Alfa 147 1.9 JTD 140 bhp (well...) small boost problem
I have a 1.9 JTD 140bhp 147 Ti (2004 older model) which has been chipped by Squadra to 175bhp. It's now done 167.000 kilometers (100k miles) and it's been looked after very well. Recently, it's being driven by my missus who doesn't have a light foot either but it only gets a good run for its money once or twice a week (> 40km drive).
So... over the last few months I've noticed it's developed a bit of a boost problem. You only notice it slightly, but I guess it will get worse.
Symptoms have first been noticeable on uphill sections, in higher gears, where you would notice flat spots in the acceleration which last around 2-3 seconds, after which it goes okay agian for a second or 2-3, repeating this cycle until it gets above say 3.2k RPM. After that the problem is no longer there really.
I've also noticed this on Spa Francorchamps, where we took the Alfa out for a good couple of laps, where on the uphill section it stopped accelerating doing 90, after which it took some time (second or 3-4-5) to set off again.
Now it hasn't got the problem on the lower revs - or at least it's not noticeable. In 1-2-3rd gear it just goes - and it goes strong!
So... we've been wondering about this little problem. I would think of some things, like maybe the air filter is really clogged up, or the turbo is on its way out (a little bit of play on the turbo axle?). I actually don't know if it could be the EGR or MAF, but the symptoms might be different for those problems?
Other than the intermittent boost (or what it seems to be) at those revs in higher gears I don't experience any other problems like more smoke or higher fuel or oil consumption.
Anyone care to guess - or suggest what I might do to come to a conclusion / diagnose the problem? I think I'll start by taking out the air filter (K&N panel) and give that a good clean...
Last edited by Kayjey; 05-07-09 at 22:07.