Hi all, The other week, I put some 89 octane in my car, only about 5 gallons worth, on top of a couple of gallons of premium that was still in the tank.

Immediately I started having loss of power, and harder starting, and some black smoke on startup, hot or cold.

After the gas was done, I put premium back in, and the problem was gone, no hard starting, no loss of power, no black smoke.

Well after that tank of premium, I refilled with premium again, and the problem was still gone. Buit now even with premium, my car is hard to start. I can crank it, it will engane, but then the engine will die unless I gas it to stop it.

It returns to idle just fine, and I am on my way.

I am thinking I might have a fouled plug, faulty cap, rotor, or maybe a wire.

Or perhaps is it the elusive OVP?

Either that, or the gas station has low octane in their premim pump so they can rip us off.

Whatever the problem is, I'd like to get it resolved.

What do you guys think? I will happily replace plugs, cap, rotor, etc if needed, or even the ovp.

What do you guys think is the cause? Remember this has only happened in the last week to week and a half, and the car did the same symptons with lower grade gas, but now it has high grade and its doing it again.

Alon

I'd start with a fuel system test & new filter! Have the fuel in the filter dumped into a clear glass jar & see if the filter has any water mixed with the gas.

Thanks, I'll look into it. Where is the fuel filter? I'll buy one and change it regardless.

But I'll also run some fuel system cleaner through

Alon

Not fuel system cleaner, but the gas antifreeze stuff with alcohol in it. It is not rubbing alcohol, so don't try that. The alcohol content will allow the water in your system to mix with the gas as a homogenous mixture so it can be run out.

STOP
 

Brother of The Benz, Alon
Your chasing your tail Alon.
The octane rating wil NOT create the condition your engine is having.
With your tank near empty your fuel pump may have drawn the accumlated crude from the bottum of the tank. This could explain why the Premium fuel momentarily corrected the provlem.
Add the Fuel Tank Cleaner as suggested.
You said you see "BLACK" smoke. This indicates an over rich fuel mixture.
Changing electronic components wholesale will only give you new parts and not address the problem.
Not to make you feel bad, but my 1987 300E with 176,000 miles still has the original distributor cap and rotor.
If the problem was with the fuel filtering, the engine would not recover after running poorly. The fuel filter(s) are located under the chassis behind a protection panel usely on the right side.
Alon you may have have numerous problems, but replacing parts without justification is not the way to go.
Address the dirty fuel approach first.
Happy Trails Beep Beep from The Spiderman in Houston!!!

I suspect low grade gas in the high test tanks.

I always run premium.

I just happened to put a few gallons of 89 octane in the car one day to see if the car would run ok on it, and it did not run as nice, so I put premium back in, and all was good. then I drove for a bit, used that tank, and I put in a new tank of premium, and the problem appeared again, which leads me to believe that gas is the culprit.

so I am thinking they either downmixed the 92 with 87, or they put 87 in the 92 tanks to rip us off. I've seen it on several news reports that stations are doing it here in los angeles.

I'm going to run some cleaner through it, techron probably, and change the fuel filter and see how it goes.

I'm going to check for a fouled plug too it could be something stupid.

The engine idles smooth, and the car's gas mileage has not decreased, so Thats why it seems strange. Like its not getting enough spark on startup only.

The rich mixture is because when I turn it over, it turns over more, then catches, then dies, then I turn it over again and it catches and holds. Its like its not getting enough fuel or the wrong grade. Because it showed a similar hard starting symptom with 89 octane, but not with premium, but it could be 87. I'll run some cleaner through. I have no idea how water could have gotten in there between fill ups, its been nice and sunny out.

Even after a spirited run of 80 + MPH on the freeway the car still shows the symptoms, and feels like its a little less powerful, which is why I think it might be bad gas?

Is that a possibility?

I don't mind changing some ignition/fuel components, but I'd rather try the cleaning approach first and see if thats the issue.

And I'd also like to try another station and see.

Or should I get the gas tested to see if its low grade, in which case, the gas station will need to be dealt with....

Alon

I have to agree with Donald.

Another thing is, try filling up at another gas station, with our gasoline cars, we use Amoco ultimate clear, BS stuff, lol.

Try the fuel filters first and if that doesnt work, do a tune up, when was the last time you replaced the spark plugs, distributor, wires, etc.?

