Dennis (Q45Tech) says the Laptop Consult Power Balance test will produce useless results. And that's due to the ECU (Engine Control Unit) Constantly trying to maintain 650 RPM's. According to him the ECU adjusts the Idle Air Control Valve/ Auxiliary Air Control valve (IACV/AAC). But if correct idle is still not achieved the ECU adjust the fuel injector pulse width (Amount of time they are open.) Then the ECU tries to modify the ignition timing to get to the correct idle. I am not calling him a liar but how could he possibly know this?
But as we all know if we disconnect the IACV/ACC and manually raise the idle speed with adjusting screw (1990-1995)* we can do a power balance test.
*1996 Q45's are said to have sealed IACV/AAC's
Can anyone with a timing light and consult cable confirm of deny this, please?
Ignition timing VS Power Balance
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Infinitiguy19
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1994 Infiniti Q45a 240000 Miles
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Infinitiguy19
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1994 Infiniti Q45a 240000 Miles
Re: Ignition timing VS Power Balance
Not one soul want to try this out for me? If I was so sure of myself I would be all my Q45 Diagnostic Idea's against one post confirming or denying this.
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elwesso
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Re: Ignition timing VS Power Balance
Can I ask why a power balance test makes so much difference to you? The bottom line with "power balance" a function basically of injector balance and compression balance.. You could just do a compression check and if they are all within spec, then it has to be in the injector. Seems like a lot of these tests, IMO, are just "news you can use", not like you'll actually do anything to fix it?
I replaced my spark plugs last week, checked my compression both hot and cold and average was about 180 PSI (brand new is 185 PSI according to the FSM), and I had less than 10 PSI max difference (between lowest measurement and highest), and the difference hot and cold was negligible.. Not bad for 180k miles..
I replaced my spark plugs last week, checked my compression both hot and cold and average was about 180 PSI (brand new is 185 PSI according to the FSM), and I had less than 10 PSI max difference (between lowest measurement and highest), and the difference hot and cold was negligible.. Not bad for 180k miles..
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Infinitiguy19
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1994 Infiniti Q45a 240000 Miles
Re: Ignition timing VS Power Balance
Power Balance tests are nice because if done many times you can eventually find the problem without tearing down the engine. I honestly did not think of a Power Balance test the way you explained it but that helps immensely, thanks. I have put off finding what wrong with my engine because of my lack of time. I have too many projects and no time/skill/money for most of the stuff. But hell if I spend $100 this winter for a BG fuel injector flush and the problem is still their then I know the issue is compression. And I will do a compression test this next summer.
I don't completely understand the way a power balance test is run. Are the injectors turned off completely or are they kept at a set pulse width? Because if they are completely turned off then spark (Ignition) would not matter. The only way spark would matter is the amount of power drained from the battery. But the amount should be the same for all cylinders I hope. But if even if the injectors are not spaying fuel I think Dennis is saying the ECU would try to maintain idle by adjusting the other banks cylinders (2 O2 sensors-1 each bank).
I think I may end up paying a trustworthy shop for a ignition timing test. Hopefully my Senior Infiniti Tech pal is still where he was last time!
Right now I need a OEM exhaust that is not cut in anyway. I was thinking about going to FLorida or CAlifornia and buying a parts car and bring it up where I am. I would hope its a Q45a or t as well...
Congrats on the compression test!
I don't completely understand the way a power balance test is run. Are the injectors turned off completely or are they kept at a set pulse width? Because if they are completely turned off then spark (Ignition) would not matter. The only way spark would matter is the amount of power drained from the battery. But the amount should be the same for all cylinders I hope. But if even if the injectors are not spaying fuel I think Dennis is saying the ECU would try to maintain idle by adjusting the other banks cylinders (2 O2 sensors-1 each bank).
I think I may end up paying a trustworthy shop for a ignition timing test. Hopefully my Senior Infiniti Tech pal is still where he was last time!
Right now I need a OEM exhaust that is not cut in anyway. I was thinking about going to FLorida or CAlifornia and buying a parts car and bring it up where I am. I would hope its a Q45a or t as well...
Congrats on the compression test!
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elwesso
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Re: Ignition timing VS Power Balance
The timing at idle shouldn't change. And the way around having the IAC adjust the idle during a test is to simply unplug it.
Also I think autozone or some other store like that loans out timing lights. You could check the timing yourself and that might help.
Also I think autozone or some other store like that loans out timing lights. You could check the timing yourself and that might help.
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Q451990
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Re: Ignition timing VS Power Balance
I think what Dennis was saying - and what I talked with Isaac about on several occasions while we were trying to get a working power balance with Nissan ScanTech, is that the ECU will do several things to try to keep the idle where it wants it. Injector pulse width, AAC valve adjustments, timing, etc. If you can't hold all of those things unadjusted - then you can't get a good power balance reading. If I remember correctly, Robert Bowen (think that's the right name... NICO ECU guy) seemed to think the ECU had something in it's programming that would tell it to not try to adjust other parameters during a test - but I was never able to duplicate any of my results with any certainty, so it was obvious to me that the ECU was still adjusting other stuff.
I think the laptop consult will tell you if you have a dead miss on a cylinder - but other than that it's not going to give you the fine tuned information that you can get from a real Consult test - such as spotting when you have dirty injectors. Even Dennis mentioned that the intended purpose of the PB test was just to locate dead cylinders - but in the field it has been used (mostly by him) to locate smaller problems, since the resolution of the factory Consult test was so good.
Heath
I think the laptop consult will tell you if you have a dead miss on a cylinder - but other than that it's not going to give you the fine tuned information that you can get from a real Consult test - such as spotting when you have dirty injectors. Even Dennis mentioned that the intended purpose of the PB test was just to locate dead cylinders - but in the field it has been used (mostly by him) to locate smaller problems, since the resolution of the factory Consult test was so good.
Heath