Warning, LONG POST FOLLOWS:

I have done my homework by reviewing the FAQ's. Some of them are helpful, but I think my problem is not covered.

Here are the symptoms and my analysis. Please, give me your opinion.

So many small things and no idea of what is related to what. The car is a 1994 940 turbo wagon with 200k miles. I do about 2000 miles yearly. Generally the car runs well and it has been maintained. I have replaced the cooling hoses at the bottom in front of the transmission and I have cleaned the air intake valve, both within the past couple years. The RPMs are usually at 600 and steady, except when they drop to nothing. Warm weather seems to be the cause, by warm I mean 50 degrees and above, but that’s one of the problems.

Last summer (warm weather) after the car was warmed up the RPMs would drop to near zero and sometimes the car would stall. With colder weather in the fall, things improved. But, when the weather warmed up as it does from time to time, even during the winter (Boston) the low RPMs and stalling would return.

A couple years ago, with an inexperienced teenager at the helm, the car was cooked a bit, when the radiator lost water. I monitored the engine by examining the exhaust and decided, without anything more objective than that observation, the head and/or head gasket had altered in some way allowing coolant to enter one or more cylinders. This was guess work based on very limited information.

A clever friend advised trying pepper and I added 3 tablespoons to the coolant reservoir with what seemed to be improved results that is, not skipping on start up. This is important because of what I have been experiencing lately.

In this very cold season, some mornings the car will start, but skip badly for the first 20 seconds. About once a week, particularly when it is very cold, the car won’t start at all - at first - but after several tries and a rest period of 5 minutes it will. Then it skips so much that there is not enough power to drive up hill (my driveway). After a half minute of running it seems to “kick” into its usual even running mode with no skipping. And if its cold weather, the RPMs maintain at 600. There is no problem until the next time it happens again when left over night. Sometimes, after a cold night it doesn’t skip, which leads me to think the problem is related to the position of the valves and/or pistons when the car is shut down. All of this makes me think water/Coolant in the cylinders.

The following may be unrelated, but worth mentioning:

1) Occasionally, the fan continues to run after the engine is shut off. I am familiar with cars in which this happens by design, but never before in my experience with 240, 740, 940. If I turn the ignition on and off again, it usually stops the fan, but sometimes, I have to do it several times. If I leave the car with the fan running it shuts off by itself. I don't find it running when I return.

2) Sometimes and this is, again, intermittent, I’ll be driving along with the heater on and suddenly the air will change to cool as if I have turned the thermostat down all the way. This will continue for a few minutes and then correct itself and things will be fine. It almost seems as if the correction occurs as a result of cornering, but that is just a foolish supposition on my part. I have recently replaced the hoses that go to the heater core at the engine fire wall and I was careful to install the valve correctly.

3) When I check the coolant … and this may be significant to the head gasket/leak theory … the coolant level seems to drop slowly, but there is no indication under the car of any coolant escaping. I know what that looks like and I would notice it. But the level does drop over the course of a week or two, so that I have to add ½ quart. This supports the theory that coolant is getting into the engine and burning off. It doesn’t explain why the car continues to run so smoothly once the initial skipping has passed. Maybe these Volvos are so good, they run well on anti freeze.

I haven’t tried another dose of pepper, but I think that would be the easiest and next step. If the problem abates, it will tend to support the coolant in the engine hypothesis. Otherwise, the car is just about perfect, meaning everything works, no dents, no cracked tail or parking lights, etc. etc., intact grill. With limited knowledge I tend to address issues as they arise, rather than being aggressively pro-active. I have done some significant work, over the years, but a motor job, meaning a head gasket is not on the list of things I am prepared to attempt, at least not while it is 10 degrees out, and probably not when it is 50 or 100, either.

Anecdotal story: For several years I stopped at my mother’s house every other day in the winter to hand feed her steam boiler, that couldn’t seem to hold its water. I disparaged the suggestion of adding a liquid sealant, thinking this was just hog wash. A few weeks ago, I figured I had nothing to lose by trying it, other than $20 for the liquid sealer. I added the sealer. The problem now seems to have stopped. This made a believer out of me and in the case of the 940, pepper might do the same thing.

What do you think? Could the skipping be something else, like an injector. I have added some dry gas recently. Frozen water in a cylinder seems to me like the best guess. (Right, if it is coolant, it won't be frozen!) Trying to start the car eventually breaks the ice down, or mixes it with the fuel enough so that after a while it fires. It then takes 1/2 minute to work the dilute mixture out of the engine.

Definately look for OBD codes, to give you some clues where to start. Run the OBD tests (they are so cool...check and see the injectors are running as well as the throttle bypass solenoid and the start injector (if it uses one).Bad starting from cold followed by poor idle then a nice warm upand no further probs can be indicative of either failed engine coolant sensor (either dead wiring or dead sensor) or the ECU is ignoring the input from a good sensor. The fact that the car runs well once warmed up suggests that the basics (plugs wires dizzy cap rotor arm etc) plus the EZK-ignition box are prob OK. So you can test the sensor by looking at its resistance at cold. (to find it, it is near cylinder 3 intake, so its not the first sensor you can see, that one is the dash temp sensor). At zero centigrade it should be about 6K Ohms. Hot engine, around 150 Ohms. If the sensor is OK and there is no OBD code then it could well be the ECU. DIsconnect the ECU (disconnect battery first and wait 5 mins) then test pins 13 and 5...you should see the same resistance I mentiond earlier. This shows the sensor is fine and so is the input to the ECU. If this is the case, then its the ECU...get it reconned or find a replacement from a scrapyard...If the sensor is dead, they are about 15 bucks on Ebay...failures caused by crankshaft sensors are more often linked to hot starting probs. They are not expensive to change, about 50 dollars..hope this helps

you stated:

The car is a 1994 940 turbo wagon with 200k miles. I do about 2000 miles yearly. Generally the car runs well and it has been maintained.

bluntly said i am amazed your turbo wagon has not given you even more trouble than it is at present.

that said, look for a faulty cps sensor or power stage ignition amplifier

let's perform a few calculations to illustrate your dilemma.

