1997 850 N/A sudden no start condition

[bcumby]

Ok - please excuse me if there are answers out there, I have just yet to find doing well over an hour of searching.

Initial problem:
A friend of mine has a base model N/A 1997 850 that just up and died on her one day going down the road. Died and then no start condition, although it seems to cough a bit like it wants to every 3-4 revolution. I initially thought "lawnmower syndrome" but then it did not really fit the criteria.

I have checked the fuel pump relay, the injector relay, the MAF - all seemingly check out fine. She had it towed to NTB originally and they checked the spark and fuel and said we were good to go there. I hooked up a CAN/OBDII scanner this morning and it came back with no DTCs...which is quite odd to me because she also said the engine light was on... Also, she said it had been intermittently starting kinda hard in the preceding weeks until it died.

Day 2-3:
Ok, so good and bad - due to the location of the Schrader valve, I cannot get a pressure without taking off the throttle, so that's on hold.

Good: I was able to press the needle and see fuel spray out of the rail and verify the IAC motor had not failed. I cranked on it for a minute with the throttle depressed and still nothing.

Even better:

I took out the airbox and disconnected, cleaned, re-greased, and reconnected both the crankshaft and camshaft position sensor harnesses - the original dielectric had gotten really crusty and it just did not look right.

While in there, I decided to take off the disty cap and noticed the rotor was extremely pitted and both looked OE - 18/19 years old and 130K miles - I wire brushed the rotor and stuck it back on and holy hell - the CAR STARTED. So, based on that early sign of success decided it was definitely time to change those. Wires were Bougicord and looked good, so just put on a distributor cap and rotor.

I went ahead and carefully cleaned what I could, even cleaning the (external - plug) terminals on the MAF the same way I did the others as they looked crusty too. Got it all plugged in and hooked up - car would now start and die immediately. This time it was setting a CEL though.

P0102 - Mass or Volume Air Flow Circuit Low Input

Unplugged the MAF and the car ran fairly decent for being in limp mode.

Am I looking at a simple MAF swap? She has a receipt for a MAF replacement in 2013, so I am not sure how or why this thing is chewing through MAF sensors...

Like a dummy, I went ahead and replaced it with cheap reman MAF....sigh. Car still runs like poo, although will kinda stay running intermittently, but not throwing a CEL.

To be clear, the car came into my hands with a cheap reman MAF and was running fine - I replaced with a reman MAF (available at local parts retailers) and car will simply not run with it plugged in.

BEFORE I order a Bosch unit from IPD or FCP, I need to know if there is anything else to check that could be causing this issue???

[Ozark Lee]

Did the receipt show that the MAF was a new or a rebuilt? 850s are real picky about parts in general and the MAF in particular. While it doesn't typically go through them quickly both the short term and long term success rate with rebuilt or off brand MAF sensors is pretty bad.

One other thing to check is the MAF connector. Volvo has a TSB that called for adding a tye-wrap around the MAF connector to keep it securely plugged in. They apparently had trouble with the connector itself not always making good contact.

Nice job with this, you went after it methodically and I think you have correctly isolated the problem.

...Lee

[bcumby]

I did not find a tye-wrap around the connector when the car came into my hands. Same as a zip tie or what should this look like?

I am willing to try anything, but I am looking at Occam's Razor here first and foremost...in the exact condition the car was in before I started hunting problems, it ran fine. Well enough to pass emissions three days prior to the breakdown.

Then, something malfunctioned. I am trying to find the one thing in the system that changed before the current symptoms started.

So frustrating, BUT, everything points to a bad MAF, so a new Bosch unit from IPD is on the way...at least that will be completely ruled out.

[Ozark Lee]

Tye-Wrap (a brand name) is the same as a zip tie. None of the cars in my fleet have it but I have never had trouble with the connection either. I think in practice the TSB has been implemented on an as needed basis.

Even though the mileage will be pretty terrible I have driven one of my 850s with a bad MAF for about a week while the replacement part came in. The throttle response was weird and it was pretty doggy but it otherwise ran fine.

...Lee

[abscate]

Be careful using Occam's razor under the hood. It's a close shave near that MAFand you can cut your tye-wrap.

Classic MAF diagnosis , well done