G'day all,

This might be long-winded but bear with me.

Only had the car a short while and thought I'd replace the factory plastic turbo inlet pipe as it didn't look very healthy (had gone soft and melted at the turbo end).

I bought a cheap silicon one (possibly my first mistake - it could be collapsing under suction when on boost) and fitted it. I tried lubing and ziptying it so I could fit it without removing the intake manifold but no cigar. Eventually I opted to remove the whole intake manifold and finally got the new pipe in place. Upon starting the car, the engine immediately seemed to be running more rough (almost as if it was running on 3 cylinders but not that bad). I went for a drive and hit boost once it was warmed up.

On boost, the car was noticeably slower than before. The exhaust note sounded different and the turbo almost sounded louder (possibly just the less restrictive air intake muffling the sound less? Or a boost leak making the turbo work harder?).. I had a strong suspicion it was running rich so I had my wife drive behind me to see if my exhaust was pouring out black smoke. 'FLAMES' was her response. So it is indeed running rich or it's misfiring but I don't think that's the case. It's slow but still smooth.

Lastly, it is still hitting 14psi of boost! It used to run about 15psi I thought but 14psi doesn't seem to suggest that the inlet pipe is completely collapsing and restricting air causing it to run rich, right?

So.. I assume I have done something silly when I put the manifold back on or my MAF happened to die at the same time (but that'd be awfully coincidental unless it's the connector because the plug was disconnected - will inspect this soon)


What I've done:

• Checked for codes - none
• Checked all sensor and hose connections
• Pressurised entire intake and found NO LEAKS
• Reset ECU and drove gently with a combination of disconnected O2 and/or MAF sensor. No difference without O2 other than CEL. No MAF makes it fuel cut making it difficult to know if it's still running as rich

Yet to try:

• Resolder MAF connection
• Check sensor readings with multimeter/Evoscan (don't have an SSMI reader yet)
• Pull and inspect plugs (boy is this more difficult on an H4 than an I4!)
• Pull entire manifold off again and make sure I didn't leave a rag inside

Has anyone got any other suggestions of what I might have done or what else I should try next? Thanks for reading!


TLDR: I pulled everything off to install a new turbo inlet pipe and now car is running mega rich. Where did I most likely stuff up?

What make/model/year car is it

my98 wrx

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MY01 JDM EVO VII - 230KW / 430NM @ 1.6BAR

Yeah, sorry. It's a MY98 WRX. It does have yellow 440cc/480cc injectors in it which I gather are out of an STI so the Unichip would be pulling back the fuel. Has anybody EVER heard of a Unichip losing its map for any particular reason? The battery was disconnected for some time while I fitted the intake but I assume a Unichip would have non-volatile memory. It would explain the sudden richness if the Unichip reset to defaults, but I don't see it as a likely theory.

Chances are your Unichip would be much better in your garden than under your dashboard.

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Air is for pussies.

I hear ya.. I've never had a piggyback before. Without even being able to adjust it (or even view anything) now myself - what a joke!! :\ It's a shame it's an MY98..

Anyone got a PFC/VIPEC or something going cheap? =P

I was always under the impression a re-tune was required after installing a turbo inlet?

Yeah for Bugeye onwards. The GC8's seem to be tolerant to a few mild changes here and there.

Im not a mechanic, or an expert, but I think everyone is pointing the finger at the ECU but I reckon something else was disturbed/upset when taking the manifold off or putting it back on.

Was there a hole in the old intake? Maybe was tuned with a hole in it and now you've plugged the hole?

My assumption is that I disturbed something in the process. But for the life of me, I can't find what! Hence me coming here to ask what is most commonly forgotten by amateurs when they pull off an EJ manifold.