I have a question???

[MangoMan]

I have a 1990 W124 300ce. I have only had the car a short while and it has been going very well, really quiet engine, no smoke, starts first time when cold/cool, second time when warm/hot, but thats not the problem.

The problem just happened earlier, went down the garage to put fuel, (BP Ultimate) then drove off, paying first of course, was ok, then after about half a mile down the road it developed a sort of flat-spot, if you put your foot down normally it hesitates really badly, feel like it's going to die on you, but doesn't, eventually picks up, untill you take your foot off the gas, then the same problem again. Now, I did notice that if you eased the throttle really gently it's ok, but if you floor it, it hesitates badly. It idles fine and doesn't stall.

It does this even when in neutral/park.

I hope I explained it ok?

Any ideas guys or gals???

It's got high mileage, (215,000) but well looked after, lots of history.

It doesn't seem like a missfire, more like fuel. I don't know if anyone remembers the days of carbs, when they used to have a little mechanical excelerater pump on them, if you disconected that, you would have the same sort of symptom.

Anyway any help would be much appreciated, I've had a few Mercs before, but never this problem, usually they just die....lol....

Cherrs, Bill.

 

[MangoMan]

...one more thing.....

....sorry, but the fuel pump is quite noisy, but no more than I have noticed on other Mercs.

It's just that I heard that they can be a problem.

Cheers again, Bill.

 

[Shude]

I honestly don't think that you're doing it any good using Optimax or BP Ultimate in it, remember these cars were designed to run on leaded fuel and were adapted to use unleaded, they didn't have high octane unleaded in mind!

Try a few tankfulls of normal stuff, see if it makes a difference, a friend of mine used to own a 300CE-24 and he was advised (by who I don't remember) that Optimax et al is a bad idea with models of that age. That said, my Father's early-80s Porsche 944 runs great on Optimax.

 

[Ian B Walker]

I would run with what Shude says. Optimax and Ultimate are hotter burning fuels. Ok if you want to get rid of carbon of the piston crowns but do have a habit of metling pistons if you are not careful

 

[MangoMan]

Thanks....

Thanks for that input, I will give it a go, although I have always used 97 Unleaded in all my cars, and they have run fine. Lucky it was on reserve and I only put in a tenner.

It was just strange thats all, I will see how she runs tomorrow and will let you know.

Thanks again.

Cheers, Bill.

 

[andy_k]

my experience says restrict the use of high octane unleaded to the 4 cylinder 230s. The 6 pot engines were built for the lower octane fuels.

A couple of tankfuls should see youi back to normal.

I'd also check the air filter as a matter of course and give the throttle body a clean out if all else fails.

HTH

Andy

 

[Ian B Walker]

You say that the fuel tank was on reserve? I just wonder if you have draged some sludge up through the system and maybe the injectors are clogged. Try some injector cleaner. Might work, wont hurt either.

 

[Brian WH]

You say that the fuel tank was on reserve? I just wonder if you have draged some sludge up through the system and maybe the injectors are clogged. Try some injector cleaner. Might work, wont hurt either.

I would second that opinion. The symptoms sound like fuel starvation caused by dirt. You should clean your fuel filter and bowl and as Ian suggests try injector cleaner as well.

 

[MangoMan]

Thanks....

....for the info there, I didn't realise that the 6's were designed for lower octanes. Thanks, I will definately put normal unleaded in, in future.

As for it being on reserve, it was only coming on when I went round a corner or bend, so it would have had a couple of gallons in still. I did think of that though.

And while we are at it, you know that knob goody (sorry) that you can adjust for ignition timing, it's got N-2-S-4-6-8 etc. in your experience where is it best to have that? (not that I have changed it's position) It's on S at the moment.

Thanks again, Bill.

 

[Ian B Walker]

....
And while we are at it, you know that knob goody (sorry) that you can adjust for ignition timing, it's got N-2-S-4-6-8 etc. in your experience where is it best to have that? (not that I have changed it's position) It's on S at the moment.

Thanks again, Bill.

<sharp intake of breath> dont look at it, go away, pretend you havent seen it. Joking aside, leave it alone as you may just end up with a rather large bill that you just dont need.

 

[Brian WH]

Don't fiddle with anything else, diagnosing is bad enough with one fault, don't introduce any more.

 

[MangoMan]

...got it...

Got all that, can't even remember where I saw the damn thing now, oh well, never mind.

Seriously, thank. I will let you know of the outcome.

Cheers, Bill.

 

[MangoMan]

New Thread Started....I have a question....cont...

Ciao.