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Author Topic: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires  (Read 4363 times)

94daves

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I just replaced the distributor, cap and rotor (along with all the belts, water pump, alternator, spark plug wires) and the engine stumbles around 4500 rpm.  It stumbles at 4500 going into first, second, etc.  Could this be something due to the timing or new distributor?  Or something else?  It did not do this before I put in all the new parts.  Thanks.
« Last Edit: June 02, 2019, 09:53:09 AM by 94daves »
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Rocketman

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Re: Engine stumbles around 4500 rpm - new distributor, cap and rotor
« Reply #1 on: November 19, 2018, 05:53:18 PM »

I would double check everything, make sure none of the plug wires are loose. Have you verified engine timing? Does the car feel like it has normal power up to the point where it stumbles?
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1.8L Turbo All Wheel Drive Capri... the "GTXR2"


94daves

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Re: Engine stumbles around 4500 rpm - new distributor, cap and rotor
« Reply #2 on: November 23, 2018, 10:10:32 PM »

The plug wires are tight.  The car feels like it has normal power up to 4500 rpm.  I just drove it again today and it was doing the same thing.  It's very repeatable.  I have not verified the engine timing.
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Pappy T

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Re: Engine stumbles around 4500 rpm - new distributor, cap and rotor
« Reply #3 on: December 17, 2018, 03:55:49 PM »

Get it fixed ??
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94daves

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Re: Engine stumbles around 4500 rpm - new distributor, cap and rotor
« Reply #4 on: December 22, 2018, 11:51:44 PM »

No, and Iíve stored it for the winter so itíll sit until March or April. 

Does anyone have any ideas?  Could it be fuel related?  It just seems such a coincidence that it started stumbling after I had some work done to it.  Could one of the mechanics knocked something off or loose by accident?
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chukT

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Re: Engine stumbles around 4500 rpm - new distributor, cap and rotor
« Reply #5 on: December 23, 2018, 12:46:12 PM »

With what you had done, I would also suspect the base timing first. Verify that it is set properly as your next step.
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94daves

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Re: Engine stumbles around 4500 rpm - new distributor, cap and rotor
« Reply #6 on: June 02, 2019, 09:52:29 AM »

I'm back at it again to fix this problem.  Timing has been checked and verified by the shop that did the work in 2018 before I put it away for the winter.  There are no codes, no check engine light.  Does anyone have any ideas what could be causing this misfire/stumble at 4500 rpm?
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Rocketman

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #7 on: June 02, 2019, 07:32:46 PM »

I wonder if your new distributor is faulty. Is it new/used/rebuilt? Do you still have the old one? What was the reason for replacing?

I saw a Capri distributor with bad internal bearings cause a miss in the past. The shaft was bouncing around and would not give a reliable signal to the pickup coil at higher RPM
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94daves

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #8 on: June 06, 2019, 04:12:46 PM »

Actually I only replaced the cap and rotor, not the distributor itself. 
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94daves

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I'm back at it again!  I still have the same stumble around 4,500-5,000 rpm.  Could it be bad wires or bad spark plugs?  If the wires were attached in the wrong order on the distributor, would I notice a stumble at lower RPM, too?
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Rocketman

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #10 on: May 20, 2020, 03:57:33 PM »

It could be a faulty cap/rotor or plug wires.

If the plug wires were in the wrong order the vehicle would barely run if it all. But, double check. Cylinder #1 is on the passenger side.

Does the car stumble when revving in neutral?
Have you tried revving the engine at night in a dark area to look for arcing on the plug wires?

A common problem with the N/A is the plastic intake tube - it cracks and opens up creating a vacuum leak. Often on the underside where it is not visible. It may be that your engine is moving enough at 4500rpm to cause the issue. Just spitballing on that one. Will need to remove to do a visual inspection.
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jdp

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #11 on: May 21, 2020, 11:09:28 AM »

I am following this one too.  My wife's NA stumbles at 70 mph which is just over 4000 rpm. I replaced the common ignition system parts twice.  Can't seem to find it either.  She only drives it around town, so it doesn't cause her any issues unless she shifts gears over 4000 rpm.  Being the good husband I am, I told her to never go over 4000 rpm.....smile! 

John
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John

Pappy T

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #12 on: May 21, 2020, 03:36:35 PM »

Hi all, glad we all made it thru the winter ! Just got mine out of mothballs yesterday , still sputters  :-\ .New cap, rotor , wires , plugs, fuel filter too last fall ... no go . It'll be going up for sale pretty soon, not for the issues but we do rv'ing now more and more . Free up garage space too . Oh yeah, grandbaby # 7 on the way too by August , she'll be needing some toys  ;) . 'll be putsin with it as I can and hopefully someone will find a solution other than dynamite ! Stay safe And healthy out there now .
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Rocketman

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #13 on: May 21, 2020, 03:40:09 PM »

Just a reminder. Make sure you've got fresh fuel in your Capris. It can cause it to run poorly
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Pappy T

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Re: Engine stumbles around 4500 rpm - new distributor cap, rotor, wires
« Reply #14 on: May 21, 2020, 05:44:57 PM »

Yep , that too ! A little seafoam doesn't hurt either .
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