Cold start issues z3 3.0 sport

[Kyle auty]

Hi all, I seem to be getting a slight cold start issues on my 3.0i. It starts fine but seems to have slight misfire whilst it’s warming up when the automatic choke is running. Once it’s warmed up and the revs drop to its normal tick over position. It’s fine and it seems to run sweet. Is this a common issue and what is the normal cause of the problem? The engine management light doesn’t come on, so I’m presuming what ever is causing this issue sorts it’s self out. But I rather know how to get it sorted so it doesn’t do it at all.

 

[colb]

I once forgot to reattach the camshaft sensor connection on my 2.5 and noticed that it needed to crank a few more times than its normal immediate start on the turn of the key. No EML with it disconnected but on a quick visual check I found the detached sensor connection, plugged it back in and start first turn of the key restored. Bit pricy to put a new one in to see if yours is failing without having a code set not even sure it would be the root of your proble but thoight I would mention it.

 

[Kyle auty]

I once forgot to reattach the camshaft sensor connection on my 2.5 and noticed that it needed to crank a few more times than its normal immediate start on the turn of the key. No EML with it disconnected but on a quick visual check I found the detached sensor connection, plugged it back in and start first turn of the key restored. Bit pricy to put a new one in to see if yours is failing without having a code set not even sure it would be the root of your proble but thoight I would mention it.

Thanks, the car stats fine. It runs for a couple of minutes warming up, and about 30 seconds in. It’s like it’s misfiring then once warmed up it’s fine. Someone said it might just be one of the coil packs that need replacing. Dose that sounds right?

 

[colb]

Couild be a coil pack breaking down, have you scanned it to see if any codes have been set, that might give a clue to whats happening, if it is a bad coil it should report which cylinder it is thats misfiring.

 

[Kyle auty]

Couild be a coil pack breaking down, have you scanned it to see if any codes have been set, that might give a clue to whats happening, if it is a bad coil it should report which cylinder it is thats misfiring.

Doing that tomorrow so fingers crossed

 

[Kyle auty]

I once forgot to reattach the camshaft sensor connection on my 2.5 and noticed that it needed to crank a few more times than its normal immediate start on the turn of the key. No EML with it disconnected but on a quick visual check I found the detached sensor connection, plugged it back in and start first turn of the key restored. Bit pricy to put a new one in to see if yours is failing without having a code set not even sure it would be the root of your proble but thoight I would mention it.

You said 2.5 is that a z4 or have you got a z3 2.5 import?

 

[t-tony]

Z4.

Tony.

 

[MRH1966]

If it's not the coil packs, try your vanos inlets side solenoid......my single vanos 2.8 had a misfire, tried all of the normal stuff, holes in rubbers, vacuum pipes, plugs and coils, MAF but ended up being this.

 

[Kyle auty]

Did the diagnostic check this morning the misfire is on 2 and 4, been told to swap the coil packs around see if the misfire moves with the packs.

 

[Kyle auty]

If it's not the coil packs, try your vanos inlets side solenoid......my single vanos 2.8 had a misfire, tried all of the normal stuff, holes in rubbers, vacuum pipes, plugs and coils, MAF but ended up being this.

Thanks I will check that.

 

[NZ00Z3]

It sounds like the old "vacuum Leak" trick to me.

Try this.

Do you have a vacuum Leak?

The proportion of unmetered air from a vacuum leak to metered air is higher at idle and lower at revs. Do this test.

With a hot engine at idle, check the 4 fuel trims, 2 short-term and 2 long-term. If any are > 8% then you likely have a vacuum leak. Rev the engine to 3,000 rpm for 30 seconds and watch the short-term fuel trims. If they reduce significantly, might even go negative, then it is confirmed that you have a vacuum leak. Smoke test the engine to find the leaks.

If the short-term fuel trims do not reduce significantly, then it’s something else.

 

[Kyle auty]

It sounds like the old "vacuum Leak" trick to me.

Try this.

Do you have a vacuum Leak?

The proportion of unmetered air from a vacuum leak to metered air is higher at idle and lower at revs. Do this test.

With a hot engine at idle, check the 4 fuel trims, 2 short-term and 2 long-term. If any are > 8% then you likely have a vacuum leak. Rev the engine to 3,000 rpm for 30 seconds and watch the short-term fuel trims. If they reduce significantly, might even go negative, then it is confirmed that you have a vacuum leak. Smoke test the engine to find the leaks.

If the short-term fuel trims do not reduce significantly, then it’s something else.

Thanks for the information, I swapped the coil packs around and so far it’s not done it again, I will monitor it and see how it goes.
regards
Kyle

 

[Kyle auty]

Can the weather effect this problem do you think , so if it’s warmer like it has been the last couple of days and swapping the coil packs around it’s been fine, but is it likely that next week when the weather is cold the problem may return.