 More D-Jet, High Idle Lean Mixture |
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| ggress |
 May 16 2014, 08:01 PM
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#1
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Newbie  Group: Members Posts: 6 Joined: 11-May 14 From: Oregon Member No.: 17,334 Region Association: None  |
Just getting a '74 2.0 running that I purchased few years back. Replaced all fuel lines, vacuum lines, and FI Harness. It runs better than I expected but not good enough.
It idles too fast (1300 / 1400 RPM) considering throttle valve bypass screw is all the way in. Also, it runs lean (using WB A/F meter). I have set the mixture adjustment on the ECU full CW to get mixture around 13.7:1. I think I have covered all the common vacuum leak issues described in other threads. Any suggestions appreciated. I have two specific questions below. 1) Is my ECU P/N correct? The base P/N is correct but not sure what the 090 suffix means. 2) With the throttle valve bypass screw turned in full CW there is still vacuum getting past the screw. Does anybody know if that is normal ? I can put my finger over the port and feel vacuum. Maybe by design it is not meant to provide positive shut off but I don't have enough experience to say one way or the other. Thx   |
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| ggress |
May 18 2014, 10:59 AM
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#2
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Newbie Group: Members Posts: 6 Joined: 11-May 14 From: Oregon Member No.: 17,334 Region Association: None |
I agree, it has to be a vacuum leak /s of some kind. I have ruled out the common leak sources mentions. I think there are a couple small leak sources rather than one obvious one. Going to try and find a smoke machine to confirm item 2 below.
1) After inspecting my TPS adjustment multiple times I found that I was over adjusting it in order to get the switch to operate properly. As a result the stop in the TPS switch was holding the throttle valve slightly open. The throttle valve shaft is worn (wobbles) this caused me to over adjust TPS to get proper function. I removed the TPS and jumped the switch so the throttle valve would be in a closed at idle. It helped but isn't the silver bullet. I plan to get the throttle valve rebuilt. Recommendations ? 2) This one has me scratching my head. Is it possible ? It looks like the manifold box / plenum is leaking where those hollow standoffs are brazed in. Has anybody seen this before ? Thx |
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| ChrisFoley |
May 18 2014, 11:36 AM
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#3
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I am Tangerine Racing Group: Members Posts: 7,992 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None 
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QUOTE(ggress @ May 18 2014, 11:59 AM)  2) This one has me scratching my head. Is it possible ? It looks like the manifold box / plenum is leaking where those hollow standoffs are brazed in. Has anybody seen this before ? Thx I've seen 2 liter plenums cracked on the bottom - where its difficult to find the leak. |
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Posts in this topic
ggress More D-Jet May 16 2014, 08:01 PM
Montreal914 You need to make sure everything is set properly s... May 16 2014, 08:46 PM Dave_Darling It's normal for air to still get through the b... May 16 2014, 09:00 PM luskesq I had a slightly high idle issue with my 1.7 (1200... May 16 2014, 10:02 PM ggress Thanks for the input !!!
I am famil... May 16 2014, 10:48 PM JawjaPorsche Chasing a vacuum leak is a pain. Have you replace... May 17 2014, 04:56 AM era vulgaris I'm in the same boat as you, except I've g... May 17 2014, 06:29 AM Jeff Bowlsby Nice to see you here Gary!
Here is one method... May 17 2014, 08:02 AM Spoke You can locate vacuum leaks pretty easy with carb ... May 17 2014, 09:40 AM
worn
You can locate vacuum leaks pretty easy with carb... May 17 2014, 12:25 PM 914_teener You can take out the plenum and use a eak penetran... May 18 2014, 03:47 PM boxsterfan Change your intake runner boots, intake manifold g... May 18 2014, 04:20 PM boxsterfan Change your intake runner boots, intake manifold g... May 18 2014, 04:20 PM ggress Everything is new, injectors / seals, FI harness, ... May 18 2014, 05:38 PM |
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