[R129 SL] 300 SL

Fri, 18 Jul 2003 09:42:29 -0400

Fuel injectors, injector seals, and rubber air rails are a BIG problem
in 1990-1992 CIS-based M119.960 5.0L engines.  If you've replaced
distributor cap and rotor, plugs, have ruled out plug wires, and your
coils are good (have you tested these?), fuel injection nozzles are most
likely the culprit.  This is usually the case in many CIS-E cars.  I had
a friend with a '92 500SL with a rough idle issue.  The pristine
black/palomino car was as it came from a time capsule.  Low mileage for
the year as well; around 50K.  However, the idle issue at above
70degreeF outside temps was obvious.  Deciding to isolate spark from
fuel, I swapped both distributor caps and plugs (remember to do the cam
seals at the time of distributor rotor replacement) and it nearly solved
95% of the problem.  To smooth out the car completely would require fuel
injector replacement.  In his case, the car ran so good, it wasn't
really necessary.

So, your intuition of fuel system fault is probably correct.

Satish

-----Original Message-----
From: r129list-admin@mbcoupes.com [mailto:r129list-admin@mbcoupes.com]
On Behalf Of Cliff Sadler
Sent: Friday, July 18, 2003 9:22 AM
To: r129list@mbcoupes.com
Subject: RE: [R129 SL] 300 SL

I'm having a similar problem, and ran across this info from the
archives:

Stumble problem after warmed up

I have a '91 500sl with 71k mi. The car has been maintained well during
its life. I live in Va Beach, Va at sea level.  The car runs great when
cold but after driving 15-30 min., the car will stumble and hesitate on
acceleration  as if a cylinder or 2 is not firing, especially in warm
weather. I went to the mountains (3500 ft above sea level) and
experienced no trouble even when hammering it out on winding mountain
roads. It thrived on climbing the 9% grades.
    I took it to the dealer and they could not replicate the problem but
replaced the distributer cap and rotor. They said it was running fine
and passed all computer checks. I dont think they let it warm up enough.
This did not solve the problem. The plugs are new and I just replaced
the Oxygen sensor. Any ideas? I was thinking about replacing the fuel
injectors.

Try this,     replace your fuel tank gas cap with a new 'Stant'  gas
cap.
I was having same type problems, and the
difference was amazing,   something to do with proper tank and injector
pressures.     cost  5.oo
I am convinced that a tune up consists
of, cleaned battery cables, ,new plugs,  distributor cap and rotor and a
new gas cap (something that is almost never changed)     Let us know if
it works.

-----Original Message-----
From: r129list-admin@mbcoupes.com [mailto:r129list-admin@mbcoupes.com]On
Behalf Of Adam Gage
Sent: Thursday, July 17, 2003 7:16 PM
To: r129list@mbcoupes.com
Subject: Re: [R129 SL] 300 SL

Don't know if the car starts off in first, probably in second, but I
don't think it's a tranny problem.  There's a definite hesitation, like
it's choking, and then it flys forward after stepping on the gas.  This
only happens when the AC is on and I've been driving the car for awhile.
I'm a little hesitant to take it to a dealer so they can "experiment" -
nearest one is in San Deigo or Phoenix.  Any recommendations for a
dealer if anyone has had this problem?

Thanks list!
Adam
(P.S. this list is great for info when there's no one to ask!)
----- Original Message -----
From: <Alvamike@aol.com>
To: <r129list@mbcoupes.com>
Sent: Monday, July 14, 2003 4:57 AM
Subject: Re: [R129 SL] 300 SL

> Adam and all,
> Is the car supposed to START off in 1st??  I think I figured out the
problem with the shifting.  I found the rubber cover over the vacuum
modulator was very cracked.  I replaced it and it shifts 1000%
better......but it starts in 1st.  Is this right??  Runs great !!!!
> Mike in Morgantown, PA
>
> The MB Coupes Website!
> R129 SL Mailing List
>

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