I have a 95 Q45. The car had been in storage for about 3 years. The car was put back into service back in Sept. The car has been running fine, not a problem at all. All the sudden about 2 weeks ago, the Tach started acting funny. It looks like at start up it goes to about 1000 or a little higher. Then if the car was to sit in the same position and idle, the needle will climb to red line, and past. sometimes it will bounce out and star reading correctly, but on the next start up it starts the same issue. This went on for about a week, then the car started to stumble. It would act up until I could get it up on the highway, then it would run fine. It may run fine for several starts, but will again start stumbling again until it can be either floor boarded, sometimes correcting the issue for the rest of the drive and may not have a problem on the next startup. But today, it started acting really bad. It kept dying at every stop. I took it to a shop, they could not diagnose the issue because they did not have the diagnostic machine. They were unsure what the issue would be. I was wondering if, first...could the issues be related? I need some help on figuring out what I need to do o get the car in proper working condition. trying to take it to another shop, but this is my only mode of transportation.

First thing I would check would be fuel pressure, otherwise it would most likely be MAF related. One thing you can check easily is when the car is idling, jiggle the connector on the MAF and see if the idle changes or the engine responds in some way.. If it does, then you could take the MAF connector off and clean it up real good and maybe bend the pins slightly so it gets a tighter contact.

I don't think the issue with the tach and the stumbling issue is related. I think a used instrument cluster will fix that issue. I've never heard of that before, definitely is interesting.

elwesso wrote:First thing I would check would be fuel pressure, otherwise it would most likely be MAF related. One thing you can check easily is when the car is idling, jiggle the connector on the MAF and see if the idle changes or the engine responds in some way.. If it does, then you could take the MAF connector off and clean it up real good and maybe bend the pins slightly so it gets a tighter contact.

I don't think the issue with the tach and the stumbling issue is related. I think a used instrument cluster will fix that issue. I've never heard of that before, definitely is interesting.

+1 on the measured fuel pressure.
just do it.
so many people have symptoms and don't provide any real data to assist with diagnosis.

@Wes-on the U13, I once had the tach do what OP is stating. Was replaced under warranty and never happened again for the next 15 years.