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Registered
Join Date: Jul 2007
Posts: 8
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Car surges/bucks in second gear
First, I would like to thank our host and everyone in this forum for the info provided. I was able to build a excellent 3.4 liter, twin plug engine that has been running great for the past 10k miles!!!!
Engine is set up as follows: 1986 911 3.4 liter - Dougherty DC20 cams, Steve W chip, 993 ignitor & coil pack and inverter box, European Headers with 74 single side exhaust. I have run into an annoying issue that I can't find any info. While cruising in 2nd gear at 2500 - 2700 rpm, the engine will buck/surge. If I give it more throttle or shift, it goes away. It seams to only do it in 2nd gear. Fuel pressure is correct and I have not found any vacuum leaks. Any help would be appreciated! Again, Thanks to all!!!! Guy 
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04-16-2008, 04:53 AM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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That engine sounds great. And I see you've managed to neatly shoehorn it into your number 8! Must be that flat six configuration.
Have you talked to Steve W about this?
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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04-16-2008, 05:28 AM
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Registered
Join Date: Dec 1999
Location: Novato, CA
Posts: 4,740
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Steve's chip may be a bit rich at those rpms (that's why they call them performance chips).
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04-16-2008, 08:04 AM
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Member 911 Anonymous
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Check your Fuel/Air Mixture, it may need to be adjusted for your SW Chip.
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'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
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04-16-2008, 06:29 PM
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Registered
Join Date: Jul 2007
Posts: 8
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Air fuel mixture was set with Innovate LM1.
I should have mention that this problem just recently started within the past 1k miles. I tested the oxygen sensor using the procedures in the porsche manuals and it appears to be working properly. Guy |
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04-17-2008, 02:46 AM
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abides.
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You might try testing the output of your TPS, particularly the area near fully closed. See if the output is "jumpy."
I have a similar thing happen a little lower in the RPMs, maybe 2100 or so (don't remember off the top of my head). I usually notice it in traffic at about 20mph. It only happens when I'm cruising at neutral throttle, so I have my foot barely on the gas. I kind of figured it had something to do with how the TPS and chip were working together. I don't know what the resolution of the TPS is, but I think I must be in one of the first couple of positions. I know that's kind of vague...
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Graham 1984 Carrera Targa |
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04-17-2008, 08:54 AM
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Marble Grey
1984 Porsche Carrera Targa
