help with a missfire on a highly modified pinto engine

[drifter69]

hi guys I have developed a misfire on my 2.2 pinto its in my sierra hatch that im building it starts off when I give it some pace over 5000rpm but one it develops the misfire its then all through the revs and the rev counter bounces around all crazy like its running on r1 bike carbs and elec dizzy with coil just wondered if anyone had anything like this in the past or may have an idea what it could be thanks in advance

[Megaflow]

The fact it starts off above 500rpm, and then effects lower rpm, makes it sound electrical to me. What electrical dizzy is it?

Does it get worse as it gets hot?

[drifter69]

it has a burton dizzy and yeah it seems to get worse when hot so I cant even get over 50mph also u can hear a sort of ticking sound when under load when its misfiring im thinking electrical too

[andyiley]

Try replacing the coil with any old cheapy from your local scrappy as a test.

I had exactly this some years ago twice on 2 different cars, the coil broke down under high load & temperature.

[drifter69]

the coil stays freezing cold it never gets even warm

[RC Developments]

Do you have an electronic rev limiter? they can be a good cause of misfires!

[drifter69]

no all electrics I have is rev pod coil dizzy plugs and leads and the lil box on the inner wing for the dizzy

[Megaflow]

I had a misfire on a x/flow many years ago that started at higher rpm when hot and got worse until it stopped. It was the Lumenition box for the dizzy.

Does it back fire at all? If so, I've got a pint on the dizzy, the circuit is breaking down when hot causing the timing to jump around.

[marshalla]

I had a weird misfire on my X-Flow powered Westfield. Problem was that the rev counter was the wrong sort for the electronic ignition. After a while, the rev counter would overheat and start to break down, resulting in bad timing of the coil and rev counter needle bouncing all over the place.

[drifter69]

should I try and get another one of them black boxes then you think

[Pumaracing]

Take the spark plugs out and see if the gaps are correct.

[callyman]

The fact you can hear it 'ticking' sounds like a HT Lead shorting somewhere.
On my C20LET I had the same, drove lovely ubut under load lead 4 was shorting onto rocker cover (hidden)
A new set of Magnecors fixed that.

[andyiley]

drifter69 said:

the coil stays freezing cold it never gets even warm

That means nothing, mine werent hot to the touch either, it is VERY localised heat within the windings deep inside the coil itself that was the issue.

Beg/steal/borrow the cheapest one you can, as I said, & give it a try to eliminate it.

[TheExcession]

Can you get it to the stage of misfiring when it is dark outside and then lift the bonnet and have a good look around all the HT stuff in the dark?

Years back I had an old Supra that would miss fire on long journeys, it was only after stuttering to a stop on the drive one cold winters night that in desperation I threw the bonnet up for a look.

The light show was quite impressive, sparks were leaping from the HT leads to the block and the coils looked like there was a disco going on inside.

Replaced the lot with second hand stuff and it ran perfectly again.

[drifter69]

right I have just been given a brand new ht from burtons and it seems a little better but still slightly there and the flat spot is still there so tomorrow I shall grab some ht leads aswell and give that a try I shall let u all know what happens with that thanks guys

[PaulKemp]

Your running a 2.2 on standard ignition
The compression will be higher than standard, no bad thing for a Pinto, what can are you running?
The ignition curve may be too flat
It may be pinking your hearing try backing off the ignition timing a few degrees, if the problem lessens then the problem is ignition timing

[Athlon]

Bob weights sticking when you push it so messing the advance when you back off?

[PaulKemp]

I've had great success with Megajolt

[Mr2Mike]

drifter69 said:

the coil stays freezing cold it never gets even warm

Is it not mounted within the engine compartment then?

[drifter69]

its mounted on the inner wing