Help Needed: Sluggish W124 260E Revisited.
 

We have a problem.

The Problem: Sluggish acceleration until past 4,000 rpm when power kicks in real hard.

What have been done so far:

1. Replaced fuel divider (symptom persisted);
2. Emptied fuel tank and cleaned fuel lines (some dirt uncovered);
3. Replaced fuel pump and filter;
4. Checked coolant temp. sensor.

The result: Nothing significant.

Here is where we need your possible causes to look for ....

Kerry

You said "2. Emptied fuel tank and cleaned fuel lines (some dirt uncovered);"

My guess is you have contamination in the injectors. Try using a double-dose of injector cleaner on less than a fuel tank of fuel. Also, I had success in bleeding the injector lines at the fuel distributor (danagerous if not extremely careful) but effective.

Does the car not have a lot of power and then all of a sudden it gets power around 4,000 RPM?

Keep us posted,

Haasman

Yes indeed, I had the injectors replaced and cleaned again to be sure.

From 0 to say 60 km/p, it is very slow. Feels heavy even when gas pedal is pressed all the way down. Then suddenly, the dam explodes and the car shoots at breathtaking speeds. At that moment, you dont really need that much torque. So, pulling out from intersections from stationary can be a little dangerous as the response time is too long.

We are still combing for possibilities, with a compression test lined up (though I think it wouldnt shed much light).

Sounds like oxygen starvation going on, which is overcome at high RPM.

Since it is not a fuel blockage, it could be a (dirty) air filter or some other air intake blockage issue.

Air intake and filter checked. Filter is new, and air system thoroughly checked with nothing blocked.

This is getting quite puzzling. A further test drive revealed a much improved performance but still very much lacking in power torque.

I understand the injector nozzles will be re-examined in an hours' time.

Perhaps a long shot, but what about your transmission fluid level?

The 260E had its tranny rebuilt with a new valve body last month. So, I think that would be ruled out.

Although, on a seperate issue, I noted that the tranny is not so smooth in the change of gears with a slight jerk despite its rebuilt. The fault was discovered where we have a faulty oil pump. That was replaced over the weekend.

The mystery continues ....

I do not think the transmission is related to the jolt at higher rpms, but as one poster suggested, what does the transmission fluid level look like? You mentioned rough shifts. I realize transmission work was done, but that doesn't mean the tech filled the system with the correct amount of Dexron-III.

Check the fluid level on a flat surface. On a cold engine that's idling, the level should be about 10mm below the low level mark. After about 20 kilometers of driving with engine idling, the level should be at the full mark.

Won't hurt to check. It's been my experience that repair shops often times over-fill systems, rather than under-fill them.

Despite the rebuild, if the fluid level is low, you will be sluggish on initial acceleration until enough fluid is spun up to produce a "solid" connection between both halves of the torque converter. When that occurs, there will be a sudden surge of power.

That happened to me once, and a couple quarts of tranny fluid solved the problem.

Fluid checked. At recommended level, original MB fluid.

I had very simlar symptoms on my 87 300E. It turned out to be a loose ground at the intake manifold near the vacuum port for the brake booster. I left it loose by accident when I did the head gasket. I drove it for a year with it loose. Could be a possability if there wes some work recently done. Hope this helps.

Thanks for the pointer. Will check it within the hour.

Ground fine. Temp Sensor fine.

Now, waiting to see whats at the end of the fuel line ...

We have had a fruitful evening.

Many thanks to all with your suggestion. Now I know the 260 has a clean fuel line, and properly grounded, with fine sensors.

When the injectors were inspected, it was all clean as it should be. No blockage or damaged ends.

That was when it was decided that the timing be checked.

The distributor cap, when opened, was somewhat eaten away by age. So, we suspected that could have been a cause.

Now, we are waiting for the part to arrive and will put it on tomorrow morning. Hopefully, this solves the entire thread.

BTW - I have offered the techs a shout of beer at the local tavern tomorrow evening for having spent many golden hours pouring over this matter .... and of course, you are all invited too (in spirit, if you're too far away) ... :)

More updates tomorrow ...

Prior to this post, I forgot to mention that the ignition box was dismantled and replaced with a new one. This was just to see if it did the performance any better. It did not, so the ignition box was ruled out as a factor.

The 260 is currently being assembled, i.e. fitting in the oil pump, and new brake pads, before it will be put on the road for the final test run. And hopefully, it will run well.