Fuel pressure results...... mutter mutter mutter After sitting for 24hrs presure was @ zero psi Key to 'ON' position reading jumps to 40psi start engine, reading jumps to 45psi, then drops to 38psi & then settles to 40psi again.... ( all in 5seconds ) ( warm engine up to 'normal operating temp' ) rev engine to 5000rpm, presure reading jumps to 52psi but settles back to 43psi fairly quickly let engine idle again .... presure drops to 40psi Drive car........ psi reading maintains an average of 43-45 psi during all throttle positions park car and idle down..... reading @ 40psi engine stops ( turbo timer ) psi jumps to 55psi then settles down to 43 psi....... Still stable @ 43psi for 1 hour after shutdown. 4 hours after test the presure has dropped to 30psi end result ...... Its not a fuel related issue "buck it" with a PH instead of a b [insert really pi$$ed off icon] Kingy NEXT IDEA ????
Have you ever had the injectors cleaned and flow tested? Maybe a partially blocked injector? It would explain your fuel pressure results. Certainly is a tricky one...
Injectors were cleaned and flowed just before xmas... Number 2 was blocked the worst ( distinct miss @ idle )
Just that .... swapped from one car to the other. Reset the voltage .... more info please I dont know how to do this at all.
This might be a long shot but I remember seeing on the US forum about some early Z's had distorted heads from the factory which resulted in a missfire around 3500rpm. I have no idea how this causes a missfire, but could be worth looking into. Some vague details here. It appears to only be for 1990 NA Z's.
Stick a multimeter probe into the white wire on the TPS (the one in the middle of the plug) and the black probe on the battery negative. You loosen the bolts on the TPS and rotate it till it reads 0.44V - 0.46V. Easy!
http://www.aus300zx.com/tech/tps.html If you dont have datascan use a Multimeter . Not saying this is the problem , but needs to be reset anyways . Do you still have your wastegate control solenoids in the car , this sound much like boost cut to me , does your ECU bring up any error codes?
Its been a few hours now so I went and checked the guage again.... now sitting @ 20psi. So I decided to re-test it just incase I stuffed up ( it happens ) I got the exact came readings as I've posted above. Only I picked up one differance....... Whether this is related is anybodys guess When i did the 'static rev test' ( this time I went through to 6000rpm ), I heard the blowoff valves letting go !!! 3, 4, more times I reved it hard and got the same thing... a distinct blowoff sound..... more revs and the louder it gets!!!! Should the blowoff valves bleed off excess boost even when the engine isnt under load ? IE: free reving .... Could this be related ? am I going mad ??? ( no need to answer that )
Put the fuel system down at this point as unlikley , Eliminate the basics first , ie boost protect , Boost leaks , Intake Pod moisture , ECU feedback etc Oh and get datascan , saves crap loads of chasing your tail for a bit over $100
The TPS is adjusted by moving the plug end of it up and down (adjusting the output voltage) look at the factory service manual in the tech section and it tells you how to test and set it up - i am going to do this tomorrow to see if it fixes the problem, however i believe that it will be the PTU as previously mentioned.
Blow off valves will go vent if there is sufficient boost after the turbos and sufficient vacuum in the intake manifold. Ztoy's bov's where going off at the tech day when he was revving it, guess it's normal. Ah well, I'll just go and drive my nice and simple NA
Boost leaks.... none bar from the blowoff valves Intake pod moisture .... I'm running a twin pod setup, both pods were replaced about two weeks ago That leaves 'boost protect' ( whatever that is ) and ECU feed back ....... Datascan and USB cable on its way from Caz......
Overrated...... Someone in Japan removed long ago and repalced it with a boost controller which they removed prior to it comming to Aust, it now sports a lovely set of cadium plated 12mm bolts shoved up the ends of the hoses It better .... when I get Datascan hooked up or I'm taking my paddle and heading for "that" creek
Sorry , should have said safety boost , but you have after market control and no solonoids so no prob , but . http://www.aus300zx.com/tech/sbi.html
god damn sh*t i was hoping the problem was fuel related. i didn't get around to doing a compression test coz the extension on my compression tester wasn't long enough. ill take it to kamikaze motorsports on thursday coz one of their mechanics heard about my car and they wanna have a go at fixing it. ill update after i get the car back. Chris
Yes the "Should the blowoff valves bleed off excess boost even when the engine isnt under load ? IE: free reving" .... bov's should be working if you free rev, as long as you make the turbos build pressure they will open once you back off. That is because when the butterflies in the throttle bodies are closed, the manifold pressure drops from positive pressure to vacuum, negative pressure. So the bov is seeing vacuum on one side and pressure on the other and unless the spring is wound up tight it will open.
