86 - 240 Air Mass Meter problem, I guess

rotory · Post by **rotory** » 17 Aug 2006, 18:42

Hi guys,
I got a faithful 86- 240DL that for the first time a week ago, started to act up on a very hot day, when leaving the mall to head home.
It took a lot of crancking to get it started and a hard time staying alive, no power, sputtered along the way to the light at the exit from the mall and stalled there. Thank god, it started when the light turned green and I had to floor it to get it going. No problem for the rest of the way home. The next morning, didn't wanna stay running after it started. took about 5 minutes before it was driveable. Its crazy since then, very sporatic and moody. Its been stalling, little to no power, then suddenly its all good. At times there is no power when I push on the gas peddal untill I near the floor, then it picks up like a lunatic.. any ways, it got worse with time.
So I looked you up (after a search on Google) and been reading up on the posts. Today was the worst, In the afternoon, it died 7-8 times right after starting so I unplugged the AMM and found that it idles good (despite the smell) and drives as long as I gas it very very little, how ever it dies as soon as I replug it. So I drove home with AMM disconnected.
What do you think? Is that it?
I'm a careful tinker and am considering taking the AMM apart if its faulty, then may be its repairable. They sell'em refurbished.
Has any one taken one apart? Any pointers?

Appreciate any help

bob

Kmaniac in California USA · Post by **Kmaniac in California USA** » 18 Aug 2006, 11:31

Sounds like a bad AMM to me. When you disconnect the AMM, the computer goes into limp mode, using fixed, AMM input values. You can drive like this temporarily, but the rich mixture will heat the cat-verter to a higher temperature.

You can buy them new, remanufactured or used in a wrecking yard. I would not try to rebuild them. When you look inside, you will see a fine, thin wire in the air path, that can be easily damaged.

I recently pulled an AMM off another 86 Volvo with a bunch of other parts a few months ago. Always good to have a spare.

cosmiclobster · Post by **cosmiclobster** » 19 Aug 2006, 15:33

Kmaniac is right - My 86 740 had the same problems.

When the AMM is unplugged, the computer does go into a limp home mode. If the car will idle with the AMM unplugged and dies when you plug it in, that is the problem.

BUT, there is one more thing you need to check!
IF preheated air from the exhaust manifold shroud is getting into the air box 100% of the time, the preheated air will make the AMM run too hot and malfunction.

When the engine is cold, disconnect and remove the preheater pipe - it's the one thats about 3 inches in diameter and looks like aluminum foil.
Plug in the cold AMM and start the car. If it runs OK for the next half hour then the AMM is NOT the problem, the problem will be the thermostat that blocks off the preheated air once the engine warms up.

Hope this helps!

wojeepster · Post by **wojeepster** » 29 Aug 2006, 18:19

try www.car-part.com for used amm I bought two for 20$ each! better than paying the big bucks.