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erratic a/f's
New symptoms.
I need to depress the gas pedal slightly on start up, and won't idle when cold. Once it's warmed up at idle the a/f's fluctuate between 12-14/1. Cruising on the freeway at around 3,000, seems to be on the rich side 11-12.5/1 Under hard acceleration it goes up to 14:1 then goes down to 11.5-12.1, under boost to 1 bar. I'm guessing this is a wur problem? I recently replaced the plugs, wires, cap, rotor, coils, and had both cdi boxes rebuilt. Where to start?
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-17-2016, 08:15 AM
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Ingenieur
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Sounds like possible air leak between airflow meter and throttle, or vacuum leak. Could be a lot of other stuff though. You could spray the starter fluid around and see if the engine speeds up. Are you familiar with that old trick?
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04-17-2016, 09:15 AM
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Mighty Meatlocker Turbo
Join Date: Apr 2016
Location: North TexASS
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As Speedy said, that sure seems like an air leak. The symptoms you describe (especially the highway cruising richness) are very similar to what I was experiencing when the injector block nutz were loose - loose enough that fuel residue had built up on the outside of the cylinder heads' intake ports - saw it when I had the alternator out for something unrealated.
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04-17-2016, 12:13 PM
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Thanks, I'll try it tomorrow.
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-17-2016, 02:02 PM
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I sprayed starter fluid everywhere, no change. I also took the i/c off and checked/re-tightened all the fittings. Still no change. Anything else I should try?
thanks.
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-19-2016, 11:45 AM
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Smart quod bastardus
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Quote:
Just thinking outside the box. Fred
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max ---"When you're racing it's life! Anything else either before or after, is just waiting" |
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04-20-2016, 08:31 AM
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Join Date: May 2005
Location: Loxahatchee, florida
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that rubber elbow going into the turbo. I have had slip loose before.
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88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's. 2019 Silverado 6.2L |
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04-20-2016, 09:12 AM
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Location: NW NJ
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Make sure the hose from the IC to the AAR and the from the AAR to the throttle body are tight, and no cracks.
That is what helps it to idle when cold and if there is a leak there, your AFR's would be all over the place.
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1988 930 Venetian Blue |
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04-20-2016, 10:11 AM
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Location: wisconsin
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Check your timing at idle if its not the aar/etc...
My car had a failed vacumn cannister and I had wacky symptoms differnt from yours, but I could see hao a failed cnnister would screw up your idle if it had failed... Easy to check, and rule out... Did you check system voltage? A failing alternator does all sorts of wacky things... good luck. bo |
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04-20-2016, 10:21 AM
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Ingenieur
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What about the vacuum limiter (or "Golden Saucer" as Fairman calls it). I believe that can cause these symptoms too, if the diaphragm fails.
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04-20-2016, 05:36 PM
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Mighty Meatlocker Turbo
Join Date: Apr 2016
Location: North TexASS
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Quote:
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04-20-2016, 05:46 PM
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Ingenieur
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I think you and I are talking about the same thing, the big canister between the upper and lower intake? I think the banned guy is talking about the distributor mounted canister.
Quote:
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04-20-2016, 05:55 PM
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Mighty Meatlocker Turbo
Join Date: Apr 2016
Location: North TexASS
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If the vacuum limiter (aka; the deceleration valve - the golden saucer mounted to the secondary intake manifold with two, semi-large diameter hoses connecting to both the primary and secondary intake manifolds, and a tiny diameter hose connecting it to the throttle body) diaphragm develops a hole or tear, or pulls away from the inside of the disc due to corrosion and age/wear, then air is continuously allowed to bypass the closed throttle plate (not just during sudden closed throttle) - this results in the 2K + idle RPM I noted.
Last edited by Rawknees'Turbo; 04-20-2016 at 06:18 PM.. |
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04-20-2016, 06:16 PM
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Turbofrog
Join Date: Aug 2009
Location: Europe
Posts: 1,677
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Also check that the wur gets 12v. Start up might be separate problem.
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04-20-2016, 10:24 PM
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Join Date: Oct 2006
Location: MYR S.C.
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first thing is to check for power to the WUR.
then check pressures. cold to warm you can also check the resistance of the heating element in the WUR.
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86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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04-21-2016, 02:56 AM
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Thought I'd start with the simplest thing to check, power to the WUR. There is NO power to the WUR. I need to remove the i/c to get to the relay, so I will get back to this in a few days.
To answer a few other questions. I swapped out the 02 sensor, it's after the turbo. I tightened all the hose clamps including the elbow between the turbo and intake pipe. There's no canister on the 12 plug rsr distributor. I don't run the valve housing (second intake manifold) I'm getting 12 volts. I'll report back once I get power to the WUR. Thanks for all the suggestions, I'm hoping it's just the relay.
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-21-2016, 10:56 AM
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The WUR does work when the pumps are running, not just with the key on.
The erratic a/f's were caused by a bad 02 sensor. I went for a short blast, all is good, and a good time to sell it. I will be listing it in the next few weeks.
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Harold '79 930/DP935 (sold) '68 VW 3.3 Turbo Crewcab |
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04-21-2016, 12:31 PM
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Smart quod bastardus
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Quote:
always confirm your gages are accurate and look for the simple things before going more complex. Do I get a discount on the sale price?   
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max ---"When you're racing it's life! Anything else either before or after, is just waiting" |
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04-26-2016, 07:08 AM
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Herman the German
