[s-cars] Power Cut for 1 second

Sat Apr 28 20:49:51 EDT 2007

Bob,

I can't say I had my eye on the boost gauge at the moment of the fault, too busy looking around to keep from crashing, but I think I'm getting plenty of boost. I had a video camera mounted and zoomed tight to my boost gauge for 2 track sessions. I can't really tell where I am on the track when viewing those sessions on tape, but the needle dances around as what I think is expected, and it does climb up to about 25 psi without any problem.

I had 2 camera's mounted with 2 remote microphones, one above the tail pipe and one in the engine compartment. I have captured the fault on tape, both visually (when you watch carefully you can see the "deceleration" when it happens, it jars the camera, like someone knocked it with their hand slightly) and audibly.

I've never felt over-boost cut-off before, so I wouldn't know if this was the case.  

I do remeber when Mihnea was tuning my car however. The first couple of pulls were outrageous, I had the biggest grin on my face as the damn thing was pulling like a freight train on steroids, but then Mihnea told me he was overboosting, and he dialed it back down. The dialing down was noticeable. I don't know how all his voodoo works, but I suppose it's possible that while his tuning, his emulator controls boost cut-off, and that's why it didn't cut-off when he was tuning? I dunno, but the car never pulled as hard as it did those first few times with him in the right seat typing on his computer. I'm sure he set it to be "safe".

-manny

---- Original message ----
>Date: Sat, 28 Apr 2007 19:58:30 -0400
>From: Robert Myers <bob at chips-ur-s.com>  
>Subject: Re: [s-cars] Power Cut for 1 second  
>To: <manuelsanchez at starpower.net>
>
>   Sounds like you might be hitting the overboost
>   limit.  WOT each time and with major boost?
>
>   At 07:54 PM 4/28/2007, you wrote:
>
>     *This message was transferred with a trial version
>     of CommuniGate(tm) Pro*
>     Fellow S-heads,
>
>     Power seems to be cut for 1 second, the time it
>     takes you to snap your fingers, under Wide Open
>     Throttle. This only happens when at the track,
>     which by the way was a blast as usual, even in my
>     4,000 lb pig. It doesn't always happen during a
>     track session, sometimes it happens multiple times
>     (say 6 times or so) during a track session.
>
>     This problem has not been experienced on the
>     street, ever.
>
>     Strangely, there was one particular part of the
>     track where this problem occurs, it is a very
>     slight left hander, I'd say 10 degrees of turning
>     on the wheel. But....it also happened on the back
>     straight, and at another part by at a short
>     straight just coming out of a right hander. It
>     doesn't happen when backing up  :-).
>
>     After the problem occurred on one lap in a
>     particular location I would not try to use full
>     throttle at the same location on the very next
>     lap, result was no power loss, hiccup or whatever
>     you want to call this annoyance.
>
>     Here is a list of what's new in the last 100
>     miles:
>
>     Plugs (the Bosch tri-electrode copper plug Javad
>     sells, previous plug was the OEM Bosch F5DPOR)
>     Coils and cables (034 DIS system)
>     Fuel Filter
>     Fuel Pressure regulator (adjustable)
>     Fuel Pump (044)
>     Car has 125,000 miles on the clock
>
>     I don't think it was bad gas because it happened
>     both when I filled up with 93 Octane at the local
>     gas station, as well as when I filled up with half
>     93 and half 100 octane Sunoco at the track pumps.
>
>     I checked the plugs at the track and they looked
>     fine, no real residue yet, they pretty much looked
>     new (well they had about 300 miles on them when I
>     checked them). The old plugs I pulled out had a
>     very slight dpec on white at the  tip of the
>     electrode, which I understand may mean it was
>     running slightly lean. It was at this time, a week
>     before the track event, that I swapped all the
>     fuel and ignition items listed above.
>
>     On an interesting note, before I swapped all this
>     fuel and ignition stuff I attended my first dyno
>     day on a dyno-dynamics dyno. The tech running it
>     said my air fuel ratio was very rich, 9:1 (it was
>     measured by a tailpipe probe), and my ATW power
>     was lower than I was expecting, 209hp/245 ft lb
>     torque (i'm essentially at sea level). I think
>     guys with similar RS2 set-ups were getting about
>     60-80 units more at a Dyno session on the west
>     coast a year or 2 ago on the same type of
>     dynodynamics dyno. I had always heard that
>     Mihnea's software ran rich. I emailed Mihnea and
>     he thought those numbers were a bit too rich. When
>     he tuned the car it didn't have the stromung,
>     FMIC, nor the new FPR, FP.
>
>     I checked the electrical connection at the MAF and
>     it looked brand new, no residue or visible wear on
>     the connector plug.
>
>     Fuel pressure at idle was 3.9 bar.
>
>     This past Thanksgiving at the same track I had
>     occasional power hiccups as described above, but
>     instead of a 1 second cut of power, it was a
>     series of stumbles, it was an audible braaaaaappp,
>     that lasted 2 or 3 sec. This was with a relatively
>     new coil pack (less than 10,000 miles), original
>     POS's as far as I know, and relatively new plugs
>     at the time.  Last November I was convinced it was
>     ignition related, as the first time it occured was
>     after I removed the coil pack and laid it on the
>     throttle body in order to check plug tightness. My
>     next run after that check was the first time I had
>     the stumble/ braaap. I thought at the time it was
>     something with the wiring and the coils thaqt I
>     disturbed when I twisted the coil pack to lay it
>     oon the TB.
>
>     The stumble/braaap didn't always happen, but it
>     happened enough to piss me off.
>
>     I know I'm down on power, as I go to these events
>     with my brother in law, who has a stock BMW 540
>     (280hp/310 ft-lbs at the crank).  When my car was
>     running fine, say 2 years ago, I would pull away
>     from him on the straights and I had lap times 6-10
>     sec faster than he did, now he pulls away from me
>     on the straights and we maintain our relative
>     position on the track for each lap. I suppose he
>     could be getting better and I could be getting
>     worse, but I think it's a power thing.
>
>     Last year I found and fixed my boost leaks by
>     replacing many of the OEM hoses in those hard to
>     reach areas. Car has Samcos elsewhere.  I have
>     pressure tested the car to 15 psi and no leaks
>     that I can hear.  The car seems to make plenty of
>     boost according to my VDO gauge but it doesn't
>     feel like it's giving it's all with regard to
>     acceleration.
>
>     Other info on the engine:
>     RS2 turbo, RS2 manifold, Lucas Delphi 37#/hr
>     injectors, Mihnea Cotet custom software (tuned at
>     PK's house in CT), Tom and Marc FMIC, Forge 007
>     BPV (2 years old), RS2 WGFV (2 years old),
>     Stromung.
>
>     So what's going on? Is the ECU detecting knock and
>     cutting power?
>
>     I'd really love to solve this one so I can smoke
>     Bro-in-law.
>
>     Manny "perplexed and wanting all of Ms Piggy's Go
>     back" Sanchez
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