Newbie here writing from Lisbon, Portugal. I apologise in advance for this long first post but after climbing a steep learning curve about car engines in general and the 406, in particular (a lot of it here, thank you), I still have the following issues and questions.
Just got an '02 RHZ (180K Miles) and it is suffering from 2 problems.
Loss of Power
On the 2 extended drives I've made I felt that it had no vim on the way to a speed of 120 and the slightest incline necessitated a downshift to 4th. I also didn't feel or hear the turbo kick in (but I have little experience of turbos, so, don't really know). Among the possibilities that I have considered (from extensive reading and lurking - especially here [for which, thanks]:
- Throttle cable slack (it was and i have adjusted it but haven't yet tested it as I can't drive it until I drain excess oil from a recent overfill (see below). I did confirm that in neutral I could get to 4000 rpm easily but I have not taken it out on the road to see whether it is more responsive.
EGR valve stuck in open state which would mean that both at idle and at WOT (when the valve would normally be shut), exhaust gases would be admitted to the combustion chamber. I am discounting this option as I understand that if this were to be the case, the car would stall at idle. Can anyone confirm this?
The turbocharger is not kicking in - are there any circumstances (aside from a defective turbo) when a turbo would fail to kick in? I understand that the wastegate is controlled by a vacuum solenoid. My understanding is that if this solenoid was to fail (either because of vacuum failure or because of electrical failure, the wastegate would not be under vacuum and therefore the wastegate would be stuck open - is that correct? It does not sound right to me because the default state of the turbo solenoid is no vacuum (until command is received from the ecu) and that suggests that, by default, the wastegate is open - i would have thought that it would be closed by default until the overboost conditions are met. Any help understanding how the wastegate actually works would be appreciated.
The engine is badly worn and is losing compression.
The throttle position sensor is defective
The MAF sensor is defective
Are there any other obvious causes of the poor performance i describe?
Pools of oil near injectors
Another issue often discussed here. I saw a warning message telling me that I need to top up the engine oil and added a litre without first checking the dipstick. Then I drove about 50Km and subsequently noticed the pools of oil in the troughs to the right (looking at the engine from the front of the car) side of the cylinder head. I'll get it drained out tomorrow but haven't driven it in anger since. The theory that sounds most likely is that this is caused by a pressurised crankcase. I am trying to understand how overfilling can cause this. I understand that the crankshaft whips up air because it is in contact with the oil now that it has been overfilled and that when those bubbles are compressed in the oil pump and sent around the crankcase, the effect is both increased pressure and oil starvation. Does that sound right? In the photo below, I have circled 2 pipes. The one in green is the one from the intercooler. The one in red joins the rocker cover about midway - that seems to me to be where the oil is coming from. What is this pipe and why is it so oily - if it is the result of pressure in the crankcase, what is the path to this pipe? And should it be hard (all the other pipes are soft and flexible).
Thanks in advance for your help.