(T) Argh! Bl**dy Cinq!

Right, Originally I had a cold running problem (bit of a misfire when cold) despite having changed a heap of stuff. Concensus of opinion was that the head gasket was on it's way.
Not having the money to do the head gasket but having a low miles nice runner in a stuffed shell I swapped engine and box over C**tmas Hols.
All went well until I first switched the ignition on. Flashing injector light before start, on constantly after start and running a bit oddly. Turned it off, checked all the connectors. All seemed to be plugged in so restarted, injector light comes on then goes out as per normal. Seemed to be running alright apart from injector being really loud. Swapped injector for spare one, switched ignition on, went to start, hydraulic locked. Swapped injector back, took plugs out, span it over, covered everything in the garage with fuel, put plugs back in. Started, took out for a spin, great when cold, really pleased until it warmed up
Horrible misfire under load at below 3,000rpm with throttle wide open but not if throttle only just open.
Rev from tickover, i.e. just stamp the pedal to the floor and it's misfiring until it goes past 2,500 rpm, however if you open put the pedal down a little the revs build cleanly.
Can anyone help 'cos at the moment it feels like I've spent 2 days of my time off work turning 2 fairly nice running cars into 1 that doesn't run particularly well

That is a PITA!

I would have thought 2 days of your life would be worth more than the £60 for the HG kit, and a skim, but as you've done it now I guess your stuck.

Are they both exactly the same enigne, ie. both cinq 1.1's?

KRistian

Ah yes, but I had the two days and I didn't have £10 let alone £60!

And yes, both 1.1 sporting cinq.
The new one feels quicker and more responsive once you get past the misfire.

If its the same ECU, was it left disconnected long enough to reset? Or is it more servere than just a learning issue? The ECU would still be expecting the old and rather different engine.

Kristian

Have you Checked the timing and crank sensor gap? is there a spark from all plugs

I've reset the ECU after driving it the first time, just in case and no difference

Split map sensor pipe or connector.

Cheers

D

im going for the the tdc they can cause all sorts of weird problems, trying cleaning to start off with

Just been outside and pulled the map sensor pipe off at the inlet, sucked and stuck my tongue on. It stayed stuck. The pipe has got a tiny bit of slack when it's pushed all the way on though, would a small air leak there cause these symptoms?

doubtful, but when i had a bit fall out the carb on my old skoda, bluetac was a temporary seal i used, if you have some lying around, its a 2 sec job to check

Just been out and with the help of some blutac scavenged from the C**tmas decs tryed sealing it. No change. Bugger!
On a carb car an air leak would raise the tickover but does the ECU do something with the idle stepper motor to keep the idle in the right place?
When I rev it and back off it drops to 1100 or thereabouts then gradually drops to 900-950ish. If you rev it when it's still at 1100 it seems to rev cleanly but if you let it settle to the lower idle it misfires when you plant it.
Is the engine 'under load' if you stamp the throttle at idle in neutral?

900-950 idle is normal and fine. I'm not sure about the misfire, I have never tried "planting" the throttle from idle, especially in neutral, but i doubt any car would like that

It's not a switch after all, and i'd imagine if doing that it will just chuck loads of fuel into the cylinder before compression, hence the misfire.

Sorry mate but I'm out of ideas.

Kristian

I had the same problem.

It was the throttle potentiometer. £30 and 5 mins later, runs a dream.

If you have a spare throttle body pinch the TPS (throttle potentiometer), swap it and see what happens, just make sure the battery is disconnected when you connect the TPS it or it'll spark it out (according to manufacturer...) and make sure you use threadlock on the torx screws, as they are not supposed to be used again!

It kind of is a switch, The mechanical part of opening the throttle opens a flap which allows lots of air to be sucked into the inlet manifold. Electrically, if I've got this right, the throttle position sensor sends a signal to the ECU telling it that the throttle is wide open, at the same time the flap being open causes the vacumn in the inlet manifold to drop, which in turn makes the map sensor send a different signal to the ECU, which in turn does something to the ignition timing and injector.
What i can't figure is whether my 3 month old Fiat leads are breaking down, or my 3 month old plugs are breaking down, or i've got too much fuel (slight leak on the injector o-rings?) or too little fuel (air leak) or if one of the electrical bits and bobs isn't doing what it's supposed to be doing when the engine's under load and making it misfire.
If, for instance, you're trickling along in traffic at 2500 in second and the car in front pulls away, when you push the throttle to the floor, you get a split second nose dive, a pop, and then misfiring acceleration up until 3800, when it pulls like a train til 5800. This is making it unpleasant to drive on my commute as you've either got to drive on a nearly closed throttle or keep rowing it to keep the revs above 3800.

hmm, when it backfires etc do you get the injector warning light, if so it will most definately be a sensor to blame, which it sounds like that is the case... lambda sensor maybe if cool when cold then dodgy when hot?