Hesitates then Surges on accel when cold - Benzworld.org

CambridgeMA · 12-28-2007, 03:40 PM

Hey there! I have a 2000 E320 4-matic (66k miles). When it is below 50F outside I get a hesitation and then a surge when I accelerate.

To better describe the chain of events. I start the car. It idles fine. I drive 100 yards to a stop sign with no problems. Drive another 200 yards to another stop sign with no problems. Then I accelerate for a third time, the car stutters/hesitates (1500rpm) and then surges strongly (2500-3000rpm). The car then works normally after it warms up a bit.

Its been doing this for 2 years in the winters (starting when car only had 45k). I've replaced the MAF and I have no check engine light.

My OBD II reader says I have "pending codes" (not sure what this means) P0455, P0170 and P0173.

Any ideas? Vacuum leak? Purge Valve? CPS?

ohlord · 12-28-2007, 04:27 PM

off when you gas up.get a new gas cap or flip the gasket.clean you maf with crc maf cleaner or get a new insert from Mercedes Benz Parts, Mercedes Parts, Accessories for 127 bucks and install it in the old maf body.
clear the codes and see what comes back.check that the maf plug is plugged in fully.
post results and more if needed.

ohlord
diy maf cleaning in the diy section

Kajtek1 · 12-28-2007, 06:06 PM

Good luck with MAF cleaning. I tried it 4 times with 0 success.
P0170 and P0173 are misfiring codes typical for MAF failure.

ohlord · 12-28-2007, 07:46 PM

pointing towards the maf,cleaning works about half of the time and the rest just replace the insert.
misfire would be recorded as 03** codes and he has none of those.
clear the pendings and do the suggested and report back.

also check that the intake tube from the air box is on correctly and all vac lines are connected.if a lot of miles on the car clean the purge valve per the diy in the diy section.

CambridgeMA · 12-29-2007, 08:01 AM

I wasn't clear in my original post.

I replaced the insert 2 weeks ago and I'm still having the symptoms & codes.

I'll check the assembly as suggested and look for disconnected vacuum lines.

CambridgeMA · 12-29-2007, 10:05 AM

Is there some trick to clearing pending codes vs. triggered codes? I click on the clear codes button, it says that the message has been sent but when I go back to Pending Codes, they are still there.

BTW, I reversed the gasket on the gas cap.

Also, I'm not sure if it will help but I'm attaching some data from the computer. Just a snippit from driving around this morning, starting with a cold car. Anything look out of the ordinary?