T4/TOAF Question

[mbonwick]

Well, I've not had a chance to get the fuelling adaptions reset on a T4, but a trip to SAWS has improved the general driveability no end.


However....(there's always a catch)...


The cold idle problem is still there, i.e. running very rich with resultant misfires (P0300 and P1316 codes). It's pretty much undriveable when it's missing as any touch of the throttle more often than not makes it stall.


So, I've taken a look at some live data from pscan, but I'm no expert so would appreciate collective second opinions...
Injector pulse width is around 9ms for approx 10-15secs after starting, with idle generally within 5-10rpm of target. Then, for some unknown reason, the injector pulse starts ramping up over say 20secs to somewhere in the region of 14ms, with the misfires setting in and engine speed dropping along the way. Ignition advance goes from a fairly stable value to all over the place, presumably as the ECU tries to deal with the misfires.
It's not lambda related, as it never actually reports switching to lambda control (& is the exact same with lambda unplugged). The sensor does heat up within 30secs or so and reports it is ready though.


So bottom line with this - does it still sound like fuel trim? Why isn't it getting better with time? What am I missing here?

[mbonwick]

Bit of a bump to this, anyone any ideas?

[marinabrian]

Take a look at the wiring that enters the plug on the MAP sensor

I would have thought that SAWS would have checked out the running issues before playing with anything else, I know I wouldn't have altered anything before curing a misfire.

Brian

[mbonwick]

Will have another critical examination of that loom Brian. From what I can recall of the pscan data, the readings seem fine from the MAP though.


We didn't go checking under bonnet at SAWS because it runs absolutely spot on when warm, and it was plenty warm enough after 80 miles down the M6!

[mbonwick]

How I wish it were as simple as the MAP connector, but it's not.


pscan data from this evening gave a believeable temperature of 29C (had just come back from work), and pressure of 100kPa stopped/40-50kPa idling. Note that because it's warm, it was behaving itself.



Unplugged the MAP with the engine running, promptly stalled (as expected). Restarted and it was hunting all over the place (again, as expected). Plugged back in and all was well again.
Sprayed the contacts with electrical cleaner, and the outside with WD40 before assembling/disassembling a few times to be sure. Wiring all looks good as well.



Interestingly, when I pulled the codes off (before I played around with the MAP), there was a P1300 - Boost Calibration Fault in there. Not one I've seen before and not sure what it means on a non-turbo engine?!




So, in short - not the MAP, what do I do next?

[mbonwick]

Well, waggling the wires around and spraying copious amounts of electrical cleaner seems to have made it better for a short while.


In the absence of any other ideas, and because the clip on the MAP plug is broken, I'm going to swap that loom with the one supplied with the metal manifold, to rule it out if nothing else.

[mbonwick]

UPDATE.....well, sort of.

I haven't had chance to get a new plug on. The idea of loom swapping came to nothing as the spare I had doesn't have the connector/pins in for the power steering pump, so will need to cut and solder. Haven't had chance to do that with work/weather/other cars.


What I have had chance to do is observe the MAP readings several times both cold and hot, and from what I can see, I think Brian is absolutely spot on.

Consistent readings between 40-50kPa when hot, but all over the place from 55-85(!)kPa when cold and misbehaving. I've even managed to get the pressure to go up (i.e. less vacuum) while increasing revs!!


So it's either a dodgy sensor (which is unlikely given I've swapped them), or a bad connection in the plug (likely, given waggling and electrical cleaner fixes it).

In summary - haven't fixed it yet, think I understand better what's wrong....and Brian was right as always.

[mbonwick]

So...finally got a new connector crimped in, and....(drum roll please)






...no improvement.
Well that's not strictly true, in 3 cold starts so far it's not massively overfuelled to the point of stalling, which is good, but it's still very lumpy when cold and definitely feels like the multiple misfires codes are accurate. Manifold pressure seems to have settled down, but when cold is still around 60kPa which seems high to me?

Will see if it settles down this week traveling to work but I'm not hopeful.


Experts - any ideas what I should do next? Could it possibly be related to related to the IACV/idle setup? Although I've done the calibration multiple times, it's not the original IACV (I had to change it as the old one cracked when unscrewed from the old manifold).

[mbonwick]

Further update, just to keep you all in the loop;

Replaced crimp joint on the TMAP connector with a proper soldered one. No change.

Checked timing again, this time using rods through the spark plug holes to find TDC. Decided it was a tooth out, so reset the timing.
Still misses when cold, but more resistant to stalling. Had code P0302 yesterday which is the first time I've seen anything cylinder specific. Still getting P1300 (Boost calibration fault) and P1316 (misfire excess emissions).


Even with the timing now positively spot on, manifold pressure still seems high (i.e. low vacuum) at 60kPa. Interestingly the IACV moves itself in with time (that is, number of steps reduces) which seems counter-intuitive to me. Surely it should be moving out as the engine gradually warms to lean the mix?

[BigBen]

Rough starting/poor cold idling on the K series can be caused by a leaky inlet manifold seal/gasket. Coolant typically enters cylinder 1 or 4 or both. This compromises sparking until the heated engine clears out the water.

A good check is to pull plugs 4 & 1 - if one or both appears 'washed' or has a pinkish appearance compared with number 2 or 3, it points to the gasket.

Edit: -
If any of the plugs are black or sooty then check the Fuel Pressure Regulator. They can develop a split in the diaphragm which can let fuel pass through and via the vacuum pipe find it's way into the plenum. Causes 'flooding' - usually most noticeable at lower engine revs.