Rough Idle Please Help
Thread Starter
Junior Member
Joined: Aug 2020
Posts: 20
Likes: 1
2003 S55 Kompressor
Rough Idle Please Help
Hi everyone,
I have 2003 S55k
I replaced valve block gaskets and right after it had rough idle, and then I did research and found out that vacuum hoses got bad (since I removed them after 17 years) and I bought new ones and put everything into their place. It still got rough idle, engine speed doesn't go below 1000. It did got to normal for a few moments but went up again. Any suggestions or ideas please help me out.
Thanks
I have 2003 S55k
I replaced valve block gaskets and right after it had rough idle, and then I did research and found out that vacuum hoses got bad (since I removed them after 17 years) and I bought new ones and put everything into their place. It still got rough idle, engine speed doesn't go below 1000. It did got to normal for a few moments but went up again. Any suggestions or ideas please help me out.
Thanks
MBWorld Fanatic!
Joined: Feb 2012
Posts: 2,623
Likes: 1,216
From: Phoenix
222 S-65
OP I'll take a stab and say that you likely replaced 'Cam cover gaskets.' Correct?
High idle implies a vacuum leak as your car is equipped with what we'll describe as a 'Speed-Density' engine management system.... A vacuum leak makes for lower intake vacuum sensed by the MAP sensor.... EMS supplies more fuel to match; hence.... High idle.
Brake pedal hard as a rock while idling? The vacuum line to the brake booster is big enough to make a high idle.
Start there.... Look over your previous efforts.
High idle implies a vacuum leak as your car is equipped with what we'll describe as a 'Speed-Density' engine management system.... A vacuum leak makes for lower intake vacuum sensed by the MAP sensor.... EMS supplies more fuel to match; hence.... High idle.
Brake pedal hard as a rock while idling? The vacuum line to the brake booster is big enough to make a high idle.
Start there.... Look over your previous efforts.
Thread Starter
Junior Member
Joined: Aug 2020
Posts: 20
Likes: 1
2003 S55 Kompressor
OP I'll take a stab and say that you likely replaced 'Cam cover gaskets.' Correct?
High idle implies a vacuum leak as your car is equipped with what we'll describe as a 'Speed-Density' engine management system.... A vacuum leak makes for lower intake vacuum sensed by the MAP sensor.... EMS supplies more fuel to match; hence.... High idle.
Brake pedal hard as a rock while idling? The vacuum line to the brake booster is big enough to make a high idle.
Start there.... Look over your previous efforts.
High idle implies a vacuum leak as your car is equipped with what we'll describe as a 'Speed-Density' engine management system.... A vacuum leak makes for lower intake vacuum sensed by the MAP sensor.... EMS supplies more fuel to match; hence.... High idle.
Brake pedal hard as a rock while idling? The vacuum line to the brake booster is big enough to make a high idle.
Start there.... Look over your previous efforts.
Brakes are normal. I forgot to say that it has P0507 code and Check light on. Also when I plugged in my scanner it says Emergency Fuel Shut-off Detected.
MBWorld Fanatic!
Joined: Apr 2009
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
I think you still have a vacuum leak... she’s running lean and the computer will not let it keep pumping fuel to match all the air getting in.
Did you check the hose under the intake manifold near the rear of the block? People often don’t connect that one securely enough... common and easy to miss, particularly when doing spark plugs, valve cover gaskets, basically anything where the intake comes off. John and I can guess, but next up will be a smoke test to find the leak.
GL
maw
Did you check the hose under the intake manifold near the rear of the block? People often don’t connect that one securely enough... common and easy to miss, particularly when doing spark plugs, valve cover gaskets, basically anything where the intake comes off. John and I can guess, but next up will be a smoke test to find the leak.
GL
maw
Thread Starter
Junior Member
Joined: Aug 2020
Posts: 20
Likes: 1
2003 S55 Kompressor
I think you still have a vacuum leak... she’s running lean and the computer will not let it keep pumping fuel to match all the air getting in.
