240 91 240 lean drivability issues. Stranded in CT

My car is having a problem where it reacts way too slow to changes in throttle. Started happening suddenly early this morning, first start of the day.

For example: Accelerating from a stop, wideband reads full lean & misfires then the lambda slowly returns itself to 1.0 and the drive ability is good cruising averaging 1.0 like it always has. Letting off throttle a little, the car runs rich then returns to 1.0 slowly. Fully letting off throttle car goes into decel fuel cut mode as normal.

No codes were set. Attempted cleaning maf with crc maf cleaner, no change.

When unplugging the maf, car is in limp mode, maf CEL codes set. Full rich all the time. Runs good
When unplugging the O2 no change occurs besides CEL

Maf resistance changes from 3ohm to ~40ohm when i repressedly probe pins 2,3. I think it’s the issue. I know reading the resistance on this part is borderline useless.

Any tips/ suggestions?

Anyone in eastern Connecticut want to sell or borrow to me a MAF? Thank you

Running an unmolested 937 ecu and 148 EZK. None of my “tuned” crap is on it.

Seems like some type of large air leak may be another possible explanation. What kind of intercooler are you using? A stock volvo one can fail and leak at the seams.

dl242gt said:

Seems like some type of large air leak may be another possible explanation. What kind of intercooler are you using? A stock volvo one can fail and leak at the seams.

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Thanks for your response

The maf is on the cold side of the IC so I doubt that?s it. I forgot to mention I leak tested all the lines and intake manifold with starting fluid to verify there is no leak. I forget what exact brand of intercooler I put in but it?s not an eBay special nor a stock Volvo. Possible it has a leak, I?ll have to check

How is the intake manifold gasket? The PCV hose coming loose can make a large air leak as can the brake booster vacuum check valve. It may be something sneaky like that.

Clean the AMM/MAF, probably has oil contamination down wind of the turbo.

I ended up driving home at 3am when no one was on the highway in limp mode at ~35mph. I monitored the wideband religiously to make sure it didn’t go too rich/lean. If you don’t suddenly mash the throttle, somehow the ECU in this mode can return the AFR from full rich to 1.0 in cruise with no AMM at all. Weird. Right when I got home I drained the old oil out and it was probably 5+ quarts of oil/gas mixture. Totally ruined oil

I have two known good MAFs and countless o2 sensors so I’ll figure out what’s wrong. I’ll update the thread with findings

dl242gt said:

How is the intake manifold gasket? The PCV hose coming loose can make a large air leak as can the brake booster vacuum check valve. It may be something sneaky like that.

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I’ll check this gasket out. Starting fluid in the area does nothing, but I admit I have pulled the intake and reused this gasket a couple times. Along with the throttle body gasket. Might as well replace both

I haven’t checked the PCV system yet, thx for the tip. I run a catch can between the breather box and pre-turbo. Brake booster check valve seems to work correctly when I blow/suck on it

VB242 said:

Clean the AMM/MAF, probably has oil contamination down wind of the turbo.

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I attempted to clean it with CRC maf cleaner and it made zero difference

It was the maf. Slapped a known good spare in and it chooches as good as new!