Extended/long cranking - no/delayed power to injectors 3-5s

[BuiltByBen]

So I have a customers beautiful Japanese market LHD 1993 500e with no sunroof and euro interior in the shop for some typical service. I think im in love! Weve done upper and lower intake manifold gaskets, new (OEM German) plugs, valve cover gaskets, driveshaft guibo, fluids, etc. After sitting for a week or two, the vehicle now has a long cranking time before starting whether its cold or hot. Starter voltage drop is very acceptable at 250mV, fuel pressure is almost instant upon cranking and battery is healthy.

I used a noid light to narrow it down to a delay with the injectors kicking on. Starts currently take about 3-5 seconds to actually start the vehicle which feel quite long. Is the DME/engine computer the only thing that controls the injectors? My next step is to see if the DME is losing power temporarily for any reason. Not sure why the injectors would take so long to get power unless the DME is the culprit.

If anyone has any knowledge of this issue with these cars and can chime in, id sincerely appreciate it. I have worked on many, but have not run into this issue yet. Thanks all! Looking forward to being a contributing member.

 

[gerryvz]

A cold engine should take 1-2 seconds of cranking, at most, before firing. If not driven for a week or two, a two-second crank would not be odd.

The fuel injection computer and the fuel pump relay are the two things that control (electrically) fuel flow. There is a separate EZL (ignition) computer that is mounted on the inside driver's side fender-well, in the engine compartment, but this has nothing to do with fuel flow, only ignition/spark control.

If fuel pressure is near-instant, then IMHO fuel is definitely getting to from the pumps to the fuel rail.

On initial cranking (or when the key is turned to position 1 or 2), the fuel injection computer is supposed to activate the pumps for a few seconds to build system pressure. You can usually hear them activate briefly if you turn the key to "ACC" (position 1). Have someone under the car or near the pumps to listen for this -- it's easy to hear. This would be my first step after not driving the car for a few days.

Are you 100% sure that it is fuel, and not spark?

You should also check the following:

• Twist the fuse in the fuse-box that controls power to the fuel pumps. Just to make sure that everything is making good contact. Fuses and electrical flow to the pumps is always a good first step to check.
• Remove the fuel injection computer in the CAN box (the one marked with "LH" on the label). Check the pins both on the bottom of the computer, and their slots down in the CAN, to make sure that good contact is being made. A flashlight helps with the inspection of both pins and connectors.
• Residual fuel pressure (at the fuel pressure regulator) -- there is a spec for fuel pressure leakdown over time, after the engine is run, although pressure will leak down pretty far if not driven for a few days. You can check the fuel pressure regulator pretty easily by removing the vacuum line to it -- if you see/smell fuel, then it probably needs changing. It's a "wear" part that doesn't fail often, but is relatively cheap (buy Bosch or MB Bosch) and should likely be changed proactively if it's not documented that this has been changed
• Pull the blink codes for the car, and especially for the LH unit. You will need a blink code reader for this -- hopefully you have one. Reset all of the codes, drive the car, and see what comes back, if anything (again, focusing on the LH computer). If you need assistance with this, there is a thread about pulling codes, and the reference doc for them, located here. If there are any electrical issues with the LH computer, such as power being interrupted or inconsistent, there are specific codes that will be stored that indicate this situation.

Other things worth taking a bit of time to check, just to be sure:

• There are also fuel check valves screwed into the end of both fuel pumps -- a cheap part, and also one that helps maintain system pressure. These don't fail that often, but are often overlooked. They are available (Bosch) via the aftermarket, and are fairly easily replaced if needed. Again, probably not the culprit. All new fuel pumps come with these check valves installed, though they are available as a separate part.
• The fuel pump relay -- the green cube relay under the rear seat bottom on the passenger side. We've been seeing more and more of these fail in recent years, so not a bad item to check. It's worth having a spare in the trunk anyway, because if it ever fails, you are stranded.
• Remove each of the electrical connectors at the injectors, and inspect for corrosion. It's a bit of a long shot, but worth it to check for electrical ingegrity.

 

[gsxr]

Ditto everything Gerry said above.

