misfire/ boost problem

[bensmith907]

SORRY EVERYONE, Yet another misfire problem.

It started with a problem with boost only. I was only reaching 0.5bar on a standard turbo with standard boost solinoid and I was getting a wooshing noise from the engine bay.

• I checked all the hoses for holes and correct orientation- No faults
• Checked emmisions hoses to check emmisions cartridge for leak- still poor boost
• No fault code

then I started getting misfires at about 4-5krevs.

• Checked all plugs
• Cleaned MAF,
• Checked all the hoses.
• Cleaned boost solinoid

Then I started getting misfires at lower revs and had very poor idle and a fault code 34 (knock sensor)

• Deleted fault code (hasn't returned for 4 days)
• Replaced spark plugs (misfires improved i.e. further up revs)
• I then removed the actuator hose to give max boost to discount solinoid and actuator diaphram... I think(pressure goes up but power is non existant. problems still there with backfire)
• whoosh still exists

Ive really lost myself on this.

I know there's alot of clever people on here who know GTIR's inside out so...

Any more Ideas, suggestions, tests or two cents

 

[skiddusmarkus]

The whooshing sounds like a leaking dump valve, will lose you loads of power and make it run mega rich.

 

[PobodY]

Is it a standard setup? Make sure you didn't lose the pipe with the restrictor in it; that's required to get the right boost pressure.

Is it definitely a "whoosh" like gas escaping? You can hear the charge whistle on mine when it comes on boost, but I'm pretty sure none of it is escaping.

 

[bensmith907]

its a recirc valve, any way of checking it?

 

[bensmith907]

Is it a standard setup? Make sure you didn't lose the pipe with the restrictor in it; that's required to get the right boost pressure.

Is it definitely a "whoosh" like gas escaping? You can hear the charge whistle on mine when it comes on boost, but I'm pretty sure none of it is escaping.

yea its Standard setup except for induction and exhaust. yea its a definate woosh that comes on just before positive boost kicks in(really hard for me to compare because it was like that since I got it)
I didn't have the restrictor untill last week it seemed to cure the boost problem for a day then nothing back down to 0.5bar then after that the backfiring kicked in

 

[PobodY]

You haven't replaced the leads with "uprated" ones have you? That has been known to cause problems and is a waste of money because the Nissan ones are very good.

I don't know how you could test that dump valve; you could try disconnecting the vacuum line. It shouldn't open when there's no vacuum, but if the spring has gone that probably won't make any difference. - What about taking it out and blocking the hoses; it won't do the turbo any harm in the short term, and it's arguable whether it really makes that much difference over the life of a turbo anyway.

 

[bensmith907]

Im not sure if they're standard, their black so I guess so. Maybe if i disconnect the vacuum hose I should hear if the wooshing increases or, plug the inlet to it and the whoosh should stop (if the recirc is at fault)

 

[bensmith907]

Im not sure if they're standard, their black so I guess so. Maybe if i disconnect the vacuum hose I should hear if the wooshing increases or, plug the inlet to it and the whoosh should stop (if the recirc is at fault)

Fail- apparently a golf ball shoved down the inlet hose of the recirc valve held in by bodge tape isnt enough to hold turbo pressure. I'll get back to that tomorrow. keep the suggestions coming. I've got a wedding to go to so probably wont reply untill 5mins after I get back tonight

 

[bensmith907]

Thanks Danny Misfire solved, the ignition leads and coil lead connections needed spraying out, not sure if boost is fixed. back on that problem tomorrow