Rough idle, but smooth driving..... video

[Nlambert]

So, as most other A4 owners have dealt with I am currently having issues with my A4 (1.8T 5 speed) and a rough idle. Also it was extremely underpowered and sluggish. Originally everything was stock and untouched.


Here's what I have done so far:

I found that the fuel filter was the original (102k miles) so I swapped it out.
Replaced the busted snub mount with the Apikol and centered it on level ground, with the engine running.
Replaced the air filter (K&N unit)
Engine mounts were replaced at 90k miles
Engine was cleaned out to prohibit sludge at 95k miles, new water pump, timing belt, etc....
Changed the oil last weekend using Mobil 1 synthetic and an OEM filter.
Spark plugs were changed and gapped to .028 last weekend


Now...... it still had the rough idle but will accelerate extremely quick and drives like a new car. I found that the crankcase vent tube was cracked and one of my check valves had a hole in it. So I bought the block off kit from Integrated and proceeded to perform the vacuum delete using the ever so popular how- to on the AZ. I went over it a couple of times before posting here.

As of right now, I am still waiting on the crankcase vent tube to come in, but since it vents to atmosphere I wanted to go ahead and start it up to see if the idle improved. I posted a video to youtube showing the outcome of the idle. **Note, I am at work and cannot link to youtube so search 97minitaco. It's the only video I have.**

It sounds like I still have a vacuum leak but I cannot find it. I originally ran a line from the TIP to the T on the valve cover but have since removed that and capped off the TIP. No change whatsoever.

I'm at a loss. Is there something else I can check? I've read probably 200 articles on the Audi rough idle and cannot nail it down.

[gmudan]

Heres the video.

[Charles.waite]

So I bought the block off kit from Integrated and proceeded to perform the vacuum delete using the ever so popular how- to on the AZ. I went over it a couple of times before posting here.

Le sigh...

1) Undo whatever you just did. Return it all to stock.
2) buy 034 silicon PCV revamp (or follow A4Darkness' brand spanking new DIY solution)
3) buy US Plastics check valves and replace EVERY check valve in the system
4) consider replacing SJP

I be your vibrations will be gone. Any chance you have a boost gauge? I'm curious what your idle vacuum is.

[Nlambert]

I do not have a boost gauge. I am curious as to why I should undo everything. Most of the system was damaged or broken. Just a question. The idle is the same as before but the driveability is much better. Makes me think I am on the right track at least.

[Charles.waite]

I do not have a boost gauge. I am curious as to why I should undo everything. Most of the system was damaged or broken. Just a question. The idle is the same as before but the driveability is much better. Makes me think I am on the right track at least.

COuld you link to the DIY you followed? The "popular" vacuum delete DIY is a joke and people always follow it only to find out they've messed everything up.

The OEM system is absolutely fine. As long as you refresh the check valves and replace any broken or worn lines with high quality silicon or rubber it'll last for quite a while. I've still got all the OEM stuff. I refreshed it all a year and a half ago with an 034 silicon pcv kit, a new SJP, all new check valves and a new PRV. My vacuum at idle is 21 in/hg and boost peaks at 18-19. Before I don't know the vacuum, but I peaked around 15 psi.

In any event, if you deleted an important component, or removed a necessary check valve, you could easily be leaking vacuum somewhere its not supposed to go at idle. Under throttle, everything is pressurized though so a vacuum leak might not affect full throttle operation.

[Nlambert]

Sure.

http://www.audizine.com/forum/showth...simplification


I also referenced the write up done by Walky Talky as well to look at the differences and similarities.

http://www.audizine.com/forum/showth...Simplification

Aside from that, I searched the AZ forum, AW forum, Youtube, and Google before attempting the removal. I spent ~ 3 weeks exploring the options and comparing benefits vs. downfalls.

I'm trying to reduce potential failure and maintenance items while not spending a fortune on repairs. I've successfully deleted the EGR system from my old 99 turbo Toyota Tacoma with no issue. It ran much smoother and reduced the carbon build up in my intake. I'm somewhat surprised that I am still having issues from this car after following much of the same procedure. Hence the reason I believe that something has been missed.

[Charles.waite]

Sure.

http://www.audizine.com/forum/showth...simplification


I also referenced the write up done by Walky Talky as well to look at the differences and similarities.

http://www.audizine.com/forum/showth...Simplification

Aside from that, I searched the AZ forum, AW forum, Youtube, and Google before attempting the removal. I spent ~ 3 weeks exploring the options and comparing benefits vs. downfalls.

I'm trying to reduce potential failure and maintenance items while not spending a fortune on repairs. I've successfully deleted the EGR system from my old 99 turbo Toyota Tacoma with no issue. It ran much smoother and reduced the carbon build up in my intake. I'm somewhat surprised that I am still having issues from this car after following much of the same procedure. Hence the reason I believe that something has been missed.

Ok, at least you followed Walky's procedure, thats the correct way to do things. I've done the N249 delete as mine was acting up and messing up my boost response. I also wouldn't be against the SJP and SAI deletes as SAI is just for emissions and the SJP can be duplicated using simpler means. I wouldn't do the EVAP delete, but thats just me.

Rough idle could be motor mounts or snub. I know they're new, but as the mounts break in they will sag slightly and make the snub contact the retainer cup and transmit vibrations. I fought that for a while and it turns out, I just needed to adjust the snub every few months. My motor mounts are shot though, I've just been putting off installing my new ones for a while. Basically as they sagged more and more, the snub would drop more and more until the engine was resting on the snub, vibrating like hell at idle, but fine everywhere else.

Try adjusting the snub again, worth a shot at least.

[Nlambert]

Ok snub adjusted. No change. Still idling rough. You should be able to hear it in the video when I stand behind the exhaust. I haven't been able to dig in it any further, but I can rule that one out at least.