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

 

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.

 

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.

 

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

 

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?

 

no sealant... just double check... same thing happened to me the last time I had spark plugs and valve cover gaskets done... excellent mechanic couldn’t figure it out... but his boss (my friend and shop owner) knew exactly what it was... it’s the intake hose under the manifold, most likely... I’m not a mechanic but John can tell you how to do a smoke test...

maw

 

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.

 

OP, as you can see, we're in violent agreement here. Just show this thread to the people who did the work and have them recheck their work.

maw

 

Violent.

 

Did you ever get to the bottom of this?

maw

 

That or we are fast closing on four years of the poor thing sitting under a tree with a vacuum leak!

 

Of course. I'm assuming it was what we said it was, but people should contribute to the common good, as you do so freely.

maw