You don't replace for no reason
 

Brother of The Benz, Johnson.
Johnson, there is no set frequency for replacing ignition components.
When one fails replace it.
The exception being, if you have to do major disassembling to get to a component and other ignition items are removed at that time, you might replace all of the items removed to gain access to the problem part, thus saving double labor at a different time. This keep everything fresh at the same time too.
As for my 103983 engine with 176,000 miles and still on the original ignition system, for this reliability, I have no answer. Just plain old luck.
My spark plugs are a different story.
Using "Copper Core" Champion RS9YC at $0.99 each;I keep rotating 2 sets.
I remove and replace with the alternate set every 7-8,000 miles.
These are the eyes of the engine. The plugs tell you what is happenning in the combustin chamber.
With the fresh set properly gapped at 0.032 inches, my engine never misses a beat and I am aware of what's happenning.
Your misfortune has to turn around soon, Johnson. Or your eventually going to have the best old Benz rolling.
I replace the fuel filter per the maintaince schedule.
I ALWAYS buy my fuel from a major refinner and a filling station that pumps a lot of gas, thus their tanks are clean.
My old tub has never drank anything less than posted 92+ octane fuel; To me it's too risky.
Happy Trails Beep Beep from The Spiderman in Houston!!!

Donald,

You said my misfortune will come around, well it did, today. It didnt come around, it came again, lol. Your not going to beleive what happened.

I took it to Jiffy lube to have the AC system recharged with R134a.

They broke the vaccumm element where the hose goes to the master cylinder. So my car does not shut off, you have to pop the hood and hit the stop button. GRRR, i am pretty pissed, i guess monday i will have to go to the MB dealer for parts, AGAIN!!!!!

They are going to pay for the part and do the repair, but i am going to have a lot of lost time driving back and forth and its embaressing as hell to pop your hood to turn off your car everywhere you go.

Well Just to try something,

I bought some techron fuel system cleaner, added it, and topped off with premium fuel from my usual station, and guess what. The car starts a little better now.

fuel system cleaner is in, And I did not get a fuel filter from pep boys, No way is a purolator going in my car and not at $49.99. I'd rather get a factory filter even if it costs more. :)

But For now we shall see. The moment I topped off with the premium fromt he other station, all was better...

I do have one question though, Could the fuel filler cap be the cause if it doesn't seal properly?

I noticed mine was a bit out of whack, so I readjusted it and it seems better now. But it was sealing well before, so its beyond me.

I also decided just for the heck of it to spend the few dollars on some new spark plugs. Copper core champions for my car. I was looking through the plugs at pep boys and almost every plug is platinum for my car. So I explicitly told the guy I don't want the platinum. it took him a few more minutes, but he finally got the page that had the copper plugs. :)

I'm gonna stick em in later. :)

Thanks for the replies guys, The insight has been most helpful. I think the fuel cleaner, new plugs, and new premium fuel should hopefully clear up the problem.

I did contemplate some octane booster, but the last time I used that stuff in one of my cars (the MGB), it melted through the fuel lines.

In anycase, I'll keep you guys posted as to my findings.

Alon

[Edited by Ashman on 06-09-2001 at 06:34 PM]

New Update.

After driving for a bit with the fuel system cleaner, I decided to go ahead and change the plugs. The existing lugs, looked fine, but no harm done with new plugs.

The car starts better now than before, so there must have been something clogging an injector or something partially.

I did notice while changing the plugs, that the Cap has some cracks near the allen bolts that hold it on. I am thinking I will change the cap.

Alon

Congradulations, it sounds like your on your way to having a better car. I would replace the cap too, its not that hard to do and not expensive. Goodluck.

At Last
 

Brothers of The Benz
It's good to read good things are happening to we who have problems.
One thing that amazes me is why most of us build our houses from the roof down!
For me, when I am performing a tune-up; I establish wheither my engine is worthy of operating properly after the tune-up.
I establish the condition of my engine before I start to replace parts.
First and the easiest is the basic dry compression test.
This tells me if all is well with the valves and if needed the piston rings.
The test for the rings is the wet compression test.
If in question, a fuel pump pressure test is performed. This is not normally performed for a minor tune-up.
I visually inspect the air filter and clean or replace it.
Now I do a visual inspection of the old spark plugs, for these are the eyes to your engine.
So much information can be learned from the condition of the spark plugs.
Never overlook the battery.
Check the charge voltage, for a low battery can cause problems we weren't aware of.
Top of the electrolyte level using distilled water.
Check the battery cable end at the battery post.
It never hurts to remove them and clean both connections.
If all turns out well; you've gathered and logged this data for comparison at the next tune-up.
After all of this Mickey Mouse testing, you know better what parts need to be replaced instead of a wholesale attack from The Blue Light Special Parts Department.
I know this may be the technique most of us use, but for those new to DIY, I hope I've helped them in a small way.
Happy Trails Beep Beep from The Spiderman in Houston!!!

hehe I understand the approach donald, and its very thourough.

