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New 3.4 motronic build won't idle
Hello
I bought a nice rebuilt motor from the late Fred Apgar which is a 3.2 to 3.4 build. It has the Sal Carcellers ECU and throttle body etc....programed to the upgraded specs. of the engine. It also has a lightened patrick racing flywheel, power clutch and clewett crank pulley. Upon first start up I can't get it to idle. Checked for vacuum leaks everywhere and no issues. Fuel pressure is good. I also had an issue with the coil but got that replaced to get it to fire. It revs strong Any ideas? Bob
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Banda 69 911T 3.4 ltr. Outlaw build 72 BMW 2002ti Alpina "Pig Cheek" build |
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03-29-2024, 09:28 AM
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Try not, Do or Do not
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Check to make sure all your grounds are attached properly.
Trans to chassis and harness to left side intake stack.
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Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net |
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03-29-2024, 10:04 AM
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Thanks Henry, I am going to double check the ground wires as you recommended. Also someone else suggested the ECU was not picking up the Patrick racing flywheel signal but I have no idea if that is possible.
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Banda 69 911T 3.4 ltr. Outlaw build 72 BMW 2002ti Alpina "Pig Cheek" build |
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03-29-2024, 01:18 PM
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PCA Member since 1988
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"Compression, fuel, spark."
You probably know this, but sometimes we all get fixated on what we "think" is the problem, instead of making sure. What testing have you done to determine whether you are lacking fuel or spark? A quick check is to squirt starting spray in the intake to help get it started, and to continue short bursts of spray after it starts to keep it running. If the starting spray does not help it start or run, then you are back to spark. If it helps, then focus your troubleshooting on fuel.
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! Last edited by PeteKz; 03-29-2024 at 10:34 PM.. |
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03-29-2024, 03:54 PM
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The 9 Store
Join Date: Dec 2009
Location: Wilmington, DE
Posts: 5,320
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Fred was a great guy and I’m sure you have a special engine. Good luck with the tuning.
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All used parts sold as is. |
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03-29-2024, 04:56 PM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
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No direct experience, but I've heard that the Motronic can get confused by a light flywheel, and can corrected by a tune. Might be worth checking with Sal Carcellar to see if your configuration is compatible.
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03-30-2024, 05:30 AM
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,115
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If it runs good but won’t idle, it’s all in the tuning resulting from the light FW. Sal, I bet can fix that up in the tune.
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03-31-2024, 06:48 AM
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Registered
Join Date: Jul 2021
Posts: 686
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Just in case it's a revvy motorsport engine, if there's overlap in the cams you won't have compression at low revs, in which case it will never idle smoothly. You will need to up the idle speed.
What's the redline? Sent from my SM-G988B using Tapatalk |
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03-31-2024, 06:55 AM
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Porsche
Retor 911
Scarab
Riley
