How does it run now?

A costly list of parts there, but I noticed the basics have been missed out - have the spark plugs and HT leads been looked at? Could possibly one of the coil packs.

Also, has the electrical connector and loom been checked under the throttle body? It is a big mulitplug/block connector, next to the inlet manifold situated under the throttle housing. Very prone for the wires to chaff through on a pipe near by, causing all sorts of running issues.

 

They were some of the first things I did, coil packs were tested and are operating spot on, spark plugs are new iridium ones, got big fat sparks.

I had the wiring loom completely off and stripped to check it all over and when that didn't change anything I swapped it from a car that had been running, again no change.
I'd changed the inlet manifold to change the injectors and the rest of the wiring and sensors to eliminate that as well but to no avail.
Had the car on a diagnostic yesterday and they said the injectors were pulsing as they should but still giving a P0340 code.
Carried out an electrical test on the cam sensor and that was working although all the symptoms say otherwise.

 

Have you checked the earth lead to the slam panel? Ours broke just before Xmas and just before it came off in my hand it was kangarooing abit.


Have you checked there's no water in the fuel tank and that's not getting to the engine?

 

Last car I heard about doing that it was the precat in the exhaust manifold had collapsed. The one before that was the battery to car body earth strap (as stated above). Have you noticed any rattling at all?

 

After xmas, car started kangarooing and not running properly.

Can you be more precise? In particular...

Does it idle smoothly?
Can you rev it smoothly?
Does engine temperature make a difference?
How bad is it?
Does it misfire every few seconds, once a minute, does it feel like one cylinder or does the whole engine cut out, or is it more like a dramatic loss of power for a few seconds but it keeps running.

Also, have you checked the throttle position sensor - that's come up a few times in recent weeks.

 

You've not changed the plugs, but you've changed the ECU? thats a bit of an odd thing to do......

 

Hi everyone,

thanks for the responses,

Spark plugs, yes they were changed sorry I might not have been clear on that, blocked cat? I hadn't considered that, it has had the rest of the exhaust replaced recently so maybe..... I'll check that anyway, the only rattling was the heat shield on the manifold but I've sorted that.
cheers.

running problems are;

cold starting is almost impossible, if it does fire you have to coax it to rev long enough to warm up a bit or it dies and then won't start again, just keeps firing and dying.(if you tow it that picks the revs up high enough to get it going)
It's a rough as a bears proverbial when cold until it starts to warm.

Once you've got it running the tick over is lumpy - not quite like an ignition miss fire but similar (the P0302 engine code might explain that)

When you try to rev it up its sluggish initially and then picks up once it gets past around 2000rpm (its better when hot)
When you do blip the throttle the engine revs then drop to around 250rpm for a few seconds before recovering to the lumpy idle.
If you rev the engine but help to 'settle' the revs with the throttle it's not as bad but its still there and really not right.

If you stop the engine when hot and the try to start it again it really doesn't want to get going again and needs coaxing to rev up again (makes it a real pain to drive when it dies at a junction)

When you drive the car there is a significant loss in power (it wouldn't pull you out of bed!) and at lower revs the power delivery isn't consistent as the revs rise to maybe 3-3500rpm (don't notice this over 4000rpm ) It's not pulling cleanly.
the engine seems smooth and doesn't miss fire when you're driving along but when you stop it and let it cool down it's a sod to start the next time.

The throttle position sensor was one of the things I'd seen on the recent threads as well and after testing it as working properly I changed it anyway just to eliminate it.

I hope this all helps because I'm struggling to think what else to do.

This car is doing my head in!

 

Have you tested the fuel pump?

 

The only check I've done was when I changed the fuel filter,
to purge it of air I left the top fuel pipe off and switched the ignition on (got a fountain petrol everywhere) but I've not checked fuel pressure, do you know what this should be?

 

I don't know the 4 cylinder K series, but on the KV6 the cam sensor is only used for starting. Once the engine is running it's not needed. So even though there's a fault code, it's probably not that.

The crankshaft sensor would have a much more significant effect though. Have you tried swapping that?

It might be worth getting a proper T4 computer on the car as sometimes the generic code readers are a bit misleading.

