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RB CAS drive gear replacement info.


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#41 Vandergriff84

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Posted 11 November 2013 - 08:10 PM

I had a Freddy intake manifold with my stock RB25 ECU, it ran like stock, stock turbo, stock 98 240sx exhaust, stock injectors etc..made 268whp and 273wtq on 12psi 

 

Thanks for chiming in on this flatrate. That is the consensus that I am getting from other sites as well. The performance shop in town that is the only shop that I know of that is familiar with the RB motors is telling me that the stock ECU wont work with the aftermarket intake plenum. In turn without even offering to do any diagnosis of the problem they are telling me that the only way to fix the problem is to get a stand alone ECU. I just can't give in to this assessment without hearing it from someone more reasonable.


Skylady Z - 74 260z RB25det


#42 NewZed

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Posted 11 November 2013 - 08:46 PM

The attached picture and text is from the 1990 300ZX EFEC chapter, page EFEC-24.  Maybe it has some clues.  Each point is an ignition timing value, but there are other conditions used by the ECU also. Maybe the ECU is acting on an erroneous condition indication.  Battery voltage, starting signal, temperature...  I'm not sure what the text means by the ECU detecting injector pulse width since it is the ECU that sets injector pulse width. Probably a translation grammar error.  I assume that the RB engine management is similar, they all seem to use this map from the early 90's on.

Attached Files


Edited by NewZed, 11 November 2013 - 08:47 PM.


#43 Vandergriff84

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Posted 18 November 2013 - 08:37 AM

I have given up on figuring this out on my own. I took the car to a Nissan specialist this morning in hopes that they can figure something out. I will post back when I hear something from them.


Skylady Z - 74 260z RB25det


#44 Vandergriff84

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Posted 21 November 2013 - 03:13 PM

So the shop called today. They claim that they were able to get it to 15 degrees with the CAS fully advances in the slots. They took everything apart to make sure that everything was installed right and they said everything was spot on. So they then put it back together with exhaust cam advanced one tooth and now they say it reads 15 degrees with the CAS in the middle of the slot like it should. Does anyone know if this is an acceptable solution? I don't want to drive it like that for very long if that will cause any harm. I am going to go drive it tomorrow and make sure that everything feels and looks good before bring it home.  


Skylady Z - 74 260z RB25det


#45 flatrate

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Posted 22 November 2013 - 06:15 PM

Doesnt really matter where the CAS ends up, cam timing should be set to stock, or degree'd in if using aftermarket cams. ts Vital that the cam timing is right on, if its not it throws everything else off.

 

My CAS is nearly all the way advanced, i know my cams are installed correctly because i degee'd them when i built the engine. I also run 20 degrees of base timing not 15 like a stock 25.

 

If it stops pulling timing then maybe its now correct?? hard to say 



#46 Vandergriff84

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Posted 22 November 2013 - 08:37 PM

So if the tech advanced the exhaust cam one tooth wouldn't that now make the intake cam late or retarded? I got the car back today and it seems to run ok but when I hit boost the wide band goes strait to 10s and the power falls on its face or flat lines and hesitates. Seems like there is still a lot to do to make this right.


Skylady Z - 74 260z RB25det


#47 Vandergriff84

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Posted 23 November 2013 - 04:04 PM

I stuck the timing light on it today to make sure that it is at 15 degrees as the tech said it was and I'll be darned if it isn't the same as it was when I took it into them. It's as if it is not going into base mode like it should because when I put the timing light on it at idle tps connected it shows -5 degrees and when I disconnect the tps it revs just a little bringing the timing up just for a second and then it drops back to idle and timing is back to -5 degrees. On other sites people are saying that when they plug their tps back in that the timing may drops to 10 degrees but never have I seen anyone say that their timing is negative. Can anyone make sense of this. Please embellish me with any circumstances where the ecu would retard timing at idle. Does it think there is to much air or not enough fuel at idle? Could the crank pulley be wrong or can it be installed out of time? 

 

I can tell that the tech put the timing belt back on too tight as it is making a lot of noise. Is it bad to drive it like this?


Skylady Z - 74 260z RB25det


#48 flatrate

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Posted 24 November 2013 - 10:25 AM

i'd put the cam timing back to stock.. If he just changed the exhaust cam then it wont have an effect on the actual events the intake is going thru as its DOHC..

