VANE Air Flow Meter questions

[Zee]

This 1986 944 n/a linked below appears to have a VANE style air volume meter:

 

http://44cup.zeroforum.com/zerothread?id=2620

 

My '88 ford Escort GT, with a 1.9L EFI H.O. ford engine has a neary identical VANE.

 

So, I thought you Porsche (or Ford?) folks might know something about troubleshooting engine performance problems where this devices is involved.

 

my engine is giving me persistent stumble just opening throttle, plus a distinct miss or cut-out most of the way through the rev range. Specifically, I need to "feather" the throttle to let the engine "catch" itself and bring in more normal performance.

 

Ignition, fuel delivery, and most of the engine harnesses have been ruled out as causes.

 

I pulled a Code 66 "VANE voltage signal too low"

 

Trouble is, I don't know what this means to my symptoms, nor what to do about it.

 

Can you folks shed some insight?

 

I have tried three VANE's in here. Two of them won't even let the car start. The present one, I have needed to adjust the coil spring under the square-ish cover so that the air door is almost totally open all the time.

 

Obviously, the spark plugs are now sooty black and this is no permanent solution.

 

Could I have three dead VANE's, or, should I think there is a wiring harness prooblem, or?

 

What am I looking for?

 

FYI, the EGR, neutral safety switch, fuel roll-over shut off switch, AC and PS have all bee n removed from this car long ago. (Occasionally I'll get a number 72 code: Transmission Safety Switch, blah, blah)

 

Fuel pump, filter, regulator all new. FI harness inspected and OK

 

Accel SuperCoil, distributor, cap, wires, plugs also checked and OK

 

My second O2 sensor could be replaced, but this problem has persisted a long, long time before O2 sensor renewal.

 

Thanks

 

 

PS Please excuse my typing. (It's always this bad)

 

_________________

#36 1988 Ford Escort GT SCCA ITB/NASA PTF

[cmchopeful]

My wifes Celica had a similar problem. I searched the internet and found solution that was so simple and it worked. Her issue was not exactly the same as the Celica's problem was with the Mass Airflow Sensor.

 

The problem arises with a buildup of residue on the wires that measure the airflow. The solution was to remove the sensor and use Q-tip with rubbing alcohol to clean the wires. Sure enough when I reinstalled the sensor the car ran fine, no more stumbling or hesitation.

 

Hope it helps.

[Driver]

If his meter is the same as pictured int he porsche, then it is not the same as your celicas. Your celica put a hot wire oput into the air flow, then measured how much air was moving by how cool the wire became. Build-up on these effects their ability to accurately measure air.

 

The system being used in the escort above is also known as a "mouse trap". Air moving through it pushed a "door" open. The more open it is, the more air is moving through it, and it sends the signal.

 

Code 66 "VANE voltage signal too low"

Check all of your contacts, ground and power, and make sure this thing is actually able to send a good signal to your EFI. You can have a perfect meter, and it wont matter if it can't shout at your computer. More open = more signal = more fuel. By propping your spring, you're making your meter "scream realy loud" at your computer, even though all the computer is hearing is a whisper.

 

I'm chasing allot of problems related to old wires, myself. Once a year the car is crippled by a bad ground some where.

[FlyingDog]

This 1986 944 n/a linked below appears to have a VANE style air volume meter:

 

http://44cup.zeroforum.com/zerothread?id=2620" onclick="window.open(this.href);return false;

It's called an AFM (Air Flow Meter). That should help with your information search. If it is a Bosch type very similar to the 944 (and 80-84 US 928) you might want to try searching the 924/944/968 section of Rennlist.com for information. There should even be info on how to convert an AFM system to a hotwire MAF (Mass Air Flow) sensor.

[Zee]

If his meter is the same as pictured int he porsche, then it is not the same as your celicas. Your celica put a hot wire oput into the air flow, then measured how much air was moving by how cool the wire became. Build-up on these effects their ability to accurately measure air.

 

The system being used in the escort above is also known as a "mouse trap". Air moving through it pushed a "door" open. The more open it is, the more air is moving through it, and it sends the signal.