For me, I knew it had to be either fuel or spark related, seems to me that it was a bit of both.

Bad fuel might have messed with the plugs, which were NGK copper core plugs, but They appeared fine, not burned or oiled or overly fueld, just the tips were greyish red in color as I think they should be.

With the fuel system cleaner, new premium fuel, and the new plugs, the car fires up instantly, and feels better.

I will replace the cap too, but since the cracks in it don't seem to be affecting it, I will just leave it for now as the cracks appear to be from the previous owners mechanic overtightening them. They are stress cracks at the bolt holes.

I will buy a new cap in a week or so just to be safe.

My approach donald is to spend the few dollars on cleaners/spark, then if that fails well $10.00 out of my pocket aint a harmful thing, especially when the stuff I did could cause no harm in the first place. :) If that fails, I start to look elsewhere. Fuel system pressure, Spark problems (I.E. Cap, rotor, wires, coil), and then I start looking into electrical.

I am not one to blindly replace parts in the hopes it will fix it.

I took some advice about fuel system treatment/cleaner, topped up the tank (the fuel system cleaner I used was Techron Complete, which also removes water from the fuel). I then decided plugs would not hurt.

Alon

You're not done yet...Techron is *very* hard on engine oil, so plan on an oil change pronto. If you're going to use Techron always use it immediately before an oil change. In my experience, though, nothing has worked better than LubriMoly Ventil Sauber for cleaning fuel systems. Check it out!

Richard, Thanks for the advice. I will look into that LubriMoly Ventil Sauber for future reference

I was going to change the oil after my next tank in anycase as I was going to run another full tank of gas to make sure I get all the techron used up. :)

I also want to make sure I wont be ordering some parts if need be like a fuel filter. once I'm going to get all greasy working on the car, I might as well fix some other stuff while I am in there. :) hehe

On another note, be warned that old electrical tape will destroy leather. I had my radio out for some rewiring, and My friend was he,lping me. he touched the steering wheel with some of the tape residue on his hands, and the steering wheel literally got eaten like acid was on it. now instead of a smooth leather wheel, I have a rough all torn up one. He himself has never seen that happen in all his years using electrical tape. We think there must have been some kind of chemical reaction to the oil form my hands or something. I literally had chunks of clack leather coming of in my hands.

I was forced to use some hand cleaner and wd40 to remove the goo so I could drive the car. After that was all done I used some cleaner and it is now dry at least and not sticky and coming off in my hands.

I think it was strange as I had contemplated buying a steering wheel leather cover because my wheel had some wear on it, and that same day my rim on my wheel got messed up.

Alon

Go to Wall-Mart and get a cn of Berrymans B-12. Follow directions and see how she does. It might run a bit crappy for that tank but it will clean anything. sound like you might have a bad injector(s).

It could very well be an injector, you never know, but the car runs perfect and gets no drop in gas mileage, and idles smooth,a nd no fuel can be smelled, which would be a sign of a leaking injector or something.

I think it has either something to do with startup enrichment, for warm starts. Cold starting is better, but warm starting is tough, and seems to be getting tougher.

At first it appeared to have worked with cleaner, but I still have no improvement now after a couple of days of it being better. Its weird, its not a consistant thing.

This leads me to thinkt he ovp might be the culprit as this sounds like one of the symptoms of the ovp from other reading I ahev done.

Alon

I'm going to talk to my mech about it and see what he says.

I second the motion by Rdetoy. Techron used to be stocked at the local MBZ dealers in Southern California years ago. It is undoubtedly effective stuff. So is the Ventil Sauber; it is excellent. They are probably the only two truly effective (gasoline) injection cleaners on the market; they are not snake oil.

Problem was that some brain surgeons thought that if one can of techron is good, then two or three is better. Or they would add it at every fill up. Wrong move. The techron would ‘wash away’ the oil from the cylinder bores (actually it didn’t physically remove it per se, it broke down the oil film and thus made it ineffective. Mercedes ended up eating quite a few engines on warranty because of its misuse, and Presto - no more Techron at the dealers.

Definitely change your oil after running through the Techron. I always use a bottle of techron or vetil sauber in the tank of gas used prior to the next oil change on my gas engined babies.

At Last
 

Brother of The Benz
You're HOME AT LAST
All is well with your Beloved
A suggestion for routine fuel system maintainance,
Red Line S1-l, 2 ounces per fill-up.
I've used this "Snake-Oil" for many years and have yet to have fuel related problems.
Happy Trails Beep Beep from The Spiderman in Houston!!!

