Still have the problem. At ~4500RPM, engine starts cutting out, tach starts bouncing (not all the way to zero)... letting off slightly it smooths out until about 5K RPM.

More investigation reveals that the problem manifests itself regardless of load or gear - it will do it in first, second, third - even in park, whether you floor it or let it creep up under light throttle. I no longer suspect fuel... as much.

I did the static checks of the RPM sensor for continuity - reads right on OEM spec. Resoldered the fuel pump relay just for thoroughness. Since it does it in park, I put a timing light on it to watch what happens - timing seems to stay more or less on target for the first few misses, then I see it getting pulled back.

I'm running out of ideas on this one - it seems to be spark related, but tied only to engine speed - could it be the RPM sensor? Or is my coil the prime suspect? Thanks for any guidance...

I had a sputtering between 1,500 and 3,500 RPM under load. I tried all kinds of things untill I did a fuel volume test and found out that the fuel pump was borderline. I had done a fuel pressure test and it was only a couple of psi low. It produced just enough pressure to run fine until you tried to accelerate.
I think your Regina has the same single, in-the-tank pump that mine has.

I strongly suspected this too, until I was able to reproduce the sputtering in park at the same RPM as when under load. I think the pump is OK.

Try taking the two halves of the coil apart, and cleaning the internal connector posts and contacts. Can't hurt.
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Gary Gilliam Sumerduck VA, '94 940 na Regina 160k '86 240 190k, 93 Camry 4cyl 5spd 245k

I had not thought of that, I'll try this as well - the price is right!

A few posts I've read with similar symptoms - cutting out at anything over a given engine speed - have turned out to be the coil. RPM sensor usually starts off as hot start problem, and even as they get worse it's not really rpm-specific.
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Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina

Yeah, this problem doesn't quite fit the common pattern of any particular component. I've just received a new RPM sensor - I'll try that and see how I'll go from there...

Hi Jason,

I lost track of your previous posts; did this begin recently or did you inherit the tbl from the PO? Are you suspecting Rex controller or problem with flexplate ring? Seems to me I remember when you had 240s you had a scope? I've taken some readings on that sensor, albeit on EZK not Rex, to have an idea what is marginal waveform, but usually higher rpm gets more amplitude. I'm assuming you've read a lot about the woes of the Rex coil or igniter.
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Art Benstein near Baltimore

Replaced the coil this evening - it didn't go away completely, but the behavior has changed. Now, the stuttering seems somewhat less pronounced, and occasionally it will break through and rip smoothly the rest of the way to the redline (testing it in Park.)

Hmmm...*scratches head*

Starting to run out of ideas here.

Popped in a new RPM sensor (thankfully, mine was not stuck - took less than 5min!), but that did not affect my problem. Separated the coil halves - the contacts looked a little scuzzy, so I sanded them - still no improvement. Checked for arcing in the dark - nothing. The inside of the distributor cap looked great. All plug wires and coil wire firmly seated, no corrosion in the contacts...

Given the results of my diagnostics, and the less-than-stellar performance record of the Regina coil/powerstage unit, I'm thinking of replacing this part. It seems like the coil is failing to keep up with demand during high-RPM operation.

I have no personal experience on the Rex coils. I hadn't even heard they could be disassembled. My understanding is the mode of failure is internal arcing in the secondary. The breakdown is most apparent at high revs and the only fix is to get another one.

Nothing wrong with being proactive on the sensor. Was your old one identified with a yellow or white tape around the vinyl cable sheath?

Finding out you could disassemble the coil was new to me too. Two screws, and the main coil comes right off.

The RPM sensor had a white band. The new one from FCP also has a white band. The old one looked pretty good, but was just starting to split the sheath near the bellhousing.

I've got a new coil on order.

Hey Art,

No, I don't have a scope per se, but a PC-enabled multimeter that can sometimes function like one.

This is a problem on the 940 I've had for ~5 years. I don't post much about it because it has been astonishingly trouble-free. Maintenance has been kept up to date- it has a fresh fuel filter, <1yr old cap/rotor/wires/plugs. RPM sensor is original AFAIK, so that's getting replaced as a matter of course. I'll also watch for arcing inside the cap.

This sounds like ignition to me, not sure of what you've done, but I'd replace the rpm sensor for good measure if you've got more than a few years on it. I had a miss that drove me crazy until on a whim I replaced the rpm sensor. I would also carefully check the ignition, in particular, the dist cap as they can arc with the black plastic cover on them. To me the timing belt wouldn't give the symptoms you describe. Good luck.

Mike

I've got an RPM sensor on order - AFAIK, the one on the car is original, at 238K miles, so its certainly due. I'll also try running in the dark to watch for arcing. The cap is not quite 1yr old.

One good thing about having more than one 10 plus year old Volvo is having test parts available. No telling what is causing the problem. You can easily work your way from front to back ending with the fuel pump. Start off with the cheap or easy DYI stuff that need replacing anyway. What kind of maintenance have you done? Has the ign. components been replaced? Worn out rotor and cap? If it was my money, I replace the crank sensor and FP relay. Timing jump a tooth or three? Two of the 5 Volvos had the timing belt installed incorrectly.
http://www.brickboard.com/RWD/volvo-1013673.html?show_all=1
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Tom F. Three Bricks, maintain two more.