Boggin when hot, fine when cold...
 

I've been reading alot and well done a lot of search and this seems to be a pretty common topic with 240's hopefully someone could help me out. My problem is when the car is cold, hasn't been started in hours it runs really good and strong, but then when it gets warmed up it bogs and feels powerless. Also my sparkplugs look whitish, im assuming im running rich. I already replaced sparkplugs and the wires and fuel filter, also changed the CTS with a friends that was working fine and still there. ANy help will be greatly appreciated. Thanks

Im new at this forum. So whats up Im Robbie. I have a 1998 240 5speed pretty much stock. What i noticed is when it gets hot and the mechanical fan is going is when it lags the most. I took out the mechanical fan and rewired the fan relay to were the electrical one comes on when the car is on. My car accually runs cooler, and gained a bit of throttle response and doesnt lag like it used to. Other things u can do.... flywheel? Pulley? They will help with ur throttle response.
If you want to do that thing with the fan, I think this guy did the same thing on ********** under installs.

Robbie

That electrical fan is between the radiator and the big fan right? Even if it will run cooler i think there has to be some mechanical problem, the car shouldn't run extremly slow when is hot

Every 240 I have driven I noticed does it. Also I noticed when i would be suckin all hot air that didnt help much.

Robbie

MY MISTAKE! I was thinking when its HOT out and it warms up. Now just normal warm up.......

Robbie

black carbon fouled plugs mean you are running rich, too much fuel

whitish plugs mean you are running lean, not enough fuel

this might indicate a fuel delivery problem, but note that its ok for them to be slightly grey/whitish this is ok.

possible causes are low fuel line pressure because of a malfunctioning fuel pump or malfunctioning fuel pressure regulator. you need to hook a gauge up to the line to test the pressure. (might want to let a mechanic check these two things)

another possibility is a vacuum leak through the carbon canister. to test, disconnect the purge line comming from the canister and plug both holes. if your problem dissapears the canister is faulty.

last, check your temperature gauge, is it going above the middle line? if it does you have a cooling problem. possible causes are leaves and dirt caught imbetween your radiator and condensor, incorrect antifreeze to water ratio, or a faulty water pump. This wouldnt cause you to run lean though, it would just make the performance sluggish when the ECU retards the timing due to high temperatures.