Help!!!

[M100 TWO]

Ratman it can only be the coil as you have changed both plugs and plug cables
from my experience it is the coil braking down under load
john

[ratman]

I'm not so sure, at this moment, because it seem an electronic cut, like an error (not detected) from a sensor.
I don't want to change parts and parts without finding the real problem!
do you know a way to check the coils?

Thanks!

[DaKa]

This must be a common problem - I recall raising the same issue previously on the forum.
I recently changed the plugs on my car from NGK to another maker and the car was 100% - I could floor it without any misfire.
About 4 trips later and after circa 100 miles since the plugs change, I had a bit of a stall at a road junction and after that it started misfiring under heavy acceleration.
I thought, no problem, change the plugs (I had a spare set) and things would be okay. Unfortunately, it was still misfiring (it came as no surpirise as the plugs I removed had no more than a little tarnish to them).
It makes me think that the problem may be to do with the proximity of the spark plug leads to one another?
I saw a subject on the forum the other day relating to how the cables should be routed from the distributor and wonder whether this may have an affect as mine are not routed as recommended.
I'll try re-routing and making sure of the connections at both ends - I'll then try leaving more space between the cables and avoid pinching them through the cable clips and report if this makes any difference.

[Monty]

It`s always worth having a spare set off coils, as i have found out when my reservoir/exspansion tank over flowed on to the coils.

[Ultimatt]

Just an extra option to consider...

I had a similar problem a few years back. Quite a pronounced misfiring under lots of different conditions.

After much frustrating diagnosis with the help of the guys here, I identified it as being the Coolant Temperature Sensor.

I had no light on the dashboard to indicate that there was a fault.

From what I remember, the sensor had become faulty and was giving a false reading - telling the engine it was -40 degrees or something like that. The ECU then over compensated by running the engine VERY rich causing lots of misfiring and the like.

Check the condition of your spark plugs. Are they heavily carbon covered, or a little damp from all the fuel. I seem to remember that was associated with the problem also.

Matt

[ratman]

I changed the coils and I had a light improvement. I haven’t big misfire only hesitations when I press hard on the throttle pedal.
Only to resume: I had big misfire problems, solved only in part changing the ignition components during 2 month: I have new wires, new coils and no warnings.
I can’t change other parts without finding the problems!

Please, who’s able, can you check my elanscan output during a run before coils’ changement???
Take a look on test 122:
Time 50s to 56s, full throttle on 3rd gear. Coughs, many bangs in the exhaust main fold, no warnings.
Time 124s to 131s 1st gear, full throttle, no full power, no warnings.
What do you think??

[ratman]

dear All,
I have the solution of my troubles:

As you know, I bought a 8mm red wire set for my Elan last September.
I bought this set because my old wires were ruined and my car had a lot of misfire.

I assembled them but the car had still (but less) misfire when it warmed up and under load.

I went crazy 4 months, changing the coils, plugs, filters, checking all the sensors, electrical connection and wires, groundings and so on without finding the problem.

Last week I opened the bonnet after a run and I checked the plugs’ connections finding that the n°1 was completely free, you can pull the connection without any “popping”, it is not enough tight.

So, when the engine warms up, the wire is completely free to be disconnected from the plug.

For this reason the electrical contact with the plug is not firm and causes misfire.
I changed the wire with the n° one of the old set and the car is going properly!!!!!!!!!!!!!!!!!!!!!!!!!
AAAAAARGGHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!! I don’t know if I have to be happy or if I have to get angry!!!!

I thought that I can have a old wire and 3 new (they can’t disturb their selves) but is not really a beautiful thing to see and one cylinder is working with a different voltage; so I tried to repair the new one, finding that it was assembled in wrong way.
I disassembled the metallic plug’s connection from the hard plastic tube (making a big hole in my finger) and I have to test it on the car.

thanks to all for your help.
ciao, F.