I searched and didn't find anything to fit my issue.

I just installed a GRS intercooler from a person who traded up to the new M7 DFIC. Well for some odd reason at idle in the 8-900rpm range the car has a strange added vibration. Any ideas? My car is a MCSa so I know the clearance under the bonnet is much closer but i'm not convinced thats the issue yet. As soon as I blip the throttle above 1k rpm the vibration is gone and I am happily motoring.

Also when running the engine with the bonnet open I hear a small strange whistling noise. Did I create a boost leak? The boots of the IC are spot on and tight. And the IC seems to touch the spark wires but I put some fuel hose over them to protect them.

Any change something has happened by chance?

Thank you

 

Do you get the vibration with the bonnet open?
It doesn't take long, you could put the stock IC back on to see if it's a vibration you just never noticed until now.

 

Is this the same GRS IC you took of? Or did you sell that one and buy another? If so ... the original one was fine ... correct?

 

Number one suspect would be a leak around the boot or leaky(perforated, rare) boot.

Finding the source of the whistle is probably the key. Several methods work. Using damp rags as dampeners can help isolate the source. as well as a piece of hose held to your ear, much like a stethoscope.
Poking around with body parts works but is usually a bit more uncomfortable.

 

Especially with the hissing sound. You might try the leak test that the gas company folks used to use before they were told to use their sniffing guages - soapy water. Mix up a batch of liquid soap and water and get a brush and apply the soapy water around all of the boot connections. If you don't see any bubbles, then try the I/C seams. If the IC tests out with no leaks, you have a bit of a scavenger hunt on your hands - you will have test the entire intake path. Somewhere there is a leak.

 

Don't forget that the intake tract is in vaccum not boost. I doubt that you'll see bubbles even if there is a leak. You can try spraying brake clean at the connections and monitoring the engine response.

 

Up to the s/c it is in vacuum; after the s/c it is in boost. As I mentioned in my original post, there is something of a scavenger hunt confronting mdsbrain. I personally would try the soapy water approach first (based on the hissing sound. If that search came up empty, then it would be time to break out the brake cleaner spray and check the intake tract pre-s/c.

 

check for leaks at boots

 

propane works great for finding leaks

 

Thank you all for your comments. I will try a few when I can. The car is currently parked and I have other isses to tend to with me moving.

Ryhplie, I see your reasoning for seeing it if happens with the bonnet open. Maybe the IC is making contact with the bonnet or the diverter.

Art to answer your question, I bought and had a GRS before and sold it when I needed $. I then bought another and its on the car.

I'm thinking the whistle is a noise I have heard before but never paid much attention. Such as it maybe part of having a CA I and it is the noise coming in at idle. But the leak test wouldn't hurt to do.

 

Unless he tries your test hanging out of the engine bay while having someone hold full throttle while on the freeway, there won't be any boost there. Infact most of the air will be bypassing the intercooler throught the bypass valve anyway. he might want to tie it shut during the test. I don't want to be rude or start a fight, but there will not be any boost at any part of the intake tract while the car is idling.

 

Or a Dyno...soapy water probably wont work but I would try to hit it with a shot of eather. You will notice a change in engine RPM for sure.

 

Hunh???

 

At idle the path of least resistance from the throttle to the cylinder head would be through the bypass valve.

For the dyno comment. Yes renting a dyno to check for a boost leak sounds like an economical and realistic choice.

No need to return a comment, I have had enough. Peace out.

 

think of the SC as a constant volume pump. When the BP valve is open, air runs from the post SC side back to the pre-SC side. A bit counterintuitive, but if it didn't, the system would build boost....

Matt

 

Ok I'll bite. First off I am talking about looking for vaccum leaks at idle, but in any case the throttle ultimately determines if the SC makes boost. If your statement were true, the intake manifold would build boost at idle when I have the bypass valve tied shut, as I did for nearly 6 months. That didn't happen. The vaccum at idle was exactly the same with or without the bypass valve.

