My 1990 300e has an odd starting pattern. I replaced cap rotor plugs and wires thinking it will solve my problem and it failed to do so. Sometimes the car will start n die right away and others it will take a few cranks to turn over and sometimes it will start perfectly fine. Car will always start tho does anyone know what the reason for this odd starting pattern and hesitation could be ? Want to hear some feed back before going ahead n replacing the starter

Before you do anything, find out what codes it's displaying at the DTC (diagnostic trouble code) socket in front of the battery (at the firewall). If you don't know about it, do a search on "code reader". I have the exact car and when it acts up, I can always read the codes to let me know what's wrong.

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03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather
90 300SEL 214k Pearl Black/ Alto Grey/Black Leather

Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio

Not a starter problem . . Can you remove idle control valve and clean it out . I to have a problem like it .I have done every thing i can think of, and more.My next step will be injectors and seals . This is the only thing i have not done. Can you get the fuel pressure tested ?. To rule that out first .

I wouldn't waste my time or money on a starter. If the engine is cranking over and it isn't slow or bogged down, the starter is fine.

This sounds like a fuel delivery issue. Does this car still use the CIS injection system? If it does, you may have an issue with the cold start valve, or you could have a problem with the fuel accumulator under the car.

If you have the latter, the fuel system will tend to vapor lock, especially if it's worst after it's sat 30-45 mins after you shut the engine off from hot and try to restart. The fuel pump doesn't "prime" like newer cars do when you turn the key, so you will have to crank the engine until the pump builds pressure and allows the engine to start. Went through this with the SL a few years ago and when I finally replaced the accumulator, the difference was night and day.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

This is most certainly a fuel problem , specifically your injectors. They leak, or get clogged. You randomness on whether it will start /stall, start fine, is depending on which cylinder valve happens to be open/ closed at the time you shut off the engine.

Try a bottle of redline fuel additive ( this is the ONLY stuff that works) if that does not work, replace the injectors and seals.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

Thanks all for the in put

I did add a fuel additive but it wasn't specifically redline I will look into trying this before anything else

Is there a diy link for the removal of the idle control valve?

This engine is CIS, not multi-point injection. ALL SIX injectors flow fuel all the time at various rates, the fuel "distributor" as it's called, doesn't inject to various cylinders like EFI does. Which cylinder is "up" and which valve is "open" has absolutely nothing to do with what the fuel system is doing.

Replacing all of the injectors and seals straight away is expensive, time consuming, and likely isn't the problem here. Can they cause problems? You bet! But I'd be surprised if that was the issue here. If you had injector issues, I'd expect running issues such as stalling, rough idle, missing out, lack of power, etc.

I'd be willing to bet this is a supply issue, either vapor lock, something leaking down (check valves and such), or an enrichment issue such as a cold-start injector that isn't firing or an idle solenoid that's stuck closed.

It's easy enough to test if the idle solenoid is stuck closed. Simply pull the plug off of it. You should have a very fast idle (1500-2000 RPM). When you reconnect the plug, the idle should drop back to normal. The solenoid is a "pull to close" design with a spring return, so disconnecting the plug will force it "wide open". If the solenoid is stuck or sticking, you won't get much of a change if any at all.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I have owned a cis run car for almost a decade, I can tell you I understand the system very well.

Injectors leak, will clog partially, or will otherwise figure out a way to dump fuel in to the cylinder. If the valves are closed, the dripping fuel has nowhere to go. This resulst in the chugging feeling that ou get when the car starts.

If the valves are open, the fuel will dissipate, and the result is longer cranking times while the unit regains pressure in the upper chamber is the fuel dizzy.

You are right, bad injectors can cause the above issues, but most likely you will just have a slightly lumpy idle , and decreased MPG (slight)

I spent a year chasing down the same issue with my 300e back in the day. After changing basically everything and giving up, a friend gave me a bottle of redline fuel additive. My problems resolved 90% with the redline, and the car was 100% perfect after changing injectors/seals/holders.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

There are constraints to the fuel-pooling in the manifold from leaking injectors. I completely agree that cruddy injectors CAN cause starting issues (had issues in the SL that were resolved with Lucas injector cleaner), but if the car sits for more than a day or two, any fuel that was pooled in the intake manifold would finally leak past the valves, rings, and into the sump, or evaporate.

I spent the better part of 10 years "tolerating" lousy starts with the SL before I finally tore into it to fix it's issues. I had varnish in the fuel distributor, gummy injectors, sticking idle solenoid, cracked vacuum fittings to the WUR, a failed accumulator, and ignition problems, all of which have been resolved now.

The injector cleaner definitely does work *IF* the injectors are gummy or have deposits built up on them. If they're just dirty, or if they aren't the issue, it won't make much difference. Still worth the money to try though since it's cheap and if there is crap in the system, it'll clear it out.

In my car, the injectors were fine, but the seals were leaking. Leaking seals = vacuum leak. Vacuum leak = mixture problem. Mixture problem = crappy running.

That said, even with leaking seals, the car should start ok if the fuel system is holding pressure. Assuming the injectors are leaking down and the rest of the system is solid, once the engine starts to crank and the CIS calls for fuel, if the rest of the system is intact, it should repressurize the injector lines fairly rapidly. If the system is leaking down on the supply side or vapor locking and losing control pressure, it will take more cranking to repressurize that part of the system and get fuel out to the cylinders.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I'm going to try the fuel system cleaner once more cuz $10 won't hurt but I will add that once the car is on there is no type of sputter or rough idle it runs and sounds like a dream. Also this problem doesn't happen after letting the car sit for 30-45 min after it running and trying to start it again it's in the morning or after the car hasn't been started for a great amount of time. Once it starts I can turn it off n it will start right back up no problem mayb chock a bit at first for 2 sec but once it reaches the idle it holds there perfectly fine.

Rs a

Have you checked your duty cycle? What kind of mpgs are you getting?

I don't know how it is even possible, but when I first bought my 300te, it ran smooth as silk and only got 8mpg.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

Unfortunately my odometer stopped working a week into buying the car which I'm pretty upset about since it has low mileage 135k to be exact so idk how to count the miles I put a 20 in it every 3-4 days of driving it (i don't drive it everyday) gas is at $2.50 a gallon for premium here in new jersey