tuning a 944NA with an Abaco sensor

ritter4242 · 06-22-2013, 03:47 PM

Well I got into the MAF is better than AFM hype.. and man do I have second thoughts. I mean the numbers were good, it made sense, and the AFM is almost 30 years old now. So I went out and got an Abaco 85mm Quad sensor.

Well the car runs, it just doesn't run.. right.. I get to 3000 RPM very slowly and then it kinda sits there and chuckles. If I put the pedal to the floor it shudders and doesn't accelerate. I'm not a big car guy and I've been learning the ropes on this car. I think I may need to replace injetcors, spark plugs, fuel lines, fuel rail etc.. but I'm pretty sure its the air flow sensor.

So my question is does anyone have one of these that turned out well? should I just sell it to one of the 951 guys and just get a rebuilt AFM? I really want to keep the Abaco sensor because my fuel economy is well.. it hasn't dropped below 30 very often. So it IS working, just not the way it should. I know the car can haul. I mean it hasn't been THAT long since it was driven with the AFM, but it sure isn't doing what I know its capable of.

AaronM · 06-22-2013, 05:44 PM

Are you sure you set up the MAF properly? If the car was running fine with the AFM then it's probably an issue with the MAF.

The early and late AFMs have different signal patterns, so if you have an early car you can't run the same MAF settings as a later car. From what I can tell, none of the supplied maps for the Lindsey Abaco MAF kit will work with the early DME.

The early cars have an AFM that uses an unregulated 12v input voltage (minimum 8v) and the output is nonlinear while the later cars use an AFM with a linear output and a regulated 5v (+/- 0.5v) input voltage controlled by the DME.

If you have an early car and are using one of the canned maps in the LR kit it looks like you're going to lean out massively as RPM climbs, which is in line with the symptoms you're seeing.

For more on the difference between the early and late 944 AFMs, I recommend here: Air Flow Meter (AFM) - from "The 944 Motronic DME" by FR Wilk* ©2001 www.the944.com

ritter4242 · 06-22-2013, 06:12 PM

I have been assured repeatedly that I have the right file (from Dave Lindsey himself) that it is file #4 selector 1.
File #4 ----- 944 AFM(S1) | 19#(S2) ~ 944 8v AFM / MAF CALIBRATIONS

Anyway I know that it is the MAF sensor, I just thought there was a possibility that since it sat for three years that the fuel system might have taken a hit or the spark plugs could have fouled.

I am looking more for how to tune the car, is there a method for determining whether it is rich or lean? this is a screen shot of the MAF settings as they came from Lindsey..

AaronM · 06-22-2013, 09:11 PM

The only way to be sure whether it's rich or lean is to check the tailpipe with an appropriate wide-band oxygen sensor.

I didn't see in your original post that the car has been sitting for three years. While gasoline is generally OK for up to 12 months, at 3 years I wouldn't trust the old fuel. Might be as simple as draining the tank/lines and running some fresh gas and fuel system cleaner through it.

Gawernator · Gawernator's Garage

No help here but cool 944... where is the front end from?

NBTF · NBTF's Garage

Gawernator, Looks like the EVOII kit from Fiberwerks.

ritter4242 · 06-23-2013, 09:29 AM

Gawernator: its from Fiberwerks

I love it!

Aaron: I used seafoam, I've changed the gas and it runs ok, I'm like 90% sure that the gas and subsequent systems in it are ok, it runs really rough on start, normally coughs itself out (its too rich) but after a few miles it warms up and runs fine at idle. So... this oxygen sensor.. where do I get one, how do I use it... any guides?

OH it also seems to be running really hot, I mean not overheating but you get out and can feel the heat through the hood (I can't get my hood liner to adhere) and its my understanding that running rich means running hot (experience from piloting small aircraft)

Thanks guys

Gawernator · Gawernator's Garage

Is it 1 or 3 wire O2 sensor? You can get both right here at Pelican but I got the Bosch universal heated sensor a lot cheaper off eBay (California car)

ritter4242 · 06-23-2013, 09:52 AM

uhhhhhh... I have no clue... How do I use the sensor to tune the car? I don't even think my car has an O2 sensor anymore. I had to replace my exhaust from the header back.