I'd start by clearing codes from all 5 powertrain computers, and see if any codes return immediately.

The fuel pumps should run for 2 seconds each time the key is turned on. Does this happen consistently with each key cycle?

Live data from SDS / HHT-Win would be helpful, if you will be working on this car long-term, it would be worth the investment.

 

[gerryvz]

One other thing I thought of, as a step 1 or 2:

Go into the trunk and check BOTH connections on the positive terminal of the battery. Particularly, the smaller cable, which is a DIRECT power line that goes to the computers in the CAN box underhood. This positive connection can get corroded or loose, and it can be intermittent in supplying power to the car's computers. Make sure the terminal(s) are both corrosion free and secure/tight.

 

[BuiltByBen]

Thank you @gerryvz very well written. I appreciate the hasty responses guys. I have just ordered a blink reader, but have definitely narrowed it down to injector pulse. As soon as injector pulse begins, vehicle fires immediately (and oh so smooth). With noid light installed into injector connector, it begins blinking about 3-5 seconds after cranking begins, surely being my delay. It happens regardless of cold or hot identical every time. I’m suspecting that connection or computer. I wasn’t sure which computer controlled injector pulse but it sounds like I have a good lead!

If you send me your email, I can send a video.

 

[Kyiv]

If you send me your email, I can send a video.

You may just upload it to YouTube and share a link here!

 

[JC220]

Injector pulse delay is an interesting one..... what key does this car have? Does it have IR central locking? Presume not if it is a 1993.

Does your customers vehicle have any alarm or immobiliser fitted?

Do you have access to another m119 car to swap the EZL for testing purposes? (Because the crank sensor signal passes through the EZL)

As said already codes are important

 

[BuiltByBen]

I will post the video as soon as I take care of the new and very disturbing chain slap the engine just developed. Either failed tensioner or broken guide at start up but only ran for about 6 seconds before shut off. Bummer. Will update in a day or two.

 

[BuiltByBen]

Injector pulse delay is an interesting one..... what key does this car have? Does it have IR central locking? Presume not if it is a 1993.

Does your customers vehicle have any alarm or immobiliser fitted?

Do you have access to another m119 car to swap the EZL for testing purposes? (Because the crank sensor signal passes through the EZL)

As said already codes are important

Sorry no access to another m119. No immobilized fitted. The key is the old brick 1 button switch blade. Button unlocks and locks all doors. Unsure if it’s an IR system. I was told by an old Benz tech friend that it may actually be the caps in the box getting weak? I’m sure I’ll get to the bottom of it as soon as chain is in order.

 

[gsxr]

Was any work done on the chains or rails? It was running ok when it came in, correct?

And it wasn't just the adjuster rattle as heard in the video below, right?

 

[BuiltByBen]

Absolutely 100% that’s the same noise I have but it doesn’t go away although Didn’t let it run for but a few seconds. He’s a very reasonable customer and a set of tensioner/adjusters are only $300 locally at FCP Euro. That’s my first order of business.

 

[BuiltByBen]

You guys are a wealth of information. Thanks gsxr

Was any work done on the chains or rails? It was running ok when it came in, correct?

And it wasn't just the adjuster rattle as heard in the video below, right?

 

[gsxr]

If the adjuster rattle doesn't go away, let the engine idle longer... it requires oil pressure at the adjusters to quiet them down. This issue seems to affect early build engines only, and while normally the rattle only last a few seconds (there's a TSB about it), if the engine was not run in a long time it could take a while for pressure to build. Although it sounds bad, there should be no risk of damage if RPM's are kept at idle. I'd try 30-60 seconds at least and see what happens, assuming you have normal oil pressure.

Forum member @werminghausen had a similar issue with his 400E this summer, but I can't recall the the root cause...

 

[JC220]

Sorry no access to another m119. No immobilized fitted. The key is the old brick 1 button switch blade. Button unlocks and locks all doors. Unsure if it’s an IR system. I was told by an old Benz tech friend that it may actually be the caps in the box getting weak? I’m sure I’ll get to the bottom of it as soon as chain is in order.

OK so the key is a 1 button IR fob. Mb star on it?