Did you check the hose under the intake manifold near the rear of the block? People often don’t connect that one securely enough... common and easy to miss, particularly when doing spark plugs, valve cover gaskets, basically anything where the intake comes off. John and I can guess, but next up will be a smoke test to find the leak.
GL
maw
Did you check the hose under the intake manifold near the rear of the block? People often don’t connect that one securely enough... common and easy to miss, particularly when doing spark plugs, valve cover gaskets, basically anything where the intake comes off. John and I can guess, but next up will be a smoke test to find the leak.
GL
maw
I didn't use any seals for the hoses they seat pretty tight. Do you think I should've used some sealant?
Where do I connect the smoke to test it?
MBWorld Fanatic!
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
maw
MBWorld Fanatic!
Joined: Feb 2012
Posts: 2,623
Likes: 1,216
From: Phoenix
222 S-65
OP You describe a vacuum leak.
'Smoke test' requires a smoke machine.... My smoke machine requires compressed air to operate. The smoke is applied via a vacuum port to the intake manifold once the throttle body has been sealed up such that the smoke does not leak out of that spot. Is an excellent way to find those pesky leaks.... esp small ones.
FWIW if the car was not doing this before replacement of cam cover gaskets first step is to revisit all electrical and vacuum connectors/vacuum hoses that may or may not have been disturbed during repairs. Things happen.
Best wishes.
'Smoke test' requires a smoke machine.... My smoke machine requires compressed air to operate. The smoke is applied via a vacuum port to the intake manifold once the throttle body has been sealed up such that the smoke does not leak out of that spot. Is an excellent way to find those pesky leaks.... esp small ones.
FWIW if the car was not doing this before replacement of cam cover gaskets first step is to revisit all electrical and vacuum connectors/vacuum hoses that may or may not have been disturbed during repairs. Things happen.
Best wishes.
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MBWorld Fanatic!
Joined: Apr 2009
Posts: 1,264
Likes: 367
'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
OP You describe a vacuum leak.
'Smoke test' requires a smoke machine.... My smoke machine requires compressed air to operate. The smoke is applied via a vacuum port to the intake manifold once the throttle body has been sealed up such that the smoke does not leak out of that spot. Is an excellent way to find those pesky leaks.... esp small ones.
FWIW if the car was not doing this before replacement of cam cover gaskets first step is to revisit all electrical and vacuum connectors/vacuum hoses that may or may not have been disturbed during repairs. Things happen.
Best wishes.
'Smoke test' requires a smoke machine.... My smoke machine requires compressed air to operate. The smoke is applied via a vacuum port to the intake manifold once the throttle body has been sealed up such that the smoke does not leak out of that spot. Is an excellent way to find those pesky leaks.... esp small ones.
FWIW if the car was not doing this before replacement of cam cover gaskets first step is to revisit all electrical and vacuum connectors/vacuum hoses that may or may not have been disturbed during repairs. Things happen.
Best wishes.
maw
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MBWorld Fanatic!
Joined: Apr 2009
Posts: 1,264
Likes: 367
'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
Hi everyone,
I have 2003 S55k
I replaced valve block gaskets and right after it had rough idle, and then I did research and found out that vacuum hoses got bad (since I removed them after 17 years) and I bought new ones and put everything into their place. It still got rough idle, engine speed doesn't go below 1000. It did got to normal for a few moments but went up again. Any suggestions or ideas please help me out.
Thanks
I have 2003 S55k
I replaced valve block gaskets and right after it had rough idle, and then I did research and found out that vacuum hoses got bad (since I removed them after 17 years) and I bought new ones and put everything into their place. It still got rough idle, engine speed doesn't go below 1000. It did got to normal for a few moments but went up again. Any suggestions or ideas please help me out.
Thanks
maw
MBWorld Fanatic!
Joined: Apr 2009
Posts: 1,264
Likes: 367
'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