365 days a year
lets say you drive this car on only 5/7 of them or 260 days.
if you are accurate about driving about 2000 miles per year your average trip of for those 260 days is less than 8 miles per trip.

in other words, your turbo wagon NEVER really warms up to run at proper (in cold weather almost no chance for it reach good operating temp and barely in warm) temperature BEFORE you shut if off once more. the carbon build up in your engine must be a sight to behold.

if i were to hazard a guess much of your problem stems from your driving pattern. there are likely multiple issues going on with this car from simply lack of continuous use at a duration sufficient to allow the engine to work at its design spec.

these design specs were created with the unstated assumption the driver would actually use them for more than 8 mile per day.

to remedy your problem/s i suggest a good indy volvo garage of which there are many in your area.

To elaborate further regarding the carbon buildup in your engine...

You could try an Italian tune-up before spending any money on new parts or at a shop. Once the car is good and warmed-up (say 20 minutes or so of driving) take the car to your local highway. Rt. 128 or the Mass. Pike are both near you. Once there, drop the car out of overdrive into 3rd gear and aim to keep the engine rpm's at about 3000+ . Try to keep it there for about 5 minutes or so. This will burn off some of the excess carbon. Even 2500 rpm's will help. Contrary to popular belief, your engine will not blow up...:)

Another option is to take it on a long, high speed highway trip - say 70mph + .

Doing any of the above will help burn off excessive carbon buildup in your engine and you will notice it running better.

I commute 22 miles a day in my 95 855. None of which is on a highway. I make a point of doing an Italian tune-up every month or two. Car runs great at 240k miles!

Finally:

1. I believe that 1994 940's have electric fans. That is why it keeps running with the engine off.

re engine "skipping": When was last tune-up? Maybe just need new spark plugs, wires, cap and rotor, air filter
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I own a Volvo or Does Volvo Own Me? Try the easy to search Expanded Style FAQ Index http://40mph.com/Brickboard_700-900_FAQ_Expanded_Index_Version/

A leakdown test will pinpoint any cylinder problems. A mechanic can perform the test fairly easiy. Even without an overheat event, at 200K, the head gasket is likely to begin failing. Because of the aluminum head and cast iron block, the heat load has sufficiently different expansion rates and, over time, degrades the gasket in a turbo motor (not as much of a problem with a N/A engine). 200K - 250K seems to be a common life span for a turbo head gasket. Pepper will not be a reliable nor permanent "fix", nor will any block or head gasket sealers. The problem is the cylinder creates a higher pressure than the coolant system and will blow out any plug the sealant can create between the cylinder & coolant passage.

But Spook is right, it may be an ignition problem. The dropping tach reading is a clue to that. At this point, you should be carrying a few replacement parts in your glovebox in case of failure, a power stage is one of those items.

BUT, I had a similar problem that I eventually traced to an intermittent in-tank fuel pump. The main pump could not supply sufficient pressure when the tank was less than 1/2 full. This was accompanied by various problems pointing to the ignition and I wasted a lot of time chasing a non-existant ignition gremlin.

Good luck. Post back...
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1999 E320-200K 1994 F150 (awaiting a new engine) 1989 560 SL-180K 1994 945T (daughter's)-312K 1986 242Ti (awaiting a B230FT transplant) 1968 GT500KR (under slow restoration) 2007 HD Nightster (son's ride)

Have you checked for codes present? Hard to believe with it running so poorly it would not set a code. When its nice and cold and you first start the car, do you smell some gas either in the engine compartment or at the tail pipe? Ya should. I am wondering if the coolant you are "burning" has affected the 02 sensor. Check for codes and let us know.

Dear robertmfranklin,

Hope you're well. Is the ignition power stage - a flat device, with a gray top, mounted in the inner fender well, behind a headlight - the factory-original item? If so, it could be "on the way out". With 200K miles, it doesn't owe you a penny. On turbo-equipped cars, the ignition power stage may be heind the passenger-side headlight (on non-turbo cars, the ignition power stage is behind the driver's side headlight).

When ignition power stages fail, they work "intermittently". Exposure to heat usually produces signs of failure, e.g., the car won't re-start when "hot". In your car's case, higher ambient temps in winter may be enough to cause failure.

Another source of failure is the crank position sensor. This sensor - mounted in the transmission bell housing, on the passenger side of the engine - usually shows signs of failure in wet weather. Water gets at the wires, through a crack or cracks in the sensor's wiring harness insulaton sheath. Water on the sensor's wires causes the sensor's signal to be lost. Without the sensor's signal, the engine control unit shuts down the fuel pump.

I'd be wary of cooling system sealers. They could clog waterways in the radiator, and so make the radiator less efficient. That makes the engine more likely to overheat.

A mechanic can do a test to see if exhaust gases are present in the coolant tank (i.e., if the headgasket has failed). If exhaust gases are present in the coolant, then the headgasket has failed. If not, the coolant loss occurs somewhere else. I recall posts reporting coolant leaks where the coolant landed on the engine, and burned-off. As a result, there were never any signs of coolant on the ground.

When was the radiator last changed? In the US northeast, a radiator might last 12 years. Anything beyond that, and you're on borrowed time. When were the radiator hoses last changed?

Hope this helps.

Yours faithfully,

Spook