1994 Occasional Rough Idle
Thread Starter
Instructor
Joined: Nov 2012
Posts: 240
Likes: 18
From: Carrollton Illinois
1994 Occasional Rough Idle
To give a base, its a 1994, zf6, with 120,000 miles. I bought it with 104,000 almost exactly a year ago. (I drive it alot 
) Occasionally and only when the car is warm and was driven with the hour, when it starts it searches for an idle anywhere from 300 rpm to 1200 rpm. It can be very rough as well. It has completely died once but started right back up with no problems. If I give it some gas usually it goes right back to the normal idle with no problems. Sometime I have to give it some gas a few times. The car runs great besides that, no problems accelerating no problems cruising or anything along those lines. I have found that a vacuum line going from the intake to some small box next it (no clue what it is) has some small cracks but nothing substantial. It has all new plugs and wires as well. My first few thoughts are a possible fuel filter issue (but if that was the problem wouldn't it be especially apparent during throttle?) The next thought is a possible vacuum leak within the EGR (I wouldn't mind removing it). But once again I would figure it would always be a problem and it would always struggle to idle. Also, there are no check engine lights.
Any ideas?
) Occasionally and only when the car is warm and was driven with the hour, when it starts it searches for an idle anywhere from 300 rpm to 1200 rpm. It can be very rough as well. It has completely died once but started right back up with no problems. If I give it some gas usually it goes right back to the normal idle with no problems. Sometime I have to give it some gas a few times. The car runs great besides that, no problems accelerating no problems cruising or anything along those lines. I have found that a vacuum line going from the intake to some small box next it (no clue what it is) has some small cracks but nothing substantial. It has all new plugs and wires as well. My first few thoughts are a possible fuel filter issue (but if that was the problem wouldn't it be especially apparent during throttle?) The next thought is a possible vacuum leak within the EGR (I wouldn't mind removing it). But once again I would figure it would always be a problem and it would always struggle to idle. Also, there are no check engine lights. Any ideas?
Thread Starter
Instructor
Joined: Nov 2012
Posts: 240
Likes: 18
From: Carrollton Illinois
I would have expected the o2's to throw a code, they look brand new as they were replaced before I got the car (No Clue as the what brand
). Is there a place that sell a new vacuum harness so I can replace them all while Im there?
). Is there a place that sell a new vacuum harness so I can replace them all while Im there?
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Last edited by antfarmer2; Jun 23, 2016 at 08:25 PM.
Burning Brakes
Joined: Dec 2005
Posts: 805
Likes: 11
From: Hickory Flat Ga
You could have it smoked and stop wondering about vacuum. A diagnostic scan would save time and parts money. These engines can be simple to fix- if you know what's wrong. Educated guesses are a false economy in this case. I wish I'd taken this advice years ago.
