My 1990 240 starts and idles a little rough for a few seconds while in park, then idles fine. Then, when I shift the automatic transmission into gear (reverse or drive), it stalls. However, if I wait a few seconds longer in park before shifting, it doesnt stall, and then the car runs fine as long as engine is warm. Seems to be getting a little progressively worse every week, but not that bad yet. (For what it is worth, I replaced the spark plugs with NGK resistor plugs from IPD, the car seemed not to have any problem prior to that, but cannot really correlate this to the problem.) Any suggestions welcome!

John,

Try using BG-44K, a very good fuel system cleaner that is not dumped in the tank but injected into the fuel rail and will really clean out the crud. Followed by an "Italian Tune Up" at 75 MPH then a complete oil/filter change to make sure all the BG44K is out of the oil.

Or try running the tank to very low, putting in a full bottle of Techron and then 5 gallons of fuel. Do same Italian tune up and then fill up and see if its better.

I have the same exact symptoms (1987 Volvo 240). I'll be watching this thread closely

A trusted Norwegian Volvo mechanic told me this symptom is due to porous fuel deposits in the intake ports near the valves, and on the back of the intake valves themselves.

These deposits "dry out" overnight, then "soak up" a good bit of the incoming fuel on the day's first start. This means the cylinders don't get the fuel needed for much more than idling (maybe poorly).

After a minute or two the deposits become saturated, letting ALL the incoming charge get to the cylinders, and it runs OK till the next lenghty shutdown period. (How long is "lengthy"? I can't say. Maybe just 2 or 3 hours?)

The fix is to run a good quality fuel system cleaner thru. Probably more than just one application. I think these cleaners are discussed in the 700/900 FAQ feature. I'm told they are most effective with a lot of short trip driving, giving the stuff more chances to "sit and soak" -- as opposed to running it thru on a long trip.
--
Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and going to be crushed unless...)
New 144 from '67 to '78
Used '62 122 from '63 to '67

Bruce,

This sure sounds logical. I'll give the recommendation a try, and will note the results here. Stan and I appreciate your detailed response.

John