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Discussion Starter #1
Hello LTers - Trying to figure out what's wrong with my 07 Exige S. Within the last couple weeks I've noticed a loss of power - mainly at the low end. For a while I thought it was just the first cam - but tonight I noticed the car didn't come to life until about 7000 RPM.

So far I've cleaned the MAF (It did throw a P0171 about a month ago), installed new coil packs/greased with a dielectric (One coil pack was caked in oil, so I changed the spark plug seal on the valve cover), and changed the spark plugs. So far - No Joy.

56,000 Miles - Mostly Highway - No codes being thrown and the Cams Looked Great...

Any thoughts where to check next?
 

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Discussion Starter #3
(Thanks for the suggestions) I forgot to mention I did change the Air Filter - I was running a K & N - switched to a paper filter.

I'll dig into the Boost Leak idea.
 

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shay2nak
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take it to a dyno and measure it.

any rattling coming from the engine bay? Recently learned that something like that could fool the knock sensor and pull timing. Octane scaling. I do have a rattle on the IC heatshield at 2800 rpm that could be the issue of my power loss. It's a quick test to check octane scaling. Gonna have my car checked out soon.


just another suggestion
 

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Discussion Starter #5
No rattling from engine bay - it's kind of odd really - the engine sounds great, no codes being thrown, no obvious leaks that I can find. Today I put in a new MAF Sensor - didn't change anything. I also picked up a new accessory belt as I'm due - I'll change that out tomorrow but will be surprised if that's the problem.

My other thought is maybe the fuel injectors or pump.
 

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Did you do a compression test across the cylinders by any chance? I was talking to one local Elise owner & he was mentioning that water gets through the VC cover & into one of the coil packs that was causing issues for him.

Have you tried resetting the ECU as well to see if this might help?
 

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Discussion Starter #7
Did you do a compression test across the cylinders by any chance? I was talking to one local Elise owner & he was mentioning that water gets through the VC cover & into one of the coil packs that was causing issues for him.

Have you tried resetting the ECU as well to see if this might help?
I have not, I did have the issue you mention however - The Spark Plug Seal went on Cylinder 3. Both the coil pack & spark plug were coated in oil. I pulled the valve cover, replaced the seal and put in a new coil pack & spark plug (new packs & plugs on the other 3 cylinders also). You could be right (low compression) but other then this torque issue the motor seems to be running fine (no codes, no loss of fluids, sounds the same). I guess I'll check it to be sure, not sure if I feel like screwing with it anymore, I may run it up to the Dealer... Today I changed the accessory belt, cleaned the throttle body - No Joy.

Thanks for the info Ned.
 

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Discussion Starter #8
Hmmm - just pulled #3 spark plug and it was dry (the spark plug seal I installed in the valve cover must be doing it's job. What was odd however is all the coil pack scews and spark plug 3 itself seemed extremely loose - I know for a fact I torqued per the spec... Maybe my torque wrench is off.
 

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Discussion Starter #9
OK (feeling motivated I guess) - just ran compression test across all 4 cylinder - all between 200 & 210 psi. I'm wondering if this isn't a fuel injector going on me - does anyone know if that would typically throw a cell?
 

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Discussion Starter #11 (Edited)
OK, I think I am on to something - when I pulled the coil packs last night I noticed that number 3 was already dirty and I had some of the telling brown "Arc Dust" on it. My guess is that the corrosion in the tube is enough that there is no longer a gap between it and the coil pack. Regardless of how much dielectric grease I put on the coil pack, it rubs on the tube and comes off because of this. Evidently I need to do a better job of cleaning tube 3, anyone have tips on best way to do that?

* Cleaned out much better, went for a spin and same thing...

Think I am out of ideas - time to run it up to the Dealer - with any luck it's something simple.
 

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Discussion Starter #12
Checked the Catalytic Converter today - Back Pressure looked good (minimal) - taking to dealer 6/20/12.
 

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Discussion Starter #13 (Edited)
OK, just returned from the Dealer - Auto Europe in Birmingham MI. One of their top techs (and a great guy) Charles went over the vehicle and could find nothing mechanically wrong - but after hooking up his PC noticed the Ignition Timings were not advancing under throttle. He could not determine why that was the case but noticed my vehicle was due for an ECU upgrade - he uploaded a new program and the timings are advancing correctly. I'm not sure what caused the original program to foul up - perhaps a bug that's been there all along and only now, 5 years later manifest itself?

Unfortunately this did not cure my issue completely (loss of torque) - Charles is wondering if my boost levels are correct also. I'd say this new program took care of at least half the issue however.

Now I am wondering if something I did this last week actually hurt.

To anyone else who experiences this loss of acceleration - make sure you're running the latest program. Thanks to Auto Europe and Charles.
 

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Discussion Starter #14 (Edited)
Ok, just figured out the rest of this puzzle - my Bypass Valve Actuator was BADLY out of whack. I'm not sure how - but somehow the linkage from the Actuator to the Bypass Valve Arm was of at least 90 Degrees. I flipped it around and it popped back into place. This was very fortunate as otherwise you might have to take off the entire supercharger to adjust it - it backs up to the front of the engine bay - very little space.

To stop it from happening again I may give this a shot -

HDM Supercharger Wonder Bracket

Also - more info in this thread

http://www.lotustalk.com/forums/f160/low-sc-boost-question-68461/

Thanks to tempaccount for starting that thread - it helped me diagnose my issues.

Bottom line - if your low on power (linearly) and don't hear your supercharger whining - definitely make sure to check your bypass valve actuator. And further - Shame on Eaton for using such a low tech, cheap, bound to fail linkage. I had a $5K supercharger doing nothing because a $5 part failed.

Also, thanks to Charles @ Auto Europe for leading me down this path - You were correct!
 
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