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Matt
Matt, Engineer
Category: Volvo
Satisfied Customers: 21122
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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I have a 2000 s80 t6. my issue is when the mass air flow is

Customer Question

i have a 2000 s80 t6. my issue is when the mass air flow is plugged in, the car stalls out, but when its unplugged the vehicle will stay running. I have replaced the MAF. any ideas??
Submitted: 1 year ago.
Category: Volvo
Expert:  Matt replied 1 year ago.

Hello

I'd next check the condition of the wiring to the MAF for any damage, hard sections or corroded connections as its sounding like the MAF signal is being corrupted somehow on its way back to the ECU

Expert:  Matt replied 1 year ago.

Hello

did you still need help?

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Customer: replied 1 year ago.
Sorry for delay, wires are all good, no corrosion or broken sections
Expert:  Matt replied 1 year ago.

Hello

ok in that case it may be due to the fact that when you disconnect the M AF it will tend to run rich which might be covering up another fault

so it would be well worth checking for an airleak afterthe airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hoseclips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas/propane around each joint in turn. If the engine rev's up you've found yourleak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however theflash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas intoeach area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter orfaulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Customer: replied 1 year ago.
will check back soon, fuel filter is new, cat and o2 sensors are new. going to check vaccuum lines.
Expert:  Matt replied 1 year ago.

understood

Expert:  Matt replied 1 year ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. so if my answers have been helpful please rate my answer.

Customer: replied 1 year ago.
todaystaetd up,if i flutter the gas pedal then i can keep it running, even idled for a little while before stalling out, cleared all codes. restarted and fluttered again, codes ECM-982A and EMC-904D popped up.
Expert:  Matt replied 1 year ago.

Hello

thanks for the extra information

with those codes, its either a faulty / dirty MAF meter, or a faulty ECU

I'd suggest cleaning the MAF as the next step, if that doesn't help then replace it

and if that doesn't help tehn have the ECU sent off for repair

http://www.ecudoctors.com/

http://stores.digitalautotech.com/StoreFront.bok