Excessive water from exhaust
 

Morning gentlemen,

Apologies for diving straight in but I am in a pinch trying to help a friend. They recently had an engine let go in their blob eye WRX, so they picked up an STI lump, turbo, inlet with injectors and loom, Walbro, base mapped (for current spec) original ECU, everything necessary to keep this bit short and sweet.

It currently idles around a grand if you fire it up, but as soon as you blip the throttle or it comes off cold start it sits at circa 500-600 rpm if that. It doesn't drop out, doesn't sound like it's missing to be fair to it, but it doesn't sound as it should if that makes sense. It also doesn't pull as it should and has began putting an uncomfortable amount of straight water (I think) out of the exhaust and popping even after a little 2k rpm blip of the throttle sat still at idle. Reliably, every blip *pop*, a noticeable mid-volume crack not a typical over fuelling on over-run 'rude boi' pop that sounds like it'll disintegrate the back box. When sat idling there's a fair bit of steam / smoke from the exhaust, BUT while it's white it doesn't look like the usual 'white smoke' I've seen before (bad times) it seems finer and doesn't really smell?

We have no codes or CEL, however we've tried unplugging various components (with the car turned off / key out, then fired up again) like MAF, Lambda, TPS etc and all make a difference and throw a code so I'm presuming everything electrical is functioning correctly. We've checked all vac lines as the first port of call. Checked coolant and oil levels changed the coolant sensor, checked for any air in the system. There seems to be a very light steam / mist of coolant coming from the exhaust housing, unsure if it's the underside of the downpipe to turbo.join, but it's all tight with new (genuine) turbo and downpipe gaskets so seems odd anything is getting out of there.

Even tried running a meaty extra ground and a new battery on the off chance it was a grounding / power supply problem so I'm thinking I've kind of been trying to avoid the inevitable... something really ain't happy.

I would greatly appreciate any input you knowledgeable folks have, as I've tried to work through it logically but I'm not remotely educated with regard to Subarus. If it was what I'm usually messing with I'd be worry the turbo had let go... or I'd be panicking that we were into head gasket territory :(

Thanks for reading, have a good one!

Just for clarity, I have read the other head gasket / similar issue threads on here, on this page and via search, just wondered if anyone had any specific thoughts given the volume of things changed.

in this weather i wouldnt be surprised if its just steam

Probably still needs a remap?
your car probably has different exhaust system and air intake etc than the sti the engine came from.
so more or less air/fuel coming in and out of engine.

Thanks for the replies guys, to be fair I think you're right.

The popping has died down a bit (but yeah you're right, the exhaust only has a back box and is aftermarket from turbo back it seems) and it has a daft cone filter so no doubt that's contributing to the extra noises.

It doesn't seem to be using coolant or oil so hopefully we've just gotten worked up over nothing. Just panic easy when it's someone elses car :D

Thanks again folks :)