89 740 power loss
 

Hello everyone,

So today my 740 seems to have lost power when pressing down on the pedal either flooring it or slightly pressing it and it even stalled and thats where i started to worry. I started noticing this in the mornings after i let the engine warm up and so when i gas it it accelerates very weak and then the power comes back but today the problem became more apparent. I dont trust the car will make it back home today and in traffic.

Might be a small problem or a big. Some back story of the car, my parents have had the car for a while now as a gift from the previous owner and it was my first car. So when I got the car I wanted the 740 went and stayed in the garage since 2016 i believe without being moved and occasionally turning it on sometimes. Last month i decided to bring it out of retirement and use it again so i had some things like brakes and lines repaired and some other things to make it pass smog. The service light turns on when the car is turned on and then the light turns off after a few minutes. Im hoping to get that checked once i get the car towed back home. It sounds like the engine gurgles when I accelerate and it makes another sound that sounds really weak. When i pop the hood i can see some light steam coming off the top of the tubes of the manifold, idk if thats normal. And another thing, a little after the car was in the garage, it wouldnt reverse when put in reverse, it would just rev, and after a while it started to reverse again like normal. So im a little scared if it might be the tranny.

I been reading some old posts of similar problems but it can be anything i guess. Is there anything that I should look out for? And check?

Thanks

i'd look at the Mass Airflow Sensor, a big boxy thing between the air cleaner and the throttle body...

and the tranny thing is a sign of it going out--it is slipping. try changing the fluid it may help.

fyi, the 'service light' is just a 7000 mile timer thats telling you its time for an oil change. I forget how you reset them.

the CHECK ENGINE LIGHT, on the other hand, is telling you that there is a diagnostic code that might effect smog (and probably effect drivability).

service light comes every 5000 miles, resets from the back of the instrument panel.
the CEL always indicates an emissions fault and no car will pass emissions test with the light on.

thank you. i was on my phone, and trying to remember the details, and you worded the CEL much better than I....

(and I really should remember that Volvo wanted a 5000 mile oil change, it was my VW Rabbit and Jetta that speced 7500 mile changes...)

my 7.3L diesel ford truck says 5000, but I'm doing 3500 because most of my miles are towing and/or heavy loads, or dirt roads... with a fumoto oil drain valve, 3.5 gallon oil changes become pretty easy.

The service light on my 89 740 is reset through the front of the instrument cluster. There is a small rubber plug located just to the left of the speedometer "0" . You remove that and stick a pointed tool and press on the small button inside. It clears the light. Plug is about 1/4" dia.

resetting the service light varies by model and year. Easy enough to google for your model and year. CEL diagnostics fall into two camps - 1995 and before many models have the LED diagnostic box with jumper under the hood (Volvotips.com is a good resource on reading codes this way), 1996 have the OBD2 ports ($39 harborfreight reader works fine for most P codes).

Hmm, the newish pods starting in 1991 have the plug in front, the earlier 740 had the reset in the back of the instrument panel, not sure what year that changed though... the '87 had it in the back. Surprised they changed it mid run...

they changed a lot of stuff on the 740 incrementally, and 91 was a big change, lots of stuff was updated to 940 even tho they still had 740 seats and exteriors. 92 got bigger radiators and the mechanical fans were deleted. etc etc.