 

How are you checking timing are you using the timing loop in the back of the coil harness or are you retrofitting a wire into the number 1 coil?

 

i haven't read your entire thread.. but have you replaced the knock sensors? checked to make sure there torqued properly etc

 

Id also make sure the engine is grounded well, and in more than 1 place.


Edited by flatrate, 24 November 2013 - 10:26 AM.


#49 Vandergriff84

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Posted 25 November 2013 - 09:55 AM

I have tried all methods of getting the timing signal but the one that works best for  me is to pull the signal from an extension wire between the coil pack and the plug.

 

I have not replaced the knock sensors but I have ohmed them out and everything seems to be OK. I also do not have any check engine codes coming from the ECU. I would think that if it were not getting knock signal or if it was faulty then it would throw a code.

 

I have a large 4 gauge wire run strait from the battery to the engine block. 


Skylady Z - 74 260z RB25det


#50 Vandergriff84

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Posted 25 November 2013 - 09:59 AM

I have been told that the front facing intake manifold should not be causing this problem and my BOV is now circulated so it shouldn't have any effect on the air coming in and going out. I have a 3" exhaust from McKinney, could that have any effect on the air flow or fuel?


Skylady Z - 74 260z RB25det


#51 flatrate

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Posted 25 November 2013 - 05:27 PM

Your method of checking timing is good

 

The engine needs to be grounded to the chassis as well.. in at least 2 different spots.

 

put the cam timing back to where it should be... Stock

 

what rpm does it pull timing at?



#52 Vandergriff84

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Posted 25 November 2013 - 06:14 PM

I took the car back to the shop this afternoon to get them to show me how they were getting the timing signal. They were using the same gun as mine but they were pulling the signal from the looped wire at the back of the coil pack harness which I have been avoiding because everyone says not to and to use the wire extension method from coil pack to plug. I do believe that the FSM says to use the looped wire at the back of the coil pack but on mine the light flash really fast which means it is picking up signal from all 6 coils not just cylinder 1. We did however notice that there is a big difference in results between the looped wire method and the extension wire. The tech hooked up to the looped wire and it read 3 degrees and mine hooked to the extension read -4 degrees. The tech also thought that the 3rd mark on the crank was 15 degrees but I have corrected him and told him that it is the 4th mark.

 

I will see what I can do about adding another ground wire tomorrow.

 

The issue that I am having is not that the ECU is pulling timing at any certain RPM but that I am getting negative timing numbers from the light at idle while setting base timing.


Skylady Z - 74 260z RB25det


#53 Vandergriff84

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Posted 26 November 2013 - 10:00 AM

I replaced the cas drive pin with the one that Stoney got from JWT as mine was broken and I had just started looking back at threads I posted on earlier in the year to figure out if this problem started before or after I replaced the drive pin. I don't think I ever really messed with the timing until I got the idling problem sorted out which I believe was after I replaced the drive pin. I used the instructions from JWT and installed it back wards as Stoney had mentioned in his thread. When I installed it I remember looking at it and thinking it might not be exactly aligned in the center of alignment dow but I figured the adjustment in the CAS slot will make up for that. I pulled out a spare cam that I have last night that also has a broken drive pin and I noticed that it is not aligned exactly center on the cam dow either but it is out the other direction which now leads me to believe that the total difference could be 10-15 degrees. 

 

If anyone has an extra cam laying around or if they have their cam gear off for some reason it would really help me to confirm this theory if I could see the drive pin alignment of another stock cam. 


Edited by Vandergriff84, 26 November 2013 - 10:01 AM.

Skylady Z - 74 260z RB25det


#54 Vandergriff84

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Posted 26 November 2013 - 10:40 AM

OK, so after having come to the conclusion that it is possible that the CAS drive pin could be aligned incorrectly I went ahead and removed the three bolts that hold the CAS on, so that I could move it further than the slots would allow and I was able to advance the timing to 15 degrees. I was able to plug the tps back in and the timing still held at around 15 degrees. The question is can the drive pin be out this much? Keep in mind that the exhaust cam is currently advanced one tooth so this should already be compensating(by compensating I mean helping the CAS to read a more advanced position) some for the drive pin if it is in fact incorrect. When I put the three bolts back in and advance the CAS all the way it only shows 10 degrees.

