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| mgphoto |
Feb 10 2026, 11:46 AM
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#1
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"If there is a mistake it will find me" ![]() ![]() ![]() Group: Members Posts: 1,431 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
About a year ago my usually good running engine began to stumble, slight backfire through the exhaust, between 1000 to 3000 rpm. I first suspected an electrical fault, as I would shake wires in the engine compartment and the issue would be gone.
This happened several times with different wires. I decided to tin the ends of the wires attached to the positive battery terminal. This seemed to work, for a while. I began testing other wires for the D-Jet, I had success with reattaching the TPS connector, for about a day. I began following a post about a member who had trouble with his 123 dizzy, his issue was related to the D-Jet pulse producing erratic fuel delivery. OK, spoke with the tech person at 123 in Europe, we could test it using an oscilloscope. I have a small pocket unit that I can test it with. This past Sunday I decided would be a good time do the test. My plan was to take the car out for a warm up drive, once around a freeway loop gets my oil temp needle to move. After exiting the freeway, I stopped at a traffic light and the car stalled, I’m used to that happening sometimes as I have a lightened flywheel, but this was different, like I turned the key off. I turned the key to restart the engine but it sounded like a rattling chain, I never heard that sound before. I tried the starter again, now it had the typical hot start problem, after a moment I got it to run but the idle was now at 3400 rpm. Since I could control it I drove it home and began checking simple things like throttle cable, TPS loose, MPS held some vacuum using the suck test. I’m going to take a closer look at the throttle body. Anyone have their D-Jet idle jump to 3200 rpm and what was the reason? Thanks, Mike |
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| rjames |
Mar 12 2026, 09:48 PM
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#2
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I'm made of metal ![]() ![]() ![]() ![]() Group: Members Posts: 4,448 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest
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Check the Plenum too. They rust out from the inside.
If it hasn’t already been suggested and you haven’t re-tried it yet, do a smoke test to see where the leak is. |
mgphoto Chasing a Ghost in the Machine Feb 10 2026, 11:46 AM
brant Return spring maybe Feb 10 2026, 11:50 AM
76-914 spot weld failure on the clutch cable tube? :beer2... Feb 10 2026, 12:14 PM
Dave_Darling A 3200 RPM idle is an air leak. A *BIG* one. Che... Feb 11 2026, 01:28 AM
JeffBowlsby The MPS mouth suck test is completely irrelevant, ... Feb 11 2026, 08:42 AM
pbanders Good advice from all. I've found that finding ... Feb 11 2026, 01:42 PM
mgphoto Big air leak!
Major clue, going to check it in... Feb 12 2026, 09:41 PM
mgphoto Ok, I’ve gotten this far.
I removed the air filt... Mar 9 2026, 12:32 PM
914sgofast2 I would suspect your AAR valve has gone bad and ne... Mar 9 2026, 12:47 PM
emerygt350 that t that the pcv goes to on a 73 is often the c... Mar 9 2026, 12:47 PM
bkrantz Is starter spray (ether) still a thing? Spray thi... Mar 9 2026, 06:50 PM
76-914 Disconnect everything from the vacuum side except ... Mar 9 2026, 09:10 PM
mgphoto Don’t see the AAR as the issue as it hasn’t wo... Mar 11 2026, 06:04 PM
emerygt350
Don’t see the AAR as the issue as it hasn’t w... Mar 12 2026, 09:40 AM
mgphoto
Don’t see the AAR as the issue as it hasn’t ... Mar 12 2026, 01:25 PM
jim_hoyland I had an air leak caused from a faulty 3-way conne... Mar 13 2026, 05:56 AM
mgphoto Ok, I pulled the hoses on the plenum, there is a r... Mar 16 2026, 01:14 PM
rjames
Ok, I pulled the hoses on the plenum, there is a ... Mar 17 2026, 04:47 PM![]() ![]() |
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