Need Help Diagnose CIS in 190E........

[boyt911sc]

Don't have any problem trouble shooting CIS problem in my SC car. I own a '87 Mercedes 190E (2.3 liter) with CIS system and currently having starting problems. Could someone with experience in MB CIS please answer this ad?

Due to the limited text and information about CIS in MB, troubleshooting this starting problem is not as easy as the 911 cars with CIS because of this board.

Haynes manual does not cover enough information to help me do the diagnostic test with the CIS fuel injection gauge. Knowing the control and system fuel pressure at this point would help me a lot. Thanks in advance.

Tony

[john70t]

The CIS components should basically be the same, just arrainged differently.
Cold start issues usually involve:

-most importantly, the cold start valve(the extra blue electronic injector-which sprays an extra shot of fuel into the intake while cranking),

-the warmup regulator(WUR)-which reduces fuel pressure and leans out the motor when it warms up by increasing the opposing control pressure to the top of the fuel metering plunger. (It's the black box on the side I believe.)

-the system pressure regulator(big canister with big fuel lines) which regulates the total pressure from the pump. This can be affected by a clogged filter, a weak fuel pump, or a bad fuel accumulator(basically a pulse dampner) if equipped.

CIS is very sensitive to vaccuum leaks, commonly from cracks in the "boot" you've removed and shrunken injector seals, and like evrything needs a clean fuel supply. You'll have to buy an expensive fuel pressure test kit that does CIS if checking it, but 20yo rubber under a hot hood should definitly be replaced.
That's a good time to check the spray pattern of the injectors by jumpering the pump and lifting the plate.

Search the archives for lots of info.Good luck

[boyt911sc]

John,

Thanks for the info. My Haynes manual is not giving me the information I need so a Bentley manual was purchased yesterday and hoping it could give me a better insight.

I'm having difficulty locating the fuel pump relay. I want to check the control and system pressure (fuel) before I go on troubleshooting the problem. Ignition has to be checked too.

Tony