Help me save Christmas! 98 V70 no start/rough start Topic is solved

[erikv11]

Open up the distributor cap and check the inside for moisture. If the cam seals go, the moisture gets into the cap and wreaks havoc.

I'd check this right away.

[abscate]

Scanning won’t help diagnose a poor running engine , usually many codes are thrown.

The immobilizer won’t cause a stall from a running engine, it inhibits starting

[S Carlson]

Open up the distributor cap and check the inside for moisture. If the cam seals go, the moisture gets into the cap and wreaks havoc.

I'd check this right away.

Dizzy cap was bone dry inside!

Tiny bit of buildup on the contacts, which I brushed away. Similar to anything I've seen in a cap that's been used about this much. Nothing out of the ordinary.

Got up early to look for an immobilizer antenna and other parts to try swapping at Holland's used auto parts, the local junkyard, which didn't have any Volvos that old. No luck.

Tried rebooting the immobilizer by locking and unlocking and also pulling the fuse for a long time.

Car started up and ran. For about 40 minutes, we idled it. Then when I was getting ready to go drive it, the engine stopped again.

I noticed that the MAF sensor value on my scan tool was not changing when I revved the engine. Oxygen sensor was going up and down in voltage, as you'd expect. After it died, I tried restarting it, and it wouldn't restart. So then I tried unplugging the MAF and THEN it started right up! And the oxygen sensor was going up and down same as before.

I had cleaned the MAF a while ago (not touching the plate, being very delicate) with MAF cleaner. I am letting it dry now after cleaning it again.

So here's my question. How bad is it to drive with the MAF unplugged? It seemed to run fine. I know different cars respond differently. Saabs for example will go full-rich in a very extreme limp mode. I don't know about Volvos, but it seemed like it was running pretty ok. I just don't want to ruin the cat or oxygen sensors driving or running it much without the MAF, but maybe someone can tell me a) if I am right to condemn the MAF and b) if it's ok to drive without it plugged in.

Scanning won’t help diagnose a poor running engine , usually many codes are thrown.

The immobilizer won’t cause a stall from a running engine, it inhibits starting

I was under the impression that the immobilizer on these 98-00 x70 cars let the car run but the ECU sort of "stops trying" and this usually causes the engine to sputter to a stop. It was detailed in a thread I read on this site. I know the ealier immobilizers are different.

[Clemens]

As for the MAF: I think mine got worse from cleaning it. The Sometimes they just gel old an weird. Like most of us
I personally think you should be running w/o the MAF for a few days. If it runs fine, that should do.
The immobilizer might allow you to stsrt the car for a second or two, but then it dies right away.

I think the faulty MAF could cause these symptoms you described. After startup and on idle the ECU might use preset values ignoring the MAF system (just like with a disconnected MAF), but as soon as you hit the throttle, the ECU looks for the MAF signal which is not there or totally wrong.

[S Carlson]

^^That makes sense! Worth it to order a new MAF then.

I went out and did it again to confirm. Plugged in the MAF and it doesn't want to start. If I can get it to start, most of the time it is super difficult to keep running, runs horribly, etc. Unplug it and the thing starts and settles right into a nice idle.

I also checked the turbo pipes and intercooler to see if I could find any massive leaks. I don't see any.

The weird thing is that even with the MAF unplugged, there are no fault codes thrown. You'd think there would be one immediately. Do I need to drive it around to throw a MAF fault? I'm kind of afraid to move it, lest it stop again. Anyway, I think that's weird, but maybe someone else here has more insight.

The MAF reads between 40 and like 150g/s when the car is running, which it sometimes will, for varying amounts of time, before conking out. The "load" value is also kind of crazy. Some very high percentage load, like 40-60%. I thought that was weird.

With MAF plugged in, when it's actively trying to die, but I'm keeping it running with the gas pedal, I'm noticing the ECU feeding in tons of timing advance. Like 50 degrees of advance. Seems crazy. Any idea what could cause this? Or is it even real? It goes back to the usual handful of degrees of advance when I unplug the MAF and start and run the car that way.

Should I also order a used ECU?!

[misha]

I was about to mention a MAF but cam sensor open circuit put me on hold to re-consider it.

You can drive with maf disconnected...but not for long since it will run pretty rich and it will foul o2 sensors and spark plugs.

When ordering a MAF make sure you buy oem Bosch 0 280 217 107...nothing else will work properly.
It's better to buy oem used one than brand new aftermarket one.

Maf sensors do fail but it's connector is more prone to failure,especially at this age of a car...so inspect that carefully.

[wizechatmgr]

When you get the new MAF, clean up your connections and hit them with a little dielectric grease, just a smidge, don't overdo it. This should eliminate the potential of corrosion in the future. Also repair the split loom if it's looking ratty, which it should be by this point.

[Clemens]

+ 1 on what Misha said. Better old OEM than generic MAF.
Don't be fooled by generic look-a-likes, there are universal Bosch MAFs around for sthg. like 100 Dollars, but they don't work. If you don't have money to lose, buy an original MAF while they are atill available (hard to get by now), or look for used ones in Junkyards or in Volvogroups.

[erikv11]

Good job figuring it out. Nothing new to add regarding the MAF; must must MUST be the Bosch, specific. MAF. Cleaning the MAF is almost always a waste of time.

Regarding the ECU question: the problem is never the ECU. Really!

[FireFox31]

Got up early to look for an immobilizer antenna and other parts to try swapping at Holland's used auto parts, the local junkyard, which didn't have any Volvos that old. No luck.

Take a longer drive out to Burlington Used Auto Parts in Shirley, MA. The owner, Johnny, is very nice and helpful. They have a few P80 cars and might let you pull the MAF off an engine (unless they're trying to sell the engine complete). Call them first thing in the morning because they're hard to get by phone after that. Bring a list of everything you need and they'll help you get the parts.

You probably already know to avoid Jack's Used Car Parts in North Billerica. They are totally unsafe, stacking cars two high so you can't get in the lower one and can't reach the upper one. Their inventory is inaccurate; they don't have the parts they say they do.