MAF, Rough running, CEL , 157 and 998, weird idle and related...

[Admin BRL]

Hello fellows Explorers!

I have tried to do my homework, searching and testing and gathering information. But only here in forum there are 120 PAGES about this subject haha... I read about 80 of them.

So, I think I have to make this right... try to condensate all info as best as I can. I say sorry in advance if I don´t do it right, but believe i put a lot of effort on it.

Background:

I have a lot of experience with old-school EFI systems. I own the "omega club" (the free one, not the paid one) , in Brazil, about chevrolet Omega. I have 4 of them, 93-94-95 and 2006. In other countries these cars are called "Vauxhall Omega, Opel Omega, Cavalier" , etc. And it´s protocol are ALDL, so, somewhat like eec-IV. So, these 4 cars I have restored from scratch. Years on each one.

If anyone want to know wth is it, go ** Clube do Omega Brasil ** . The forum is behind that basic homepage. And the 1st picture are from SpeedHunters, greeeeat them. My car pics are in "AMIGOS" (friends) , then bottom of that page.

With no more delaying, let´s begin:

Important informations:

Battery stays disconnected for long periods, because I don´t use the car.. I am restoring it, was parked 8 years. Bought the car recently to restore it.

Sparks, cables and coil are new. but all info below, I done with old and new parts.
Removed fuse box in engine, cables too, ignition module, to do a great clean, grant these ground points around there and solve some relay malfuncions. all good there now.

Disassembled and cleaned MAF sensor, checked oring seal, mounted it back. Idle actuator cleaned, checked for leaking, checked the actuator itself. all good. gasket ok too, and no leaks after mounted.

Checked vaccum lines for false air .

I take ECU, opened it, changed the capacitors because all 3 had leaked, searched for broken lines, cleaned and mounted it back to the car.

Questions:

KOEO:

• At the MAF, the third pin should be +5v or gnd?? I have read both at the forums, to the same engine and MAF. I am lost on it.

I have measured MAF / Connector plugged and disconnected, KOEO.​

-> Connected: 12V, gnd, gnd, 1.xx VDC.​

-> Disconnected, measuring at cable connector: 12V, gnd, 5V (!!!!), 0.0x VDC.​

​

KOER:

• First start. Why this behavior? I don´t think is expected. Understand that is something at circuit, but idk all sensor components to this engine, and the work value of them.
• Impossible to find other MAF like that here in Brazil, even a used one. But I can find the 5.0 (and 3.8, sold at same) mustang MAF, but isn´t cheap here.. at least it is buyable. If I use the 5.0 MAF, instead the original, will at least work ?

Background:

Engine starts nicely, quick and fast. keeps 1500 RPM approx. , then starts to decrease, until 900 RPM.
Sometimes CEL gets ON and don´t go off. Othertimes take some time to appear . Meanwhile, idle vary between 1200-700, slowly, learning engine behavior (I think).
Pulling codes, it says 175 and 998. Sometimes says only 998. the canister valve is broken , so I tapped the vacuum line at intake, but the valve is disconnected.
When idling at 700, disconnecting the IAC (idle actuator) doesn´t change nothing, even when is connected. on higher idle, it changes the RPMs. I had checked, cleaned and tested the actuator, all good.

Once it backfired (!!!) and dies and don´t start anymore. I mean, it starts and dies immediately. Then, I disconnect MAF and IAC (idle actuator) , and it started. then, Connected IAC and keep running but no change on idle (700RPM), then when I connect MAF and it dies immediately.

I shout some bad words to it, kicked the bumper, disconnect the battery and MAF and let it there. 30 min later, come back, connect battery, and start the engine. Starts right away. Connect the MAF and.... keeps working. fine. WTF... I shaked all wires trying to find some problem, cable broken, misconnections, but nothing changed. Except CEL showing on, like before.

No cylinder fail, no gas smell. but taking it to go around the block, it feels 998 (so limp...) ...

Sorry about my long post. I´ll try to keep all the questions and updates here. Thanks to anyone who will to help me.

 

[Admin BRL]

none...

 

[eddiehudson]

I don't know if this will be of any help but ROCK AUTO says these cars use the same MAF.

FORD	AEROSTAR	1990-1995
FORD	CROWN VICTORIA	1992
FORD	EXPLORER	1991-1994
FORD	RANGER	1990-1994
LINCOLN	TOWN CAR	1991-1992
MAZDA	B4000	1994
MAZDA	NAVAJO	1991-1994
MERCURY	GRAND MARQUIS	1992

 

[Admin BRL]

I don't know if this will be of any help but ROCK AUTO says these cars use the same MAF.

FORD	AEROSTAR	1990-1995
FORD	CROWN VICTORIA	1992
FORD	EXPLORER	1991-1994
FORD	RANGER	1990-1994
LINCOLN	TOWN CAR	1991-1992
MAZDA	B4000	1994
MAZDA	NAVAJO	1991-1994
MERCURY	GRAND MARQUIS	1992

Here in Brazil only have Ranger from this list... and this model was imported too, so, only few available. If was a 95-99 model, there is less dificult.

Many thanks for your reply! Helped me, because now I am sure about which cars use the same MAF. I still thinking about test the 5.0 Maf.. will see.. (even because I don´t have the right one to buy here).

 

[Admin BRL]

=== MAF UPDATE ===

Okay. Because the lack of maf sensor here in Brazil, i take mine and... opened it. I don´t recommend if you don´t have eletronic skills.

to open it: i crack the glue from the black cover to the metal piece. then it comes loose from the metal, but still gripped somewhere. I keep forcing gently until it gets apart from metal , completely.

Then I discover the internal wires from connector ... i have snapped them . 3 wires.

With this info, and a multimeter, i could check the pins from inside, and discovered that pins 2 and 3 are factory bonded, both are same.

If you look into the "electronic part" , which still in metal base, it have only 3 wires. So.... 4 wire connector, 3 wire internal... makes sense pins 2 and 3 be the same, jumped toghether from factory.

Inside the sensor there is some crazy isolator, kind of silicone which never gets dry. i left it there, all of them.

Then, looking to the 3 wires at board, i think it maybe was broken before. then i welded 3 longer wires, and welded it internally to the connector at plastic case. So, this way I can open and close it without rip it again.

Mounted it all, put back in the car .... no more errors until now. looks like at least one of these 3 wires was internally broken..