1987 260E Low power issue - Round 2
 

Starting new thread with updates and everything compiled.

Background:
Car ran great for over a year, averaged 21-22mpg.
Last Sept water pump blew and the car was running at 110C for a few days while I tried to diagnose what was happening, never overheated though.

MPG dropped to 12-13avg and power SUCKS. I would guess a 50% drop in power. Its just lifeless.

Parts Replaced / Tests done

• Plugs/Wires/Rotor/Cap <--- done last year brand new
• Compression Test GOOD -- average 180psi all cylinders, variance no greater than 5%
• New fuel pumps, fuel filter, fuel tank strainer, fuel tank inspected, all fuel hoses replaced
• Fuel Distributor + EHA brand new
• O2 sensor new
• Injectors are brand new + also checked spray pattern
• Coil swapped with spare
• Car goes into closed-loop. Duty cycle 55% and fluctuating
• Fuel pumps now gets 1L in 30secs (spec is 1L in 40secs)
• Fuel Pressures are 5.1/5.5 bar -- pressure holds @ 3.1bar. So pressures + holding pressure GOOD.
  

Ideas where to look now?

Plugged cat a possibility?

Here's a couple of images of my cluster. Notice the vacuum gauge.
Heres the vacuum gauge in Park - with the engine warmed.
http://farm7.static.flickr.com/6005/...83c80243_z.jpg

Here's an image with the transmission in idle.
http://farm7.static.flickr.com/6017/...06ca782f_z.jpg

Note that the car has just passed the 200000 Kilometres mark.

If your vacuum is not at those levels you will not get optimum M.P.G. and low end performance.

This car idles very silently - the heater fan is noisier the the engine at idle. Very good M.P.G.
The last item I replaced was the valve for the return fuel to the charcoal canister. It seemed like there was a leak from that. I also replaced the inlet manifold gasket.

Good post...Another person also referenced this site to me:
http://www.secondchancegarage.com/public/186.cfm

My vacuum at idle is low according to that site! ...I posted it up a while back (Sep 2010), but didn't get any responses on it.

I'll compare readings with my wagon too for reference.

http://w124-zone.com/downloads/photo...2010/fpt-5.jpg

I've never seen it greater than 14....

So either worn rings or exhaust restriction....I hope the later. I never overheated the engine, so I can't see why the rings would be toast?
With my compression being ~180psi, is it safe to say my rings are probably OK? I did the test dry too, did not squirt any oil in because the readings looked ok.

I have a VERY good feeling we are onto something here now!!

Thats it! Its the cat!

This is adding up now.
Another reason: About 6months prior to the issue, I was noticing vibrations on the freeway (load only) at ~90mph.....3months later, its vibrating at 75mph, then after the overheating, 65mph.

It would VANISH as soon as I let off the gas. Its obviously exhaust backpressure causing it. So the issue has been creeping up on me, but it finally gave out after the running hot.
I thought maybe my center bearing was going bad, but the fact that it did not vibrate when I let off the gas just didn't add up in my head at all....

It all makes sense now!

I bet when your injectors screwed up and the A/F ratio went wacky it melted the cat.

easy way to tell if it's the cat-remove the o2 sensor and drive it. it it's better, you need a cat. good luck, chuck.

Hmm....Ran the vacuum test as shown on the site, but I am not really getting the reading I was hoping for?
http://www.secondchancegarage.com/public/186.cfm

Its almost like I get #11 -- retarded ignition timing, but the timing is not adjustable?
http://www.youtube.com/watch?v=bQSrkRXla0E

I just ran the car @ 3000rpm and it stayed steady at 17inHg....According to the site, if the exhaust was blocked, I should have slowly dropped. :confused:

I left the gauge attached and took her for a drive, and its completely different results.

Upon acceleration it drops to 0 and stays there until I almost completely back off the gas. I then, for comparison (since my wagon has had cats replaced) plugged the vac gauge into my 300TE and did the same journey and she did NOT go to 0, but stayed around 2 then began to gain vacuum again unlike the 260E.

In addition to the vacuum gain, the gauge responded much quicker on the 300TE too.

Video of 260E:
http://www.youtube.com/watch?v=euhKbv7ECmA

Anybody think this points to blocked cats too?

Took car to exhaust shop, he doesn't believe the cats are blocked....

He used a temp gun on the inlet/outlet of each cat:

Precats: 25C difference from in/out....he states it seems like there is probably not even anything in there anymore, possibly hollow?
Main cat: 100C difference...barely anything.

