[16saabs]

Have had probs with CEL coming on and off recently, and had asked for help, but at weekend(sun) while waiting for a replacement, I thought I would try and see if anything would 'help' as I know you have to be carefull re cleaning etc, so I just sprayed BRADEX East Start through the gauze at the end onto the filament and the amount of crap that came out the other end was suprising??, but the filament was now silver, not black so then I put it back on switched on and NO cel, but as soon as I started it came on again so though ah well I tried. went off to work mon morn and cel still on as norm after 5 mls and suddenly had a 'missing/stumble ' feel so quick change down a few revs for a hundered yds and then changed back, cel still on but running'ok' then noticed after another mile CEL had gone out(as it did sometimes) but it has'nt come on since, done 90mls+, so might have settled , so if you have a prob with CEL and suspect AMM give it a good clean out and see how it goes.
exhaust tail pipe seems clean instead of black as well and engine revs at idle has dropped back from 11-1200 to 8-900 which it should be, so should be better mpg again

 

[Starkey]

Ok, I may try this. Can we get a few vets to confirm its ok to clean the AMM like this and what the best product to use is, and what to be carefull of.

 

[mmoe]

I've cleaned them with carb cleaner before without any issues (actually fixed the issues to be more accurate). The way I see it is that if your AMM is already acting up and very dirty, it couldn't possibly make it worse because it's already broken essentially. If it doesn't correct the problem, you're not any worse off than you already were.

 

[900t]

There is even an AMM cleaner fluid in spraycan some autoparts stores carry. I am unsure if it is carb cleaner or brake cleaner but it is one of them. Brake cleaner can kill ya if it gets superheated so maybe stick with the carb cleaner.

 

[Starkey]

Well my AMM is not broken but I do think it could be improved with a good clean, but I dont want to break it just for the sake of attempting to clean it.

Whats the best way to clean it? Just shoot some carb cleaner into it? Is there anything that I should not get cleaner on? Details, details!

 

[Tailspin]

Whats an AMM?

 

[Starkey]

Whats an AMM?

Air Mass Meter

 

[TooMany2cvs]

Lucas or Bosch? They're very different internally. IIRC, the Lucas meters air via a small bypass venturi, whilst the Bosch measures the main flow.

 

[16saabs]

I just sprayed the fluid at the sensor through the gauze so it did'nt get a 'straight' blast but deflected etc, but jsut a light spray and it cleans the crap off I sparyed the inside of the body as well hence the extar muck that came out , but it has got nearly 225.000 mls on it and probably never been cleaned before lol

 

[ludichris001]

if i may add my 2 cents.. LH2.4x 'learns' fuel trims, it would be wise to disconnect the battery overnight after cleaning the AMM to wipe the ECU's memory, that way it isnt trying to compensate for a clean AMM when its 'used to' a dirty one. if CEL comes on while cruising the other possibility is that an o2 sensor is starting to fail.

 

[Starkey]

Thanks for the tip! I am going to do that now.

 

[Rodentmaster]

if i may add my 2 cents.. LH2.4x 'learns' fuel trims, it would be wise to disconnect the battery overnight after cleaning the AMM to wipe the ECU's memory, that way it isnt trying to compensate for a clean AMM when its 'used to' a dirty one. if CEL comes on while cruising the other possibility is that an o2 sensor is starting to fail.

.........problem there Chris is the ECU will be quick to get back the CE light............it sounds like the AMM has drifted. I've been through a few of these trying to get a good air meter cheap.

 

[ludichris001]

.........problem there Chris is the ECU will be quick to get back the CE light............it sounds like the AMM has drifted. I've been through a few of these trying to get a good air meter cheap.

yes, i agree with that
what i meant was that if the hotwire was dirty (even though it has burnoff) and it was sending a lower voltage signal to the ECU, then the ECU would read it as less air passing through the AMM, which would most likely cause a lean out, which would then be picked up by the 02 sensor.
the ECU will try to richen the AFR to compensate, and each time adding to the long/short term fuel trims.
therefore if you clean the wire, it will be reading the right amount of air passing through, which is more than what the ECU has adapted to, so it will think there is a problem - CEL on.

im not 100% sure on how fuel trims work with LH systems, with the ECU's i have worked with they have both long and short term fuel trims, the short term can be added or subtracted to, the long term can only be added to.
if LH is the same then the long term will need to be wiped

 

[Jim Mesthene]

At SAAB LH school, they specifically cautioned against trying to clean the Air Mass Meter.
I don't see what harm it can do to a malfunctioning unit, but I'd avoid bathing one that shows no sign of trouble.

 

[Starkey]

Ludichris your tip helped me the most. Of all the things I have done the past month to sort this idle issue nothing changed. I cleaned everyting, tested everything, replaced nearly all my vacume lines. I un-hooked the battery last night on your advice and this morning its idling at 900 cold. This car has never idled that low. Will this stick or will the computer adjust the idle back up if another problem persists? I looked at my AMM and it was clean anyway so I did not bother to touch it with anything.

 

[16saabs]

completely agree Jim, e.g don't mend it if it ain't broke,
but mine was but now is'nt so worth a go, nothing to lose, still running fine

 

[Starkey]

Well I spoke to soon. After a few miles the idle went back up to just under 1500 and now the check engine light is comming on which it was not doing before I unplugged the battery overnight. I'm stumped :roll:

 

[Rodentmaster]

Starkey............

yours is a MY-88?
LH 2.2?

Re: Idle? Confirm TPS (Throttle Position Switch) action carefully...........ie: scrutinise the idle (mode) switch point. Some idle issues can arise out of the alignment and condition of the TPS.

LH 2.2 don't have adaptive ability so, I'm not sure if the power cycling is just a coincidence or hindrance at this stage. Error reporting sadly is limited on the 2.2.........I think the CE will be an AMM based issue.

 

[Starkey]

Yes its an 88, but it has LH 2.4 because its a non-turbo. I need to pull the codes its a simple as that. When I first purchased the car the cel was on, after doing some work on the car (alternator, starter, vacume leaks) and putting it back on the road the cel never came on again but it would still idle at 1500. last night I unplugged the battery just to see what it would produce and this morning when I start it up everything is fine and the car was at 900rpm. I went to work in my Volvo and came home at lunch to start it again and drive it around the block, after a couple miles the cel came on and the idle rose back to 1300-1400rpm sitting at stop signs and in the parking lot.

 

[Rodentmaster]

TPS investigation is still relevant here though......

TPS was changed to a variable resistor in the 2.4.2 version (91 on).

Does your AMM have the adjustment screw? Metal body? No: -005?