Engine miss when hot

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John Alves
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Engine miss when hot

Post by John Alves »

Hi all
I have a new addition to the family, a 1968 1500sp beetle which I am slowly sorting out.
The latest issue is a slight engine miss when cold, after the motor is warmed up, she runs like a bomb,
Any ideas on trouble shooting this?
Last edited by John Alves on Sat Dec 15, 2018 5:26 pm, edited 2 times in total.


No sense being pessimistic. It wouldn't work anyway.

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Re: Engine missing when cold

Post by 73type2 »

Perhaps electric choke is not set correctly?
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Re: Engine missing when cold

Post by fig »

Check your manifold heat risers. They are probably blocked.
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Re: Engine missing when cold

Post by Tony Z »

fig wrote: Mon Oct 01, 2018 3:29 pm Check your manifold heat risers. They are probably blocked.
aftermarket exhausts sometimes have ports for the heat risers, but they are usually designed wrong and dont allow flow, so they block with carbon

also, check for vacuum leaks
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John Alves
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Re: Engine missing when cold

Post by John Alves »

choke is working, heat risers are blocked off, my other two air cooled cars don't have heat risers and have no issue ????
I have checked for vacuum leaks, will check again
did all the usual when I bought the car, points gap, valve gaps new plugs, set timing, replaced dizzy cap with one I had lying about.

could it be a sticking valve which loosens up with heat?
No sense being pessimistic. It wouldn't work anyway.

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Re: Engine missing when cold

Post by Tony Z »

try advancing your timing 2-3 degrees
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Re: Engine missing when cold

Post by John Alves »

thanks Tony that did the trick
No sense being pessimistic. It wouldn't work anyway.

1958 1600 TP Karmann Ghia
1968 1600 TP Beamish buggy
1968 1500 SP Beetle
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Re: Engine missing when cold

Post by John Alves »

Worked for a while and them came back with vengeance, I replaced the dizzy and coil from my other ride and all is 100% now.
Could it be a faulty Chinese condenser? I don't have a spare condenser as all my other rides have been converted to electronic pick up
No sense being pessimistic. It wouldn't work anyway.

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Re: Engine missing when cold

Post by retrovan »

Bash the sides of the condenser with the flat side of a spanner, and it will work again,

Till you can get a Bosch condenser from Diesel Electric.

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Re: Engine missing when cold

Post by John Alves »

The saga continues, I now have a minor miss when cold, runs ok for about 20min and then miss comes back when engine is warm, It feels like a total loss of power but for such a short time and not steady, I connected a multi meter to the coil positive and ground and as the miss happens so the voltage drops to about 10v then back up again,
Is this an indication of a intermittent short on the coil power wire or could the voltage drop also be caused by something else?
No sense being pessimistic. It wouldn't work anyway.

1958 1600 TP Karmann Ghia
1968 1600 TP Beamish buggy
1968 1500 SP Beetle
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Re: Engine missing when cold

Post by retrovan »

Still sounds like a condenser.

Or bash the bottom of the condenser with the round edge of a 19 spanner to dent it.

But to be sure, fit a blue Bosch coil

Herman
1952 Split Beetle 1835cc
1968 Fastback 2Lt.type4
1972 Low Light Bay Panel Van 2Lt type 4
1975 Fleetline Panel Van 1914cc
2020 MeFusco Beetle Truck 2Lt type 4
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Re: Engine missing when cold

Post by John Alves »

not using a condensor I switched to a working dizzy with igniter system
No sense being pessimistic. It wouldn't work anyway.

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1968 1600 TP Beamish buggy
1968 1500 SP Beetle
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Re: Engine missing when cold

Post by Tony Z »

ignitor system isnt reliable
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John Alves
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Re: Engine missing when cold

Post by John Alves »

I know, but this one was taken from my ghia and is working
No sense being pessimistic. It wouldn't work anyway.

1958 1600 TP Karmann Ghia
1968 1600 TP Beamish buggy
1968 1500 SP Beetle
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Re: Engine missing when cold

Post by retrovan »

May be incorrect coil for the ignition, try moving the coil from the Ghia with the unit and try again.

Herman
1952 Split Beetle 1835cc
1968 Fastback 2Lt.type4
1972 Low Light Bay Panel Van 2Lt type 4
1975 Fleetline Panel Van 1914cc
2020 MeFusco Beetle Truck 2Lt type 4
1972 FT Hahn SP 1776 cc
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