1.8 TDCI MAF problem?

Ciano35

Hi everyone,

So my car has a problem where it won't rev past ~3.5k when putting the shoe down. Starts boosting well at 2k, continues all the way up to around 3.5k and then won't rev anymore.

I unplugged the maf sensor and now the car has good boost from 3k rpm up to redline, but no boost up until 3k, so I have to rev the engine really high to get any boost.

I've had this problem since I bought the car 2 years ago.

Worth mentioning that I reconditioned the turbo last year, and I don't get any warning lights on the dash.

So is it probably the MAF sensor? Want to make sure before buying because money is a bit tight at the moment.

Car is a 1.8 tdci mk1.5 focus. Thanks for helping.

Cian.

Ciano35

Anybody have any ideas

Foxhole Norman

Have you got the codes read in it? That should tell you exactly what's wrong with it.

Ciano35

Foxhole Norman wrote: »

Have you got the codes read in it? That should tell you exactly what's wrong with it.

No I haven't done that yet. I have an obd2 reader but it isn't compatible with the focus unfortunately. Would it still log codes even if there weren't any warning lights on the dash?

Foxhole Norman

Ciano35 wrote: »

No I haven't done that yet. I have an obd2 reader but it isn't compatible with the focus unfortunately. Would it still log codes even if there weren't any warning lights on the dash?

Yeah it should, it might also still have codes from previous lights that were up. Get it plugged in before you buy anything.

Ciano35

Foxhole Norman wrote: »

Yeah it should, it might also still have codes from previous lights that were up. Get it plugged in before you buy anything.

Thanks Foxhole, will do.

Ciano35

Update on this, scanned the ecu but no codes at all. Checked all the vacuum hoses but can't find any splits or holes anywhere. Cleaned the maf sensor with the proper cleaner and no change. Took out the turbo actuator control solenoid, tested it and it works perfectly. Clueless on where to go from here!

Foxhole Norman

Ciano35 wrote: »

Update on this, scanned the ecu but no codes at all. Checked all the vacuum hoses but can't find any splits or holes anywhere. Cleaned the maf sensor with the proper cleaner and no change. Took out the turbo actuator control solenoid, tested it and it works perfectly. Clueless on where to go from here!

Have you tried driving with the MAF disconnected? MAF cleaner from what I've read pretty much never works.

Ciano35

Foxhole Norman wrote: »

Have you tried driving with the MAF disconnected? MAF cleaner from what I've read pretty much never works.

Yeah tried that a few times and it does allow the car to boost at high rpm, but then there's no boost below ~2700k. With the maf plugged in, there's good boost up to ~3000k, at which point it feels like the turbo suddenly stops boosting and car doesn't want to rev anymore.

Ciano35

Another update, have a new code. 'P0121 Throttle Position Sensor A circuit range or performance', so going to look into this.