 

I've changed the crankshaft sensor as well but if that wasn't working the car wouldn't run at all, it also drives the rev counter as well as giving a signal to the ecu,

I agree about needing the cam sensor to start as it allows the ecu to correctly phase the fuel injectors which would also explain the lack of power when the engine is running,

I had this on a T4 on Friday and the only thing it showed were the P0430 and P0302 that I'm getting on my reader, they guy said that the injectors were pulsing properly and couldn't figure out what would cause the fault when the cam sensor has tested as working.

This is why I'm chasing my tail with this, so far everything has tested out ok but it still isn't working. I'm just missing something but don't know what.

 

ignore this. just reread your first post.

 

Get some professional help?

 

Re-professional help

Yep, Tried that and they didn't know either

 

Compression, fuel, air (and exhaust channel), spark and timing - that's what's needed to run.

1) Compression and timing - These have been checked.
2) Fuel - the injectors (or the signal to them signal) could be knackered but fuel starvation would not cause such inconsistent running.
3) Spark - it's difficult to test quality/consistency, but if the old plugs were black then this is a possibility
4) Air - it's not being starved. Is there a mass airflow sensor (MAF) that could be faulty?

Ok, that's the basic list. In any mystery, it's always worth reviewing the basics just in case something has been missed.

Assuming the compression and timing really are ok, and the ignition coils and leads really are ok and the injector is ok, then the only possibilities left are faulty ECU, sensors, and/or faulty wiring.

1) Pull every fuse and check with a meter.

Given the difficulty of getting the car running, you might want to try 3) then 2).

2) Pull each sensor (ideally while it's running since it's difficult to start) to see what difference it makes. Hopefully, removing one of them will result in smooth running. Also, waggle the connections - see below.

3) Check every engine-related electrical connection. That means disconnecting, testing the continuity of the wire if possible, cleaning the connection, spraying with WD40 (or greasing for high-current connections). Start with connections that haven't been touched so far.
Where wires have been replaced, you can skip the continuity test, but waggle gently and look for loose posts. Sometimes bad connections are hidden from view but there's usually looseness that can be detected.

I also vaguely recall a mysterious problem similar to this being caused by a broken/bad connection at the back of the car (tail-light area). Perhaps someone with a better memory than mine can help on that front - I think it may also have been related to a blown fuse.

 

When I got my 45 1800 it would kangaroo at start. I remembered on my old 400 that as you pulled away a click sound of a component sparking into life happened. On my current 45 this sound needs coaxing; i.e. I allow the car to idle for a while then slowly pull away until I hear the sound, then normal service is assumed. It has been suggested it might be the MAP sensor...

 

Thanks for your thoughts on this,

Compression was tested ok and the injectors were changed with the inlet manifold to eliminate them from the equation and they were reported as working fine by the t4 diagnostic guy.

The coil packs tested out ok and were giving 4 good sparks - it doesn't feel like an ignition problem when running but you never know.

There is a combined MAF/IAT sensor which was changed when I replaced the inlet manifold (It's fitted to it) Although they both were giving the same readout on the data stream.

I'd originally removed the engine wiring loom to strip the plastic covering off to inspect and test every wire which didn't show anything and in the end I replaced it, again to eliminate it.

I did remove all the fuses to do a VISUAL check but I haven't done a full test on them so that's the next job.

I'm also very interested in what you were saying about a broken/bad connection at the back of the car (tail-light area) So I'll be having a look at that as well.

Cheers.

 

RE MAP sensor

Does anyone know how to test the MAP sensor?

 

How about the coolant temp sensor? So on a cold start the ECU thinks its already hot and doesn't add enough fuel?

 

hi I had an audi with the same sort of symptons which turned out to be a blocked cat.....

 

With a little help from google, I found the thread I was thinking of
http://forums.mg-rover.org/showthread.php?t=444720

It's not quite how I remembered it, but it's worth taking a look

 

Thanks a lot for this,
It makes for interesting reading, I'll take a look at the tailgate wiring tomorrow.
Fingers crossed it gets me somewhere.

 

Remove the battery to car body earth strap and inspect it for damage.

 

My Porsche 944 did this and it was the coolant sensor, I know it's a different car but sounds like fuelling to me, good luck though. Porsche was a bugger to start once warm, way to much fuel flooding it iirc.
My ZS did this but it was me being a knobhead not doing the neg on the batt tight enough and was jumping around on bumpy roads.

 

There was also a recent thread where the earth near the engine ECU was corroded and was giving starting problems.

 

Thanks for your posts guys, i shall get my other half to check these out this afternoon when he comes home from work.

Natalie