Sigh. New issue. Boost hesistation

[Entaran]

So, I know my TPS is semi shagged (Doesn't read WOT properly, only gives 4.3k resistance fully opened and that's adjusted properly)

I know my idle stop sensor only reads when it wants to and i've adjusted it like 15 times.

I'm near certain my o2 sensor is fine.

I don't have a datalogger or eculink yet.

---

What I do have is a boost hesitation. Basically, as soon as you hit 6psi+ it starts pulling back noticeably (worse than offboost acceleration) and generates these great big smokescreens of black fuel smoke behind the car. Needless to say, fuel economy went up **** creek.

I'm seriously over this ****. I spent a fortune buying a GOOD vr4 and all it gives me is ******* ****. Between this and the wheel I'm ready to throw a match at it.

Someone please tell me where to start looking or I'm going to slam it into a tree and claim the insurance.

 

[Entaran]

Oh and if it matters, it idles perfectly, the base timing is -5 BTDC (checked earlier today) and neither of the fidanza cam gears has slipped/come undone/adjusted itself.

 

[Lister]

shagged knock sensor?

 

[Entaran]

Would phantom knock cause this?

 

[JayRome]

your running 272's, and your still on the 2.5" exhaust i made for the car when Dan had it? and stock intercooler piping? ...... you could just be maxing out everything like i did.....

 

[Entaran]

I doubt it jerome. Not even close mate, the car sometimes runs perfectly under boost and pulls HARD. But most of the time it just tries to kill itself. If it was maxxing out the problem would be constant

 

[Entaran]

Cracked the *****. Ordered my ECMLink just then. It'll be here in a week, I'll deal with it until then.

 

[Lister]

If the original knock sensor is shagged, it will give you insane knock counts, and retard the timing.

 

[JayRome]

or your AFM sucks balls....

 

[bazeng]

What should the base timing be on a vr4? is it 8deg btdc?
Anyway, phanton knock. How are your lifters?

Try and disconnect your knock sensor (would this disable it all together?? not sure as I didn't play with my stock ecu for long enough)

Blow off valve leaking under pressure?

 

[CLuTZ]

Are you logging? You should be!

 

[MDK87]

Boost leak test as baz said?

 

[Entaran]

Thankyou dane for your suggestions last night.

Fouled heat range 7 plugs (replaced with new heat range 6 plugs)

Broken (??) hoseclamp on lower intercooler piping underneath battery sort of area. Replaced clamp and now everything is back to normal. Even the idle is more stable (go figure).

Car's sitting happily on 15psi again. ECMLink still inbound as I paid for it yesterday.

It's always the simple **** in a really annoying spot eh?

 

[Entaran]

Are you logging? You should be!

Will be soon. Give them a week to send me the ecmlink

 

[MDK87]

GVR40 posted a good link about spark plugs but I can't find it.

When you increase the heat range number, doesn't that mean the plug is meant to run cooler?
Why would you go down?
So were your plugs running too cool??? :huh:
Or were they just fudged and time for new ones?

 

[Entaran]

Brand new. I think they were rooted from the car overfuelling like a bitch while the intercooler pipe was leaking air everywhere. So basically, did it in the last few days. I went back to stock (6) because that's what I had sitting on my shelf.

 

[Dean]

Yeh same thing happened to me little while ago.
Very frustrating!
The air leak would have meant additional air getting in, therefore more fuel would have been dumped in to compensate.
Plugs fowl straight away.

 

[boostboy76]

Like Entaran says though, if the BOV was leaking, surely the issue would happen under hard accelaration/boost on a consistent basis, but it doesn't.

As the issue is intermittent (the hardest kind of issue to troubleshoot regardless of what it's on) then it's probably not that. It has to be something that is kicked off by the hard accelaratuon / high boost conditions AND something else.

Unfortunately, when an issue is intermittent with a car, it's almost always something electrical.

Would definitely be a lot easier to troubleshoot when you get the ECMlink andcapture some data at the time it occurs.

 

[boostboy76]

Sounds like we all need some sort of Vacc guage that can report on the pressure of the entire system under the bonnet if a leak crops up!

 

[bazeng]

Chuck in some 7's as soon as you can, those 6's are too low for our engines with 15psi.. It'll be fine on cool days but once you get warmer weather (like now) you could risk pinging or missfiring.

Make sure you are using the bpr7es not the bpr7es-11

Your plugs would have been fouled by the engine running pig rich from all your pressurised air leaking out and not making it to the engine.

What sort of clamps are you using?
Do your pipes have beads on them?