Weird Coughing/Popping Noise & Rough Idle

xeroxed · 06-27-2010, 05:18 PM

So i have a 2001 coupe with 175,000 km on it. Two days ago the car started shaking while idling, the shaking goes down when i put it into park - but if i have the brake on and its in D - the car shakes and wants to move forward... this sometimes happens when the engine is cold and sometimes when its warm .. off and on ... also, theres a weird coughing noise coming from the exhaust when this is happening. The engine is idling but the revs jump from 700-1100 every couple of seconds..... now i did some research... could this be spark plugs and wires?

[ion] C2 · 06-27-2010, 05:53 PM

vacuum leak

mbeals · 06-27-2010, 06:50 PM

Do you have a lack of throttle response? Does it like to stall when you give it gas after coasting down?

Check all of your vac lines, including the tiny one connecting the tb to the map sensor. They should feel smooth and soft. If they are hard, dry or cracked, just replace them. You can buy vac and rubber fuel rated line (for the lines right off the manifold) for less than a dollar a foot. Just buy a few feet and cut to length as you install them.

If that doesn't fix it, get a vac gauge and put it on a manifold source and see how it acts.

Philbar71 · 06-27-2010, 10:16 PM

Also it's not a bad idea to clean your IAC (Idle air control) valve or replace it if it needs to be.

zzyzzx · 06-28-2010, 09:00 AM

I normally use and recommend a MityVac to check for vacuum leaks. You need it to check the devices that use vacuum since they can leak as well.

My #1 pick is a vacuum leak, IAC that needs to be cleaned or replaced, or a dirty intake.

xeroxed · 06-28-2010, 06:13 PM

Hey guys, thanks for the help! The check engine light was on because the EGR valve, the two bolts used to put it in place .. one was broken (thanks to a stupid persian mechanic).. the other was bolted really tight to help seal... and it obviousely failed. This was also causing a misfire in the engine... hence the jumping of hte revs... cough/popping sounds coming from the exhaust. Took the guy 3 hours to remove the broken screw ... cleaned out the throttle body system... cleaned the egr valve... and now shes running smoothely! I'm also gonna get some injector cleaner and run it through.