Starting problem - Cranks but won't fire without ether

[gsxr]

You absolutely should be able to repair your original 1992 module. I'd be really surprised if it's not fixed with new capacitors. Clicking fuel pump relay is the most common symptom when the capacitors fail. If you end up needing a replacement 1992 module with WOT enrichment, there is one for sale at this link.

 

[Alphasud40]

Remember the only difference between the module you purchased and your module is the software configuration. That can be moved to the new module by swapping the EPROM from your original one to the new one. It’s the only chip in a socket.

 

[Jim Rosenthal]

Good to know. Based on the Mercedes PN on the LH module, it is the early one from 1992 with WOT. We should know something within a day or two, whether the replacement I bought will work. If it does, I am going to try to repair the original module. Thanks again to all for all the help.

 

[Jim Rosenthal]

An update: Sal tried an LH module (not from a 500E) which we found on eBay. The car started and ran. I am going up to drive it tomorrow and get some miles on her. I am also going to open up the original LH module and see if it is damaged inside. If it is not repairable, a 500EBoard member has put me in touch with a gentleman who has one he will sell me. If I can repair it by soldering in new capacitors, I will do that.

I'm looking forward to driving the car tomorrow and seeing how it acts. It IS one of my favorite cars to drive- that endless well of power is addicting.

Thanks to all of you for the expert help which was invaluable- that is not too strong a word.

 

[Jim Rosenthal]

Okay, some serious progress. We replaced the LH module with one from another 5-liter V8 car, but not a 500E; I think it was from an S500 a few years newer. Car fired up immediately, road tested, runs perfectly. Plenty of power, perfect idle, accelerates like crazy. The odometer and trip meter still don't work. (see this thread)

We looked inside the car's original LH module. All the caps look fine, which doesn't tell me much. Although I'm fairly decent at soldering, the size of the components and how close they are together gives me pause, and plenty of it. What I would like to do is send the old LH module off and get it rebuilt- if anyone knows of a source for that, please advise me.

Thanks again to all. I'd forgotten a bit how much I love driving the 500E. Really, there is no other car like a Mercedes-Benz.

 

[gerryvz]

ANY 5-liter (W140, R129, etc.) LH fuel injection computer is 100% compatible with the E500E, as long as it is from a 5-liter engine. Even a 4.2 liter engine LH computer WILL WORK, but it is NOT advisable to use this other than for testing purposes.

MB, in fact, has superseded all of the individual LH computers from all the chassis / models down to a single LH computer applicable to all of them, over the years. For simplification, of course. There are differences between the WOT and non-WOT (post-1992 model year US) computers, of course, but this doesn't AT ALL affect how the engine runs in everyday driving. The WOT capability only adds 7-10 HP when the engine is at Wide Open Throttle, which is not very often in real-world driving.

There are threads here on the forum from folks who have repaired their LH units with new capacitors. However, I recommend sending the LH unit off to a qualified professional for testing and cap replacement; otherwise, just use the new one you got, throw away the old one, and purchase a spare 5.0 liter LH computer for the rare case you ever need it again.


I just now ran down in my basement to check my parts shelves. I came across a total of four spare 5-liter LH units (one being WOT), and five MAFs.

I'd forgotten a bit how much I love driving the 500E. Really, there is no other car like a Mercedes-Benz.

I just got home 10 minutes ago from a trip up to North Baltimore to the Baltimore Zoo to visit my wife's niece, who is a zookeeper there. We took the E500 this time, not her 2023 Lexus IS500 F-Sport (a rare bird in and of itself). Despite the traffic on 97, 695 and 83, it was a wonderful trip. Coming home, we took US 50 over the Severn River bridge to the MD 450 exit (just on the other side of the bridge), which is just 2 minutes from my house. We did 95 MPH over the 50 bridge over the river.

As we exited 50 onto MD 450 South toward the Naval Academy, I casually mentioned to my wife, "I think that's the fastest I've ever crossed that bridge," and she asked, "How fast were you going? I thought you were just doing the normal 55." She had no idea we were almost doing 100 MPH over that bridge.

 

[Jim Rosenthal]

The 500E, and the 6.3 and 6.9 cars, are in my experience in a class by themselves. MB probably builds current cars just as fast, but they don't have that bank-vault solidity, and they aren't, in my limited experience, as fun to drive.

 

[Alphasud40]

My V126 SEL felt really good at 130mph. So relaxed and solid feeling makes me yearn for Autobahn speeds on our highways on rural stretches.

 

[gerryvz]

The main reason I sold my 300SEL 6.3 and 450SEL 6.9 some 20 years ago, is that neither of them are practical cars to have as a daily driver. This is why I still have my 560SEC, which I bought on 9/11/2002 (one year to the day after the 9/11 attack), because the 126 has proven itself as the earliest MB chassis that is indeed practical to have as a daily driver, even completely outclassing the W123 for this purpose.

There is no comparison between a 300SEL 6.3, or 450SEL 6.9, and a 500E/E500 at any speed over 100 MPH. The 6.3 is markedly less stable due in part to its suspension and aerodynamics (I owned a 57K mile original 1969 6.3 in the late 1990s through early 2000s; I also owned a 70K mile 1977 450SEL 6.9 in the same era).

Not too long after I purchased my E500, in 2003, I took my old friend Dan Smith (who at the time owned 5-6 300SEL 6.3s) out for a drive in the Willamette Valley farmland near his house in Newberg, OR. We were going 140 MPH on a flat, straight country road, and he said to me that any of his 6.3s (two of them fully rotisserie restored at that time) would have been shaking apart and completely unstable at that speed, and there is no way he would have taken them up to anywhere near that speed. He was pretty damn impressed with the .036.

 

[Alphasud40]

Beautiful cars but you needed a fuel tanker in tow to feed those monsters. 13mpg and $5 premium ethanol free got to be expensive to drive the 560SEL on a daily basis. My SL500 has become my daily until my next project takes over as the next daily. Too small but still runs strong and I’m getting 22-23mpg with the 722.6 transmission.

 

[Jim Rosenthal]

No question that the 124 chassis is much better than the W109. It should be; It's nearly twenty years newer. But the older cars have their charm and I do like driving mine. I had a new 280SEL4.5 in 1973. I drove it from Illinois to Yosemite, and in those days, much of the Western stretch of I-80 had no limit on speed. The car would cruise all day at 100+mph, limited only by the car's robust appetite for fuel, and the driver's bladder capacity.

 

[Jim Rosenthal]

Yesterday, we reinstalled the original LH module into my 500E, after one of our forum members installed new capacitors in it for an astonishingly reasonable price. Car fires up and runs perfectly. Last evening it was raining cats and dogs here in MD, so the car hasn't been road tested yet- I'm hoping to do that this weekend; we're supposed to have some decent weather.

Thanks, Dave, for the repairs to the module! The depth of expertise on this forum is formidable. Having this kind of knowledge and help makes owning a car like the 500E not only possible, but rewarding. Thanks to all for their help.

 

[Jim Rosenthal]

Road tested today; ran almost perfectly, a very slight stumble one time, but it wasn't warmed up and it was only momentary. The rest of the time, car pulled like a locomotive. Added bonus: I turned on the freshly overhauled Becker radio and there was "An American In Paris". Bernstein and the NY Philharmonic, one of my favorite pieces of music. It hardly gets any better than this- driving a 500E on country roads and listening to Gershwin. Now I can finally touch up a few small dings and detail the whole car. Thanks again to all.