We have finished the swap, but the idle is almost non existent and my boost guage shows only 3hg of vaccum. We used a smoke machine to find and fix any leaks. After doing this we are now seeing 3 hg of vaccum at 700rpm where as you should see about 15-20hg of vaccum. Without any throttle given the car will idle at 700rpm steady for a few seconds then die out. Now if i rev it to 1000 rpm and hold it the cars runs smooth and the vaccum improves to around 10hg.

Now this is where it gets interesting. As i give it throttle the vaccum automatically increases. At around 1300 rpm i am getting 17hg of vaccum(WTF). We are now thinking that the cam timming may be off. Also when revvig it to around 4k-5k rpm it feels like it isn't getting full power(revs slower than normal). Does anyone have any suggestions as to what may be going on here? Could it be a simple adjustment to the throttle body needed?

I am getting no codes and my AFR is at 14.7 at 1000rpm. Also the maf voltage reading on the obd2 scanner showed 1.7 which is within spec

 

I'm going to guess major vacuum leak somewhere or maybe a MAF issue.

 

Sounds similar to the problem I had after installing injectors and a MAF. Mine just wouldn't idle and the vacumn was non existant. Turned out I forgot to tighten down two bolts behind the intake manifold on th VQ30 (likely the EGR bolts).

 

yea i thought it was a vaccum leak, but when we did the smoke test we fixed all the apparent leaks.

Doesn't MAF failure prevent you fom revving over a certain rpm? Or does that only occur under load?

 

It could be a dieing maf.

 

Could be, but would i still get a maf voltage of 1.7 at 1000 rpm?

 

Dunno, but do you hear any hissing?

 

Your maf was fine before the swap right?

I don't want to say it, but I think everything is pointing to the cams?

 

Do you have tilley's cam spacers(the new ones) or were they drilled? It is the Nismo cams correct?

 

I think whoever drilled them might have dialed in too much overlap.

 

Well they were drilled by Stephenmax and he made the spacers for them. They are Nismo R-tune cams. He said he drilled them just like all of the other cams he has drilled. Would the drilling location change for a aftermarket cam as opposed to the stock cams?

 

Yea thats what i am thinking also. Man i am going to be so pi$$ed if these cams are fawked!

 

How do cams affect vaccum?

 

An agressive cam will idle poorly without much vacuum at low rpms. The more the overlap the worse it is since there is less time during which the cylinder is sealed, plus charge dilution occurs. That's why you get a lope if it does run. Richening the mixture can help somewhat but of course OBD2 and closed loop feedback make that more of a headache to do.

 

Idle at 1100 FTW!!

 

I wouldn't be surprised if the R-tune cams advanced the overall cam timing a few degrees. I know for sure that the "Ebay" cams that a couple 3.5 swappers here are using advance the timing 2 degrees. If you installed these in a proper, full 3.5 motor with the VTC sprockets and all the cam timing would be advanced by design. What this means is that whoever drilled the cams would have to drill so that the dowel pins would be in a location such that the cam would be installed in a retarded position relative to stock. This would bring the timing back to stock. With an operating VTC system, it wouldn't be that much of a problem, but with static timing you'd have excessive overlap. Hope that makes sense.

 

ding ding ding

 

So that would mean that the cams are pretty much worthless now since they have already been drilled? This really pi$$es me off if this is infact the case. I guess i will have to put the vq30 cams in now

 

I think you should:

1. Find out if the R-Tune cams indeed advance the cam timing by design.

2. If stephen max made provisions for that.


This is still speculation at this point, but a good possibility.

 

If they are in fact drilled incorrectly for your application, you can just get them plug-welded and re-drilled. It is not that big of a deal.

 

Im am not making fun of you or your thoughts, because I totally agree with what you are saying, and to my knowledge the nismo cams are advanced like 3 deg from stock so that sounds like you do have to much overlap, but if you read just this line, which it stuck out to me, I got a good laugh out of it.

 

Your right, they can be welded and fixed, but at this point they are useless to me since i am in crunch mode trying to get this car running. I need to get it up and running ASAP

 

well did talk to him yesterday and he said he drilled them in the same location as the other 3.5L cams he has drilled. So after reading this thread i think we have found the issue.

When shopping for cams i remember seeing something about the cams advancing the timming. I will be honest, when i purchased the cams and contacted stephen my knowledge on cams was very limited(and still is). That is the reason i got stephen to do the cams since he was experienced with this. I figured he would know what steps to take.

 

See if tilley or stephen max can overnight you drilled 35 cams or if tilley can send you the non drilling adapter. Those will prob be the quickest options to not use the 30 cams.

 

This would also explain the motor revving out slower at high RPM. Because of the excessive overlap, boost is exiting out the open exhaust valves. Higher revs = higher boost = most boost escaping.

 

wow thats terrible to hear.. good luck

 

Well i just talked to Stephen and he did infact drill them the way he drills stock VQ35 cams. Now i also talked to 96sleeper who has the JWT cams and he said Tilley drilled his the same exact way as mine. So in THEORY mine and 96sleeper's cams are drilled the same.

If this is true then i guess it is back to the drawing board trying to figure out what the cause of the problems are.

 

The JWT knockoffs and the R-Tune cams don't necessarily advance the timing the same amount.

 

I realize that. While talking to stephen i asked him about this and he said that the amount they are advanced would not be enough to cause the symptoms i am seeing. He knows more about this than i do so i am basically rellaying any info that i get from him.

 

Disconnect the CAM sensor and see if the car turns on, if it does, how does it rev?

 

Well the cams HAVE to be the issue. How else can there be insufficient vacuum without there being an external vacuum leak?

 

Can you remove the charge pipe and let the car run w/o boost? Does it still rev wierd?

 

I'm not saying it isn't the cams. I am just saying it may not have to do with the drilling postions. For all i know right now the cam timming could be off due to the timming chain jumping a tooth or two. Say the exhaust cams timming is off. Wouldn't that increase overlap on the exhaust side therefore causing a lack of vaccum?

 

Yea i am going to try that tommorow. I think first thing in the morning i am going to put the stock injectors in, take the charge pipe off, and do the IACV re-learn procedure.

If that doesn't work then of come the SC oil pans and timming cover.

 

Don't know if this helps but I think you are right. As I was reading in the altima forums, the Nismo cams are 2 degrees more agressive than the JWT and JWT knockoffs.

Mike

Link: http://www.nissanclub.com/forums/eng...highlight=cams

 

That means that there is 4 degrees more overlap than stock. That combined with the higher valve lift could cause all kinds of idle issues.

 

You need to somehow perform the IACV learning procedure IMO.

Why do you need to replace the stock injectors?

 

Thats what i thought i remember reading. So now the question remains if that extra 2 degrees is what is causing all the problems.

 

No i mean take out the power enterprise injectors and put in the stock injectors. Just want to eliminate some of the variables.

 

Stock is 6 degrees of overlap. You're currently at 10 degrees.