I've got a 1990 260E automatic, with 265,000 km on the clock. It might be of importance to note that leaded petrol has been phased out in our country since January 2006, and I have been running the car on Lead Replacement Petrol since then.
The car recently developed a starting problem. The problem developed very gradually, in the last two weeks. It began with the occasional flat spot as the car was taking off from standstill. Then it began taking longer to ignite, and would idle roughly at first. Then, 2 days ago, it stalled as I was taking off from standstill. Since then, it will only start, very reluctantly, after the second or third very long swing.
Anyone have any suggestions or similar experiences??? Other drivers of older Mercedes have also been experiencing similar problems with their cars, citing the Lead Replacement Petrol as the problem.
"260E" wrote in news:1160380532.636139.86960 @m73g2000cwd.googlegroups.com:
265K on a gas car without overhaul is a lot of km. What does the compression look like in all cylinders? That will let you know about ring wear and valve sealing.
AS to your problem, I think that E has a hot wire mass air sensor. It might be interesting to swap it with one from another car for a test.
When was the fuel filter changed last time? What's the fuel pressure on the injector? When did it last have its oxygen sensor in the exhaust manifold replaced? It's probably all carboned up.
There are a lot of things it "could be" and very hard to trace by remote control....
Thanks for the response. I will have the cylinders pressure tested and post the outcome in due course.
I worked on the car yesterday, and found that the distributor had oil in it. I replaced the camshaft seal, the rotor and the distributor cap... but alas the problem prevailed.
The fuel pumps were both replaced at 210,000kms,and I last replaced the fuel filter at 250,000 km's. I will check the pressure on the injector, thanks for that tip.
Hot wire air mass sensor??? If that is the little black plastic gadget that sits on the back of the air intake, than I have replaced it to no avail. Am checking the fuel pressure regulator later in the day (metal gadget on front of intake), will post the outcome later.
The oxygen sensor in the manifold??? I have never replaced it, will do so.
What is of interest now is that the car starts perfectly from cold. The problem only manifests itself when starting a hot engine, and once started, it only occurs at low revs. The engine runs perfectly at revs above 3000rpm.
So the oxygen sensor in the manifold probably impacts differently at higher temperatures, and the airflow in the manifold is also different at low revs. Perhaps this is where my problem lies.
"260E" wrote in news:1160644198.357943.126830 @c28g2000cwb.googlegroups.com:
Oxygen sensor is in the exhaust manifold. It tells the computer we have complete combustion or too rich so the computer can adjust the injection. Here's how it works:
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Of course, being in the exhaust, it's always sprayed with carbon, gook, fine metal shavings from engine parts, unburned fuel, water in the unburned fuel.....all trying to destroy it and make dealers very happy like the rest of the stupid internal combustion engine. It's one of their favorite little profit centers on fuel injected cars.
Now we're getting into the realm of another favorite dealer profit center....EGR, exhaust gas recirculator. At high RPMs, a stuck-open EGR valve, or one being told to open up by the computer that tests it in low gear every time, has little effect because at high RPMs the throttle plate is open through the MAS sensor which feeds it fuel.
However at low RPM, if the EGR valve stays open, exhaust gas blasts its way into the VACUUM in the manifold, the mixture drops so low it doesn't support firing in the cylinders, and the car runs like crap....if at all...it's running lean, which is real hard on pistons and exhaust valves as lean means high exhaust gas temperatures...burning the exhaust valve edges off. Not good.
A Mercedes shop can hook the computer to it and read the EGR position, MAP (manifold air pressure) and see what the mixture is doing as it's running like crap. Troubleshooting it with the right information isn't rocket science, but takes the right equipment.
When was the last time its EGR valve was cleaned, or better yet, replaced? Again, this profit center is subjected to constant barrages of exhaust gas crapola to clog it, eat it and stick it...mostly to the owner. YOU can test the EGR valve, if it's closing, easily. Just unplug it. The check engine light will come on on all newer cars, but they run just fine without an EGR blowing exhaust gas into the intake to satisfy EPA bureaucrats. If the valve sticks open, of course, it will still blast gas into the intake even disconnected, so the unplug test isn't
100%. I'd be tempted to replace the EGR valve, anyways, as it probably has needed it for a long time.
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The oxygen sensor may perform quite differently between cold and really hot in the exhaust manifold. Again, the key is the test computer's opinion, the best.
I have sorted the car out. It was with the fuel pumps. The pumps had been replaced in 2003, so I did not expect it to go again so soon. However, leaded petrol is being phased out in this country and i am forced to use Lead Replacement petrol on my car. It is possible that the lubricating properties of the Lead Replacememt petrol is just not good for fuel pumps.
Or it could just be a coincidence.
Larry, thank you for your responses, I have made note of your explanations, since my car is old and will require attention to the abovementioned components sooner or later, I reckon I can start to get part numbers and start buying the spares so long, and have them all replaced at the next service.
"260E" wrote in news:1161606483.880219.63370 @i42g2000cwa.googlegroups.com:
You're quite welcome. I love fooling around with them and have been since about 1975. I feel so old when someone asks, "What year is that Mercedes?", when I'm driving my '73 220D....(c;
My current project is more mundane. I use a 1988 Chevrolet-chassis Union City Body stepvan in my electronics service business.
It looks like:
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spent 13 years driving between the aircraft engine shop and the C130 cargo planes at Pope Air Force Base in NC doing 15 mph, delivering parts. It had only 60,000 km on it for $US3500...a bargain. It has a 6.2L GM diesel V-8, automatic transmission powering it. I'm converting it to run on used vegetable oil from Chinese restaurants who have already committed to me to supply about 1200 litres per month for free. They even help me carry it to my trailer when I go to pick it up...(c; After the conversion, it will be cheaper to drive the big stepvan than my 220D! Diesel fuel in South Carolina is currently about $US2.55 per US gallon. The unit is a Frybrid
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It starts on diesel fuel, then when the oil gets hot (>160F), a computer switches it to frying oil until you get within a km of your destination. You then press the PURGE button which switches it back to diesel fuel to purge the frying oil out of the injection system back to diesel fuel so you can restart it cold for the next trip, when the cycle repeats.
I drove an 86 300SD turbocharged diesel sedan that had been converted. It has more power on frying oil than on diesel fuel! 21 US gallons of frying oil will power it 1300 miles! There are many diesel Volkswagens around here with similar equipment running.
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