[Warning Light] random engine misfire

[raptor]

hey guys, i did have a post up - but its been deleted during the hack, so here it is again.

After an engine swap 1.4i, ecu made by sagem. the new engine doesnt seem to be running correctly.
On idle it's fine and ticks over nicely, however when on a short drive it keeps registering fault code P1336 along with other linked codes with the message random misfire. after googling this code, it comes up with crank sensor, injectors and the spark plug rail all being possible faults, with no definitive answer. my question is, is this possibly the ecu still in a limp home mode ? which is most likely to be causing the fault? and if the old catalytic converter is packed up ( from the explosion of water and oil running through it) can it also be causing the misfires from backed up pressure? or is that just a google answer.
thank you

[brajomobil]

hey guys, i did have a post up - but its been deleted during the hack, so here it is again.

After an engine swap 1.4i, ecu made by sagem. the new engine doesnt seem to be running correctly.
On idle it's fine and ticks over nicely, however when on a short drive it keeps registering fault code P1336 along with other linked codes with the message random misfire. after googling this code, it comes up with crank sensor, injectors and the spark plug rail all being possible faults, with no definitive answer. my question is, is this possibly the ecu still in a limp home mode ? which is most likely to be causing the fault? and if the old catalytic converter is packed up ( from the explosion of water and oil running through it) can it also be causing the misfires from backed up pressure? or is that just a google answer.
thank you

If you think that back pressure is causing the misfire then remove lambda probe from exhaust but leave it plugged in so ECU can read it and make a short drive. Check for codes.
Or remove catalytic converter and make a short drive then check for codes.
Or youtube for measuring back pressure.
Also check again the sparks and HT wires. Sometimes HT wires seems visually OK, but they are NOT inside.
Are you sure that engine is ok. Did you test compression on it ?

[Gadgetman]

If the ECU is in limp home mode, the 'check engine light' will be on. No doubt about it...

Is it the same type of injectors on the new engine as the old?
(From the post it sounds as if you used the ECU off of the old engine with the new engine. Which saves a lot of hassle with security codes and such on BSI models, I guess. )
I think older models came with Bosch injectors, and later ones with Sagem?
Anyway, they're not interchangeable, physically, and doesn't really have the same timing, either.

I assume the new engine also used a Sagem ECU so it was a straight swap.
(Other models may have a matching connector, but the pinout is horribly wrong, requiring a swap of the loom... )

If the Cat is blocked, the engine will run for a few seconds, then die...
As suggested by Brajomobil, unscrew the O2 sensor, but don't disconnect it.
DO NOT touch the tip with your bare hands!
If it runs better, you have a partially plugged system.

[raptor]

cheers guys will check this all out on the weekend and get back to you.
thanks again