 D-jet idle and lean issues. |
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| Literati914 |
 Jun 27 2025, 09:41 AM
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Senior Member  Group: Members Posts: 1,983 Joined: 16-November 06 From: Dallas, TX Member No.: 7,222 Region Association: Southwest Region  |
1.7 w/ original D-jet.
I have the idle screw on the TB cranked all the way down/closed (which doesn't seem right tbh) and the car's idleing around 900rpm - which is within the recommended 850+/- , and the idle does not really "surge" too much but is not necessarily rock steady either. I'm also getting a steady 16.5 A/F on my gauge during idle and warm driving. So too lean. BTW, the CHT gauge has never gotten over 300 so it's not trying to over heat. I'll be spraying the vacuum connections to see if I can find leaks - but other than that, what would be the most obvious culprit(s)? My theory is that the idle screw needing to be closed (for a reasonable idle) is just combating say, a bad AAR or something. Sound logical? What tests can I do to the AAR or other items to look at first? |
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| rjames |
Jun 27 2025, 01:56 PM
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I'm made of metal Group: Members Posts: 4,301 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest 
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You may have a vacuum leak, but it sounds like you’ve compensated for that via the idle adjustment screw. That makes me think the vacuum leak is not the cause of your lean mixture at idle.
Did this condition just suddenly happen? |
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Posts in this topic
Literati914 D-jet idle and lean issues. Jun 27 2025, 09:41 AM
ctc911ctc I vote:
Vacuum leak throttle body and Plenum
Go... Jun 27 2025, 12:58 PM emerygt350 Mixture is unaffected by leaks. Idle rpm is. I a... Jun 27 2025, 02:29 PM Ishley My ‘72 has the idle mixture knob on the ECU. Jun 27 2025, 04:09 PM
emerygt350
My ‘72 has the idle mixture knob on the ECU.
... Jun 27 2025, 04:14 PM Literati914
My ‘72 has the idle mixture knob on the ECU.
... Jun 27 2025, 05:38 PM Literati914 You guys asked if this condition just started - we... Jun 27 2025, 05:54 PM rjames
You guys asked if this condition just started - w... Jun 27 2025, 06:17 PM Ishley My 72 ECU knob does nothing. I have an Air fuel ga... Jun 27 2025, 05:58 PM JeffBowlsby A reminder that the ECU idle mixture knob is only ... Jun 27 2025, 06:40 PM Literati914
Did restoring it include a motor rebuild or a new... Jun 27 2025, 08:02 PM emerygt350 What Jeff said. That is a good sign that your TPS ... Jun 27 2025, 08:06 PM Literati914
A reminder that the ECU idle mixture knob is only... Jun 27 2025, 08:18 PM Literati914
A reminder that the ECU idle mixture knob is only... Jun 27 2025, 08:20 PM brant 16.5 at all conditions seems wrong
Idle mixture d... Jun 27 2025, 08:21 PM emerygt350 Did you set the TPS according to the instructions?... Jun 28 2025, 05:26 AM JeffBowlsby That TPS board is worn out, should be replaced. Jun 28 2025, 08:13 AM Ishley You might want to try a new O2 sensor. I’ve have... Jun 28 2025, 10:45 AM emerygt350 I have been using disposable Amazon o2 sensors. 29... Jun 28 2025, 02:07 PM Literati914 Yes the MPS still has original rivets and opeque p... Jun 28 2025, 08:00 PM JeffBowlsby TPS calibration method 1.7L if you don’t have it... Jun 28 2025, 08:58 PM emerygt350 These cars will do fine without the TPS so it can ... Jun 29 2025, 04:02 AM Literati914 Yea I think I actually have two separate issues go... Jun 29 2025, 11:49 AM |
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