sx needs help

gremlin · Post by **gremlin** » Sat Oct 21, 2006 12:38 am

Hey guys this morning I was driving and decided to open my car up and stretch its legs but something was wrong. My turbo whistles and does its thing and the boost guage shows that its boosting. But for some reason it isn't kicking in. There is no pull at all when the turbo starts boosting. The guage shows its booostiong and the dunpvalve goes off and everything but no pull. And the engine wont go past 5500 RPM. Anyone have an idea what the problem could be?

Gary57 · Post by **Gary57** » Sat Oct 21, 2006 9:14 am

Where is boost gauge pick up??

gremlin · Post by **gremlin** » Sat Oct 21, 2006 5:58 pm

The boost guage reads directly from the intake manifold

Gary57 · Post by **Gary57** » Sun Oct 22, 2006 7:46 am

If the boost is there,I am stumpt, Maybe your problem lies with the tuning. Check for air restrictions aswell.

Daniel · Post by **Daniel** » Sun Oct 22, 2006 8:52 am

It would still show boost even with a boost leak unless its a mahooosive one.

Gary57 · Post by **Gary57** » Sun Oct 22, 2006 2:10 pm

I would start by checking if the exhaust is blocked, then the fuel filter. If either of these were the problem you would get the boost but at high rev the car will bog down.

gremlin · Post by **gremlin** » Sun Oct 22, 2006 11:49 pm

Me, Freddy and Derek checked the spark plugs and ran a compression test. thats all fine. the theory we have is that it might be the fuel pump or management system. i am going to take the car to smart racing this week and hopefully it will be ready for westbank. thanx for the help Freddy and Derek

Vlade · Post by **Vlade** » Mon Oct 23, 2006 7:21 am

Sounds like a boost leak, if it sounds like the turbo is boosting its sh!tters off and you have no power... it's most likely a leak...

I had something similar when my one of my actuators bolts fell out, and was a small 4mm hole... car had no power and there was a load whistle noise

Phinx · Post by **Phinx** » Wed Oct 25, 2006 8:40 am

Have you check you ECU for any codes?

In all honesty it sounds like an Injector or Spark issue, if it was a boost leak it would show on your gauge.

Are you running the Stock Pump, Has anything changes since it last ran well?

Vlade · Post by **Vlade** » Wed Oct 25, 2006 11:13 am

Phinx wrote: In all honesty it sounds like an Injector or Spark issue, if it was a boost leak it would show on your gauge.
well?

Not entirely... Remember, your turbo will try and compensate for the lost air, the actuator will stay closed till the required pressure is reached, your AFM will be all wrong because its reading that the car is taking in twice as much air, but its only getting half that its taking in, and thus the car will be over fueling and that can be the reason for the no kick in the butt feeling...

But the whistle is the give away on the boost leak...

Draco · Post by **Draco** » Wed Oct 25, 2006 11:35 am

I differ from your sight of the guage Vlade, the guage reads directly from the intake manifold, thus it takes a pressure reading from the turbo or pressure coming in from the turbo into the intake, whether the wastegate is open or closed it measures the presure made by the turbo into the intake, if the turbo pushes 1 bar the guege will show one bar.

Gary57 · Post by **Gary57** » Wed Oct 25, 2006 11:38 am

Yes and for the turbo to make boost it need combustion. That is why I said if the exhaust or fuel filter is blocked at high rev it will bogg down.

Draco · Post by **Draco** » Wed Oct 25, 2006 12:10 pm

true what you say Gary, only problem is he boosted 0.8 bar before as is the same now, that means combustion is right for it to boost 0.8

Vlade · Post by **Vlade** » Wed Oct 25, 2006 12:12 pm

Derek-son wrote:I differ from your sight of the guage Vlade, the guage reads directly from the intake manifold, thus it takes a pressure reading from the turbo or pressure coming in from the turbo into the intake, whether the wastegate is open or closed it measures the presure made by the turbo into the intake, if the turbo pushes 1 bar the guege will show one bar.

Think of it this way...

Your turbo can lets say have an efficiency of 1.2bar, the stock wastegate is set to open up fully at 0.7bar, so the turbo is still capable of 0.5 bar more...

Now lets say you are loosing 0.2bar of the pressure from a boost leak, your turbo just works a little harder to compensate for that 0.2bar pressure loss, since its still seeing the pressure as 0.5 and it will work its arse off till it sees 0.7... and that is why you hear a whistle and also hear the turbo work a little harder...

In a case where you are loosing a huge amount of air, you will notice is on the gauge

I have experienced both cases above, I have even had a leak under low pressure then when the system comes up to 0.5 the leak closes up...

Draco · Post by **Draco** » Wed Oct 25, 2006 12:27 pm

I understand your theory and that you experienced it, but your guage will still show you the leak, the pressure will go up to the full boost you want and then fall down a bit as the pressure escapes and then go up again. I also speak from experience so lets agree to disagree, hope gremlin gets his probs sorted out.