dpizi

Hey guys, looking for some advice.

I was driving my 95 C2 yesterday and for the first time in 17 years of ownership it left me stranded. Details are:

Rolled up to stop sign and car just died. Popped the engine lid and saw nothing unusual. Engine turns over fine and occasionally will fire and run for a few seconds to a couple minutes and than just dies. Most of the time it would crank and fire but it immediately dies. After having it towed home I ran Scantool and it has a MAF sensor code #21. Forum searches seem to indicate that the MAFS does not go bad that often and that cleaning can sometimes correct a problem. I picked up some CRC cleaner this morning, pulled the MAFS and cleaned using cotton swabs that others have recommended. It did not seem excessively dirty. I reinstalled and car started up and ran for about 5 minutes before it died again. While the car was running I had Scantool running and inputs from MAFS showed about 0.80 v at idle and up to 1.10 to 1.20 v at about 2000 rpm. While watching I saw the volts drop to zero the instant the car died.

It looks like I will be ordering a new MAFS but I just wanted to see if there was anything else I should consider?

Many thinks
Dave

Endoman

Sounds more like the crank speed sensor to me.

dpizi

Thanks, let me check into that.

pp000830

Motronic (DME) /fuel pump relay 993.615.227.00 You may have a bad sensor but it may not be the reason you car stops running.

Pull the relay and pry it open and look for a cold or broken solder connection inside or simply swap it out and see what happens.

dpizi

The DME relay was the first thing I thought of when it happened. I will look in to both DME relay and crank sensor and follow up once resolved.

Again, thanks
Dave

IainM

The connectors on top of the engine get baked and can oxidize
try making and braking the MAF connector a few times to cut through crud
you can cut up an eraser to clean exposed contacts but usually you only get half the problem
if that fixes then clean & apply dielectric grease to protect
worth a shot

enjoytheride

Remarkably, the car can actually run ok without any MAF signal at all. It seems to treat an absence of signal differently than an implausible or faulty signal. So you might try unplugging the MAF wire harness and see if the symptom changes.

nine9six

This sounds like a good and reasonable thought... You have a MAFS code, so try to rectify what you know is wrong.

Vorsicht

I recently had a similar issue where the car would just randomly stall. I would be able to re-start right away though and continue driving. Every time the car stalled I got a code 21 (bad MAF signal).

It turned out the problem had NOTHING to do with the MAF. I had a bad battery. Once I replaced the battery the stalling went away.

So, just a thought - how old/good is your battery?

PS I also had a problem several years ago where the flywheel reference sensor (crank sensor) went bad and caused stalling so that should be on your list as well.

dpizi

Lots of good advice here, exactly what I was looking for. I am tied up with a couple other things at the moment but I will let folks know once I get it resolved.

pp000830

CRC Spray Electronic part or motor cleaner is great for cleaning connectors.

pp000830

Yes, have experienced this too. I wonder if one just leaves the sensor off one experiences that wonderful savory, partially burned hydrocarbon, exhaust smell from the good old carburetered flat six days?? Maybe a few more ponies too, one can dream can't he!

JM993

Quite the contrary, throttle response suffers and the car will run like crap with the MAF disconnected.

pp000830

Good to know!

dpizi

Much happiness today. A new DME relay seems to have solved my problem. No check engine light or MAFS code. I did learn something new, I always assumed that when the relay died the car would not run at all.

I'll probably do some preventative maintenance on the connector and perhaps change the crank speed sensor. Seems like cheap insurance to me.