'84 Won't run when air flow meter is connected

[drawlusyk]

Hello,

I have been reading posts and testing for a week now with no success so I hope someone here can help.

1984 1.9 l
Drive it every summer and runs great.
2 weeks ago noticed the water pump was leaking.
Took it off and replaced it with a new one
At the same time, i took the alternator off and had it cleaned/fixed up.
I put the water pump back on and filled it with antifreeze.
While waiting for the alternator to return from the shop, i decided to clean the engine.
I sprayed some degreaser all over, waited and then hosed it off with a garden hose.
I did not have the engine running at the time.
I got the alternator back, put it on.
Started it first go (like always) and went for a drive.
I made it about 1km and it sputtered and died.
Towed it home the next day.
Decided to replace the fuel filter. No luck.
Let it sit for 3 days thinking it was just something wet. tried again and only ran 20 seconds.
Opened the air flow meter box and noticed it was wet. (didnt have it silicon sealed)
Dried it out. still didnt work
Took it completely apart and cleaned it. Tested the resistance between pin 2&3. goes up linear until about 1/3 the way and then decreases to nearly 0 at the opposite end of the carbon strip.
Leaving the plug off the air flow meter the van continues to run and it can be reved up.
As soon as the afm is plugged in it dies again.
Sprayed quick start around hoses in hopes to see if there is a vacuum leak while running but idle remains the same.

Any other trouble shooting ideas?

Regards,
Dennis

[Ahwahnee]

[Bassyaks]

If the van can be revved with the AFM disconnected it means the van is running very rich, check temp sensors.
Maybe you knocked the connector off while cleaning.

[Howesight]

Your symptoms describe a classic AFM failure. The engine will idle quite nicely with the AFM disconnected. It will also rev above idle with the AFM disconnected. Try driving with the AFM disconnected and you will see that the engine seriously lacks power.

The AFM gives a load signal to the ECU, which is why the engine will not have power if you try the test above. The AFM also allows the ECU to provide transitional enrichment when throttle opening occurs.

Try running the engine for a few minutes, say 5 to 10 minutes with the AFM disconnected, until it is at operating temperature. (This is to ensure that excess fuel, if it is in the engine or exhaust system, is burned off.) Then connect the AFM and re-start and check for black, smoky, rich-smelling exhaust. If that occurs, your AFM need replacement or rebuilding. It is a sensitive bit of kit that is not easy to rebuild properly, so the rebuild route is recommended.
_________________
'86 Syncro Westy SVX

[drawlusyk]

Thanks for replies

@Ahwahnee ok i'll turn on van, connect to pin 2&3, slide the sensor along the carbon strip and check voltage. Do you have any idea of what a 'correct' reading should be?

@Bassyaks thanks. I actually checked carefully when i put things back together that the temp sensors was connected and not touching any of the surrounding guard.

@Howesight I have previously done what you have stated here. Leave disconnected, warm up, put plug on afm and it sputters and dies within 10 seconds. Restarts fine runs for 10 seconds and dies again.

It would be nice to know one way or the other if it has failed. Strange that last week before the waterpump change and engine clean it was working fine.

I have noticed there are some on ebay....
http://www.ebay.ca/itm/Mass-Air-Flow-Sensor-Vane-A...mp;vxp=mtr

that i will resort to getting if i can not figure things out within the next few days. It would just be nice to know about the tests to find out definitively if it has failed.

[Ahwahnee]

[drawlusyk]

Looked at
https://www.youtube.com/watch?v=LjSyZ2-VOZg&feature=youtu.be

And did a test myself. I did by moving wiper directly and by moving the airflow vane directly. I got the same results.

My test is here...
https://www.youtube.com/watch?v=8Wc-3iKYRqA

Also checked the temp sensor resistance and got 1.2k ohms.
http://www.the944.com/afm.htm says 30°C should be min 1.5kohms with 10% tolerance so i take this to be acceptable.

I adjusted the top screw of the wiper arm slightly so I can get the van to idle.
BUT
Stepping on the gas just kills the engine.

[drawlusyk]

Another thing i noticed(now that it will idle), is after its warmed up and i shut it off, i can not start it.

???

[Wildthings]

When you have any kind of problem with the FI system checking and cleaning the grounds is a good thing to do.

What voltage are you seeing between pins 3&4? What voltage between pin #4 and the engine block and between #4 and a good ground on the body?

[drawlusyk]

Between 3&4 was 4.92v
Between 4 and engine ground was zero (0.02v)

[drawlusyk]

Testing voltage between 3&4 and 4 and ground was done with key on but engine off.


I stripped, soldered new connections and used a new bolt to hold down all the ground wires on the left side of the engine.

[drawlusyk]

Well after a month here is the update......

Decided to order an air flow meter from ebay. Was a 3 week delivery so after purchasing i did a few other updates.

-replaced the exhaust elbow pipe that holds the o2 sensor
-of course also replaced the o2 sensor
-replaced the tempII sensor near water pump.

that didnt fix anything but at got nice new shiny parts.

waited and just received the AFM. i replaced it and varooom. good thing its working now because i would have been at a loss as to what to replace next.

so for those of you in similar situations, even though the readings from testing the AFM might be correct, in my case there was still something wrong with it and replacement was the only solution.

thanks to those who offered their suggestions.

Dennis

[Wabisabi0214]

I had exactly the same problem with my '89 and did all the tests in the Bentley and voltage test on AFM which were all normal. Decided to swap in my spare ECU which cured the problem. Next time I have a similar issue I will check the ECU first since it is so quick and easy to eliminate if I have a spare.