scooby2004Lee

iTrader: (1)

Hi everyone, just drove back from the ace cafe and was cruise the motorway at 80mph. See a bit of open road ahead, sitting comfortable at 3,000rpm i thought i would open her up. Stuck me foot down on the accelerator and the car "choked" (Held back), then the engine management light came on. Drove carefully at 70 for about 2minutes and my defis showed good oil pressure and tempreature, no other lights where on! So i decided to make sure the turbo was ok, gradually built up speed and the turbo kicked in fine. Thought ok i will floor her again and see what happens, absolutly fine, she drove normal the whole way home, giving me the full 1.5bar of boost and no hesitation. Just wondered if anyone new what this could be or had a similar problem. 2004 STI with 331bhp and full decat down and up pipe. Thanks guys any advice would be great

Ste RB5138

Most likely to be a sensor failing/failed.

I am not sure how you can diagnose Newage's though

-Spooky-

could have been a fuel cut if you hit a sweet spot... was it quite an agressive jolt back?

scooby2004Lee

iTrader: (1)

Yeah, big time! I just been down to torque of the devil and the Engine managment light came on and the fault was OVERBOOST!!!!! Apparently its because of the cold weather, going to start a new theard to find out how to cure this.

speedking

You are doing your bit to cure cold weather by driving around in a gas guzzling car

scooby2004Lee

iTrader: (1)

LOL you know it mate, maybe if we all get together and do a three day drive, blackpool will be as hot as Las vegas, we could drive through forest which would be turned to desserts! I want hot weather

redwards

iTrader: (6)

I get exactly the same thing. It's fuel cut caused by boost creep.

Splitpin

If you're looking for ways to sort this out Lee, the best thing to do before going any further is to have a word with whoever mapped your car, or, if that isn't convenient, someone else equally knowledgeable.

The solution to this problem could be in the wastegate control maps in your ECU - or possibly, if the spike is relatively small and not serious enough to do harm, in raising the fuel cut threshold a tiny bit. May well be, as RSEdwards says, boost creep, so whichever it is you need to know in order to take appropriate action. Anyone advising you of a way forward at this point is guessing, and could be wrong.

We also don't know at the moment, and have no way of knowing, whether it's a big, dangerous, det-inducing spike, or a small, harmless one (with a very low cut level in the ECU), and depending on which end of that scale you're at, the solutions are different.

You need someone who knows logging the car's behaviour in order to work out the best way forward - so that's the point at which our ability to help via the internet is very limited. Go get on the phone!

dynamix

iTrader: (3)

As the man said ^

scooby2004Lee

iTrader: (1)

Thanks guys thats brill! I will ask my mapper where the problem is, he said if it continued to "Overboost" then he can tweak it, BBBUUUTT, i would lose 5bhp so i dont understand this, because surely if my car is able to boost better than the 1.5bar he has mapped it to he should tweak it up giuving me more power???? I dont really iunderstand the term overboost, am i right in saying that because the car is getting colder air it is boosting better/harder and as the ecu only thinks it should be able to achieve 1.5bar it is restricting it??

dynamix

iTrader: (3)

The boost spike would be happening at lower rpm than your peak power so it wouldn't reduce that. It may reduce peak torque and how quickly it spools in lower gears but it needs sorting as although it 'may' be safe it is quite inconvenient hitting boost cut.

Splitpin

You seem to be making a very sweeping assumption there. How do you know your car is capable of boosting better than 1.5 bar? If it was, presumably it would have been at that higher level to begin with - unless you specifically asked for it not to be?

Again we can't get involved in the details of that discussion because we're not in possession of the full facts. Only thing we can do at the moment is assume the mapper knows what he's talking about and that your car is currently mapped close to the edge of its safe envelope. If you or your mapper knows better, that's something we can't comment on.

Sounds like you've got a pretty good grip on it in fact. It simply means that the turbo is producing more boost than the target preprogrammed into the ECU

Almost. The key point is that the ECU is trying to regulate the boost pressure to 1.5 bar, but, for one or more of a number of different reasons, can't, and as a result, the emergency fuel cut (which will be set at a number a little bigger than the target) is activating to stop the engine running into a dangerous position.

You need to log the car to determine exactly when/how and by how far the target is being exceeded, before determining the most effective way to stop it.

If the remedy involves losing 5bhp, well, it's 1.5% of the total power output so you won't notice it anyway. As said above though it may well be that it can be fixed without any power loss - and at the same time you could ask your mapper to check whether it's possible to get any more.

scooby2004Lee

iTrader: (1)

Split pin that is amazing advice. As i say because it has happened only once and never again, been fine allday etc he said he doesnt want to change it now. If it happens again then we can tweak. Can i fit the newage sti 3 port boost solenoid without doing any damage??

dynamix

iTrader: (3)

Would need mapping for a 3 port as it would overboost madly without.

Splitpin

^ What he said. Boost control maps need to be completely reconfigured for a three port - but you should get more accurate pressure control and better spool/throttle response in return.

bluenose172

iTrader: (2)

Why have 2 posts for the same issue?

scooby2004Lee

iTrader: (1)

well i said earlier in this post that i was going to start a new one because the title for this one wasnt accurate to the problem