Gawernator · Gawernator's Garage

Lol - so I just realized he was talking about a wideband sensor. Disregard what I was saying

ritter4242 · 06-23-2013, 09:57 AM

haha thats totally ok x) so whats a wideband sensor?

petrolhead611 · 06-24-2013, 01:51 AM

running hot is a result of a lean mixture

AaronM · 06-24-2013, 08:46 AM

Quote:

Originally Posted by ritter4242

So... this oxygen sensor.. where do I get one, how do I use it... any guides?

It's the sort of thing you'd see at a dyno tuning station. When they hook up the car to the dyno they will also stick a probe in the tailpipe to measure the mix and make sure the car isn't running lean.

There are also wideband sensors you can buy to install with additional aftermarket gauges, but that would require being able to install the part on your own.

ritter4242 · 06-24-2013, 01:54 PM

Is it really that hard to install the wideband sensor?

AaronM · 06-24-2013, 01:58 PM

Quote:

Originally Posted by ritter4242

Is it really that hard to install the wideband sensor?

Not really, but you'll have to be able to weld in a bung on the exhaust before the cat to get a reliable reading. Plus you need a place to mount the gauge in the car.

It's usually just easier to do a few dyno pulls and judge from there using the shop's tailpipe probe unless you really want to have a wideband gauge in the car.

ritter4242 · 06-24-2013, 02:05 PM

well screw it why not! SO I don't have a cat, and I can run over to a shop to get a new bung thrown on (I've got a guy, does great work) What do I do with the sensor, like how do I read it, know its lean or rich? I'm gonna send my afm to abaco and get the right file to the sensor is working, and then I plan on tuning the ECU (DME?!) and getting a really nice setup out of it

So any recommendations on tuning systems for the NA? I don't want a new sensor (like rogue's setup) just a chip and computer program.

AaronM · 06-24-2013, 07:20 PM

You have to buy the sensor and gauge driver, then install it in the car. The (quality) kits I've seen run $200 to $250 not including a pod to mount the gauge in.

You'll need to know what air/fuel ratio you are targeting. Stoichiometric is 14.7:1 Higher numbers are leaner, lower numbers are richer. At idle or low-load cruise the gauge should read right around the 14.7 point. At WOT and full load turbo cars will drop into the 10-11 range, leaning out a little at by redline. NA cars will probably only want to drop into the low 12s under WOT full-load conditions.

My guess is that if the engine isn't even wanting to rev past 3,000 RPM, is running hot, and your fuel mileage is "great" you're probably going to see the gauge pegging out at its maximum (leanest) reading.

BisimotoJulio · 06-25-2013, 05:17 PM

A wideband sensor setup with gauge is a well worth investment to monitor true and accurate air/fuel ratios. I personally use an AEM Electronics wideband UEGO with Digital display gauge on all of my projects! Best of all these kits are accurate to 0.1 AFR and come complete with gauge, Bosch O2 sensor, weld on O2 bong, and wire harness.

If you are in need of one, I happen to have a handful of new units that I can let go for $155 including shipping to the Continental USA. Shoot me a pm for more information.

ritter4242 · 06-26-2013, 01:58 PM

Well that settles it! So plan of action:

get O2 sensor
tune the damn thing
tune the DME

so the next hang up I have is how do I tune the DME? is there a chip and software that'll work the first try? (bit of sarcasm there) I will tune the MAF so its close to the original AFM and then try and tweak the MAF and the tweak the DME, I'm not looking to make a suped up racer, I would just like a little more performance out of my little girl

Bisimoto: that sounds great! so its the gauge, sensor, wiring. so just stick the thing on the exhaust, connect the wires, and turn the car on? If you could upload a picture of the kit that would be awesome

I'll send you a PM

AaronM · 06-26-2013, 06:30 PM

Quote:

Originally Posted by ritter4242

Well that settles it! So plan of action:

get O2 sensor
tune the damn thing
tune the DME

so the next hang up I have is how do I tune the DME? is there a chip and software that'll work the first try? (bit of sarcasm there) I will tune the MAF so its close to the original AFM and then try and tweak the MAF and the tweak the DME, I'm not looking to make a suped up racer, I would just like a little more performance out of my little girl

To be clear, in the case we're talking about here you're mostly just checking to see if you're running lean or rich to get a baseline for what to do next.

The MAF kits work by emulating the signal that the DME expects from the original AFM. Theoretically you can do that by looking at the graphs in the link I already provided. The wideband O2 sensor and gauge just help you know what's going on if something's off a bit.

If you've done any modifications to your car other than the MAF and haven't changed out the DME chip, that could very well also be causing your problem because you need to have a new chip that takes into account the modifications you've done too.