I took my Z out for a nice long run this evening and have noticed its only boosting up to 6psi. Over the winter I installed a front mount intercooler and have noticed when boosting at 6psi as soon as the throttle is released if I listen carefully I can hear air releasing (same noise as a dump valve only quieter) - it didnt make this noise before... Is this noise normal due to a larger intercooler and hard pipes? Or is something not right?

 

I have read the codes on the ecu half expecting to see code 34 but it read 55.

 

Where do I go from here? Boost leak test I guess?

 

Thanks, Dan

Looks like you've answered your own question there. :)

 

You can start by checking all the hoses that you installed and making sure they're all seated correctly. Then make sure all the clips are tightened.

Safety boost can be activated without reading a code. Boost leak test first then reset the ecu.

Ok will do thanks guys, what's the easiest way to make the tester?

 

Thanks

There's one on ebay. You can start by checking the hoses and fitment though.

http://pages.ebay.com/link/?nav=item.view&id=380857412041

Cheer for that, ordered it, I will check all obvious joints in the meantime, when it does arrive and I hook it up what's the procedure?

 

Also, will resetting the ecu be necessary if I have no codes and no check engine light? Is this done by completing the accelerator pedal sequence?

 

Many thanks

Ecu info Dan

 

http://www.zmods.org/index.php?page=ecu_diag

 

Boost test. http://www.300zx.co.uk/forums/showthread.php?175673-Boost-Leak-Test&highlight=boost+test

Edited March 17, 201411 yr by Gaz 300

Ecu info Dan

 

http://www.zmods.org/index.php?page=ecu_diag

 

Boost test. http://www.300zx.co.uk/forums/showthread.php?175673-Boost-Leak-Test&highlight=boost+test

 

Cheers, I got code 55...

A friend of mine in the industry suggested removing the two hoses that join onto the bottom of either air intake before the throttle bodies and temporarily blanking them, on taking it for a run it boosted upto 9 before I let off, he said the turbos now have no control and would run away with the engine.. Has this confirmed there is no boost leak? Whilst waiting for my boost tester what else should we be looking for?

 

We have so far tested one solenoid and are getting 12v when throttle is applied.. Is this correct?

Cheers

A friend of mine suggested removing the two hoses that join onto the bottom of either air intake before the throttle bodies and temporarily blanking them, on taking it for a run it boosted upto 9 before I let off, he said the turbos now have no control and would run away with the engine.

 

Ok sounds like what you did was disconnect the pipes to the turbo actuators, this in theory means the waste-gates will not open and hence no control or limit on the amount of boost, however a leak or even faulty recirc valves will negate this, given the recent inter-cooler work a leak is most likely and a large one at that.

 

 

Jeff TT

Jeff, the car will go past 9psi when the hoses to the turbo actuators are blanked. What makes you suggest there is a big leak? I am still waiting for my leak tester to arrive but can't get my head round why it boosts so smooth to 6psi. It hits 6 very easy at low revs. Then stays at 6 steady throughout the rev range. Would you think if there was a big enough leak for the turbos only to produce 6 that you would be able to hear it and it would take a lot higher revs to make 6psi? With the pipes from the upper boost hoses blanked it boosts with no issues hitting way over 9 if I stayed on the throttle..

 

Thanks

If the car has a boost leak and I over ride the boost solenoids with a manual boost controller would the car still only boost to safety/6psi or would the leak be "masked" and boost to whatever I desired?

 

Sorry if it seems I'm repeating myself just trying to learn what's going on.

 

Thankyou

depending on the severity of the leak, you could still boost past 6psi, but need more wastegate duty to do so if you had a controller. If this has only happened since fitting the FMIC then very likely you have a loose coupling or even a leak from the IC itself

Jeff, the car will go past 9psi when the hoses to the turbo actuators are blanked. What makes you suggest there is a big leak? I am still waiting for my leak tester to arrive but can't get my head round why it boosts so smooth to 6psi. It hits 6 very easy at low revs. Then stays at 6 steady throughout the rev range. Would you think if there was a big enough leak for the turbos only to produce 6 that you would be able to hear it and it would take a lot higher revs to make 6psi? With the pipes from the upper boost hoses blanked it boosts with no issues hitting way over 9 if I stayed on the throttle..

 

Thanks

 

 

The way to view the turbo`s as air pumps, they pump air into the system to a pressure above the normal air pressure outside of the system, however if there is a leak in the system the initial air been pumped can exit via the leak, as the turbo`s spin faster they will over come the amount of air been lost and then build boost within the system, however as the boost rises in the system the leak air bleed will also rise exponentially so the more boost the faster the leak, despite the turbo`s trying to pump more and more air pressure into the system there is a moment where nothing more can be gained and in your case that is 6psi. of course you could also have leaking recirc valves if still fitted, trouble is if they are leaking then a boost leak will not detect them leaking as they feed back into the front of the turbo.

 

 

Jeff TT

So as I understand a boost leak test won't show if my recircs are faulty

? Would you suggest changing them for atmospheric bovs?

 

Thanks

 

- - - Updated - - -

 

So as I understand a boost leak test won't show if my recircs are faulty

? Would you suggest changing them for atmospheric bovs?

 

Thanks

 

 

Or is there a way to blank the recircs just for the boost leak test?

So as I understand a boost leak test won't show if my recircs are faulty

? Would you suggest changing them for atmospheric bovs?

 

Thanks

 

- - - Updated - - -

 

 

 

 

Or is there a way to blank the recircs just for the boost leak test?

 

 

See what the boost leak shows first before spending any cash, you can temp make something up to block them for the test.

 

Jeff

Thanks very much, I am hoping my tester will arrive tomorrow and I will post results up.

 

As I understand I should plumb it where the maf sensor goes then pressure the system up (10psi) and listen for leaks?

 

Thanks

5psi

Thanks for all the help so far guys. My tester arrived this morning. But it looks more complicated than I was expecting.

 

What do I do with all these parts??

 

Many thanks

 

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The silver bit is the important one.

Tonight I have compressed air into the system and got 0psi. I removed the front bumper and have checked the placement and tightened all the clamps and then rechecked, again 0psi.

Just try Turing the engine over half a turn or so.

Thanks, just tried again and still zero. How long should it take to see any pressure there?

Thanks, just tried again and still zero. How long should it take to see any pressure there?

 

what are you using for your air supply

12v tyre compressor,