Poor Accelleration - 740

UK spec 1989 740 GL Estate. 2.0ltr Auto fuel injected. Pre Lambda Sond model with std (not catalytic) exhaust. 123,000 miles and always regularly serviced by Volvo.

The car was never particularly good on accelleration, it used to do 0-60mph in about 12.5 seconds. The car has done only about 15k miles in the last 4 years and as my Son now has as his daily driver this is the first I have driven for the last 2 1/2 years.

The car feels very sluggish on acceleration but cruises along fine once the speed is up. 0 - 60 mph acceleration now a dismal 17 1/2 seconds (previously 12 1/2) so something is up.

Accelerate away from stop using the throttle gently (i.e. normal traffic speed acceleration) and the car appears fine. Put your boot on the gas pedel and the car hardly seems to acceletate any quicker. Engine revs ok (once it gets up there).

The engine had the cylinder head gasket replaced at 119k miles by Volvo which cures the water coolant loss but this according to Son did not make any difference to acceleration pre/post gasket change.

Car starts fine, ticks over fine and generally goes well enough. Aparently the car has lacked acceleration for quite some time now. Brakes do not appear to be binding - at least the disks do not seem to run hot when you put your hand by them after a run. Hand brake is not sticking on. The air filter is due for a change, has done 10k miles but it's not that mucky. No Lambda Sond or cat on this car (just before they were fitted in the UK. Fuel consumption has not changed and still does about 23 mpg around town and

25/6mpg (English) out of town which it has always done. Oil consumption is negligible.

When accelerating it feels as if either the engine is not getting enough fuel (the fuel filter was replaced at 100k) or it is being choked by not enough air going through the air filter. Removing the air filter does not appear to make a difference.

Could we be talking a sluggish fuel pump. I seem to recall that the older

740's had 2 fuel pumps, could it be one of these failing that is now starving the engine of petrol. How can I check?

I really am open for ideas. I am totally stumped at the moment.

Many thanks

Andy

Reply to
Andy
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My first question (not knowning the specifics of this car) is what fuel is being used (octane rating)? If it has the anti knock sensor tied into the comouter, my first idea is that a low-octane fuel will cause excessive pinging upon acceleration which will retard the timing quite a bit.

If it can run at a high RPM (like near red line in any gear) for any length of time then it should accelerate at low motor speed decently. Try a tank of good fuel.

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Reply to
Randy G.

Another of my many "long shot, but easy to check" ideas that occasionally pan out... with the engine warm, put your hand on the top of the air cleaner box (where the filter is). It should feel barely warmer than the outside temperature. If it has a fever, the wax pellet that controls the intake heat has failed - common enough - and the hot air is taking its toll on the performance. Check it anyway, because I'm told that sort of failure is hard on the expensive AMM.

Mike

Reply to
Michael Pardee

You're right about it killing AMMs, though in this case he doesn't have one. Since the car is pre-lambda it has K-jet mechanical injection, something that went away here after '81 except in the 240 Turbos.

Reply to
James Sweet

Its an auto yes? Is the kickdown working fine, and more-over when it does kickdown are you reaching 'full' revs before it selects the next gear? Not familiar with the B200F but think it ought to be in the region of

5000-5200rpm.

Secondly, with an assistant in the car pressing the pedal to the floor, with the trunking off, check you are actually getting full throttle. The number of times i've seen a stretched or mal-adjusted cable...

Tim..

Reply to
Tim..

This may be a long shot but a 740 I had, had problems with the ignition amplifier (located behind the air filter)causing a weak spark, finally it gave up on the motorway. just a thought. - Roy

consumption

Reply to
Roy Bolton

Reply to
John Robertson

This weekend Me, Ricky (Son) and a techi are going to give Lola a good seeing to. Before then we are going to have it MOT's as this needs doing anyway by 3 Oct to see if this throws anything up. Have taken on board all suggestions here and other forums and will work through. Inshalla, we will actually be able to pin point what is causing the problem but I would settle for it just working ok again.

Will give feedback when we have something to tell.

Bye the way have already tried the 'thrashing the bollocks off it trick'. To no avail. The car has always been driven sensibly with a bit of stick but not screwing it. My wife certainly never hung around in it when she was the principal driver and neither do the kids. I do know what you are getting at though. Did the same on an mid 60's Austin 1100. Belonged to an old lady who never exceeded 45 mph. Held it down in second and gradually increased the revs then 3rd until it went from prob a max 3 to 3.5k rmp to 5 to 6k rmp and was fairly screaming. Did this for a 50 mile journey and together with a replacement air filter (theirs was VERY shitty - unlike ours) did the bizzo. The elderly lady thought we were miracle workers.

Andy

Reply to
Andy

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