So in all, he said if the cats were blocked, there would be a large difference between in/out temps. He said for me to look elsewhere for performance issue.
The guy said the performance was right, but the transmission shifted hard (but we all know generic mechanic bob doesn't really understand these cars) and I politely declined the $98/hr diagnosis he suggested. The transmission shifts very firm, maybe a tad too firm, but its not a thud, its a firm shift -- always been like that, so thats not the issue at hand.

Guess its time to move onto the next check....I'm thinking I should get a leakdown test done now, although I'll have to buy a compressor -- a useful tool for many, many uses!
Then maybe ignition + valve timing? Although my distrib + cap were brand new and we all know both values are not adjustable.

GUYS!

I just figured it out!!!
The oxygen sensors heater element wasn't working!

Alright so....back in...November I replaced the o2 sensor thinking maybe that was the problem...no difference, THEN I discovered the fuel contamination. Well....I bought the generic Bosch O2 sensor and spliced it in.

I asked the question about the 2 white wires having a specific orientation and the responses were shouldn't make any difference, so I spliced it in and forgot about it.

I checked it out right now by plugging it back in while holding the sensor with my hand and voila! No increase in temperature at all!
So....I then reversed the two poles at the plug so it was now in reverse orientation, and HEATER WORKED.

Plugged it back in and massive difference. The car at first was slow, but the more I drove it, the more it picked up.
I would say I just recovered 95% of the power.
I'm thinking though since the sensor has been driven without any heating, it might be trashed already, what do you think? I'll probably get a new one, splice it in, test the heater, then call it a day

Phew....! I KNEW this was something simple. I just couldn't figure it out! Damn happy now. Gonna get a new sensor, drive on the freeway really hard then get'er smoged! Fingers crossed on that one LOL.

Maybe someone's looking down on me -- my 300TE's radiator hose blew off today on the way to an interview and it was a royal PIA fixing it in slacks, shirt, tie, vest...what a fiasco.

Wow congrats on nailing it yourself! Last generic O2 sensor I bought was maybe a year ago and it was under $25. If you can get one at that price why not swap out the fouled one?

Got the new sensor in -- definitely much better, but not quite back to normal yet.

I have a feeling its a possible EHA deal now. I'll do some more testing :)
The EHA was brand new, but it was exposed to the crap I found in the fuel system, so I am not sure whether its clogged inside possibly? I have never taken an EHA apart, so I don't know if there is anywhere inside that could clog?

There is nothing you can "clean" or change in the expensive EHA. there is just a screw that can adjust fueling (for more or less fuel to be delivered).
did you to rebuild your fuel distributor? test your injectors?

you got pm regarding compression test

Distrib is rebuilt, injector spray patterns are perfect, so its gotta be EHA related. At least that's what I believe, who knows...

I'll just adjust the screw and see what happens.

Have you checked ignition timing?

Its fixed isn't it? How can I check it exactly? the rotor + cap have less than 10k mi on them.

I think I'm 95% there now.

Took an old EHA out of my parts box -- looked kinda crappy. Cleaned it up with some carb cleaner inside + out. Plugged it in....ran like crap. Starts fine, but as soon as I pressed on the gas the rpm's would drop, so either its not producing enough fuel, or far too much. I decided on the former.

Took it off, unscrewed the back screw, gave it 1/2 turn clockwise aka rich. Plugged it back in and WOW!!! HUGE difference. Car runs QUICK off the line. I'm truly feel like its 95% back to normal now.

The only place its different is downshifting. The downshift button on pedal seems sluggish and the car does not "pull" too hard. I'm thinking maybe another 1/4 turn rich might do the trick?
So the new EHA I bought might still be ok -- just needs an adjustment, possibly lean as it "feels" like its flooding.

I have 2 weeks paid time off work right now because I am switching jobs, so I can finally wrap this up! :) Financial institutions and conflicts of interest....

And FINALLY success!!!! After a full year of running like complete crap, perseverance has paid off.

http://www.w124-zone.com/downloads/p...0260%20az1.jpg

Wasn't even close either. Looks like the 24yr old cat is still functioning amazing!!

Do any of the #'s give any indication as to mixture being a little rich/lean? Just curious...
I wish they showed O2 + CO2%....

I did throw in 4 bottles of ISOheet and ran in 3rd gear 4500rpm on the freeway for 15mins as usually too :) Held idle at 2500rpm while waiting for ~10mins in line