390 running problems as as soon as engine is warm.

[maston]

Hi All,

I would just like your opinions please on this running fault.
I have my own idea but would just like to hear from you guys too please.
My 390 when started from cold runs well (no missfiring or anything) but as soon as the engine warms up and the fast idling finishes it missfires badly, very badly !!!
What do you think the problem is please ?

I look forward to your replies.

Many thanks

regards

[mrzigazaga]

Hi Ian…Just wondering if its the same thing that was happening when we went to Jennings to look at Phil's SEAC..Im sure that your car was warmed up then?..Could this be something not related to temperature?..Just thought i would ask mate..Cheers..Ziga

[maston]

Hi Mark,

It is mate but now does it as soon as warmed up from cold.

[mrzigazaga]

Mmmm…Could it be a dodgy wire?..Maybe there is something that is near either the engine or exhausts that has a fault and when it gets hot the wire expands and pulls apart..What state are your HT leads in…Cheers…Ziga

[smash]

You're not losing any fluids are you?

[maston]

I am hoping it is a knackered cts (coolant temperature sensor) ?
I have got a new one and will try it.
Do others agree it could be the probelm please ?
Thank you

[maston]

Smash , funny you should say that but I was yes as had a burst hose from the water pump , now fixed

[maston]

bump

[QBee]

390 running problems? that's a lot of problems to solve.....

[QBee]

Get hold of a mate with a similar car and a kindly nature, and swap over the coil and try that. And then the lead to the dizzy. Then the dizzy cap. And then the HT leads. It sounds to me like electrical insulation is breaking down with heat.

[superwedge]

i had the same thing .its the tem -
sensor,

[njhucker]

Sounds like the temperature sensor. Not the coolant temperature sensor, but the one that is part of the efi system

[njhucker]

Sounds like the temperature sensor. Not the coolant temperature sensor, but the one that is part of the efi system

[adam quantrill]

Agreed, in bad cases it chucks out lots of sooty smoke when you rev it.

[Jack Valiant]

After this afternoon fella I was just thinking that the mis fire on or over 5k revs may be the rev limiter / bob weights in the dizzy.

Get the correct temp sensor and a set of new NGK plugs and the job will be a good un.

Like wise get the correct connectors and clips for the coolant hoses. More importantly the beast is running again!

Chris

[QBee]

Any news OP? I don't mind being wrong, but would like to add the solution to my knowledge database if possible. Temp sensor is now lodged for the future.....

[maston]

Firstly, big thanks to Chris (Jack Valiant) who popped over yesterday, I would be lost without Chris' endless help and expertise

Now, went out in again today, the running was intermittent again.
Parked up for a bit and then when I started it it was missfiring straight away (engine was cold too).
Bonnet up, time to have a look again.
I think what may have been happening is a couple of the leads (cheap silicone jobbies) may have been arching over each other etc (number 3 and 5 HT leads were touching each other) and as I wiggled number 3 lead suddenly no miss fire and perfect running !!!
For the short journey home (5 miles) is was perfect
I have now repositioned all the leads so that none of them are touching each other and will see how it drives this week.
In the meantime I have ordered the correct cts which I will collect Monday.
I will keep you all informed.
Regards

[mrzigazaga]

maston said:

(cheap silicone jobbies)

Ian…Do yourself a favour and get some good quality HT leads..Do not buy cheap and nasty ones…Please…Some things are false economy and thats one of them!..Ziga

[QBee]

Glad you possibly have a resolution. Can I beg that you park the cts for at least a couple of weeks, unless the problem returns? It would be so nice not to confuse things by changing two things at the same time.

[Jack Valiant]

Ian....... As I said, get the correct sensor on as the one you had was incorrect and who knows the history of the other one!!!

Re the leads, those ones you have are nasty to say the least ... as Zig mentions invest in good quality set. As I said get some new NGK plugs into her and check the plug shrouds as they can cause issues when old. Do not fiddle with other issues until those are all done as you will be chasing down blind alleys and even introducing other problems due to rushing.... Do it right and do it once!!!!!!

Chris