It is not a constant volume pump in the context that you describe because the volume is dictated by throttle position. Anyone with a boost gauge can verify that. Consider this, if the bypass valve is tied shut and the throttle is at 5% (approx. idle position) where would the volume of air needed to create boost be coming from? Boost can only be created when the volume of air passing the throttle exceeds the volume that the engine can pump on it's own. Visualize the airflow from the throttle to the engine if the SC belt were removed and the SC was not spinning.

This is now way off topic, but what's new.

 

Here's why: the example you are using (not building boost at idle) doesn't work at all. First off, the ECU will close the TB as needed to make the right vacuum level in the intake manifold to for smooth idle at the right RPM (it also plays timing games as well, but that doesn't matter here). So when you wire tie the BP valve closed, the TB has to be more closed, because the SC is still spinning and stuffing air to the intake side. If it were to build boost the rpms would either rise, or the car will run lean. Idle is closed loop, so the motor activly does what it needs to to maintian idle speed.

Think of it the other way... Why would any air go around the SC if it were spinning? The answer is it wouldn't, and it doesn't.

And yes a ROOTS blower IS a constant VOLUME pump. The fact that the TB side is at vacuum doesn't change the fact that the SC sweeps X amount of volume per revolution. The mass of air delivered is a function of the SC speed, as well as the pressure and temp of the air before the SC. (This isn't exactly true, but close enough). I think MB uses a clutch on some of thier SC drives. Then no air would go through the SC, and a BPV would flow as you describe.

None of this has didly with finding vacuum leaks at idle (the eather or the stethiscope technique are the best). But the fact is that in a Mini air goes from post SC to pre SC, "backward" through the BP valve.

Matt

 

Fisrt, you are going way out of context if you think that I am claiming that a roots blower is not a constant volume pump.
Think and teach what you like. I post to try and add something, not feed my ego. If you are going to twist my comments to make it appear that you know everthing, go ahead. My original post stated that there would not be any bubbles to detect because there is no boost at idle to cause the bubbles. That is true. If you were trying to right wrongs you would have posted against the idea of using soap to create bubbles to find a boost leak.

Best wishes to NAM, but I will no longer be posting.

 

I sent him a PM to try to diffuse things....

Now back to your regularly scheduled content....

Matt

 

Happy happy joy joy

 

002 and I have no issues. We've PMed each other, and may even help each other out in the future.....

Matt

 

I bought my GRS from TonyB and his modifications are great but they cause fitments issues on my MCSa. The back peice TonyB added is making great contact with the diverter and caused the vibration @ idle. As soon as I removed the diverter and dropped the bonnet the vibes are gone.



So does anyone know how to disolved JB Weld? Is it possible? Also the whistle noise I heard sounds like air going into the intake.

 

Sorry to hear about this issue. So, the aluminum back strip that I added is hitting the GRS fiberglass diverter on the bonnet? Just want to make sure that I understand... If so, given the size of the mounting holes in the diverter, you might be able to losen those screws and adjust where it locates.

I'm just not so sure that the vibrating sound you are hearing is aluminum hitting the fiberglass. I would tend to think that this would not be audible, but I could be wrong...

Otherwise, I never had to remove JB Weld before. I can't imagine it being easy though... From their website:

Q: How can I remove J-B Weld after it is fully cured?

A: When fully cured, J-B Weld can only be removed by grinding or filing it off, or by directly heating the product above the 600 degree maximum temperature threshold.

 

I probaly need to post a pic of it. But it appears that when the diverter is installed it is making good contact with the back peice on the IC. The peice is showing some wear from the touching and so is the fiberglass foam. Although I don't know for sure why this touching is causing the problem. But when the diverter is installed the hood vibrates so I wonder if when my engine was replaced if its sitting a smidge higher then normal. Therefore making the area closer.

Till I figure out a solution I am happy with the diverter and cooler air is staying off the car.

 

Wow I had the exact same vibration!! I was like CMON...then I heard a clunky clunk...pulled over..and that piece in the back of the intercooler that you added had broken off and the vibration is gone Should I try to reconnect it?

-Spence