P0174 appearance...

[Ardent]

From the pic.

The seal looks present to me.

[Whisperhead]

Back again folks - the car appears to be running ok, though it is still fairly noisy.

Yesterday while driving home, the fan started running and I had only been driving for 5 or 6 minutes, which I thought was odd - I drove it again with the OBD reader hooked up to Torque Pro, and it showed the coolant at 100+ degrees, which was then activating the fan. Came on a few times, though at high speeds the airflow was helping cool it, but it hasn't done that before. I was pretty thorough when burping the system during my coolant change.
It didnt appear to be overheating though - so maybe it was an air pocket that cleared, since it hasn't occurred again since. Ill keep an eye on that.

On a side note, I checked for DTCs and found two: P0150 and our old friend P0174 again.

P0150 registers as Powertrain: O2 sensor circuit (Bank 2, Sensor 1), a sensor I have just replaced, less than a month ago.

Thing is, the car is driving alright. Just these little niggling issues that keep cropping up to mar the enjoyment a bit. Im gonna check the sensors again, maybe swap them to see if the code follows the sensor? Maybe I just got really unlucky and it was dead on arrival.

In other news, the oil leak looks to be potentially coming from the timing cover on the right side of the engine (where all the pulleys are) - that job is beyond my skill, so it's a garage job again - I found a better one who recently replaced my suspension for me, I won't be going back to those other idiots. JapanParts appears to be down today, so I'll have to track down part numbers another time. Im going to get a cam cover gasket and the PCV breather pipe too.

At least the car is keeping life interesting!

[Gaz mr-s]

Coolant.... start the car & let it warm up....if you use the OBD once the temp' gets in the mid-80's the thermostat opens & you should be able to feel the heat going across the radiator.  The fan should come on before 100 C....not sure of exact figure.  Once properly hot bleed it again. The strength of the puff should give some idea compared to before.

Getting to 100C in 5 minutes suggests either a stuck thermostat or a very strong air lock.  I've been told that the thermostat fails 'open' though, maybe someone else can verify that ?

The fault codes....  Previously you have cleaned the MAF. P0174 suggests it might not be working, - if you haven't changed it, I would.  Use ebay to find the part no' of a Denso....it is a common fitment & you should be able to find a cheaper one than an 'MR2' listing. If it turns out NOT to be the fault, it's useful to have a spare.

If the post cat is a recent Denso & you find that replacing it sorts the issue, I'd be looking for my money back. 

If I were you I would not be taking the manifold sensor out,- there is internet gossip that suggests the sensors do not like tools on them,- fragile inside.

[Ardent]

Very fickle those manifold sensors.

Even looking at them the wrong way can be enough to upset them.

They really don't like being disturbed.
Look if you must, but be prepared for a code 10 miles or 2 trips later.

[Whisperhead]

Nice one folks. Car still seems to be running alright, the fan hasn't repeated its little tantrum again yet either but I'll try the suggestions anyway, better to be thorough. Thank you all, if the situation develops I'll be back. Appreciate it!