aright guys
i hav just had to fit a new 1.25 (couldn,t insure bigger ) in my mk4 fiesta. everything is working good but im not getting a spark.
we have checked the voltage and its all correct appart from the wire into the coilpack which is reading around 8 volts.
we have tried a new cps but still no luck.
we think it might be because we have used the old fly wheel off origonal engine (1998 new one 2000) other thought is that i might need a new ecu.

CAN SOMEONE PLEASE HELP !!!!

cheers

 

engines not from an auto is it?

 

if you have wrong flywheel then the cps wont be getting the correct signal mate

 

Yeh its deffo a manual and sweet when I next have time ill try the flywheel.
I'll keep you posted
Cheers

 

the fly wheel is giving out a full voltage its weird.
does a mk4 fiesta have a way of checking for faults for example a obd?
cheers

 

Yes the diagnostic plug is in the passengers footwell behind a blanking trim on the "A" post.

I have seen this twice before though, it would crank but wouldnt start, no spark. it turned out to be water ingress to the module. Left it on a radiater over night (with the top removed) (the bolts are a strange imperial size, 7/32" springs to mind) and it fired up fine once refitted!

I siliconed the top on the module and siliconed up any gap on the module and as far as i know the car is on the road today, albeit with wet carpets as the owner of the car didn't want the water leak investigated! !

 

You need an oscilloscope to read the CPS. As the voltage is flicking on/off so fast, you will never see a 12v read on a normal volt meter. I presume the coil pack centre wire has a 12v feed. Get a scope on the outer 2 wires and check for coilpack feeds

Matt

 

my cps on the mk 3 FRS went south for me, if you get a scope you should see a square wave signal for cps input and output to the coil pack.

hope this helps: http://www.picoauto.com/tutorials/trigger-signals.html

 

Cheers again guys I defo think I will try the whole radiator thing

 

what module James?

 

another way of checking cps output is to put a meter on ac volts and connect to cps then crank.should read between 0.2 and 2volts

 

We also have no fule injection

 

Just read your original post again. You said the coil pack middle wire is reading 8 volts. Have you tried a new battery? 8 volts won't be enough to power a 12v coil pack or a 12v fuel system!

Matt

 

engine management module/ecu/pcm.

in the passengers footwell on the A post

 

Yeh we realised that the 8v was the problem we Wer trying to don't the cause.
My m8 is a machanic but he is a vag man haha. N cheers again James gonna get that out tonight

 

Right. Ecu was taken out and dried. Still no joy. The cps wont give out 12v as it is there for a small signal only to tell the ecu when to fire the plugs and the injectors.... The battery was drop charge tested and was fine... Even tried it with another battery in parallel to make sure. Checked all injector conectors for feed and all reading 12v. Checked all wires and no damage. (doesnt help there all black and a nightmare to trace) in my honest opinion the car is beyond economical repair.

 

Was the car a 1.25 before? And if so have you fitted the same style engine? I.e blacktop?

If you have mixed and matched engines and flywheels you may just need the other cps.

Matt

 

if you have a scrap yard near you you can hopefully pick up a cps for a fiver!