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Engine sputters at 5k in 2nd and 3rd- Advice?

 
Old 10-13-2007, 03:17 PM
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camboinc
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Default Engine sputters at 5k in 2nd and 3rd- Advice?

So I got my car back earlier this week with all new gaskets valve adj, new plugs, wires, rebuilt distributor, new K27HFS from Steven and new muffler from Rarlyl8. Car is way faster and so much fun. However, I am getting some engine sputter or almost cut out starting at 5k rpm and higher in 2nd and 3rd. Boost is staying up but when i hit 5k the car starts bucking- almost feels like a fuel delivery issue. It doesnt happen all the time, but most often. Can't make it happen in first either.
Any ideas? is it a fuel issue, bad coil, or maybe distributor?

Help!
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Old 10-13-2007, 04:43 PM
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do you have a wideband a/f gauge?
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Old 10-13-2007, 08:27 PM
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nathanUK '81 930 G50
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Tripping your overboost safety cut off switch?
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Old 10-15-2007, 08:37 PM
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if im tripping the overboost nathan, any idea on how to stop that?
thanks!
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Old 10-15-2007, 08:38 PM
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mdurbhan, dont know if i have a wideband air/fuel switch. how can i tell?
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Old 10-16-2007, 01:57 PM
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nathanUK '81 930 G50
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You could bypass the switch by earthing the wire that runs to it but you really need an aftermarket boost gauge (don't trust the stock gauge) to see what is going on. You want to be very careful on the throttle and make sure that you do not exceed 1bar so you don't damage your engine. If you don't go over 1bar with WOT in 3rd and the problem has gone then get a new switch. If you go over 1bar then maybe the wastegate is playing up or not connected right.

Have you tried blowing into the wastegate hose to see if it holds pressure OK? Are you sure you have the hose connected to the bottom of it and nothing on the top?
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Old 10-18-2007, 09:21 AM
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Nathan,
thanks for the tips. Ill poke around in there this weekend. Drove about 100 miles yesterday and no sputter after 5k rpm. just the high idle issue.
i dont get the drop in idle 40 seconds after a cold start like i used to. just kind of stays high. eventually works its way down from 3k to 1400rpm.
AAR or WUR possibly?
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Old 10-18-2007, 12:45 PM
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Your high idle (3000 rpm is way high even for a stone cold engine), testing the AAV as a potential culprit is simple. Just clamp the hose completely shut and it will take the entire gizmo out of the equation. If your idle still remains too high, t hen you've got something else going on
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Old 10-18-2007, 02:09 PM
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thanks mark. can you tell me how to identify the AAR hose? drivers or pass side? (obviously under the air box...)
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Old 10-18-2007, 06:34 PM
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nathanUK '81 930 G50
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It's in the right hand side of the engine bay.
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Old 10-18-2007, 09:29 PM
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Just right of center of the engine, big 1" black hose attaches to it from the intercooler.
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Old 10-18-2007, 11:43 PM
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thanks guys... ill try it out tomorrow.
appreciate the help!!
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Old 11-09-2007, 05:43 PM
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Twas the overboost switch. no more cutout at high rpm. had my mechanic fiddle with the idle and fixed that as well (all of this n/c of course). its even faster now! crikey! just need to make sure my stock boost guage is reading properly. i have received suggestions her on replacing the boost guage with an aftermarket unit. can ayone tell me the most cost effective way of doing this and keeping the stock appearance in the dash?
thanks!
brian
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Old 11-09-2007, 08:41 PM
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The best way is to replace the clock with a mech boost gauge. Nobody would think twice about it unless they know about 911 Turbos. North Hollywood Speedometer has the kit to retro them.
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Old 11-10-2007, 06:19 AM
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nathanUK '81 930 G50
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IA does the gauge to replace the clock too.
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