| "At WOT just off-idle acceleration is a little jerky as if something is working intermittently." I do not understand this test! Are you flooring it and realeasing the clutch quickly as in - dump the clutch like at a drag strip? Explain please. As far as the timing advance curve it is programmed into the ECU as a look up matrix. If chip is stock this would not change. What I was suggesting is when you check the timing with a timing light at idle and see the 15 BTDC value then gradually increase the rpm and note the timing readings. They will increase as the rpm increases and reach a max amount at some rpm. Just verify that this is happening and note the values of degrees and rpm. Note any irradic movements especially if you hold the rpm at a steady amount like 1500, 2000, 2500. A bouncing back and forth of the timing values at a steady rpm might be a sign of CAS and/or timing belt issues. Here is a brief explaination of the timing advance look up procedure [ http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&slide=24&cycle=off&scale=0&design=default&total=190 ] By removing the oil cap my NA does have and always did have a drop in rpm and engine vacuum (about 1/2 to 1 " Hg). Here is a diagram of the PCV piping system [ http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=189&design=default&total=190 ] Note that the system is somewhat open in that air entry hoses connect to the intake tubes for each side of the engine before the throttle bodies but after the filter. Thus when engine on there is vacuum draw from these locations. When the oil cap is removed that provides a rather large hole for ait to enter thus engine vacuum drops. I would give all the vacuum hoses a close inspection to make sure there are no cracks, small leaks, etc. Here is a test procedure for the EGR system [ http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=125&design=default&total=190 ] Look into this test [ http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=98&design=default&total=190 ] This section of the service manual has lots of stuff that couild also be used to help flush out your problem. As you can see there is a lot of controls in the Z.
ZUL8TR in Orlando,FL |
