1987 300 SE Euro - 103 Engine

Wouldn’t you just love to have a few weeks with no car issues whatsoever…?.

That said, I am posting again regarding an intermittent engine stumble, shudder (or big hiccup while starving momentarily) - at Idle – like when waiting for the light to change. This is once engine reaches temperature. Since my last post this became almost constant with car stalling very often. When mechanic strongly suggested replacing the fuel pump, I did so reluctantly but unexpectedly had a wonderful quiet car week. I thought the problem was solved. Until this afternoon when it happened again. By holding the brakes and flooring it at the same time I got through the light, yet feel quite frustrated.

No trouble starting cold or hot.
Fuel Filter and Fuel Pump – new
Cleaned Idle Control Valve. The breather hoses are good.
Spark Plugs look good,
-Checked fuel pressure relay solder points –looks good. I know this is not conclusive. So I removed it and bridged the 15/87 terminals. Everything cool. Well, only to an extent since I was not able to reproduce the problem while the FPR was removed.

These items below have been replaced within the last 30000 miles. I am not sure if any are maintenance items or not.Are they likely culpirts ?
EHA,
Distributor cap & Rotor
Plug wires
Gas Tank cap

So I am looking for direction here. William Rogers suggested looking at the Ignition Coil, but I do not know how to check it. Could it still be the FPR, or can I rule that out? Any Ideas would be most welcome.

IMHE, if the fuel pump relay acts up, it will simply kill the engine. Same-o with the coil - you would not be able to keep the engine alive with the gas pedal and the brake.

With that said, this is very similar to a problem that I had with my 300E. I'd suggest replacing the air flow pot. Lots of posts on this.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

the coil can actually do this but it is usually is consistant whenever you accelerate it will cause a stumble.
m

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)

ctalor 738, I had read many of the Air Flow Pot threads and initially thought this not to be applicable to my situation. Most people quote Idle surges & Hot start issues as the reason for replacing the pot. Not my issue, I think.
Was that your experience as well ?
Maybe I am just reading my own car's symptoms incorrectly and my engine stumbling should be considered Idle Surging or Hunting. It definitely is intermittent now with the fuel pump replaced.
mhingram, I've been told that when going south the Coil might do this intermittently, but can find no procedure (in the CD) to check for it.Any Idea where I can find such info ?

got to think positively.....

there are ways to test it, steve has written a note out there on it too. However, i do not have the equipment to test, i just replaced mine it was $100 for my 560 should be less for yours i would hope. A good shop should be able to scope it for you too.
m

__________________
Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)

gidpor

I recently went through running problems on the 91 300e. After replacing numerous parts it should have started right up. Finally to be sure, I replaced the plugs that didn't look too bad. The engine started right up.

Also, it seems these engines run well when relying on a good cap and rotor. If in doubt, replace them and check the insulator behind the rotor.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

last night I reread some of the threads and this one in particular seemed most appropriate - It talks about my symptoms exactly and as an added bonus addresses my thoughts about MB repair as well. It was posted by can-do and ctaylor738 that has helped me here, was also active on that one.

http://www.peachparts.com/shopforum/showthread.php?threadid=73986

The price for the coil is actually around $140 these days, so I will wait with that and the air flow pot for just a bit - I will first look into the cap/rotor/plug wires. Even though they all have around 30000 miles on them (Is this a lot ? a Little ? ) I will check them out. Initially I did not think they would be faulty,because of their relative "newness" but I am reconsidering.

More to come

gidpor, recommend that the distributor cap and rotor be inspected and cleaned every 30k miles, possibly replaced every 50k - 60k miles. Spark plugs should be replaced every 30k miles. Ignition wires should last for 100,000 miles+ if you use Beru or Bosch ... depends somewhat on how many miles you drive annually. If you only drive 5k miles per year the wires probably won't perform effectively for 20 years.

__________________
Fred Hoelzle

I did the wires, cap, rotor, and coil. Everything helped a little, but the basic problem was still there. The coil was a waste of money.

I think the problem is fuel/air/engine management related.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Ctaylor,

I need your insight on my problem:

My car won't start. But, when I pour few ounces of gas in air intake, it starts after at least two cranks. I have driven the car at least 45 minutes without any hiccups. But, I could not restart after I switched-off. I have replaced fuel accumulator & fuel pumps runs, sparkplugs relay & OVP are fine.

1. Can fuel filter cause this problem altjough there is no hiccups?
2. Can fuel check valve cause this problem?
3. Do you agree that ignition system working? Because the engine starts & runs after pouring gas in air intake.


What else should be checked?

My insight and $.85 will get you a cup of coffee. But here goes.

You clearly have a fuel problem if you can pour gas in the system and start the car. This tells me that gas gets to the cylinders through the sensor plate, rather than being delivered by the injectors. Once, started it seems to run, which means that then it starts getting fuel through the injectors. Presumably you are not driving around with someone pouring gas!

Possible culprits -

Fuel filter - disconnect return line into container, run fuel pump and see if you get a liter or so in 30 seconds

Air flow sensor plate rest position incorrect - no air moving at start, therefore no fuel to injectors, once engine starts, enough flow generated to get system working

No air through idle valve - same as above - try disconnecting

Bad fuel pump relay. Runs in ON but not in start. Jump 30 to 87 and see if it starts.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks for prompt reply. First of all some clarifications: (a) This problem of not starting happened all of a suddent without any warning. (b) When I drove the car, it kept running with just few ounces of fuel which I added in the air intake when I started the engine. It means that fuel supply must have started coming from the main tank otherwise, the car can not keep on running more than 45 minutes till I turned it off. Correct?

I will certainly check the fuel filter. The reason I did not check yet because when I drove the car, I did not sense any hesitation or symptoms of clogging. Do you agree?

I swapped the fuel replay from another 300E running car, but no change.

Do you think distributor rotor/cap can give similar problem? Again, if this is the problem, then engine should not even start- when I add fuel in the air intake.

Ferdman - I think I am still in the zone with these parts, or just about,but in any case I am planning to check them out this weekend.
ctaylor738, I have not forgotten the airflow pot .I am Just taking a small detour here with the stright forward and less delicate items.
With that in mind I see that benzidude has taken this thread down a different road so I am signing off until I have some results.
Thanks again for the input.

Well , it has been about a week now since I replaced the Plug Wires, Distributor Cap & Rotor (Beru) and no stumbling at all.
I am keeping my fingers crossed and will report again in a week or so.
The thing is, like all DIY's who know their cars very well, I do hear an occational ( very faint) miss from the bowles of this motor...Not sure of it's origin, but perhaps it is the airflow pot lurking in the backround.