car jerking forward when stopped

[nickc280]

when I stop at a stop light my cars seems to be jerking forward when I let up on the brake a bit. when the brake is firmly pressed it is OK but if I let up at all it is seems jerky. If I was to let the car move without any gas it is real noticable. Please help, oh yeah I just bought the car but didn't notice it really until today.

[jnenad16]

sounds like the rpm is high at idle, possible MAS or idle module problem. can you describe the symptoms a bit more, such as the rpm, does it fluctuate or is it steady, things like that.

nenad

[nickc280]

the rpm seem a bit bouncy they are low though nothing to high, I haven't noticed them higher then normal, also the check engine light was on a few days ago and I ran the codes and got P1700 Transmission upshift delay switchover valve withought function (logic chain). whatever the hell that is, then I cleared the code and it hasen't came back in at least a couple hundred miles that I'v driven in the last couple days

[jnenad16]

that might be your problem, causing the car to jerk. I say replace the Transmission upshift delay switchover valve, which is lokated in your computer compartment, next to the OVP relay( you will see a white or green vacuum line connecting to it). also check that vacuum line, it might be leaking and causing the valve not to function properly.

nenad

[nickc280]

i thought it was on the side of the tranny???? I read that in another thread about the same error code. Is it under the hood in the computer area? where exactly is it located at and what do i look for? also when I was doing my oil change today I noticed a white small hose in the rear area by the oil filter that wasn't hooked up to anything it just had a rubber conection piece on the end and was just sitting there, I think there was a green one right next to it that was hooked up to something? any ideas where this loose vacumm looking hose goes? it is probably 1/8" thick

[jnenad16]

that white one goes to the vacuum connector next to the brake booster. as for the upshift delay valve, there should be a green vacuum line going from it directly into the upshift delay vacuum element that is located in the back of your transmission.

nenad

[nickc280]

I have been hunting and hunting for the other end of that white vaccum line? with no luck at all, I searched the area by the brake boost like mentioned but didn't find anything

[jnenad16]

hm, wish I still had my c280 so I can take a look at it and tell what to look for. if you want, post your email so I can send you the vacuum diagram.

nenad

[nickc280]

here is my email if you have the diagram that would be great, nick325ic@yahoo.com
Thanks

[Perinchery]

Nenad,

My 96 C220 does the same...When I brake and just before coming to a stop, the car surges forward, the RPM goes high for a moment and then come to a idle..its as if somebody is accelerating the car when coming to a stop... The check engine light is not on...Although the tranny jerks a bit during upshifts...
Any thoughts would be appreciated...

________
96 C220

[jnenad16]

I had a customer today with nearly the same symptoms, I turned out her tranny fluid level was low. I topped it off, took it for a test drive with her in the car, all good. she said it didnt happen after that.
but I'll send you the diagram as soon as I get off from work.

nenad

[nickc280]

thanks, you have been very helpful