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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #1
This problem began after the engine wiring harness was replaced. Overall the car runs fine once it gets going. When turning the ignition, it starts but initially it feels like it wants to die. Once the idle picks up its fine. Although, the idle rpm is initially low. At times however, it cranks but would not start. But it will hold idle if you press the gas slightly.

Once it gets going its fine and does not stall.

The only thing I suspect is the MAF sensor. Could it be anything else?
 

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1994 C280
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111 Posts
I dont think the MAF is involved when starting. I think it might be your intake air temp sensor. Try pulling it out and having a look to see if it is gummed up and report back.
 

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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #3 (Edited)
Intake air temp

Thanks. Is this sensor in the air intake area? Where exactly is it and what does it look like?
I'll chk my service manual for the location.

Update: found the temp sensor and cleaned it with maf sensor cleaner which I believe is essentially a contact cleaner. Car started fine after but I'll observe tomorrow after several starts if it remains stable.
 

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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #5 (Edited)
http://memimage.cardomain.com/ride_images/3/1758/1101/29393050001_large.jpg

You can see a small electrical connector on the cross over pipe just by the switch over valve (box looking thing) of the intake manifold
Update: found the temp sensor and cleaned it with maf sensor cleaner which I believe is essentially a contact cleaner. Car started fine after but I'll observe tomorrow after several starts if it remains stable.

If not I might order a new one as its only $12.60 at Autohausaz.

Thanks for the feedback. This makes more sense as to the possible cause of this problem. And if it is the cause, its cheaper than replacing the starter from overworking it.
 

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1994 C280
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111 Posts
Always cheaper to look after your car than neglect it. Not to mention the strain you would put on your battery and as you mentioned the starter. Hope the cars sorted now.
 

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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #7
Always cheaper to look after your car than neglect it. Not to mention the strain you would put on your battery and as you mentioned the starter. Hope the cars sorted now.
Thanks again. I'll report back in the next couple days if the starting has improved.
 

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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #8
Well, either the IAT sensor is bad or thats not what is causing it. Nothing changed. I'll order a new one tomorrow. For $12.60 I guess you can't go wrong. I'm sure this is the original IAT Sensor.

Can you tell me how the IAT sensor works with the starting of the car?
 

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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #9
MAF

ok, I'll try one more time:

With regards to the MAF, what does it mean when I remove/disconnect the MAF and the symptoms don't change. Or to ask it another way, what should the symptoms be if the MAF is disconnected? Thanks.
 

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1995 C220
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2,757 Posts
My car has had that problem before and after I changed out the wiring harness. I've changed the MAF, IAT, Oxygen sensors, to fix other problems as well, but never changed the starting issues. It runs fine, but sometimes you just have to give it gas in the morning to keep it running on initial crank. I'm now leaning toward an idle control valve, but I think this is built into the throttle body and is quite expensive, so I've never messed with replacing it. I dont think its a sensor any more though because I've replaced all but the crank/cam sensors and nothing has changed.
 

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96 C220, 85 300D , 84 300D (sold), 80 300TD (sold)
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188 Posts
Discussion Starter #11
My car has had that problem before and after I changed out the wiring harness. I've changed the MAF, IAT, Oxygen sensors, to fix other problems as well, but never changed the starting issues. It runs fine, but sometimes you just have to give it gas in the morning to keep it running on initial crank. I'm now leaning toward an idle control valve, but I think this is built into the throttle body and is quite expensive, so I've never messed with replacing it. I dont think its a sensor any more though because I've replaced all but the crank/cam sensors and nothing has changed.
Thanks for mentioning this, George. Does not make me feel any better but at least I know its just not me. I spoke with an MB head tech at the dealer the other day and he suggested using Techron (by Chevron) additive with my gas when I fill up and see if it improves. He said its one of the MB approved additives that can clean the fuel passages. I just did it the other day and observing. I don't think its doing anything but I'll do it a 2nd time just for kicks.

I was about ready to get a used MAF for $50 from a 95 C220 but am holding off.
 