 

It would be super awesome if some one could post a picture of a stock cam drive pin alignment. =) 


Skylady Z - 74 260z RB25det


#55 flatrate

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Posted 26 November 2013 - 06:22 PM

This is an RB26 cam, i just snapped the picture.. it should be the same as an RB25??
 
click the picture a couple times... it gets bigger
 
 
 
 
 
dx3l.jpg
 
Uploaded with ImageShack.us

Edited by flatrate, 26 November 2013 - 06:23 PM.


#56 Vandergriff84

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Posted 26 November 2013 - 08:23 PM

Thanks flatrate, I think this confirms my suspicion. JWT directions say to align the half moon with the center of the cam gear alignment dowel but in the spare that I have it looks like it is a little more to the right side of the dowel as it also looks in your picture and another that I have found online. It appears that I installed the new one a little to the left of center on the dowel. I never would have thought such a minute difference would make such a mess when the CAS has adjustment in it. I guess stony didn't have this problem because he has the magic box. For now I am going to open the slots a little on my CAS to see if I can get it to 15 before I go through the process of replacing the drive pin.


Skylady Z - 74 260z RB25det


#57 Vandergriff84

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Posted 02 December 2013 - 12:53 PM

Ok, So to confirm my suspicion from my last post, the cam alignment key was out just enough to keep me from getting the sensor advanced past zero. For now I have just opened the adjustment slots on the CAS so that I can advance it further to 15 degrees. I apologize for the rabbit trail that this thread has gone through and I appreciate everybody's help with figuring this out. I will make a comment on the pinned thread that Stony started about the correct position for the drive pin so that the next guy going through that process with a stock ECU will know what to watch out for. For those who have standalone ECU's this isn't a big deal because you have the ability to change your phasing I believe.


Skylady Z - 74 260z RB25det


#58 Vandergriff84

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Posted 02 December 2013 - 01:23 PM

Ok, So I had done the JWT drive pin several months ago while I was still trying to get my idling down to stock specifications so that I could correctly set the base timing and I wanted to let everyone know that plans on doing this with a stock ECU to be careful of the placement of the drive pin. I believe that the instructions from JWT are a little off and the reason for this is because after inspecting other stock cam drive pin alignments it appears that the correct alignment is just to the right of center on the dowel pin and not dead center on the dowel pin as the instructions say from JWT. I came across this as I've been trying to figure out why I couldn't get my base timing advanced above zero and after pulling out all my hair for the last six months thinking that the ECU was retarding the timing even in base mode. I started to question the installation of the drive pin and when I had checked to see if mine was installed correctly I had seen that it was just a hair to the left of center on the alignment dowel but I figured that it wouldn't matter since the CAS should have 30 degrees of adjustment. Well the CAS does have plenty of adjustment but the small amount of inaccurate placement on my part combined with the slight inaccuracy from the instructions from JWT kept me from being able to advance past 0 degrees in base mode which left the car running rich and making very little power. I did this installation with the cam still in the motor which led to the slight misplacement on my part and I would recommend that any one looking to do this plan on taking the cam out as the instructions say and visually make marks for the correct placement of the drive pin based on the stock pin that's broken before you remove it. This way you are sure to put the new one in the correct alignment.


Skylady Z - 74 260z RB25det


#59 stony

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Posted 02 December 2013 - 01:43 PM

Agreed. especially when using a stock ecu where you cant set the timing. I'm using the aem... in fact when we were on the dyno with my timing set at where i thought it was supposed to be, i had to advance the timing just to got it to go past 5000rpm. SO it was way WAY  more retarded then we thought. 


5.3 truck motor, BTR stage 2 cam, BWs480, custom intercooler, AEM Infinity, 2 speed powerglide, Fully built Ford 8.8, 4:56 gears/spool, 4 link suspension.


#60 stony

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Posted 04 December 2013 - 02:11 AM

You have also confirmed that when people say just line the teeth up and put the cas sensor on are wrong. without the half moon in there the cas gear chatters on the drive gear causing pretty big variations in timing. This would explain why my timing while on the dyno would just drop off on the dyno. also would explain why my torque and power curve were never really smooth. at any rate glad you got it figured out.... I never though about notching the cas sensor like that to get the timing back to where it needs to be. Way to think out of the box ;>


5.3 truck motor, BTR stage 2 cam, BWs480, custom intercooler, AEM Infinity, 2 speed powerglide, Fully built Ford 8.8, 4:56 gears/spool, 4 link suspension.





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