ginger devil

Please can anyone help?
Had a heart wrenching moment as whent to overtake a car today,
there was little boost about(5PSI)when its usually about(14/15PSI)
Its just started to play up. Is there anyone who knows what it could be, as im a bit worried. MY97 UK TURBO.

Lee.

scrappydog

Lee,

first - have you done a search to check through the archives? Lots of information and you may find someone with the same symptoms and a solution.

second - don't panic, it's not usually serious, just annoying!

Is the boost now permanently limited to 5psi or does it fluctuate? If it all boosts smoothly, but is limited to 5psi then it could be either:
1) ECU has gone into "failsafe" mode
2) Boost solenoid related problem.

I've only had experience of boost solenoid related problems - which is the most common and usually cause by overfilling with oil at service. Fix will either be:-
a) Dirty boost solenoid - easy to fix (clean with brake cleaner/degreaser)
b) Blockage in one of the pipes or restrictors leading to boost solenoid - easy to fix (just clean/replace pipe)
c) Faulty boost solenoid - more expensive, but easy to replace.

If you search the archives everything will become clearer!

Andy

ginger devil

Thanks Andy.

mutant_matt

One other thing to check, were you in 2nd, around 3000rpm for several seconds before you booted it for the overtake?

Ta,

Matt

ginger devil

Hi matt,

Yeah probably, It stuck at 5psi, so i keept my foot on the gas then after about 5-8 seconds the gauge shot around to 15psi, As full boost was back the car started to accelerate. Got the next roundabout it did the same 5psi and no more.....

Cleaned the boost solinoid and hoses today and it apears to be OK!
lee

mutant_matt

The reason I asked is because there is a bit of code in the ECU whic works like this:

3000rpm in 2nd for more than a few seconds and the ECU thinks it's being noise tested. So, when you floor it, it produces half the usual boost to keep the noise levels down (to pass the EU noise tests). Apparently, lots of Turbo Jap cars do this to pass the test.

There are two ways round it:

1. Stay in 3rd whilst looking for an overtaking opportunity and change down to 2nd when you start the move

2. Stay in 2nd, come off the gas then back on when you want to go

Either way, you need to have not been sitting @ 3000rpm in 2nd for a while when you put your foot down if you want full boost.

Ta,

Matt

GF8

I have similar problem with my MY96.

My stock car can reach 0.7bar, but I had several occasions that boost was limited to 0.4bar. I tried resetting the ECU, and it can be back to 0.7bar. I suspect the ECU had toggled to the "failsafe" mode. I am using RON98 unleaded petroleum.

The search function in this BBS does not work on my PC. Can anyone point the link or explain what cause the ECU to set to the "failsafe" mode? What should I look at or fix to prevent this happen?

Thanks.

mutant_matt

You can clearly tell when the car is running in "Failsafe" or "Limp Home" mode becuase not only will it only produce half the usual boost, it has a lumpy idle, won't rev and general runs very bad and misfires a lot. It's not remotely subtle when this happens!

Matt

GF8

Why does the ECU jump into the "failsafe" mode? I am running with RON98 which should satisfy the engine's requirement. Is there any problem in the engine?

nom

Well, 'failsafe' is presumably there so that it fails safely
Presumably there's something up... if the CEL light's not on, & it resets with an ignition cycle, I think it's more 'panic mode'. I managed to get 'panic mode' on demand through a weak mixture which I had briefly - what this was causing was erratic det at spool-up, so the ECU panicked & cut boost back. Hey-presto, det gone completely.
So, I'm guessing that the real question is 'what would cause non-transient det'? If you haven't fiddled with the car at all before it started (as in put on an induction kit), and it was a MY99+, I'd say MAF problems every time. As it isn't, it could well be a leak somewhere in the inlet, presumably after the MAF. Or dodgy fuel, crud in the fuel (water?), or a bit of all combined with some hot weather - not sure what the weather's like at this time of year in HK!

GF8

Nom, thanks for your advice. Mine is a MY96. What is MAF?

scrappydog

GF8 - <<My stock car can reach 0.7bar>>
Shouldn't it be reaching 0.85 - 0.9 bar (12psi+)??

MAF = Mass Airflow Sensor; is "main" sensor that will affect air/fuel ratio. Not to be confused with MAP = Manifold Absolute(?) Pressure sensor.

Best advice is to check your ECU error codes, see:
http://www.saxonfields.freeserve.co.uk/Scooby%20Page/ECU%20Diag%20Page.htm

Cheers,

Andy

GF8

Andy, thanks. Mine is a MY96 wagon. I understand the boost limit is lower than the sedan.