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DSPTurtle's Avatar
 
Join Date: Jul 2001
Location: Suntree, Florida, USA
Posts: 2,229
More on Bucking

So, a interesting happened on the way home from the dance... actually it was from class in Orlando (I live 50 miles from my Sat morning class). This is usually our special time together on the highway and the morning ride was awesome. But, on the way home she started acting funny about half way through the trip. As the car would approach boost RPMs it would hesitate, stay at current speed and then blast forward only to slow again and then blast forward again. Sounds like fun but it was actually pretty scary to drive as the car squats and gets light when the power came on. As most of you know, it was on the dyno earlier in the week and the AFRs were within spec (a little rich for some of your taste but my trusted Pcar guru said no problem). Anyway, not sure what the heck was going on but it kept the same problem when I got into town driving and tried to play in first and second gear. I got home and pulled the IC and reseated everything (different reason in a different post). Although the IC and up pipe had more oil then usual in it but I pulled it straight away after the 50 mile trek while everything was still piping hot so maybe it just did not have time to drain back down. I really hope oil in the intake is truly "normal" and the turbo is not eating itself!!!
Any ideas on what the heck is going on?
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JB - BreitWerks
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Engine Rebuild & Restorations
Old 09-22-2007, 12:51 PM
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Location: Suntree, Florida, USA
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More fun than a barrel of monkeys... I just went out for another ride. Seems like it is shutting the motor down at .5bar boost. So maybe it is the overboost switch. No idea where that is or how it works but I am sure in a few searches I can find something on it. Oh yeah, now car is idling like crap and for the first time ever blowing black smoke out of the tailpipe. Jeez... she is so sensitive. Anyone want to trade for a 2007 997 turbo? Just kidding... shh, she will hear me!!!
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JB - BreitWerks
www.breitwerks.com
321-806-8664
Engine Rebuild & Restorations
Old 09-22-2007, 01:27 PM
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Join Date: Jul 2001
Location: Suntree, Florida, USA
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Man she is picky, but running perfect again!
In the interest of valuable archives I will post the results...
Went through the archives and found all of the info on what to do:
1. Grounded wire going to overboost switch and went for a ride... no luck.
2. Pulled over boost switch and checked continuity. No resistance with no pressure (good). Put 1.5 Bar into the switch and it went to infinity. (Switch must be good)
3. Pulled green plug from back of CIS to engage fuel pumps with switch in "on" position. Lots of fuel pump noise but did not no where the rear fuel pump was. Located rear fuel pump by tracing lines (tucked above driver's side rear control arm). Jacked car and laid down near it after turning key on. Lots of noise but no vibration at all from pump so figured rear pump was not working.
4. Got smart (for once) and decided to check relays for fuel pump before removing pump. Had to locate relays (relays are in front trunk, two big red circles closest to the windshield). I looked in the rear fuse box first... duh. Once I pulled the fuse box cover it became readily apparent what the problem was. The relay closest to the windshield had worked its way out of the plug. I pushed the relay back in, turned the key to on and could clearly hear the rear fuel pump running.
5. Took car for a ride and everything was back to normal. Idles fine, pulls strong and is a good as ever.
So, the symptoms were that the motor started surging on the highway with any input to the gas pedal. Later in the day I test drove it again and the car would die after about five hundred yards, I would coast a little restart the motor with the key and get another five hundred yards. Apparently the front pump would pressurize the system so the car woudl start and run for a minute then the front pump could not keep the pressure high enough to keep the engine running. So the symptoms got progressively worse (probably because the relay was working its way out of the plug).
All's well that ends well. And yes, those relays do get warm. My next purchase from our sponsor will include a few of those big red relays to throw in the tool bag
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JB - BreitWerks
www.breitwerks.com
321-806-8664
Engine Rebuild & Restorations
Old 09-23-2007, 06:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
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