Hi, I found this forum and have been very happy with all of your honest posts and willinigness to help. Here goes...

1991 560 SEL Gasoline 8CYL

1) Check engine light does not appear to work..How do I test this?
2) Engine starts very hard COLD. I have keep pedal to floor to start. Once warm no problems. What may cause this?
3) Incredibly POOR Gas Mileage == 7 MILES PEr GALLON yes SEVEN
4) Can not drive faster than 70MPH. Transmission seems to go into safe mode. This may relate to very poor acceleration. Transmission fluid is max and color and odor are NOT burnt. Is this transmission or computer problem. Check Engine Light may or may not work.

I changed all fuses to new and COPPER. Over Voltage Protection is NEW.

Is there any place I can find good drawings of the engine bay and parts realted to Vacume Lines etc.

Thank you very much and look for your expert opinions and help. If I need to dig a grave and bury the vehicle I can do this...with a tear in my eye of course..

Any suggestions on a good reliable pre- 2000 and post 1990 MB vehicle?

It's my understanding that there are only two controls for the fuel/air mixture. The first is the cold start valve and the second is the air mass sensor. The air mass sensor (4" hinged "plate" under the air cleaner) some how mechanically controls the opening size of the fuel ports in the fuel distributor. You might also have fuel delivery presssures which are too high. I cannot imagine how rich the mixture must be to only get 7mpg!

Another explanation might be that your transmission is not shifting out of lower gears, but you didn't say what your revs were at 70mph.

The transmission shifts through all the gears. However, when passing 70mph the transmission seems to disengage all together.

Someone mentioned the catalytic converter may cause the 7 MPG problem. The exhaust smells very much like an exploded firecracker. Very sulphur smell.

The fuel mileage is an issue as is the lack of power. If the road is flat and smooth the ride is wonderful. If you have to pass someone it wont happen. No acceleration...

I will keep looking and thinking

Any smoke involved with above symtoms?

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1989 300E 144K

Sounds like a clogged catalytic converter. The hard starting, no power at highway speed, sulfur smell exhaust, low MPG's. Had identical problem with several American cars I have owned in the past.

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jcciem
'94 SL5000 60,000
'91 350SDL 545,000
'91 350SD 197,000
'00 E55 AMG 77,000

Had the catalytic converter checked out and it was fine! Was told it was relatively new. The exhaust pressures were excelent. The transmission also checked out OK! So it looks like we are back under the hood. By the the fuel filter and fuel pump are also good. Would bad fuel pump relay cause the lack of power.

None of the local autoparts stores can connect to the computer to read any codes. Any idea on what to read the computer codes with on a 1991 560 SEL? Thanks again

start by checking your mixture.

Was the car originally bought in CA?

Transmission cannot go into safe mode.

What happens when you accelerate? When the engine is Cold? When warmed up?

How does it idle?

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'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E

Perhaps it's time to drop a Chevy V-8 in the thing, and call it a day...?

Nick

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[SIGPIC][/SIGPIC]

I had the transmission check and it checks out fine both Mechanically and electrically. Had the plugs and wires changed . The exhaust was changed and the catalytic was fine. Full pump and filter replaced. Replaced all fuses with copper. The Current limiter is good.

Hard to start when cold. Must keep pedal to floor in order to start
Seems to have better power when cold. Once warm, starting is easy. Idle is smooth at about 800 rpm.

There is no A/C in vehicle at present.

Vehicle dies exactly at 70MPH (Engine running but NO POWER)
Acceleration when warm is non-existant. I am afraid that pure gasoline is going out the tailpipe and I may see flames. However, there is no raw fuel odor. to be getting only 7 yes SEVEN mile to the

Did you check the function of your oxygen sensors?

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"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

I'll say one thing for you, Nick, at least you're consistent.

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" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

The symptoms you describe can have their roots in multple vacuum leaks. Please check out the vacuum supply to the transmission. 800rpm at idle (warm engine) is a little too high indicate possible vacuum problem. Should be 500 to 600rpm. Does you car have an "Economy" gauge in the dash? If so, it should be pegged to the left side at idle. That gauge is a vacuum indicator and if it is not pegged at idle, you certainly have a vacuum leak.

At the age of your car, it is probably time for the rubber vacuum connectors to start deteriorating. Inspect all you can find and if you find one split or rotted, replace them all. They are very inexpensive.

A Chevy engine in your Benz is blasphemy. These engines are very durable and worth putting some effort into. I always thought the use of vacuum to control so many functions was a weak point.

You may also want to check out the function of the engine temperature sensor that feeds the fuel injectionj computer. There is nothing in the rules that says you can have only one problem at a time.

Don't give up. You have a fine car that is worth the effort.