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1995 C220
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2,757 Posts
When my MAF went bad, it was causing it to stall at lights. It would start to shudder for no reason then just die. Always started back up, and ran great when moving just would not idle or start well. MAF fixed idle at lights when warmed up, but still an issue on cold starts. Nothing I havent been able to live with just annoying. I've also tried GM fuel injection cleaner with no change. Havent tried replacing any injectors yet, thats also an expensive option. When I did my wiring harness I did use some throttle body cleaner all over the intake manifold while I had it off, there was some film in there. Cleaned up nice but didnt make a noticeable difference. Have you allready checked for rot in your wiring harness?
 

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1995 W140 S320 LWB, 1983 w126 280SE Euro
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111 Posts
This problem began after the engine wiring harness was replaced. Overall the car runs fine once it gets going. When turning the ignition, it starts but initially it feels like it wants to die. Once the idle picks up its fine. Although, the idle rpm is initially low. At times however, it cranks but would not start. But it will hold idle if you press the gas slightly.

Once it gets going its fine and does not stall.

The only thing I suspect is the MAF sensor. Could it be anything else?
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IM STILL HAVING THE SAME PROBLEM! It's a 1996 mercedes C-220 i also replaced the wiring harness, so all the wires are fresh and i even got a new throttle body... im wondering if t has anything to do with the ECU????
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my MAF is working like it should, i even cleaned the air temp censor, im just thinking of grabbing an ECU and just dropping it n mine to see if t makes any difference or would that mess things up? lol
i had to bend the tab on my throttle body just so i can have a higher idle its like my throttle body does not know what to do at all, no communication what so ever. if i leave the ta flat the idle is near stalling and when you turn on the A/C forget it, it's like the car has a bad case of the chills and shakes everything...
so im guessing ECU??
also can anyone tell me what this box is for that is located right behind my ECU is??

 

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1995 W140 S320 LWB, 1983 w126 280SE Euro
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111 Posts
I think that is the cruise control module, should have a green box on it that looks like a relay with a fuse in it.
cool thanks for the info =) do you know if by any chance if i change the ECU it will correct my idle problem? or would i risk bringing another cars problems to mine?
 

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1994 Mercedes C220, 1996 Chevrolet Tahoe LT
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6 Posts
Check throttle body wiring bundle

Maybe the problem is the wiring to the throttle body.

While I was replacing the wiring harness on my 1994 C220, I noticed that the cable bundle sheathing from the throttle body had been sliced open a little bit to expose the wires (probably a mechanic showing a customer the condition of the car's wiring). I opened up the sheathing more, and saw that the wires were seriously deteriorated similar to the main engine wiring harness. The wiring is unavailable as a replacement, and because the housing itself seemed fine, I was initially going just to replace the wiring myself. However, once I saw how complicated the inner part of the throttle body wiring is...

Mercedes throttle body rewire

...I decided against it. Since a new throttle body runs upwards from $500, I thought I would take it to a "small motor" shop or some such place and see if they could rewire it for me. Ultimately I found a used one in almost-new condition on ebay for $200 that was manufactured in 2005 (after the shoddy insulation problem was remedied, supposedly). The date of manufacture printed on the blue label of the one in the attached image reads '94', and the replacement I purchased has '05'.

Removal and installation is very simple, and I used the hard rubber flange from the old one on the new one. The only difficulty might be the connector to the main engine wiring harness, which on my car is under the intake manifold bolted to the support bracket. Since I already had the support bracket out for the wiring harness procedure, it was no big deal.
 

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W163 ML320, W220 S500, R230 SL600TT, R170 SLK230, W140 S500, More
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607 Posts
My 96 C220 had fits until I changed the wiring harness, after that never any problem at all. I bought a spare ECM for it that I didn't need, it's a known good working one, if anyone would like it you can have it for $150 including shipping anywhere in the USA.
 

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95" W124/ E220 MasterPiece and 01" W210/ E200 KOMPRESSER
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243 Posts
Try to clean ISA (Throttle Body / IDLE SPEED ACTUATOR) and lube the butterfly crankshaft at the both ends.
This ISA has been improved and updated with the change to its tiny bearing...and need to lube once a while.
The classic syndrome: *roughly 500 RPM* feel like it is going to die....or even cannot crank.....
95 C220 runs HFM system..and needs to reset HFM....
Don't speed money on sth people recommend but they don't really understand how it works...
 
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