Well, the engine has been rebuilt but I seem to be having some vacuum issues. My gauge only reads between 5 - 7 hg. Here are my symptoms:

Rough Idle
Plugs are black
Running really rich (FP is at 55 psi on 30# injectors)

Here is what I have done so far:
Timing is aligned properly all markings are prior and after tension was applied
Checked all the vacuum hoses for proper connections (even the evaporator)
Compression is 185, 190,190,190 on 8.8:1 Wiseco's

For some odd reason, I cant turn the FP down. I have the SFMU with the same settings as before the rebuild.

Now I accelerate, and the vaccum comes to normal but the idle is what is throwing me off. I am all out of ideas to correct this problem, any suggestions?

Originally posted by hunntyr
Well, the engine has been rebuilt but I seem to be having some vacuum issues. My gauge only reads between 5 - 7 hg. Here are my symptoms: Rough Idle Plugs are black Running really rich (FP is at 55 psi on 30# injectors) Here is what I have done so far: Timing is aligned properly all markings are prior and after tension was applied Checked all the vacuum hoses for proper connections (even the evaporator) Compression is 185, 190,190,190 on 8.8:1 Wiseco's For some odd reason, I cant turn the FP down. I have the SFMU with the same settings as before the rebuild. Now I accelerate, and the vaccum comes to normal but the idle is what is throwing me off. I am all out of ideas to correct this problem, any suggestions?

Update:
Changed the Disk/ring combo on the SFMU along with putting in a new diaphram and I was able to lower the FP to 30psi so that is a start.

I also rechecked for any vacuum leaks and found one in the throttle body to intake gasket. I resealed it and I still am steady now at 6 hg. In the RPM range, from 1500 + she runs beautifully, Idling is the problem so I am now leaning more towards ignition timing being the problem. Now when you look it over, the cam markings are lined up and when I "attempt" to look at the oil sprocket marking, it looks to be aligned. I say attempt because I am looking down into the timing belt cover. The cover is cut in half and is pulled away enough to see the timing mark on the oil sprocket.

Is there any tool that can be used to ensure that the timing is accurate?

yes a timeing light

I just had the same problem and simptoms after a rebuild. Did the motor have vacuum problems or idle problems before rebuild? Or did you replace any sensors during rebuild? On my 95 if you replace either the cam or crank sensor you have to put on a new pigtail on the harness. (Make sure the wires are soldered on in the correct order). Now if you didn't have this problem before rebuild and did not replace anything electrical related to ignition it is probably a mechanical problem (timing belt,rings) or an assembly problem(leaking gasket or warped head). I would take off the crank pully and timing belt cover and get a clear look at the timing marks on the crank/block because my problem was when I put on the timing belt I did not manually turn the crank the 1/2 notch to line up the timing marks after I installed the belt thinking that when I applied force on the tenisoner it would automatically line up. To my suprise and many dumb ideas later I finally went back and checked, followed the correct procedure exactly, got everything lined up and now it is all good. YOU REALLY NEED A CLEAR VIEW OF THE TIMING MARKS.

Originally posted by fourtrax
I just had the same problem and simptoms after a rebuild. Did the motor have vacuum problems or idle problems before rebuild? Or did you replace any sensors during rebuild? On my 95 if you replace either the cam or crank sensor you have to put on a new pigtail on the harness. (Make sure the wires are soldered on in the correct order). Now if you didn't have this problem before rebuild and did not replace anything electrical related to ignition it is probably a mechanical problem (timing belt,rings) or an assembly problem(leaking gasket or warped head). I would take off the crank pully and timing belt cover and get a clear look at the timing marks on the crank/block because my problem was when I put on the timing belt I did not manually turn the crank the 1/2 notch to line up the timing marks after I installed the belt thinking that when I applied force on the tenisoner it would automatically line up. To my suprise and many dumb ideas later I finally went back and checked, followed the correct procedure exactly, got everything lined up and now it is all good. YOU REALLY NEED A CLEAR VIEW OF THE TIMING MARKS.

No vacuum problems prior to rebuild
I did replace the crank position sensor and connected it with the new pigtail in the correct order
I sealed all the gaskets with copper spray
The head was checked for warpage

I am going to get a locking tool for the Cams and try to help.

The more I think about it the more it is leading me to believe that it is mechanical because when the motor was out, I timed it and it turned over fine. Coughed a little bit but that was to be expected due to the rebuild. On the original start up, I turned it off after about a minute because I saw the timing belt starting to slip off the cam gears. It was slipping because the oil pump sprocket was not all the way on so I corrected that and then tried to get the timing back. It just still slips that 1/2 tooth, hopefully the locking tool will help.

It pretty much sounds like a timing problem. There is a good article on this forum outlining the rebuild process for this motor. In the article it has the procedure for the timing belt alignment. Last time I checked the article was in the mods and tech section. Just make sure when you are done that all the timing marks line up and then go from there. Can you believe that I didn't tell you to search!

this is pretty common, it happened to me durring my last rebuild. There are some good threads on how to set the timing correctly. Mine would keep jumping half a tooth off and would lope at idle.
Nick
97RS

Everyone thanks for the replies. Timing is done right now. inhg is steadly at 10 but now I have a really stupid question to ask. Would a bad lifter or adjuster cause low vacuum? Reason why I ask is because I started hearing some ticking out of cylinder 4. Let me know what you guys think.

Originally posted by hunntyr
Everyone thanks for the replies. Timing is done right now. inhg is steadly at 10 but now I have a really stupid question to ask. Would a bad lifter or adjuster cause low vacuum? Reason why I ask is because I started hearing some ticking out of cylinder 4. Let me know what you guys think.

Hey guys, I think I found the issue. There is a bent bolt on the intake manifold that is causing air to leak out. This is going to sound really funny but this is how I found it. DRY ICE. Yeah that is right. I took dry ice and put a piece on each intake port on the manifold. Sprayed a mist of water on them to get the ice to fog up. I was able to then see the where air was pushing out of the intake and noticed the bolt. I am on my way to Napa now to get the bolts and hopefully everything goes well.

Update:
Anyone wanna buy my car? I am soo done with this car right about now that I am seriously thinking about it. I re-torqued the intake manifold with the new bolts and now same problems just sounds louder.

Timing was done and redone and checked with the timing light etc.
Changed out all the gaskets and did them all over again.
All vacuum lines are connected and I still cant get it right.

Originally posted by hunntyr
I re-torqued the intake manifold with the new bolts and now same problems just sounds louder.

You did install the intake mani bolts from the bottom threading up right? If you bolt them in from the top down, you'll get a mad loud vacuum leak. Just checking, cause this happened to me once.


http://www.dsmregistry.com/detail.php?carid=1185

Well I went out and bought a 350Z because of this...tell me what you think. I think I have given up...gave the fiance the "bitch" she can set her straight. If you can't see the video below let me know.

http://s25.photobucket.com/albums/c85/IcyStormFL/?action=view¤t=Hector003.flv

Originally posted by hunntyr
Well I went out and bought a 350Z because of this...

Well damn! :order

Now this is Ironic...I had issues with a engine rebuild also and went out and bought a 4G (2006 GT) earlier this month ...

Originally posted by DR1665

Originally posted by hunntyr Well I went out and bought a 350Z because of this...

Well damn! :order

Yeah I know it was pretty interesting last night and even this morning when I look in my garage and I see a torn apart 2gnt and I look in the driveway and see a nice Silverstone 350Z.

So where's the pics of the 350??

Originally posted by BlackMagic
So where's the pics of the 350??