Lately, my 1989 740GLE is showing rough idle at park and rougher when engine has become hot.
Consumes a lot of gas, some smoke upon stepping on the gas pedal.
Runs very well on highways. When on local streets, esp. when stopped at traffic lights, engine
seems to grasp for more air, engine shakes as if it is being choked.
Several mechanics have tried, but I think I was simply ripped off.
Pls. let me have your advise. Thank you very much.

 

Please give some info on what has been replaced and looked at.
Then I will be able to help you a little more.

 

Thank you for the quick response.

Here are the parts replaced:
1. Idle Control Valve..new
2. Air mass meter...used/pre-owned
3. Electronic control module locate at lower right kick panel, Jetronic/Bosch...pre-owned
4. 4 plugs/wires/dist. cap/rotor...Volvo/new
5. Fule injectors have been elelctrically tested..they are all working.

One mechanic suggested to replace temperature sensor located at intake manifold, I did not agree (yet).
Another mechanic suggested that another computer by the driver side/steering wheel area ( called Ignition computer?) should be replaced too....I did not agree(yet).

Question: Member "Mannkar" has similar situation as I have.
He said he replaced the "Air Flow Manifold Sensor". Is this part same as "Air Mass Meter"?

Thank you again.

 

Yes they are the same thing the air mass meter and the mass flow sensor.

2 things I would look at is the coolant temp sensor and the O2 sensor.
Sounds like you are running rich.
Is the smoke you see black?
Also check good for vaccum leaks that can also make it run rich.

 

Thank you.

Yes, the car is running fuel-rich. The fuel smell is very strong, I can smell esp. when windows are down.
At some point, it was black heavy smoke. The tail pipe ID at port end is now black.
After the Jetronic computer was replaced, the smoke lightened up, it could be greyish now.

I will have the parts you suggested be checked/replaced.
The vacuum leak check too.

Thank you very much. I will keep you posted.

Terry

 

Your welcome I will be waiting to hear from you.