Needing help about fuel injection system malfunction, avensis 2.0 vvti D4

[minimax]

Hello!

A few weeks ago I bought a nice  2003 avensis 2.0 (150K km , vvti D4 petrol engine, azt250L) which looked in quite good condition. Unfortunately I quickly got nasty signals , starting with erratic stalling at idle and difficult start (hot and cold cranking not starting). I First had a p0037 error code pointing to a bad O2 sensor, which I changed few days ago (bank 1 sensor 2). Meanwhile I also got the p0192 (fuel rail pressure sensor circuit low) and p0191 (fuel rail pressure circuit range/performance) codes, although they come and go.

After changing the O2 sensor and cleaning the MAF things seemed at first better, droved 100km without a problem, but recently the car stalled twice while running triggering the p0192 error, very bad experience I can tell. Both happened within 10 minutes of cold start, then engine re-started well and drove me home without a problem but for peace of the mind I really would prefer to get this  resolved.  About other symptoms,  car has a somehow inconstant idle speed ,  sometimes high,  sometimes low, most of the time perfect. Probably unrelated but very strange is that the tuner volume has a life of it's own. Battery and spark plugs are looking ok.

On a low budget I would prefer to check out the obvious before sending the car for a dealership inspection. As I understand the problem points to either a malfunctioning fuel delivery, or a bad fuel pressure sensor. Now I must say that I am a little confused about the azt250 injection system.

- Firstly, it appears that it has two fuel pumps assy. (fuel pump part 23100-28030 next to the fuel rail and fuel delivery part 77020-05110 in the tank). Is it more likely that one or the another is malfunctioning ? how can I test this ?     
- Next, I didn't manage to locate the fuel filter, is it built in one of the fuel pump's ?

Any advice about this problem would be greatly welcome,

thanks for the reading.

TM

[Ivan B]

I've got some problems. Looking for decision.

 

[ulflun]

Did you fix it? What was the issue?