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Drfatz

Her first real run!

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Alright so I finally got her on the road! I had her inspected and registered so she is all legal.

So now my thoughts. She handles FANTASTIC! I have the new lotus suspension with urethane bushings on V8 wheels and Yokohama Advan Neova tires, I have only driven one car that handles as well and that was an Elise so I can be happy with that B)

As for the engine and power I am not so pleased. First off she stalled a few times when I pulled up to stop lights and she stumbles STILL when I initially press on the throttle to pull away from a stop. My biggest concern is the seemingly lack of control of the boost. She has NO boost until about 4,000 RPM at which point the boost surges to well over 20psi and keeps climbing so I have to back off the accelerator to get the boost to drop back down. I am concerned because all of the pluming is hooked up properly to the boost control solenoid and the wastegate is opened up almost all the way and the boost still climbs to 20psi and keeps going if I'm not careful. I am wondering how do I get the boost to come on earlier? If I tighten up the wastegate I can get boost earlier, but then I will blow up the engine because shes pulling to much boost. :lol: Currently I am running the stock S4S code with a Garrett GT3071R BB turbo and a 3" high flow exhaust. I have a wideband O2 sensor hooked up and she jumped to only about 16 AFR on initial boost but then promptly dropped to 12-13 AFR all the way to red line.

My thoughts are perhaps I need an after market boost controller to help bring the boost on sooner and keep it from overboosting.

Thoughts comments?

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20psi? wow. I don't recall what the s4s tune is, but 20 psi sounds a little high. As for your AFR... that's common -- i've noticed that they all run very lean on initial throttle application. However, your AFR with boost is probably about right... 13 is a little lean, but as long as that's not happening at 20psi, you're okay. 13 is about right for 7-10psi I'd say, then 12-12.4 for 15psi and then very low 12's for 20 psi. I think you have a wastegate actuator problem if you're over-boosting. Possibly your wastegate itself is sticking? climbing over 20psi is odd, and not getting boost early is a problem that I would associate with a bad actuator. What RPM is your boost starting up and in which gear?


Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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Hi mark thanks for the reply. The wastegate is brand new but most likely not adjusted properly. As for boost it dosent come on until after 4000 rpm in first gear and then the boost just keeps climbing to 20 and beyond if I don't let off the accelerator. Needless to say it happened once and I made sure it never happened again. Any thoughts on aftermarket boost control? I have read these can cause problems with the stock ecu.

-graham

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I would check to make sure that the boost controller is working properly in the first place... and I would lubricate the shaft of the the wastegate actuator with engine assembly lube (the red stuff, not lithium grease). 4000rpm in first is a little late for boost in 1st. I get boost at about 2800 in the s4. This tells me that the actuator is sticking, or that you've got a leak in your wastegate itself. It's also possible that the wastegate spring is too tight. You can give me a buzz if you like (403) 581 6875. I would bypass your boost control solenoid and see if it's still getting too much boost (route a vacuum line directly from the boost side of the turbo to the wastegate). If it's still getting too much boost and coming on too slowly then your wastegate is not functioning properly.


Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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Its possible the control solenoid is bad. I should mention that the wastegate actuator came with the gt3071r and thus is not lotus spec. I will try the bypass tomorrow!

Cheers,

Graham

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yes... it is possible the control solenoid is bad... this test should determine that... however, it is possible that your actuator has much too high of a spring pressure.

Edited by Mark T-C

Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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