2G Loud bang/thud from engine on 3rd gear pull

[dontblowup]

1997 eclipse GST

only happens in 3rd.

I was doing a 3rd gear pull last night and all was going fine, half way through maybe around 5k rpms my whole engine made a loud thud sound and I could feel it through the car, it kinda felt like my engine shifted from the back to the front on the motor mounts. It happened for a half a second and was back to normal even when I still held on the the gas. I tried a second time and the same thing happened. Car runs just fine after all that like nothing happened.

Any idea what's happening?

Car only has a full turbo back exhaust, Injen intake and a Greddy BOV

Thanks

 

[streetraceboi]

Sounds like good ol fuel cut

 

[pauleyman]

Sounds like good ol fuel cut

I thought the same but on a basically stock car??

OP are you SURE those are the only mods?

 

[dontblowup]

Yes stock turbo stock injectors stock intercooler the car does have the balance shaft delete. The engine was replaced by the previous owner so unless there was something done that I can't visible see those are the only mods done which I'm the one that did them.
Before I recently fixed my boost leaks this never happened. My stock bov was leaking bad while in boost. I'm Also running a 2.5-3 inch downpipe to a full catless 3 inch exhaust, could this be causing boost creep which in turn causing maybe a fuel cut?

 

[pauleyman]

Yes stock turbo stock injectors stock intercooler the car does have the balance shaft delete. The engine was replaced by the previous owner so unless there was something done that I can't visible see those are the only mods done which I'm the one that did them.
Before I recently fixed my boost leaks this never happened. My stock bov was leaking bad while in boost. I'm Also running a 2.5-3 inch downpipe to a full catless 3 inch exhaust, could this be causing boost creep which in turn causing maybe a fuel cut?

Yes it could. Do you have a boost gauge?

 

[streetraceboi]

I thought the same but on a basically stock car??

OP are you SURE those are the only mods?

Yea I remember back in the day after throwing a turbo back and hard piping I experienced fuel cut for the first time. It was the good ol SAFC days. Pepperidge Farm remembers

 

[streetraceboi]

If you've got a manual boost controller try turn the boost down a bit. That SHOULD help it.

 

[dontblowup]

I don't have one installed yet but that's the next thing I want to get along side wideband and oil pressure. I don't drive the car a whole lot since I'm focusing on re doing the interior and exterior so gauges will be done soon. What would be the fix for boost creep besides getting a smaller sized exhaust?

 

[pauleyman]

I don't have one installed yet but that's the next thing I want to get along side wideband and oil pressure. I don't drive the car a whole lot since I'm focusing on re doing the interior and exterior so gauges will be done soon. What would be the fix for boost creep besides getting a smaller sized exhaust?

https://www.dsmtuners.com/threads/turbo-boost-creep-creeping-t25-14b-16g-merged.19752/page-2

 

[dontblowup]

Thanks for the link

Thank you guys for all the info as always. I'll check back in once I get around to addressing all the issues and let you know what worked.

 

[DSSA]

Boost creep and/or a post-MAF boost leak. Either or can cause fuel cut. It basically happens when the ECU reads higher MAF intake than expected.

 

[pauleyman]

post maf leak sounds more likely. hard to say without boost data.