 

Code 66 "VANE voltage signal too low"

Check all of your contacts, ground and power, and make sure this thing is actually able to send a good signal to your EFI. You can have a perfect meter, and it wont matter if it can't shout at your computer. More open = more signal = more fuel. By propping your spring, you're making your meter "scream realy loud" at your computer, even though all the computer is hearing is a whisper.

 

I'm chasing allot of problems related to old wires, myself. Once a year the car is crippled by a bad ground some where.

 

Written simply enough so a 6th grader could understand it! I'm a 5th grader, but I catch on quickly..... Yes, this describes what appears to be going on.

[Zee]

This 1986 944 n/a linked below appears to have a VANE style air volume meter:

 

http://44cup.zeroforum.com/zerothread?id=2620" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

It's called an AFM (Air Flow Meter). That should help with your information search. If it is a Bosch type very similar to the 944 (and 80-84 US 928) you might want to try searching the 924/944/968 section of Rennlist.com for information. There should even be info on how to convert an AFM system to a hotwire MAF (Mass Air Flow) sensor.

 

You can convert these systems? That's exciting.

[DBrehm]

I think you may find the answer to your problem at http://www.turboford.org" onclick="window.open(this.href);return false; ,all of the turbo 2.3's use the same VAM (in ford speak ,Vane Air Meter),also the same base computer.

[K Shaw]

Do you have ground and a proper signal voltage to the VAM?

 

The escort has the same basic VAM as the turbo fords/P cars/and some jap import cars.

 

kyle

[Zee]

Do you have ground and a proper signal voltage to the VAM?

 

The escort has the same basic VAM as the turbo fords/P cars/and some jap import cars.

 

kyle

 

Well, that's what i was trying to ask... just which pins are which, how thes the current flow, etc. I have an Ford electrical/vacumm manual which is providing some clues, and a guy on a Focus forum is sending me some good info.

 

But, yeah, the Code 66 is that the voltage is too low -- going in or coming back to the ECA is what I need to find out

 

Now all I need is time to get beck under the hood!

[K Shaw]

I dont have any wiring diagrams for escorts just mustang/thunder bird stuff.

 

Got a decent diagram? Scan it and post it so that I can take a look at it.

 

kyle

[944-Spec#94]

worn wiper tracks in the AFM

 

I had to fix mine on my 944 for some odd cutting out. I also just found out of a couple other 944's that adjusting the arm to run on new tracks also resolved some odd cutting out.

 

This site covers the 944 AFM in great detail. I am not sure how similar it is your's, but this can be probably be very helpfull.

 

http://www.frwilk.com/944dme/afm.htm

[Zee]

worn wiper tracks in the AFM

 

I had to fix mine on my 944 for some odd cutting out. I also just found out of a couple other 944's that adjusting the arm to run on new tracks also resolved some odd cutting out.

 

This site covers the 944 AFM in great detail. I am not sure how similar it is your's, but this can be probably be very helpfull.

 

http://www.frwilk.com/944dme/afm.htm" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

 

Yes, this AFM pictured is identical to the one on my Ford 1.9L EFI. What stood out to me in the photo under the "inside the AFM" section, specifically the isolated close-up of the 1984 thick-film ceramic substrate. It discusses "The dark grooves in the wiper track are clearly visible. This is damage from the wear of the wiper contacts showing its age."

 

Lastly (for now!) I mused about the last statement in the photo gallery about NEVER adjusting the clock spring tension...Releasing some spring tension to allow the door to open easier is mentioned in several Ford Escort forums and former tuning articles as a way to improve throttle response. What I have found that this adjusting does is to move the door all together from it's factory position within the air flow chamber (where it is open about 3/8 inches maybe). Even rotating the ring gear a few notches counter-clockwise will reposition the door into the curved (swing area) of the AVM''s housing. This puts the door out of the straight-thru air flow region from the beginning. I have a hunch this raised the voltage output, as well, because I got my car running a little better at the Weatherly Hill Climb after rotating the ring gear roughly 90 degrees from factory. Maybe this boosted output voltage enough to run the car near normal? Plugs were very sooty afterwards, though.

 

Ahh, I thought these were intentional grooves cut in to deliniate and form individual tracks within the sweep area for the two points on the sweep arm. Indeed, one of my three units, (I have one on my workbench) does sport these "wear tracks".