I decided to check the OVP after reading about how the fuse fixed Donna's problem with her 300E. Some of her symptoms seemed similar to mine.I pulled the OVP fuse, and reseated it, car seems to start easier now and idle smoother and a tad higher than before.

What do you guys think?

I have not had a chance to test it after a good amount of driving or any driving yet, but I will later today... :) hehe

My fuse looked virtually new but taking it out and reseating it might be all it needed.

I'll keep you all posted.

Alon

You might need to replace the unit. Maybe you should take it out, clean it and then reseat the whole unit and see what happens;)

Gasoline
 

This has been an excellent discussion, and I would guess we've all learned a lot. I'd like to add one more note: Be sure to avoid getting gasoline at a station when the tanker truck is filling the station's underground tanks. When the station tanks are being filled, the gunk in the bottom of the tanks is stirred up, and if you're drawing your gasoline at the same time, you're likely to wind up with some of the gunk in your automobile tank. It happened to me ONCE. Never again. Happy motoring, everybody.

Ashman,

You mentioned fuses and it is worthwhile to note that if the fuses in your car are original, then they are 10 years old. It costs next to nothing to buy a replacement set, and it takes next to no time to remove old/replace new and clean the contacts with contact cleaner. Not only does this increase the reliability of your electrical system, it can *cure* some otherwise incurable problems. It is a quick, easy and very worthwhile thing to do.

Regards,

The first thing I did when I got my car was to replace every fuse in the fuse box with new ones.

The problem varies from day to day, its very strange.

Yesterday it was very hard to start the car. Today it has been much easier to start it, and that is since I messedwith the fuse ont he OVP. I did not change the OVP fuse, I merely took it out and reseated it.

Last night after I did that, the car started up instantly,a nd idled a bit higher.

Today the car is not starting instantly, but it is starting much much better than the day before.

I suspect that this is an OVP issue. The car is getting the same gas mileage, there is no fuel smell anywhere near the fuel injection and there is no dripping fuel. Spark is good, fuel is the right kind, oil is fresh, engine idles smooth as can be, and does not stall or idle rough. The only problem is cold start and warm starting, which are both about the same, it seems to make no difference when hot or cold.

Generally I can get it fired up then it dies, then I try again, and it cranks a bit and then starts. After this it runs fine btu still has the hard starting.

Should I go ahead and replace the ovp as a precation?

I'm actually calling my mech now to ask him, but I want to hear from all my friends here as well.

Alon

Hard Start.
 

I think you should Alon,
have your ignition coil check too.
If its the original.

Clauser1

I have a '72 280SE 4.5 that basically has the same problem. I've just about done everything to try and find the culprit, but have been unable to. After 6 months, 3 different mechanics and some new parts I'm thinking of donating car to charity, but really would like to try and 'fix' it since it runs fantastic when it wants to. What is an OVP and does my car have one? Thanks!!

Alan,
Just change the OVP and get it over with! It's cheap, easy and likely a culprit. Even if it isn't, it's good preventative maintenance!

Mbztrio,
I don't think your car has one... The OVP is Overvolt Protection Relay, it protects the cars electrical system from getting fried, but can go faulty after a few years and cause all sorts of electrical problem. If you want to learn more, do a search, this topic has been discussed a MILLION times! :)

Good luck Alon and just change it. :eek:

Hello. "OVP" is a new one on me. (I'm a junior member.) Does my '84 380SE have one? If so, about how much would a new one cost? Can I replace it myself? I'm a great believer in preventative maintenance.

This is weird,

I just filled up at a different station than my usual one, this one is near my office. The gas price was low compared to my usual station, I needed gas, so I got gas, the car starts better now.

I have a feeling the gas stations are screwing with the gas, mixing it down or something.

I'm going to see how the car does tomorrow on this gas, if it is better, I'm going to geta hold of the owner of my usual station to complain...

I think I will change the OVP. I didn't get a chance to talk to my mech either, I got busy...

Alon

well today the problem is not there, car starts as it should.

I think the culprit is bad gas.

Looks like I have some talking to do to the gas station and possibly the BBB.

Alon

Ashman: Glad to hear problem was gas, and not car. Yesterday, I posted a note warning about getting gas when tanker truck is filling the station's tanks. I forgot to mention avoiding stations where there is construction. I once filled up at a station where ground was being excavated, and I wound up with half a tank of water. Good luck with the station owner and the BBB. You also might want to check with the state agency that licenses the pumps. Weights and measures, or some such thing.