Car jerking hard at WOT

[bryan.catano93]

Originally Posted by Irace86.2.0

That is the question. Either the spring is sticking (unlikely if new and in good condition), or the spring is not the correct rating (ie 9psi, also possible but probably not likely), or the manifold pressure line going into the wastgate is leaking, cracked, not hooked up correctly, or has popped off (easily checked), or you are getting wicked boost creap (unlikely at your psi setting and turbo size).

after i talk to my tuner im gonna change to the 7psi spring, just to rule the spring out. do you mean the flange that connects the wg to the manifold? ill inspect it today

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[Irace86.2.0]

Originally Posted by bryan.catano93

after i talk to my tuner im gonna change to the 7psi spring, just to rule the spring out. do you mean the flange that connects the wg to the manifold? ill inspect it today

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Looks like you wastegate setup is fine. Whether the boost is attached to the turbo or intake manifold shouldn’t make a difference. You just need to make sure the nipples are clear of obstructions and there is integrity to the hose.

Changing the spring is a good idea to rule it out. I believe some people are able to tell which spring is which by just looking at them.

[bryan.catano93]

Originally Posted by Irace86.2.0

Looks like you wastegate setup is fine. Whether the boost is attached to the turbo or intake manifold shouldn’t make a difference. You just need to make sure the nipples are clear of obstructions and there is integrity to the hose.

Changing the spring is a good idea to rule it out. I believe some people are able to tell which spring is which by just looking at them.

imma check both connections today once again... and check the integrity of the manifold. some people were saying it could be the tune too.

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[Irace86.2.0]

Originally Posted by bryan.catano93

imma check both connections today once again... and check the integrity of the manifold. some people were saying it could be the tune too.

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I don’t see how a tune could alter boost beyond the max of the wastegate spring if you dont have a way to bleed boost from the hose going from the turbo to the wastegate; it is all mechanical unless there is an electric boost controller.

[bryan.catano93]

Originally Posted by Irace86.2.0

I don’t see how a tune could alter boost beyond the max of the wastegate spring if you dont have a way to bleed boost from the hose going from the turbo to the wastegate; it is all mechanical unless there is an electric boost controller.

im in the first map after the base tune. should i try changing the 9psi spring to 7psi spring and try the car out? or is that not good. tuner will answer until saturday

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[bryan.catano93]

changed the spring to a 7psi (red and natural springs) and it hasnt changed. same thing its happening

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[Kodename47]

Makes me wonder if the MAP sensor is correctly scaled and reading more pressure than actual....

[Irace86.2.0]

Originally Posted by Kodename47

Makes me wonder if the MAP sensor is correctly scaled and reading more pressure than actual....

I agree that the map sensor could be malfunctioning or scaled wrong, but this sounds like there is a leak in the hose:

https://www.yourmechanic.com/article...wastegate-hose

3. Oscillating turbo boost pressure

When the wastegate is not relieving pressure on a consistent basis, it will commonly cause the boost pressure inside the turbo to oscillate rapidly. For example, if during normal acceleration your turbo boost climbs consistently as your car accelerates and reduces slowly once you stop pressing down on the accelerator, this is what is supposed to occur. If your turbo boost drops quickly or rises quickly without the application of the throttle, it could be caused by a blockage in the wastegate or a broken wastegate hose. If this is the issue, it's likely that you'll have to replace the wastegate hose.

[Kodename47]

Originally Posted by Irace86.2.0

but this sounds like there is a leak in the hose

But the boost isn't oscillating.

[Irace86.2.0]

Originally Posted by Kodename47

But the boost isn't oscillating.

It oscillates between 1.83 bar and 2.12 bar at the same time the rpms oscillate.

[secho]

Originally Posted by Irace86.2.0

It oscillates between 1.83 bar and 2.12 bar at the same time the rpms oscillate.

Yes, but once it hits a 2bars, it cuts the fuel. Then there is some hysteresis to resume fueling and then it repeats and oscilates. It is not mechanical.

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[Kodename47]

Originally Posted by Irace86.2.0

It oscillates between 1.83 bar and 2.12 bar at the same time the rpms oscillate.

As @secho said, that's the result of fuel cut. No fuel, no exhaust gasses to spool turbo, boost drops.

[bryan.catano93]

thank you so much for all your input. the help is greatly. appreciated and im glad this platform has some people willing to help.

i checked the wastegate line to the turbo and its fine. so thats ruled out. changed the spring and no change. my turbo filter was loose so im gonna check if that makes a difference( doubt it) tuner should be back saturday so it could. be that. my kit is used and the po said it worked perfectly so im not blaming it in any defects.

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[bryan.catano93]

something to add is, at the beggining i got a base mapfor a 3bar map sensor and i have a 4 bar map. ( i didnt specify that in my mods as i wasnt sure of what options came with the kit) he then sent me another base map for a 4barmap sensor. so there could be a slight possibility he used the first base map to do the first revision? ( highly doubt it but possible). but i imagine the car wouldnt start if that was the case?

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