Matt87GTA

My MAF failed a few days ago and I just recieved the Wells MAF I ordered and installed it, but the car does not seem to like it - AT ALL.... Runs like poop.

I got a look at some scantool data quick and it shows me in cell 8 with 27-29 g/sec at idle (~650-700RPM - had to kind of feather it a bit to keep it running until it warmed up). I also am stuck in closed loop....

So what are the rest of you guys with Wells MAFs seeing? Am I to assume that the one I got is miscalibrated or malfunctioning?

TIA,
Matt

Matt87GTA

I screwed around with it again a little bit today dand got it to idle on its own once it warmed up a bit. With a steady (well, as steady as my car idles given the components) 650 RPM idle it is reading 27 grams/second and is in cell 8.

I reviewed some data logs just be sure that I wasn't losing my mind and sure as $hit, the car idled around 7~8 grams/second once it was warmed up and all with the stock Bosch MAF (when it was still working, of course)....... I am still getting no closed loop..... No SES light either, but the threshold for the high MAF signal error is set to like 45g/sec, so........

Anybody out there successfully running this sensor? Logged any data?

TIA,
Matt

Vader

This is what I got:



That equates to roughly 37g/S at 800RPM. 8g/S is WAAAY too low at idle, unless you're at about 14,000' elevation.

Matt87GTA

OK, well at least this seems to point at my Wells MAF working as designed and intended....

But I am still confused on the g/sec at idle.... I looked over my logs again and my Bosch MAF was definately reading around 7~8 grams/second...... What do the rest of you see with stock Bosch MAFs (or Wells MAFs of course)????

So Vader, am I looking at totally resetting my MAF tables in the PROM in order to get this Wells MAF to work? I can do that, but I really don't think I should have to....

TIA,
Matt

Oh, I'm in MN, so that's a negative on the 14k feet .

Mark 89Formula

Matt,
My readings with the Bosch MAF are very similar to yours; 6-7 g/s at 650 RPM. Just for comparision I see 25 g/s at 2800 RPM in neutral. The Wells doesn't look like a direct OEM replacement based on your readings.

Matt87GTA

I am about ready to agree with you Mark..... But what in THE f*ck???? I thought this was a known direct replacement part for MAF TPIs??

I found this on Wells' website......

I know they are talking about a digital MAF in that blurb, but they still speak of the lower g/sec figure as the normal one. I just may give them a call tomorrow....

Matt87GTA

Well, I called Wells and talked to one of their 'Techs' .... The guy really didn't tell me much. He just gave me the standard "the sensor is designed to operate per OEM specs, so...... :lala: " But I called the place I got it from and they will be sending me out a new one - when? Who knows.... These things appear to be selling quite fast.

I would still appreciate some scantool results from other Wells SU-145 equipped TPIs if at all possible.

Thanks,
Matt

Jim85IROC

iTrader: (2)

hmm. My GTA runs exactly the same as it did with the bosch. I'm going to have to hook my X-ray up to it and see what it tells me.

Matt87GTA

That info would be much appreciated .

Matt

Jim85IROC

iTrader: (2)

I forgot to grab it tonight.

I'll try tomorrow.

Matt87GTA

Roger that.

-Matt

Jim85IROC

iTrader: (2)

I hope you all appreciate this. I sat in the parking lot at work, trying to re-learn how to work my damned x-ray for the first time in a year, all before a cup of coffee.

Anyway... 6g/s at idle. I was running too late to screw around with higher RPM or driving. The car drives identical to how it did with the stock MAF. It idles perfectly.

Can somebody give me the cliff's notes of this thread? Maybe it's because it's early (and I STILL didn't have my coffee ), but the way I'm reading this thread is that we should be seeing 6-8g/s but Matt was seeing 27-29 with his Wells. Right?

tpi_roc

Im running 9-10 g/sec at a 750-800 idle

AlexJH

I get 7-8 gr/sec at a 600 rpm idle.

I think you got a bad MAF.

Matt87GTA

Mucho appreciation .

Well that is enough information for me to assume that the Wells MAF I got is FUBAR'd... or at least not calibrated correctly.

You got it. With nothing else changed on my car (aside from the fuel pump), the Bosch suspended wire MAF would read 7-8 grams/sec at about 650RPM and the Wells exposed circuit MAF reads 27-29 grams/sec.

I am not sure when the *new* (or should I say other) MAF is going to get here, but I will keep you guys posted on how it reads on my ride.

The part that really has me confused is that Vader is seeing what I am seeing and he said ( I think ) that his car runs fine???????

Boy that 808 code is lookin REEeeeeeaal nice right now .

Matt87GTA

Thanks for the input . Is this with a Wells MAF? Those figures seem about right since your idle is a hair higher than what we have ours at.

Jim85IROC

iTrader: (2)

Good point. I forgot to mention that my car is a 5-speed 305, so it's going to idle at a somewhat lower RPM, plus it's got less air demand. Next week I'll probably be moving the wells MAF to my IROC, so I'll see what it does there too.

tpi_roc

I hear that!



No sorry I'm running an old 85 ('870) MAF

Jim85IROC

iTrader: (2)

Speaking of which... I discovered that the wells seems to work ok on an 85 (at least to run and idle) but throws a code. I didn't try driving it.

More worthless albiet fairly interresting information... the 85 MAF seems to work just fine on the newer cars. This surprises me because the newer ones use a constant-voltage system and the 85 uses a frequency-bases system, but the 165 must have a good enough buffer, and must convert the signal to approximately the right voltage. I drove the GTA for a couple weeks with the 85 MAF, and guys that have upgraded to a 165 on their 85s were able to keep using the stock MAF.

tpi_roc

Like me

Jim85IROC

iTrader: (2)

And you still get 9-10 g/s at idle. Cool. It amazes me that the old style MAF is compatible. The older MAF is substantially more reliable than the 86-89 unit too.

Vader

Yes, the Wells analog MAF has been working just fine on my car for three years (well, "fine" for a 305 TPI, anyway).

I only took mV readings and presumed the MAF function was relatively linear. I'd have to look at the MAF scalar tables in the PROM hac to make sure of that. I'd also need to try an AutoX-ray to verify that computation.

I use AutoTap on my OBD-II cars, and I just now looked ay my '96 LT1 to see what it reports at idle - should be close enough for comparison. I got 7.38 g/S @ 700 RPM idle. I'm guessing the MAF tables in the old '165 aren't as linear as I thought. Worse yet, I discovered my oil temperature on the '96 is at -34°F! Funk! not even 4,200 miles and the temp sensor has crapped out on me. That's what it gets for being a garage queen, I guess.

If your '85 (FM) MAF is working at all in the '165 ECM cars, it must be due to the external buffer module on the back of the ECM. They must be pretty liberal.

Matt87GTA

That would be cool if you could get some gr/sec data on that sensor. I would start my car again and check the voltage output of the sensor, but It really doesn't like to idle when it is cold and I fear that I will foul all of the plugs if I run it anymore the way it is (pumps very generous amounts of black smoke with the current 'bad' Wells MAF on it). And I just slammed plugs in it and don't want to have to do that again so soon.... I suspect the same thing about the MAF. In fact I think I remember Bruce or somebody saying something about that phenomenon with the analog MAF before.....

And you really gotta let that Imp out of the cage more often!!

Thanks again,
Matt

Matt87GTA

Well, got the new MAF today.... Strapped it on the GTA and got the same readings....

I am really looking into just going straight to the 808 code now. I wanted to get the MAF back on and do some more tweaks and do the 808 conversion at my leasure, but now it looks like I will have to get to it right now.