Hey everyone, this is my first post and I need some help. I have a 1990 244 DL with around 247,000 miles. I got the car from the second owner about two months ago. The car has been running very well, the only problem being that the car will occasionally lose power while driving. It happens most often at stoplights on acceleration; It feels like the gas pedal just sinks in and nothing happens. The car seems to completely lose power. This only happens for about 5 seconds, and then gas returns to normal. It's never really a serious issue, but it makes me nervous to drive the car. Just recently I was in a left turn when it happened and I thought I was going to get hit.
As far as troubleshooting goes, the car has been completely serviced and everything seems to be fine. I initially suspected it was a fuel issue, so I began by testing the fuel pumps by jumping fuses 4 and 6. Both pumps were loud and sounded strong, but I've read they can still be failing even if they are audibly working. I am thinking about replacing the fuel relay and fuel filter next.
One sort of weird question is whether powering devices with the cigarette lighter could be causing a problem? It seems like the stalling tends to happen when I have a Bluetooth speaker plugged in, but that could just be a correlation without causation.
Thank you all for any help you can offer!

 

I wouldn't worry about the electrical socket use, that's not it.

This kind of very infrequent issue is hard to find. You'd have to measure fuel pressure while driving which is quite burdensome and impractical. Fuel relay is unlikely to be involved, same as the filter.

I'd suspect the MAFS, you'd have to swap it with another to eliminate it as a cause. Or it could be some other electrical gremlin, etc. No easy solution.

 

Thank you so much for the quick response and for clearing things up. I looked through the records of the previous owner and the MAFS was replaced around 7 years ago. I also remember that the mechanic who did the first round of maintenance mentioned something about it when I first picked up the car. Would you recommend just going ahead and replacing it?
Additionally, is installing a fuel pressure gauge+setup completely pointless?

Thanks again!

 

I wouldn't just go replacing the MAF at this point as good ones are hard to find. Good used Bosch MAFs are much better than the new replacements that are currently available. Another item to check first is the crank position sensor. They can become intermittent prior to failure. The crank position sensor is located on the top of the bell housing where the engine and transmission meet. It has a fat black coaxial wire that runs to a connector on the firewall. Inspect the wiring on it. If the insulation is cracked and flaking off then it should be replaced.

 

The MAFS are becoming a problem--even the new ones are often bad. And I think they are the reason for many unsolved driveability mysteries.
The CPS related issues usually will cause the car to stall, not stumble, but it's a good part to have in good shape, just make sure it's an OEM quality.

 

Thank you both for the help. I won't have the car for most of the day today but when I get it back I will inspect the CPS to see if there are any issues.
It seems like the MAFS was replaced multiple times on this car so it doesn't surprise me that it is difficult to find a quality one.

 

You cannot check a CPS visually. It may be bad even if it looks OK, it may be good even with frayed wires. Hard item to test as it fails intermittently, obviously. If you change it, get an OEM one, it's a crucial part.

 

What would you recommend as the best plan of attack then?

I am looking at replacing the CPS just to be safe.
When you say OEM, would you mean this Volvo original one (which is horribly expensive):
https://www.fcpeuro.com/products/vol...AaAkQzEALw_wcB
Or something like this:
https://www.ipdusa.com/products/2130...-271949-246753

 

Not familiar with MTC, but Bougicord is fine, they make the OE wires.

 

+1 on Bougicord. OEM was Bougicord.

 

Thanks for the input. I think I might go ahead and order a new CPS because from what I understand, even if it does not solve the problem it can make the car run better and seems to be a good bit of preventative maintenance.

I've been looking more into the MAFS, and I was wondering if there was some way to test it before putting either a lot of effort into finding a good one or a lot of money buying a fresh one.
I was looking at this thread for reference but I don't really understand:
https://volvoforums.com/forum/volvo-...-sensor-90165/

Thank you again for taking the time to respond before and I think I have the information I need to solve the problem. Have a great day.

 

I never tried this test, it may work OK... Do it and let us know.

I have had many MAFS issues over the years and being lazy and having spare MAFS around I'd just swap them and if you hit it right you know it immediately--all the problems that were driving you crazy go away.

 

I completely forgot to mention this initially but the car will also occasionally idle pretty roughly for a little bit then warm up for a while and go back to normal. I forgot to mention this but it seems to coincide with the weird stalling fuel cut issue. I would say it happens 1 out of 5 times driving the car.

Could this occasional rough idle narrow down the issue?

Thanks again.