 

Now, I'll share with you, and the others, what the Ford Focus enthusiast and back-in-the-day Escort tech, Jim Roal has shared with me so far:

 

(quoting our email conversation now)

 

 

Donald:

 

I was a mechanic at the Ford dealer when this car came out so I know them well. Very similar EFI system to what my T-Birds had. I had 5 turbo coupes: 1983, 1985, and 2 1988's. All have vane meters.

 

First simple check to see the VAF signal voltage at key on engine off (KOEO), Should be about 0.5V I believe. At warm idle no loads, the VAF signal should be about 0.9V to 1.5V. The VAF should have 5V to it. There is a VREF wire and a RTN (return) wire. The voltage between those wires should be 5V +/- about 0.2V. If it is not, check the wiring from the ECU to the VAF. A very common problem with VAF's is the potentiometer on the board wears out. A quick fix for that is to loosen the board and reposition it so the wiper hits a different path. Another problem is the connection from the signal terminal and the moving wiper. Some of the later ones has a wired added there to improve the connection but the wire can break inside the insulation still.

 

Actually, it is very likely you just have plugged injectors. The deposit resistant injectors did not come out until a few years later. We do have better gas (has detergent in it) but still the older injectors can plug. That was very common in those days. Common like I serviced multiple sets every day. It's worth a try. The best over-the-counter is Chevron Techron. Mix up a very strong mixture of that and take it for a hard drive. That still may not clean them enough and you may need to have them serviced at a shop with an injector cleaner machine.

 

Another thing to check is fuel pressure. You should have 40psi with the engine running and the vacuum regulator disconnected. When you connect the vacuum line it should drop to about 32psi or so.

 

Another common problem with Escorts was the PCV valve would come apart and make a huge vacuum leak. This car cannot handle air leaks into the crankcase so do not use any external vented breather caps. It is important to keep the crankcase vent connected to the hose after the VAF.

 

I assume you have set the timing correctly? Make sure the SPOUT is disconnected when you set the timing.

 

Is your cam still in time? The timing belt can slip. Make sure it is timed right and the belt is in good shape and has proper tension.

 

Another common problem is the throttle position sensor. Those do wear out. In the case if the TPS and VAF it is best to check with an analog volt meter or one with a bar graph. Sweep them while reading voltage on the signal wire and make sure you don't have skips.

 

Jim Roal

http://jimroal.com" onclick="window.open(this.href);return false;

 

 

So, here Jim also gives some possible remedies we AFM-challanged can attempt at home!

Hope this helps. I have yet to carve out the time to go see for myself. BTW, my PCV system is also blanked off and/or just blowing off from the valve cover to an oil catch can. Evidently another issue.

[Zee]

here is a summary of my attempts to fix the poor contacts in my VAM (vane air meter). This was from my email to Jim Roal.

 

"I made the adjustments and checked the ohms between pin 6 & 22 to check the Ait Remp Sensor similar to the 1986 Porsche model VAF. got 1.4 there, so, this is OK.

 

Did KOEO test and former Code 66 is gone. Now have code 67 (neutral switch signal. My switch is eliminated altogether)

 

Engine ran a little better, but with stumbling around 2500 RPM and higher

 

Tried to check pin voltages with engine running. Got RTN voltage of 1.49v w/o SPOUT and 1.63v with it installed (i was checking base timing prior to KOER test) not sure I'm doing this right, so, I'll try this again.

 

Could not proceed to the KOEO test.....

 

Step 3 im mt Sunpro Code Scanner has me setting the base timing (8 degrees BTDC on this 1.9l I believe). With the SPOUT out and the BAP connector disconnected and jumper-wired, the comuter is supposed to raise the timing +20 degrees +/- 3. This should give 25 - 31 degrees BTDC.

 

only got it to 15 degrees. that's only a +7

 

What do you think? Bad ECU?"

[Zee]

Well, for anyone who wants to know (because you have this air flow syetem), after much treaking crankshaft/camshaft pulley alignments, ring gear in the AFV (cover is off) and opening the throttle plate a lot more, I managed to get on to doing the Timing Test and KOER test.

