Rough idle after AUX Water pump replacement? Help!

**rat9** · 10-17-2011 09:16 PM

My aux water pump was starting to leak more and more so i followed a guide i found for taking off the intake manifold and replacing the pump. I am pretty sure everything is connected again and i didn't mess with anything but the pump. Now the car idles very rough. There is also a strangle whistling sound when the engine first starts that i have never heard before. It evens out when i get above 2500rpm and sounds fine. No error codes are thrown. I re-used the intake manifold gaskets... are they not re-usable? Could it be that i cracked the spider hose or whatever the hard plastic hoses are in the back? Did a sensor wire break? How do i debug this? Would a video help people?

**JDM EJ1 95** · 10-17-2011 09:25 PM

check all vaccuum hoses for leaks..

re check EVERYTHING over and over agian.. if it wasnt there before its something you did while replacing the AUX pump

the pump replacement itself wouldnt have ANY sort of adverse effect on idle!

isolate the sound and i bet you find the problem..

**amd is the best** · 10-17-2011 09:32 PM

The cracked spider hose and/or the fact that you reused the IM gaskets could certainly cause idle issues if you have created a vacuum leak. Do you have a boost gauge installed? What is it pulling for vacuum at idle?

**bigern45** · 10-17-2011 10:48 PM

vacuum leak. pressure test needed. fyi..

**rat9** · 10-17-2011 11:08 PM

Ok, I read about pressure testing and i will make one from home depot parts and try that tomorrow. I have never done a pressure test with an air compressor.... Jeep people just spray carb cleaner everywhere while the engine is on until the rpm spikes.

I am ordering the center boost gauge... finally. When I saw the price I almost shat myself. Do people install vacuum gauges permanently? If so, where?

**wannabeS4** · 10-17-2011 11:14 PM

I had the same problem recently and realized I hadnt torqued that intake mani down all the way, fixed my rough idle. I agree you probably have a vac leak somewhere.

**EuroxS4** · 10-18-2011 03:53 PM

I'd say check your IM Gaskets maybe your didnt change them or you broke on of the 1 million plastic hoses under and behind the intake.Happens every time.Thats why many people relocated the aux water pump to resolve this issue and make it more accessible.

**rat9** · 10-18-2011 04:56 PM

I put in about 10 psi and i do not hear any leaks ... i am going to try soapy water next. Any ideas ?

Tried soapy water, only some tiny bubbles where one of the hard plastic hoses connects to a check valve. The system holds a few psi for quite a while so i don't think its a vacuum leak.

**rat9** · 10-18-2011 07:21 PM

I tried running the engine without the MAF sensor plugged in and it seems to run exactly the same...... thats not what is supposed to happen right? Did i break the sensor somehow?

I should be getting a code reader in a few days so maybe it will report no signal ?

**EuroxS4** · 10-19-2011 05:05 PM

check fault codes first.If you have any sort of leak the engine will be runnning lean and will have lean codes on short term fuel trim and long term.report back once you've pulled the faults thats the best way to go.

**rat9** · 10-20-2011 10:20 AM

with my shitty code checker i pulled the code p0300 (random misfires). I get the good bluetooth code reader soon!

**shorterthanrich** · 10-20-2011 10:36 AM

You definitely have a vac leak or damaged the MAF sensor/wires. Are you sure no dirt/grit snuck its way in between the intake manifold and the heads? i.e. messed up your gasket seal?

**rat9** · 10-20-2011 05:09 PM

i just watched all the stats using torque lite. Now once it has heated up it seems to run better. The maf is showing what looks like logical data, the coolant temp looks right. It just seems to run really really rough when its cold and just at low rpm. I might take a video of it and post it. What engine data would be out of place at idle? My timing advance is 10-30 ... is that normal ?

**rob** · 10-20-2011 08:31 PM

Read this post.

http://www.audizine.com/forum/showth...lem?highlight=

Hope it helps.

**rat9** · 10-20-2011 09:00 PM

Yeah the solenoids are plugged in right. i did not disconnect the fuel lines when i did this either.

After some more testing i have noticed that on initial start-up it is working fine when the rpm is about 1200 and its cold. Only does it start to get really rough when the RPM drops to the normal 800. It is now quite repeatable. Where are the check valves that people say fail?

**acoleman** · 10-21-2011 12:00 PM

Did you open the throttle body while pressure testing? If there is a leak at the intake manifold, I don't think it would leak during a pressure test unless it's open.

**rat9** · 10-21-2011 01:34 PM

I did not open the throttle body.... i thought since it doesn't make a perfect seal it would not block anything... am i wrong about this? I think my next step... unfortunately... will be buying new intake manifold gaskets.

**acoleman** · 10-21-2011 04:32 PM

Originally Posted by rat9

I did not open the throttle body.... i thought since it doesn't make a perfect seal it would not block anything... am i wrong about this? I think my next step... unfortunately... will be buying new intake manifold gaskets.

Ya you're probably right. Sounds like new intake manifold gaskets should do the trick.

**rat9** · 10-24-2011 04:48 PM

Ordered the intake manifold gaskets and spacers. i will report back with my results. Thanks for the ideas!

**rat9** · 10-26-2011 09:15 PM

I replaced the gaskets and this time really moved the intake all the way off so i could clean it all and have a good look. I am sure everything was clean and torqued this time. I also replaced the spark plugs and coolant sensor. Nothing has changed.

My MAF reads about 10 when at idle, I also noticed that the timing advance fluctuates between 0 and 20 when it is at rough idle... is this related to the problem? Shouldn't it just stay at about 0?

**acoleman** · 10-26-2011 09:30 PM

Originally Posted by rat9

on initial start-up it is working fine when the rpm is about 1200 and its cold. Only does it start to get really rough when the RPM drops to the normal 800. It is now quite repeatable. Where are the check valves that people say fail?

My S4 is doing the exact same thing as this. I'm getting it checked out on Saturday, I'll let you know what I find out.

**rat9** · 10-28-2011 03:25 PM

So i am playing with the spider hose now looking for cracks, does anyone know if the pancake pcv valve is supposed to be a check valve or do anything other than be an elbow? Mine has full air flow in both directions and that seems wrong..... ????

**rat9** · 10-30-2011 10:31 AM

Well the consensus is that the pancake valve is NOT a simple check valve and mine is working fine. In other news I have sprayed out the check valve that connects DIRECTLY into the accordion pipe and i think i have solved my problem! This check value was NOT installed when you do a pressure test so that is why it took so long to find. I should probably replace this valve but cleaning it seems to be working for now.