 RPM Surge After WOT, Weird Idle, Worried I’ll damage my engine |
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| drewvw |
 Aug 23 2019, 07:40 PM
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#1
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new england car guy  Group: Members Posts: 1,631 Joined: 24-February 06 From: Boston, MA Member No.: 5,630 Region Association: North East States  |
Hi All, experiencing a tricky problem and I’m worried I’ll blow the engine if I don’t figure out.
73 1.7, fly cut heads, SSI/aftermarket exhaust, mostly stock otherwise. Core Symptoms: - Idle rpm inconsistent. Steady, but it seems to keep changing its mind on whether it’s 400, 1000, 1500. Decides again after you’ve been driving and slowing down for a stoplight or something. Gets a bit better when warm. - If I floor it, when I change gears the RPMs continue to zoom to redline levels. Can’t say for sure it’s an air leak type of surge, might be sensor or linkage (investigating next) based. Does not seem “floaty” like air if that makes sense, more hard. I’ve owned the car a long time and it general it runs great. But this has been an issue all summer. Just replaced exhaust and shored up SSI. Pretty Thorough review of vacuum lines, points, sensors, timing, etc. Swapped in another MPS. Looking for ideas here, tonight was scary with the RPM revs. Will update as a evaluate more. Thank you are any help! Drew |
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| theer |
Aug 23 2019, 07:59 PM
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#2
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Senior Member Group: Members Posts: 691 Joined: 31-July 15 From: Dover, MA Member No.: 19,014 Region Association: North East States 
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Throttle cable sticking... return spring weak/broken?
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| dr914@autoatlanta.com |
Aug 24 2019, 08:58 AM
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#3
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914 Guru Group: Members Posts: 8,161 Joined: 3-January 07 From: atlanta georgia Member No.: 7,418 Region Association: None |
I would agree to first check for a sticking throttle cable. THEN
Check the vacuum retard/ advance, and the advance weights check the decel valve check the aux air valve check in general for vacuum leaks, most probably a split in a vacuum elbow, or a hose directly connected to the intake manifold QUOTE(theer @ Aug 23 2019, 06:59 PM)  Throttle cable sticking... return spring weak/broken? |
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Posts in this topic
drewvw RPM Surge After WOT, Weird Idle Aug 23 2019, 07:40 PM
Rand Sounds like a vacuum leak. Are we to assume it is ... Aug 23 2019, 07:47 PM
drewvw Yup, stock D-jet. Have put in a good amount of ti... Aug 23 2019, 07:56 PM Rand What would fly cut heads and ssi exhaust have to d... Aug 23 2019, 07:58 PM drewvw
What would fly cut heads and ssi exhaust have to ... Aug 23 2019, 08:04 PM theer double post Aug 23 2019, 08:00 PM Rand No, sticking cables don't cause hunting, they ... Aug 23 2019, 08:02 PM 76-914 Sounds like the MPS is going south. :beer2: Aug 24 2019, 08:46 AM Rand Hey Geo, how does a cable cause hunting idle? Stic... Aug 24 2019, 09:00 AM rjames
Hey Geo, how does a cable cause hunting idle? Sti... Aug 24 2019, 06:51 PM Rand
Hey Geo, how does a cable cause hunting idle? St... Aug 24 2019, 10:58 PM drewvw Thanks guys this is helpful. Looking to get back ... Aug 25 2019, 07:59 AM rhodyguy If you disconnect the throttle cable at the thrott... Aug 25 2019, 10:08 AM drewvw I've done another round of investigation, here... Aug 29 2019, 12:31 PM |
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