Air Injection Solenoids and why you get a CEL
03-08-2012, 06:38 PM
#16
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I have been running without them for 4 years now and the only negative is I have to remind Mike to turn the codes off when he tunes my car 
For the Do it Yourself'ers out there, this thread is a great start. Otherwise we all know local shops that will take great care of you
06 WRX Air Pump Removal - is it safe?? - NASIOC
For the Do it Yourself'ers out there, this thread is a great start. Otherwise we all know local shops that will take great care of you
06 WRX Air Pump Removal - is it safe?? - NASIOC
You're driving a ticking time bomb!
03-08-2012, 06:49 PM
#18
Exhaust gas is just that, a gas, which like a fluid takes the path of least resistance when moving from one place to another.
Add to it the pumping effect of the piston, and the exhaust stream in our applications, will have positive pressure.
Under boost, the exhaust gas between the exhaust port and turbocharger will have about the same pressure as the intake manifold.
Look at the pictures LIC posted; they show carbon deposits from the exhaust gases backflowing up the fresh air tract.
We have seen several cars with these ****ty valves and the associated CELs.
Some owners have us repair them, others don't
A few of the No Repair customers are still driving after 4+yrs and 50k miles will no issues.
In the last seven years, we've had to replace valve guides on exactly one engine; a DOHC EJ25 N/A with 300k on the clock.
Here's some light reading on the venturi effect: Venturi effect - Wikipedia, the free encyclopedia
Most of the 07+ engines we've taken apart show 6-7 thousands play at the exhaust guides. If this is acceptable to you, roll with it. Our recommendation, however, is to replace the guides as it doesn't add much cost to the job.
Thanks
-- Ed
03-08-2012, 06:51 PM
#19
I tend to agree with Ed: Remove the valves from the heads and block them off. In CA leave everything in place but turn the codes off. If you want to try and dig into the closed loop maps and fix the 15-20 seconds of funky idle go for it...if you even can!! I have been running without them for 4 years now and the only negative is I have to remind Mike to turn the codes off when he tunes my car
-- Ed
03-08-2012, 08:39 PM
#21
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Car Info: MY04 STi some call it a race car
Not sure on your business model but for us we take care of more everyday non modified cars than modified. Most folks just driving there Subaru whom aren't "enthusiasts" are not into being advised on that they should remove parts that came on the car, that can affect smog (visually), and ultimately that may have an issue with warranty if said "modification" is done.
Sure you can all argue it doesn't affect smog, its not a big deal to rip it out, its not this, its not that...bottom line is IT DOES affect the ability to smog if you remove them and has warranty repercussions...and as a business telling a 60 year old customer to just not worry about those things is not how we conduct things. We do give them the options/scenarios but I never advise on non modified/enthusiast individuals to make that incorrect choice and potentially have even more issues in future.
Race cars....take them out, it saves weight
-Noah
03-08-2012, 09:06 PM
#24
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The problem is not under boost, but rather under cruising conditions. There is not enough back pressure to prevent the leak from sucking in fresh air.
Here's some light reading on the venturi effect: Venturi effect - Wikipedia, the free encyclopedia
Most of the 07+ engines we've taken apart show 6-7 thousands play at the exhaust guides. If this is acceptable to you, roll with it. Our recommendation, however, is to replace the guides as it doesn't add much cost to the job.
Thanks
-- Ed
Here's some light reading on the venturi effect: Venturi effect - Wikipedia, the free encyclopedia
Most of the 07+ engines we've taken apart show 6-7 thousands play at the exhaust guides. If this is acceptable to you, roll with it. Our recommendation, however, is to replace the guides as it doesn't add much cost to the job.
Thanks
-- Ed
Maybe something else is behind the rash of loose valve guides?
03-08-2012, 10:39 PM
#27
But it certainly could be something else. Do you have any ideas?
-- Ed
Last edited by EQ Tuning; 03-08-2012 at 10:47 PM.
03-09-2012, 07:20 AM
#28
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Let's examine the picture below, which I do not claim to be mine:
Let's assume v1, p1 are in the cylinder, v2/p2 are at the valve seat (which can be taken to be a "nozzle/constriction"), and v3,p3 are the exhaust port. All the area shown outside the diagram is to be considered atmosphere.
One can see that the pressure p3 is greater than the pressure p2...can't argue with science...so logically any opening near p3 would allow the fluid/gas to escape to the atmosphere, not the atmosphere into p3.
Let's assume v1, p1 are in the cylinder, v2/p2 are at the valve seat (which can be taken to be a "nozzle/constriction"), and v3,p3 are the exhaust port. All the area shown outside the diagram is to be considered atmosphere.
One can see that the pressure p3 is greater than the pressure p2...can't argue with science...so logically any opening near p3 would allow the fluid/gas to escape to the atmosphere, not the atmosphere into p3.
03-09-2012, 07:36 AM
#29
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Causes of valve guide wear:
1. Normal wear.
2. Manufacturing defect(s).
3. Overheating.
4. High Exhaust Gas Temperature.
5. Improper Concentricity.
1. Normal wear.
2. Manufacturing defect(s).
3. Overheating.
4. High Exhaust Gas Temperature.
5. Improper Concentricity.
03-09-2012, 07:54 AM
#30
I've also seen brand new heads that do not have this issue, so manufacturing defect is out.
None of these cars overheated or blew head gaskets.
That just leaves high exhaust gas temp. Since I've seen the issue on cars with widely varying setups, from different tuners including stock tune, OTS maps, and various custom tuners, I would rule out improper tuning as the cause. So what else would cause high EGT's on smog pump cars specifically?
-- Ed