1991 300E - runs rough, can she fix it? - Page 2 - PeachParts Mercedes-Benz Forum

mbzr4ever · #16 03-05-2014, 05:22 PM

Quote:

Originally Posted by Hirnbeiss

When you say the tranny slips, is it possibly only downshifting? i.e, is it staying in gear, just a lower one?

Doesn't happen all the time; at first I thought I had a 4 matic or similar, and didn't know how to drive it properly.

Usually happens when going up an incline - it will downshift to like 2nd, and rev high (3 to 4 rpms)
Or it will start in first, or after 1st/2nd, won't shift to a higher gear and will continue to rev in the 3 to 4 rpm zone.

Hirnbeiss · #17 03-06-2014, 06:32 PM

Is the control pressure cable adjusted to the zero-slack position?

of course you also have to ensure it has enough ATF too.

mbzr4ever · #18 03-06-2014, 06:37 PM

Quote:

Originally Posted by Hirnbeiss

Is the control pressure cable adjusted to the zero-slack position?

of course you also have to ensure it has enough ATF too.

Yes, the ATF level was the first thing I checked.
Will have to research the control pressure cable.

mbzr4ever · #19 03-08-2014, 05:27 PM

Fault codes are coming up as:

11 Air Injection system
16 Exhaust Gas Recirculation (EGR)
17 Oxygen Sensor signal
18 Current to Idle speed signal

Would cleaning out the idle control valve remedy 18 (Current to Idle speed signal)?
Just saw a video on this, using mineral spirits.

Doing more research and MAS keeps coming up as a possible issue, now remembering the AC/heater/fan doesn't work.

Also, how do I know if I have the 717.4 or 722.4 transmission?
B2 piston replacement also looks to be in order?

sigh. now I'm really missing my old 240D with the manual everything.....

mbzr4ever · #20 03-30-2014, 09:16 PM

Cleaned out the idle control valve, made no difference.

Tried to change the spark plugs, but they were too tight to get out - was afraid of breaking them, so I left them alone.

Guessing I have the 722.4 transmission.

Checked the fuse behind the battery, was ok.

Any ideas on what I should check next?

lorainfurniture · #21 03-30-2014, 09:51 PM

O2 sensor?

Btw the plugs are a must, one way or another. Try heating them and then putting an ice cube on it right away. Spark plugs on the m103 need to be changed every year/ 16,000 miles.

mbzr4ever · #22 03-30-2014, 10:15 PM

lorainfurniture,

I didn't try the heat/ice - I shot some PB blast into the area, hoping one would budge...but nothing.
Heard horror stories of broken spark plugs, and didn't want to risk further.

I had the new plugs, and even that special torque wrench ready to go.

Should I look up cleaning the O2 sensor or just replace it?
Fortunately, I don't live in a state that the car would have to pass an emissions check.

lorainfurniture · #23 03-30-2014, 10:37 PM

Pull your passenger side carpet and you will find the harness for the o2 sensor. It should give a reading from .03-.07 I believe.

You think the spark plugs are tight? Wait until you try cranking on the o2 sensor.

mbzr4ever · #24 06-26-2014, 08:50 PM

Quote:

Originally Posted by lorainfurniture

Pull your passenger side carpet and you will find the harness for the o2 sensor. It should give a reading from .03-.07 I believe.

You think the spark plugs are tight? Wait until you try cranking on the o2 sensor.

Finally changed the spark plugs.
Pulled the carpet but nothing obvious sticks out like the o2 harness

Ferdman · #25 06-27-2014, 05:29 AM

Typically the Oxygen sensor connecting lead is blue with a black grommet where it penetrates the driveshaft tunnel. The grommet is likely just under the carpet edge on the side of the tunnel.

mbzr4ever · #26 10-01-2014, 01:13 AM

So I've been working on the 240D and the Ford in between, but while waiting for parts, decided to drive the 300E again.

I stopped at the point of changing the O2 sensor, debating if I should just clean it or replace it - but now I have a new issue:

The check engine light is off, but the ABS light is ON!
Hard to start, idles very, very rough, sometimes almost dies or dies.

***Weird, before it was revving too high, now too low*****

lorainfurniture · #27 10-03-2014, 11:20 PM

Quote:

Originally Posted by mbzr4ever

So I've been working on the 240D and the Ford in between, but while waiting for parts, decided to drive the 300E again.

I stopped at the point of changing the O2 sensor, debating if I should just clean it or replace it - but now I have a new issue:

The check engine light is off, but the ABS light is ON!
Hard to start, idles very, very rough, sometimes almost dies or dies.

***Weird, before it was revving too high, now too low*****

The abs system is powered throughout the OVP relay. It is a silver relay with a red top located behind your battery. It usually has 1 fuse on top, or 2. Sometimes the whole relay goes bad (bad solder joints) and must be replaced. It typically causes the abs light, and shuts down the "E" part in you "cis-e" fuel system.

CIS-E stands for continuous injection system, electronic assist. The electronic stuff really does work at keeping idle.

mbzr4ever · #28 10-03-2014, 11:32 PM

Quote:

Originally Posted by lorainfurniture

The abs system is powered throughout the OVP relay. It is a silver relay with a red top located behind your battery. It usually has 1 fuse on top, or 2. Sometimes the whole relay goes bad (bad solder joints) and must be replaced. It typically causes the abs light, and shuts down the "E" part in you "cis-e" fuel system.

CIS-E stands for continuous injection system, electronic assist. The electronic stuff really does work at keeping idle.

Thanks for that info - I pulled a red 10V fuse from a device from behind the battery.
The fuse looks intact; are you saying the rest of the unit could be defective?

This is what I order, correct?
http://www.pelicanparts.com/catalog/SuperCat/3321/MBZ_3321_ELSWCH_pg5.htm#item24

lorainfurniture · #29 10-04-2014, 09:11 AM

Quote:

Originally Posted by mbzr4ever

Thanks for that info - I pulled a red 10V fuse from a device from behind the battery.
The fuse looks intact; are you saying the rest of the unit could be defective?

This is what I order, correct?
1991 Mercedes-Benz 300E Base Sedan - Switches, Motors, Relays, Fuses & Wiring - Page 5

That looks like the correct unit.

mbzr4ever · #30 10-06-2014, 07:10 PM

In looking at the engine again, I noticed the blower strip fuse was gone - no wonder the fans wouldn't work!

Also, found this to be helpful:
OVP relay, Over Voltage Protection Links