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Old 04-14-2009, 01:20 AM   #1
Scooby Guru
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
2005 2.5RS Wagon
Regal Blue Pearl

Default Problems with Cams

OK, so I initially gave this thread a whirl in the NA Powertrain forum but it came up dry. I figure you guys may just know a bit more about getting engine interals up and running

I have a 2005 2.5RS with intake, throttle body spacer, EL headers, and a cat delete. Since it's an 05, the ECU is tuned via RomRaider and EcuFlash. I just installed the Delta 2000 Grind cams and things are less than stellar.

Before you ask, yes, I read the huge Delta Cams thread and tried all the suggestions in it. I'm now looking for ideas that might not have made it into that big thread.

Specifically, I have two discrete problems that may or may not be related. The first problem is that the cams didn't produce cammy goodness. In fact, you could quite easily mistake the car for stock. The second problem is that the car will not return to idle without stalling unless the idle speed target is at or above 950 RPM.

Looking at the performance aspect first, these cams still make the car feel like stock. In fact, I could not pull away from an 07 2.5i and he ended up having to lift to avoid catching me. If you look at the graph below, you can see that the engine loading is lower with the cams. Engine loading is a measure of how much air is making it into the cylinder each time it fills. A plot of engine loading and torque will have the same shape so a change to engine loading shows up as an equivalent change in torque. As you can see, the cams' loading is lower than the stock loading except for in the last 1000 RPM. All the cams really did is shift the entire load plot 600RPM to the right and reduce the loading some. From the glowing reports so many rs25.com members have made, I don't think this is how it's supposed to feel or behave.

The second problem is that the car refuses to return to idle without stalling. It will idle fine on first start and will idle fine if you can manage to use your right foot to get it stabilized back to idle. Even if the idle speed target is set to 650RPM, the car never throws any misfire codes. Immediately after an ECU reset, the engine will stall without any fight at all if you let off the gas and let the engine try to return to idle, just like you shut it off with the key. After a couple hundred miles of driving, the engine will sometimes manage to barely make it to idle and other times will stall after struggling for a moment. Immediately after a reset, when watching the engine via RomRaider, the ECU will shut off the injectors when I lift my foot off the gas (which is correct) and then simply never turn them back on before the engine dies. After some driving to get it to the point that it fights for a moment before it dies, you can watch the injectors turn back on, then the car goes really rich, stumbles and bounces up in RPM, then goes really lean, stumbles and drops in RPM, then goes really rich again and dies.

I have had a professional mechanic remove the valve covers and rocker assemblies to verify that the cams are correctly installed, then confirm that my lash job was correct. Valve lash is set at 8 and 10 based on Delta's recommendation. However, Delta made that recommendation based on the assumption that my stock lash was 10 and 15 (according to Qman on rs25.com). Looking it up, my stock valve last is actually 8 and 10. Neither Jon nor Ken at Delta addressed this when I PMed them so they must not think it's a problem. I have also tried all the tricks to teach it how to idle listed in the big Delta Cams thread without any improvement.

Other random things people have asked me:
The MAF has been cleaned
The air filter is new
The spark plugs have about 10k miles on them and are set towards the tighter end of the stock gap range

Can any of you think of anything?
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