Sorry for the dramatic subject, but I'm at wit's end. Any help would be *greatly* appreciated.

CAR: 1988 German-model 190E 2.0 Sport. 85k miles, US Emissions Pkg, CIS and all the same engine electricals as the US 2.3

SYMPTOMS: Surging/Stalling after cold start. Severe engine hesitation under low-rpm load following start (hot or cold). Injectors do not shut off on deceleration with any computer I've tried.

TESTED/REPLACED: New O2 sensor. New plugs. New cap & rotor. Wires OK. New Fuel Injector Seals. No vacuum leaks. New over-voltage relay (working). Fuel Pressure Regulator OK. Aux Air Slider Valve appears to be OK (9 Ohm Resistance). O2 voltage at idle = .56, full throttle 0.93, cruising 0.15. Coolant Temp Sensor OK. Fuel pressure OK. Engine running better than ever (9.6s 0-60 runs w/auto) and getting better mileage than ever (27hwy, 23 city).

REMAINS IN QUESTION: Electro-hydraulic Actuator, Engine Computer.

STRANGE THINGS: Voltage across Terminal 3 & Ground fluctuates around 6V with the throttle slightly pressed. Fully released (when switch is not actuated), voltage is constant 12.2V under *all* conditions. This did not happen with donor computer I substituted in, but engine still surged. Computer was from an '84, i.e. not an exact match. Is this 12.2V thing a "limp mode"?

When I unplugged the EHA, there was *no* difference in idle.

When the Aux Air Valve is unplugged, idle is glass smooth at 1200rpm. (750 with it plugged in, surging slightly when warm, massively when cold. Idle sometimes jumps to 1100 and stays there when warm).

Currecnt to EHA (with EHA disconnected) following cold or hot starts is 0.13A.

The car has spent 4 weeks total in 3 different shops (including the Dealership), and we're all stumped. I'm hesitant to spend any more money, but my next step is to replace the computer and the EHA. But will it help?!

REWARD: If you help me, I will love you forever, say nice things about you forever, and more importantly, not post any more long messages.

[This message has been edited by 190E 2.0 Jason (edited 05-09-2000).]

The engine's control system is in limp mode. You have to check every single component to figure it out. I have seen altitude capsules cause this, air plate sensor can cause this, and so on.

If you are near Atlanta, I can repair it.

------------------
Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I *wish* was close to you! I'm outside of Pittsburgh.

I guess then what I'll do is continue checking all of the other components I've missed. The big one is the EHA. At the dealership this afternoon, I tested the resistance of a new one (19.5Ohm, just like the manual says), so I'll test mine tonight and see what it says. If not, it's back to the drawing board to test the rest.

If anyone else has had a similar experience, please don't hesitate to throw any suggestions my way!

Thanks to all,
Jason

Update: I checked the last 3 components I hadn't checked: the EHA (20.5 Ohm, OK), the altitude sensor (couldn't find it, my car may not have one), and finally, the throttle position switch. BINGO!!

The swicth activates for full throttle, but not for no-throttle. I jumpered the wires, started the car, and it ran OK. Now the problem is that the dealership says my part number doesn't exist, so we looked for the US-car equivalent (remember, mine's Euro). Apparently,they don't make the switch anymore without purchasing the entire *throttle body*. Does anyone know where I can get a switch? BenzMac? I'll search this site in a minute, but I'm a bit pessimistic.

For what it's worth, my part number is 006 545 1824

Thanks for all your help... after 3 months of diagnostics, I've finally got a lead!!

Jason