Replaced Turbo, Now Surging

[Charles Young]

Recently finished installing a TA49 in place of my stock turbo. Car ran great before. Now, under higher boost (20ish plus) the car surges forward, then slows, surges, slows.... At first I thought something was happening with my tranny, then noticed the boost gauge bouncing around while doing the surge/slow thing. There are a couple indications of an exhaust leak where the turbo and down pipe bolt together. I reused the old gasket there so I took it apart and used high temp RTV to help seal it up. Could an exhaust leak at that point cause the symptoms I am having? Any other no-brainers to look at before I drive it again? All suggestions are welcome, thanks!

 

[pacecarta]

mostlikely its the ta49 , its not defective just a result of the wheel ratios and its common to have surge between 17-21psi when going part throttle but usually its a quicker chop chop chop surge not slow as you describe

did you get a new chip burned for the turbo
being lean doesnt help and a new chip would help with that
are you on alky? to be running 20+psi i hope so

 

[RmvBfrFlght]

...There are a couple indications of an exhaust leak where the turbo and down pipe bolt together. I reused the old gasket there so I took it apart and used high temp RTV to help seal it up. Could an exhaust leak at that point cause the symptoms I am having? ...

An exhaust leak there won't cause surging issues, although having the gasket there can. If the gasket is still there, remove it and use a thin layer of RTV to seal it. The RTV is more to protect the bare metal surfaces during warm up, helps prevent rust from forming.

Having a gasket there when using the internal WG can easily cause the puck to not seat properly.

RemoveBeforeFlight

 

[Bescurred]

My 44 and alky does the surge thing too at part throttle 14psi-19psi..its really bad now that I put the PTE SLIC on.

Does it do it at wot? Are you sure your hoses are snug?

 

[Charles Young]

mostlikely its the ta49 , its not defective just a result of the wheel ratios and its common to have surge between 17-21psi when going part throttle but usually its a quicker chop chop chop surge not slow as you describe

did you get a new chip burned for the turbo
being lean doesnt help and a new chip would help with that
are you on alky? to be running 20+psi i hope so

I do have alky but didn't get a new chip and didn't know I'd need on e with just the turbo change. I'll look into that. Thanks!

 

[Charles Young]

An exhaust leak there won't cause surging issues, although having the gasket there can. If the gasket is still there, remove it and use a thin layer of RTV to seal it. The RTV is more to protect the bare metal surfaces during warm up, helps prevent rust from forming.

Having a gasket there when using the internal WG can easily cause the puck to not seat properly.

RemoveBeforeFlight

Thanks - I'll remove the gasket!

 

[Charles Young]

My 44 and alky does the surge thing too at part throttle 14psi-19psi..its really bad now that I put the PTE SLIC on.

Does it do it at wot? Are you sure your hoses are snug?

Not sure about WOT. Will check hoses for sure. Thanks!

 

[TurboBob]

still using the stock boost solenoid, make sure the connections are tight, any datalogs? if the chip has lower boost in 3rd gear or for high knock, it may be commanding different boost if there is knock or a flaky 3rd gear switch.



B

 

[Charles Young]

still using the stock boost solenoid, make sure the connections are tight, any datalogs? if the chip has lower boost in 3rd gear or for high knock, it may be commanding different boost if there is knock or a flaky 3rd gear switch.



B

Yes I'm using the stock solenoid and will check all connections. I'm using the translator and Extender chip but the chip is probably several years old. Is it a likely culprit? Sorry but no data logs.

 

[TurboBob]

so, is this at WOT, or part throttle? have you tried turning the alky up or down? Its probably not the chip if it didn't do it before. The TA49 can be prone to surge, but its a fast fluttering kind of thing.

I would turn the boost down and see if it helps.

Bob

 

[hawkfan]

My 44 and alky does the surge thing too at part throttle 14psi-19psi..its really bad now that I put the PTE SLIC on.

Does it do it at wot? Are you sure your hoses are snug?

Same here. The tornado fixed the surge until I added alky.

 

[Charles Young]

An exhaust leak there won't cause surging issues, although having the gasket there can. If the gasket is still there, remove it and use a thin layer of RTV to seal it. The RTV is more to protect the bare metal surfaces during warm up, helps prevent rust from forming.

Having a gasket there when using the internal WG can easily cause the puck to not seat properly.

RemoveBeforeFlight

I didn't have much time last night to evaluate so before removing the gasket I decided to just try moving the WG by hand to see how it felt. What do you know, it was stuck, at least partially. Jiggled it and it started moving freely. No time to remove and seal so decided to check other things noted above, lower the boost and drive it to work today. Too much traffic to do much WOT "testing" but the problem appears to be solved. Boost gage still flutters a little in the high teens but the surging you can feel is gone. I'll do a bit more testing and go ahead and remove the gasket but I'm pretty happy thanks to the help from the TB.com team! I never would have thought about me messing up the WG puck. Thanks to all who chimed in!

 

[belsie]

When apart take a flat stone sharpener ( used to sharpen blades & knives) and level surface of turbo & downpipe so the seal is the best it can be. Also mark the puck surface area and improve flow as necessary..............