia tune it's running on an old eec tuner so with any missing values, the eec tuner uses the stock values. I've used this tune successfully when I was running 10psi--big change was exhaust and pulley upgrades to 14psi, so the only eec change was the MAF table to account for the MAFia.

[mikel]

Well, first thing I see is it goes way lean when you hit that flat spot in the MAF.

ALso, in the first post, you say (just realized this) that it seems fine at 13.25:1 AF up till this occurrence...is that correct?
You really are toooo lean if you're running it like that under load with boost at WOT.

[kmac1]

Yes, the maf flatlines, but so does your rpm trace. Is the AF consistent the whole time? Its hard to decipher the af trace. Or does it shoot lean very fast? I am thinking your engine has a restriction or the belt is slipping at that RPM. If RPM is not climbing and sitting there so will the maf V. Are you making maf adjustments and seeing no changes? Can you post your tune? There are many possibilities here, I think I can help you out if its a tune issue...

Kevin@Diablo

[recharged95]

Mike: in the runs, I added an extra 5% to the MAF tables (24 + 5 from LMAF OEM curves) and that brought the A/F down to between 11-12 from my 1st post.

Kevin: note the rpm is at least off by +40. It's a LM-1 with a RPM converter. I'm using the inductive method to get an RPM (at zero rpm is shows 40!) and MAF voltage--I thought it could be the measurement technique, but I've seen >4.8 without the MAFia before (will double check though). The A/F hits above 12 (12.2-ish) when I hit over 6000 rpms and rises slowly (11.8->12.2 for instance) after the MAF flat lines. The 3rd run is pretty messed up, lots of tire smoke in 2nd and 3rd (deserted road), first 2 runs on a controlled strip.

One thing is I'll look at the OEM tach and I'm definitely over 6000rpms, letting off @6300... Yeah, the trace is coarse since the LM-1 was less precise than I thought it would be. Was thinking belt slip too, but I retorqued it and there's no dust and the boost gauge was still climbing at 6000. Only thing that popped in my head was that is always happens around 4.7V regardless of RPM, and I know the stock tune has max MAF volts @ 4.783 (but I set it to 5.0 in my tune). As for restrictions, I have an 12" length U-pipe that reduces from 4" to 3.5" inlet and an AEM 5x4" filter that's open, connected right to the flange. Could be the filter??

I'm going to try a couple of pulls this evening EDIT: without the MAFia installed and if the same result occurs, maybe reinstall the MAFia & set it on 3. I'll see about posting my tune--it's a older EEC tuner file (gen 1 Eec-Tuner), so the MAF values are in kg/hr...

[recharged95]

(Jun23) EDIT-CLARIFY: the following pics are NOT using the MAFia.

ok, ran the risk of a bad A/F curve (luckily my engine is O-ringed and built to hold up on abuse), but here's a couple of runs w/o the MAFia installed:



Looks like it flat lines at max volts (5) around the same rpms range as before. I'm not worried about A/F for these runs since the tune is off (as long as I don't blow the engine ), but the A/F appears to hold with some noise. I'm thinking it's not belt slip as the car pulled fairly smooth, boost on the gauge looked good. I can also conclude the rpm inductive clamp is plain noisy (junk). I think it's narrowed down to air filter, MAFia, or ECU program. I'll try the MAFia again on setting 3 and see if it flatlines as well.

[kmac1]

I just noticed you are running 42# Lightning injectors. You may be at the limit of those. A stock 90mm maf and 42# injectors max out around the same power level and you have pegged the maf. Do you have a strong pump and adjustable regulator? Can you log anything in the PCM like they do with the Bin Editor stuff? Also check your fuel pressure. Do you have a Fuel Pressure gauge that you can monitor? If you have the stock regulator you should see about 54psi at full boost(or 40psi + boost pressure).

If this were my car, here is what I would do.

1. 60# injectors
2. Mafia on setting 2 and rescale the tune so the maf peaks 64#(1750kg/h) This will keep you away from any fuel/airflow clips in the stock pcm.
3. Adequate fuel pump. Far too often I get cars that are out of pump, the tuner tries to compensate in the maf curve or wot fuel multiplier and they can never get consistent AF readings due to this.

If you do the above I think you will find you have much more control.

Kev

[recharged95]

kev, thanks for the info. Everyone I know has told me to goto 60# injectors, but waiting cause I'm "thinking E85" (which would need 82's). I run 2 - 255lph pumps (Gss340) and a aeromotive AFPR. It peaks at 45psi with a base of 32# (vac on)

I'm going to try the MAFia on setting 3 so I can rule that out if it flat lines and maybe narrow it down to a restriction or the ECU. Would the ECU limit MAF voltage if I max the injectors out? Also, I presume 1750kg/hr is 25xxcfm/hr (using older eec tuner files format)...

[recharged95]

Also kev, can't log into the bin-editor, I have the SN94/5 T4M0 which needs the tweeter R/T to log anything . Only means to log is to hook up wires to Innovative's rpm converter (a pain).

[kmac1]

Set your base fuel pressure with no vacuum on the regulator to 40psi. Put a little load on it too to make sure it is still 40psi. Sometimes you may have high pressure at idle due to small return lines etc.. and a bit of load(fuel consumption) will help the pressure read what it should for base. Once you are sure your base is 40psi, hook the vac/boost line back up to it. You should see 40psi + manifold pressure now when you run it. If you are only seeing 45psi with 14 psi boost then you have an issue. Check your filter and make sure no hoses are leaking in the tank or one pump not working.

The pcm will not limit the output voltage of the maf. The limit is the PCM not being calibrated to use any more than a 5 volt input. Mafia setting 3 isn't going to tell you anything because you haven't even maxxed it out on 2 yet.

Kev

[recharged95]

ok, I'll up the base fuel to 40, but even if that stablized my A/F would that still be the cause of the MAF voltage flat-line? After looking at both sets of graphs, I think I can conclude that I'm hitting something either way with the MAFia install or not (since the ceiling occurs in the same rpm range)..

So, I'm starting to think there's a restriction (air filter or MAF) if the ECU tune looks good (link in post #4). I'll get a picture of my inlet setup posted...

[kmac1]

yep, inlet restriction or belt slip will be a cause of maf flatlining in this case.

Kev

[recharged95]

Here's what my inlet setup looks like (no kinks):


It's the filter-->LMAF-->4" - 3.5" rubber reducer 90 deg. elbow-->3.5" plastic elbow-->S/C inlet. Is there a way to tell if the rubber reducer is collapsing? (that's a short radius reducer, likely 5").