I will need to look more but I suspect you have an immobiliser issue there with the delayed injector pulse. Were any ECUS swapped in the car?

 

[gsxr]

OK so the key is a 1 button IR fob. Mb star on it?

I will need to look more but I suspect you have an immobiliser issue there with the delayed injector pulse. Were any ECUS swapped in the car?

Joe has a good point. Can you post a photo of all the modules in the CAN box, or at least the part number on the LH module?

I'm not sure how the immobiliser works, or if the 124.036 ever had this "feature", even with IRCL. I thought it was only on 140 chassis. (??)

The LH module should *not* be the immobiliser type (018- prefix on the part number).

 

[JC220]

Joe has a good point. Can you post a photo of all the modules in the CAN box, or at least the part number on the LH module?

I'm not sure how the immobiliser works, or if the 124.036 ever had this "feature", even with IRCL. I thought it was only on 140 chassis. (??)

The LH module should *not* be the immobiliser type (018- prefix on the part number).

Yes the part number of the LH Engine ECU would be interesting for sure. My 1995 W140 had early DAS in it and if this w124 has option code 885 the IR fob would be linked to an immobiliser.

If the OP is certain the negative injector feed does not start to function until after 5 seconds of cranking over or so to me the immobiliser or engine ECU could be playing a part in that. Sometimes they only operate the K38 relay but as my 1995 W140 had shown even an LH ECU can have pretty smart injection disabiling features which do not appear in any of the MB literature until 1997 year or after.

Try putting a fresh battery in the key fob and using a spare key if you have it. And re-sync the key too.

Other factors can be at play of course this is just a suggestion to keep in mind.

 

[Ceresbum]

About length of starting time.... it looks like 4 sec cranking could be considered ok....

 

[gsxr]

About length of starting time.... it looks like 4 sec cranking could be considered ok....

Note that 4-second spec is for CIS-E mechanical injection.

I'm not sure what the acceptable limit is for LH-SFI injection but 4 seconds would be excessive on a properly-running electronic-injected engine.

 

[J. M. van Swaay]

I recently had the slow start after sitting problem you describe on both my 124’s. (E500 and E320). In both cases, the rubber fuel hose from the dual electric pump assembly to the metal feed line that goes to the engine bay had leaks. It was a faint smell of gas that tipped me off to this problem. The leak(s) in the hose were not easy to see. They only become obvious when I moved the hose around a bit while there was still pressure in the system. Replacing the hoses solved the “long crank time before start after sitting for a few days” problem.

It’s a long shot I know but it’s easy to check.

J. van Swaay

 

[J. M. van Swaay]

Just reread all of this thread, if there is an “electrical delay” issue with the injectors, the fuel hose probably isn’t the problem…

 

[gsxr]

@BuiltByBen - any update on this?

 

[BuiltByBen]

@BuiltByBen - any update on this?

Yes! Apologies for not getting back to the board on this. As customer came to pick up vehicle upon first start the plastic timing chain guide failed. The reason for the long crank issue I'm almost 100% certain was due to timing chain and/or guides starting to fail causing bad or delayed signal.

Guide that broke was down by the crank and difficult to see, but fairly obvious with valve cover removed. Replaced timing chain, tensioners, guides, water pump, oil crossover tube gaskets, cam seals, rebuilt dual power steering pump, resealed front timing cover, and probably several other items I'm forgetting.

Was a long road to recovery but the vehicle ran absolutely perfect afterwards and is still leak and hesitation free today.

 

[gsxr]

Thanks for the update, @BuiltByBen! Good to hear the engine is running well now.

Was the broken rail down by the crank #29 in the diagram below? Or was it the long rail #3 on the passenger side?

 

[BuiltByBen]

Pretty sure it was #29

 

[BuiltByBen]

Out of all the forums I have used, this one and its members have been one of the most helpful and knowledgeable. I enjoyed working on it as much as driving it

 

[gsxr]

Pretty sure it was #29

That is really unusual. I don't think I've ever heard of anyone reporting rail #29 breaking. This is the only one that requires removal of the timing cover, which as you now know isn't fun.

Thanks for the update!