Last important issue to resolve. Mechanics also a bit stumped. It can take 30-40 seconds to turn over when 'cold' (60 degrees in NorCal now).

1. New battery - tests fine
2. Newer spark plugs and wires
3. Throttle body cleaned
4. Recent oil change and checkup
5. New oxygen sensor
6. New fuel filter. [Updated]

Shop boss / owner says the fuel injectors on this model / year rarely go bad. It has 230,000 miles.

** His thought now is to adjust the fuel injector (?), but the tool they use is infrequently used, and they can't locate it. **

(As a non mechanic, I bought the Techron fuel additive for the 1-in-a-thousand shot, and added it yesterday.)

Any thoughts? Thank you in advance.

 

If this is a 1984 240 - there is an idle mixture adjustment on the air mass meter. It will not help your car start - it is only for the idle mixture.

Yes, injectors rarely go bad. O2 sensor is not needed, and has no effect on starting. (many a 83-84 o2 sensors were intentionally left unplugged, the cars ran better)

It might be hard to start because it is too lean - due to a bad air mass meter, unfortunately those were always the really expensive ones, with the aluminum bodies.

 

old/hard injector seals can also contribute to a lean condition.

 

Learned something new. I've never had these changed, that I recall, after 30+ years driving a Brick (on my second).

Is this something that should be done as part of a 75,000 mile tune up? Do I have 1 or 2 fuel injectors?

How long should it take a mechanic to change?

Thank you.

 

You have 4 injectors, one for each cylinder mounted in the intake manifold spraying on the back of the intake valves. Air leaks can certainly cause hard starting and rough running due to a lean condition, and intake manifold gaskets commonly break due to expansion and contraction from heat - but that usually creates a rough idle for the air leak is closest to just one cylinder. Injector seal leakage was very common on the CIS cars (75-82) - those were just two orings on each injector that would get hard. Later cars don't seem to be a problem, with electric injectors using a better retention method. Very easy to check - spray carb cleaner at the seals, gasket, anywhere un-metered air could get in - if the idle changes you've got a leak.

 

yeah, my CIS 1990 mercedes had the same injector seal problem. caused it to stumble at idle intermittently, and stall when trying to roll away from a stopsign, especially if you gave it too much pedal too soon.

new seals, new injectors, and it runs like a new car (4 of the 6 injectors had sloppy spray patterns so we replaced all 6 on principle).