T5 hesitant at lower revs...ideas?

[Wasp]

Hello again and thanks to all who replied to my last question....... I do however have another. As the title suggests,my old T5 is less than progressive at the lower end of the scale. On boost and open throttle....brilliant. Part throttle lower down,not so and worse when cold. Catching up on years of economy motoring I have replaced the following over the last 1k or so miles........ Plugs,leads,cap and rotor. . MAF sensor and air filter (Pipercross) and possibly one or two other things that don't relate too closely (pcv). Fuel filter is at the back of my mind as it's been a while. All parts replaced that matter are from PFV and the MAF made no difference (thankfully very cheap from fleabay) so I wonder if I could respectfully ask for some further assistance from your wealth of experience......... Many thanks once again.

[LeeT5]

Are you oiling your MAF? If so, don't! Get rid of the piper cross foam filter and fit a stock box with a cotton panel filter, K+N, Jetex are two examples. Better quality and washable. Again, do not oil.

Sounds like you may be having ETM issues or a possible air leak.

Have you plugged in and pulled any codes?

In the mean time, I would start buy removing the ETM and giving it a good clean with Carb cleaner and a microfibre cloth. When its like a mirror, refit and test drive. The car may need to learn the new behaviour of the clean ETM and the best way to do that is to remove the Battery earth whilst you clean it. The car will run on default base settings until all new parameters are taken into consideration, but you'll be surprised at what a difference it can make.

I had a S40 3 weeks ago that idled crap! After I removed the battery and cleaned the MAF and the ETM, reconnected the battery and started the car. The customer said it hadn't driven so smooth in all his time of ownership and he'd had it 6 years!
His MPG is is up and the car no longer stalls or cuts out when stopping at traffic lights etc.

[Wasp]

Many thanks for your reply. I should have stated that it's an 850 so no ETM. The filter is of the dry type which I replaced my previous oiled K&N with as I was concerned about residue clinging to the MAF. I cleaned that with contact cleaner to no avail so replaced it to eliminate it as a cause. I replaced most of the vacuum pipes (apart from the cruise control) when I had it mapped and plumbed the mbc a couple of years ago and had a good look the other day when changing the pcv and all still seem fresh with tight connections. Seems I'll need to gain access to a code reader then and I'll definitely try disconnecting the battery and leave it awhile when I get the chance. It's more of an irritation than a problem really as it has happy days and not so happy days which is odd in itself and it's also fair to say that it has a bit more of an appetite for fuel these days too. Hmmm. Thanks again.

[LeeT5]

As it's an 850, have you removed the flame trap?

[Wasp]

You mean the box part of the pcv? Should I have?

[LeeT5]

You mean the box part of the pcv? Should I have?

No. The black box you're referring to is the Oil trap for the PCV breather system.

The flame trap is a little white perforated plastic disc that lives in the pipework between the PCV oil trap and the Intake large hose. All dealers remove is as part of a technical bulletin, but if you're T5 didn't frequent the dealers, then it's possible it's still in there.

It's common that they block up and will cause stalling and poor idle along with reduced power.

Best thing to do is remove the Throttle cover and check that none of the Vac tree connections are split.
Remove the IAC valve and clean it with Carb cleaner. Make sure you move the valve and use copious amounts of cleaner.
Remove the Intake hose (large jubilee) and check the Flame trap has been removed.
Then clean the throttle housing, again, with copious amounts of carb cleaner and and a lint free cloth (microfibre is best) and make sure the throttle butterfly is gleaming! It's better to remove the housing if you can to get it properly clean.

Once you've done that, reassemble and road test. Don't forget to disconnect the battery so that it learns the new throttle settings. (The ECU will have learn't to adjust if the throttle was dirty, so you want it to learn from stock settings for a 'clean' throttle).

Try that and see how you go.

If you can get any fault codes then that will also help steer in the right direction.

Here's some pictures to help you find it:

http://www.tracystruesoaps.com/tutorials/850hg/air_intake_pcv_conn.jpg

http://www.tracystruesoaps.com/tutorials/850hg/flame_trap.jpg

[Wasp]

Thank you sir....... I'll report back.

[Wasp]

Hello again..... I've had no time to do very much (nothing in fact) but my old clunker is now running very sweetly. As a mechanic some 20 years ago,I wonder what is really built into these old cars we think we know and love. All I expected from replacing the PCV was less pressure on the engine seals and gaskets although I did find and clean the PTC (Positive Temperature Coefficient) valve which lives in the intake for the turbo (in case anyone is wondering) and was clogged with gunge. Something else which vanished was a very coarse sound similar to a main bearing under load or maybe a loose exhaust baffle . Bizarre. Moreso the running of this old T5 seems to even out now the more it is driven. Thank you Lee for your input and to all.