I have a 1997 940 classic LPT. After about 20 miles, under acceleration when I get to 2500 revs it starts missing, the rev counter flicks off and on also. If I get to 3000 revs it gets better, then a bit more and it can cut out completely, rev counter to zero although the engine is still turning, engine fires up and rev counter comes back if I lift off the throttle. One hot day crawling about town it got so bad I couldn't get more than 1200 revs until I stopped for ten minutes, then back to normal, 2500 revs. Been for a diagnostic at the main dealer but of course the fault was not present. Any ideas, and thanks for looking.

 

1997 940? they stopped selling 940's in the US after 1995, most of us won't be familiar with anything newer.

the tach is usually connected to the ignition coil, which in turn is switched by the power module, which in turn gets timing pulses from the ICU, which in turn gets the master timing from the crank position sensor. at least, thats how a bosch LH 2.4 car with EZK116 ignition is wired.

 

oh my wild guess? check the wiring to the crank position sensor. this is on the back side of the engine head, above where it joins onto the transmission, and near the intake manifold side. if that wiring insulation is flaking off, thats your problem, replace the CPS (Crank Position Sensor).

 

Thanks, all suggestions start with this, still trying to find it! I'm a bit perplexed that the fault is so specific to the revs and that closing the throttle restarts the engine.

 

940 turbo won't start, lots of troubleshooting already done. I'm stumped. - Volvo Forums - Volvo Enthusiast Forum - Volvo Community - Volvo Repair
Just follow this wire in the picture, lower down the thread,
and you will get to the other end of it betweeen the engine and transmission.
Fuelrelay otherwise?

 

Done the fuel relay bit before, but that's usually a non start until you take the top off it and push the points together. I found the crank sensor, ruffled the wires up a bit, and it's been fine since. I'll take it out tomorrow and check the wires carefully.

 

There's so much here I don't understand?

 

LPT == low pressure turbo? which, really, is all redbrick turbos. guessing its a B230ET or B200ET

 

Haha, I should have known that. I was thinking Liquid Propane T.... something with T. I'm still confused about 1997.

 

940s were sold overseas until 97 or 98. they had a stripped down version of the 960-II/S90/V90 body style, and various world market engines we didn't get in the US, like the B200ET.

 

Sorted, I think. Ran OK until a damp day, took the sensor off, the insulation is badly degraded, third uninsulated core exposed, and the white wire kinked, parted at the first pull. New one coming from the dealer, why could they not find this fault on diagnostic?
Of interest, maybe, to you in the US. This car is a technical writeoff, I bought it in 2007 from the worst driver on earth, all the sills beaten up, some door handles knocked off, dents all over, I've gone from 114000 miles to 185000. The previous owner was a well known river Thames boatbuilder, he received a visit from Neil Armstrong, gave him a lift to the station in this car, after which Neil said he was more frightened in that eight miles than all the trip to the moon.

 

In Europe and the rest of the world they got 940s til 1998. With manual trannies, turbodiesels that got 40mpg, various gas motors, etc.

When it comes to Euro brands the US gets pretty pathetic car choices, may be 20-30% of what Europe gets...

 

The truth hurts.

 

in 1996, the US mandated OBD-II and I don't think Volvo wanted to retrofit that onto LH2.4 or whatever, nor did they want to adopt some new Motronic system to the B230 family. The modern whiteblock in the 960 and 850 supported it.