 

I changed the camshaft alignment by one tooth relative the crankshaft position. what led my back to this mechanical - as opposed to fuel- or electrical investigation was the poor starting and engne operation just trying to move the car off the tow dolly and into the garage! Much sputtering, backfiring, etc. too much, I thought for one sensor flaking out to make all this ruckus.

 

Timing corrected, what was also happening was the throttle wasn't opened enough in the first place so that when the computer performed its "2 minute" timing advance drill during the Timing test (ScanPro scan tool used), it would rev, then decelerate the engine, which would die to a stop. After opening the throttle enough, the computer would eventually rev in a two-step process to 3000, then to 3500 RPM before allowing the engine to fall to a thriving 900 RPM level. With this, the engine would stay running under computer control (no SPOUT)

 

(Note: I was getting KOEO codes telling me the HEGO showed "rich" i.e. I needed to lean out the mixture, follow me here?)

 

So, I set the base timing at 8 degrees BTDC (Mustangs and engines from 2.3L up use 10 degrees, I believe). Before this, I was working somewhat blind on timing, as the car didn't have a timing belt cover, thus, no tiiming marks.

 

OK, mechanical things ruled out now. On the VAF, I metered it according to the excellent web page cited above and found adequate computer-to-VAF VREF. Air temp sensor also gave corect Ohms. But, in repeated KOEO and KOER tests, I kept getting everything from Low Sig TRN voltage to High Sig RTN voltage, some HEGO errors to ECM failure codes.

 

At warm idle, for example, SIG RTN was not 0.9v to 1.5v, as the articles commented. I had 1.7+/

 

I noticed the rev testing still had that familiar "blap-blap" stumble mid-throttle and near WOT. But, I also discovered that if I "helped" the VAF's sweep arm along its path a bit while slowy increasing throttle, this condition would resolve.

 

OK so it seemed the coordination between the SIg TRn and throttle positions wasn't ideal. That's what led to more throttle plate adjustment, on-quarter turn in at a time, and, a little movement, one tooth at a time, on the VAF ring gear. (This is the thing you're not supposed to adjust, as says the Porsche article! My VAf is a guinea pig anyway)

 

With engine warm, at idle and no load, I moved the ring gear and could see the SIG RTN dropping to within the 0.9v - 1.5v range. I think I left it at a 1.4v. This also resulted, BTW, in a corresponding drop at rest, engine off, of a SIG RTN voltage lower than called for (.5v) because mine dropped to .25v by now. I anticipated a hard-start condition, but no.

 

Later, once the engine had time to cool a bit, I noticed this parameter rose to the 1.7v level again. But, I didn't take to time this time to run the engine back up to warm and re-test. It was bedtime.

 

So, now things are pretty close. not perfect, but now ALL codes are cancelled out!

 

The engine still has some of the stumble, especially cold.

 

I have some more harness connectors to check, gounds to verify, and I am going to pull the fuel rail to check this and R&R the FI harness.

 

The Ford Engine/Emissions Diagnosis "H" volume is bought over eBay.

 

I have 85% confidence in the engine now. Not enough to go hill cliimbing this past weekend. A test and tune at Island Dragway next Sunday,maybe, after my follow-up on things. I want this solved.

 

Thanks to all your helps, it will be.

[Zee]

okay, THANKS everybody!

 

I believe this stumbling issue is resolved for now. (See my post just above)

 

Although the thing still stumbled a little bit while yet in the paddock, it didn't seem to factor into the three passes I made at Island Dragway Sunday.

 

The only thing I noticed was I was still only in third when crossing the finish line, and tach was around 5600 and below a self-imposed limit of 6000

 

at this point, the engine felt a little flat and wasn't pulling, Upshifting to 4th dropped the tach to about 4000 with little pull as well.

 

(The U-turn at the end was loads of fun, though! )

 

It did seem to have better low-end torque than top-end speed.

 

My slips were better than this Spring's outting, but not as good as last year's testing when it did mid-17's at 76.xx MPH

 

Yesterday the best was an 18.01 at 73.5 MPH at 20 degrees BTDC on Kuhmo Ecsta All-seasons 205/65-15's

 

But it is running smoothly! That is the main thing.