 D-Jet: Can you compensate for Throttle Shaft air leak? |
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| jrmdir |
 Dec 7 2021, 02:37 PM
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Member  Group: Members Posts: 224 Joined: 13-May 21 From: Central Ohio Member No.: 25,544 Region Association: Upper MidWest 
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After months of chasing a rich condition on my '73 1.7 I decided to once again try pressurizing the system and applying soapy water. Glad I did because I found two more leaking hoses and a leaking Cold Start Valve gasket. But the worst culprit turned out to be a leak around the throttle shaft.
There are a number of threads about options for adding bushings and or seals, but am I right in thinking this would mainly impact idle mixture? If so, I'm wondering if other system adjustments, e.g. ECU knob and/or MPS could overcome the effects of this leak - at least until I find a machine shop to fix the TB. Thanks in advance for any suggestions. Ron |
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| emerygt350 |
Dec 7 2021, 09:17 PM
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Advanced Member Group: Members Posts: 2,151 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
I never really connected that with idle. I assumed when the djet knew it was at idle (the TPS tells it so) that it just ignored the mps and determined a mix based on ECU parameters. I sort of doubted that since mps adjustments appear to alter idle richness.
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| 914_teener |
Dec 7 2021, 09:32 PM
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914 Guru Group: Members Posts: 5,205 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
QUOTE(emerygt350 @ Dec 7 2021, 07:17 PM)  I never really connected that with idle. I assumed when the djet knew it was at idle (the TPS tells it so) that it just ignored the mps and determined a mix based on ECU parameters. I sort of doubted that since mps adjustments appear to alter idle richness. The TPS will help with driveability and adds enrichment for acceleration. You can drive the car without it...but it will "buck" somewhat. So driveability is different than AFR readings. Think like this: Your accountant tells you what youv've spent.....your needs and desires decide what you spend on. |
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Posts in this topic
jrmdir D-Jet: Can you compensate for Throttle Shaft air leak? Dec 7 2021, 02:37 PM
emerygt350 How much left on the idle adjust screw? If that i... Dec 7 2021, 03:24 PM JamesM Leak wont affect mixture with d-jet, just idle spe... Dec 7 2021, 03:38 PM
914_teener
Leak wont affect mixture with d-jet, just idle sp... Dec 7 2021, 09:15 PM emerygt350 Little curious about a rich condition and vacuum l... Dec 7 2021, 03:41 PM r_towle It’s unmeasured air.
I agree that you could turn... Dec 7 2021, 06:26 PM emerygt350
It’s unmeasured air.
Which should lead to a ... Dec 7 2021, 06:47 PM jcd914
It’s unmeasured air.
Which should lead to a... Dec 7 2021, 07:01 PM Dave_Darling
So vacuum leaks in D-jet cause a rich mixture.
... Dec 7 2021, 10:24 PM JamesM
It measures manifold vacuum and temperature.
The ... Dec 8 2021, 01:13 AM JamesM
It’s unmeasured air.
I agree that you could tur... Dec 7 2021, 07:00 PM r_towle
It’s unmeasured air.
I agree that you could tu... Dec 7 2021, 10:26 PM jrmdir Thanks to everyone for the great input.
I had a D... Dec 8 2021, 08:51 AM emerygt350 Just out of curiosity, what do your plugs look lik... Dec 8 2021, 10:29 AM |
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