RB27 Tuning Update! Need Help.... Issues stilll...

[KDeiwert]

I was helping Shocker tune the car. The first thing that we did when we got to the dyno was lower the spool-up and boost timing down by 4º from where it was when we first linked up to the ECU. These timing values came in from another tuner who knew Microtech very well. We were unable to veiw the factory base maps that the ECU came with, which is a shame, because the last tuner that touched the car overwrote them while tuning.

I feel that the A/F ratios were deffinatly in the safe range. There are a few thoughts on varying A/F during spool up, but most tuners will taper the A/F's down to the target (in this case low 11's:1) near the transition from vaccume to positive pressure, and hold this target A/F until redline. I feel that this is a common practice.

The timing starts high around 20-21º and drops down to 15.5-16.5º by about 6 psi and maintains this timing advance until redline. Typically you would have timing drop lower during spool-up, but Microtech does not allow ignition timing to be retarded past the static/base engine timing, which for the RB25 is 15º. This comes preloaded from microtech when you specify what engine the ECU is for, and for this RB25, the ECU should have been set to 15º from Microtech. That is not to say that it can not be changed, but typically a change in an engines base ignition timing will cause it to run a bit rough around idle unless you have a pretty high tuning resolution in those areas. A DSM for instants has a base timing of 5º. In that case, with Microtech set to 5º, timing could be retarded as low as 5º during spool-up, and then proceede to ramp up as the RPMs climb.

I think that the timing during spool may be a bit high, but it was lowered with this understanding before we even started the car on the dyno. It is deffinatly a possibility that this engine is very sensitive during spool-up, but without an EGT gauge it would would have been hard to tell somthing was wrong, as there were really no other indications till the gasket blew. Again, though, without changing the static timing, it would be impossible to retard timing much more than it already was.

I am interested in helping find the solution to this. I have heard that the intake quench areas on the RB series heads cause some issues in high HP cars, and that they often have to be cut down considerably, sacrifcing compression in return for an engine that will live. Cory and I will be working through this to find a solution and get the car back together.

[GTRs13]

Here is a 93 octane POWER FC tune:

http://www.dreweldridge.com/05...P.txt

-Twin T25's-z32 MAF-370 injectors-Walbro

Basic setup. Supposedly running for a few years w/o problems.

But this is a Power FC piggybacking a stock ECU.

Many more variables with the standalone.

What kind of fuel were you using on the dyno?

I'm an ex DSMer, how you doin?

It is too bad that the timing can't start close to 5* and then work your way up.

I mean, the 4g63 and rb25/26 have the same size pistons.

Total timing is greatly decided buy the size of your piston, forced induction or not, and octane fuel used.

Personally, I would have set the static timing to 16 degrees, and just make it up with boost.

20* total shouldn't be that bad on 93 octane, but here were are..

Damn, I wish you guys luck.

[gawdzilla]

i think your ecu might be to blame here. i think something is going to crap between what you are punching in to the maps and how your spark is actually being timed at the motor.

you are not monitoring detonation, right?

i dont think it's an injector lag/fueling issue. that would be pretty evident on the wideband, no?

[Shocker]

i think your ecu might be to blame here. i think something is going to crap between what you are punching in to the maps and how your spark is actually being timed at the motor.

you are not monitoring detonation, right?

i dont think it's an injector lag/fueling issue. that would be pretty evident on the wideband, no?

ECU is a possibility if its telling us one reading while doing another. I will post the latest up on the Microtech forum and get some opinions. This topic is on SkylinesAU right now I'm getting flamed a decent bit, but they do generally know their s***.

Det monitoring now, mircotech has no way to do this, a lot of times it is complete useless in picking up det compared to regular engine noise coming from the valve train, injectors, open wastegate ect ect.. Microtech ecus have worked for years without that shouldn't be an issue now.

Injector lag you can change, its the one chart I posted up. However in bold print in the user manual it clearly states not to change these values.

Carl there are two %'s coming off the CAS that the ECU reads. Id imagine these are what you are talking about.

[Carl H]

im not sure how the microtec utilizes the cas but i know that most aftermarket units cannot correctly read the cas signal as it is too 'fine'.i'd start leaning twards something wrong with the ecu...like it firing a cylinder when its not supposed to...not too far fetched.one of the vh guys his vh was only running on 6 of the 8 because the firmware was forcing the other 2 cylinders to fire on the exhaust stroke or some nonsense like that.

[GTRs13]

Det monitoring now, mircotech has no way to do this, a lot of times it is complete useless in picking up det compared to regular engine noise coming from the valve train, injectors, open wastegate ect ect.. Microtech ecus have worked for years without that shouldn't be an issue now.

Yeah...but now you have holes in your pistons. I'd say its an issue.

Detonation is not always audible but:

In my Boss' Twin 40R Viper, it sounds like a lightning storm.

In a Honda, one "Clacking Spoon" noise at high boost and that is it.

You Need to have knock feedback.

http://www.jandssafeguard.com/

[Shocker]

im not sure how the microtec utilizes the cas but i know that most aftermarket units cannot correctly read the cas signal as it is too 'fine'.i'd start leaning twards something wrong with the ecu...like it firing a cylinder when its not supposed to...not too far fetched.one of the vh guys his vh was only running on 6 of the 8 because the firmware was forcing the other 2 cylinders to fire on the exhaust stroke or some nonsense like that.

I know AEM had an issue with our cas and most ppl run a trigger wheel. Good point.

I'm gonna through my main post up on the microtech forum, see what type of feedback I get.

[KDeiwert]

http://www.skylinesaustralia.c...67999

This above link is a thread I found talking about RB powered cars using Microtech... its deffinatly not definitive by any means, but perhaps an indication that people have had issues with the ECUs on the RB cars.

I have some screen shots of a couple excel tables I put together that I will post up tonight. If you compare the timing map that GTRs13 posted up from a Apexi PowerFC, and compare it to the timing map that is on your car, it would seem that yours is considerably more conservative on timing. I will post it up later. Obviously every car is different, but one with the same basic set up should not require 15º less degrees just to live.

[Shocker]

http://www.skylinesaustralia.c...67999

This above link is a thread I found talking about RB powered cars using Microtech... its deffinatly not definitive by any means, but perhaps an indication that people have had issues with the ECUs on the RB cars.

I have some screen shots of a couple excel tables I put together that I will post up tonight. If you compare the timing map that GTRs13 posted up from a Apexi PowerFC, and compare it to the timing map that is on your car, it would seem that yours is considerably more conservative on timing. I will post it up later. Obviously every car is different, but one with the same basic set up should not require 15º less degrees just to live.

Interesting how most dont like them.

Heres Jazz's old Rb25 with the lt12s on it.

http://www.youtube.com/watch?v=VyEYY6Yj96I

Hes getting tuned at CFT car ran amazing made almost 600 if I remember correctly.

EDIT: I wish racebread was still up so I could pull up his graph along with his build on it. He was running a 67mm as well.

[scottymizt]

Hey shocker a buddy asked if i could chime in i can offer some info on the stock cas and problems i ran into with the haltech i have. My rb25 would run ok with the stock rb cas idle good, start good but once i got into boost it would run like crap sometimes and then others it would run just fine. I found with my haltech e6k that i had to advance the timing to make it retard and vise versa. I wasnt sure why because according to haltech the e6k shouldnt have any problems with the stock cas trigger wheel. The stock wheel has progressivly bigger windows in it with the smallest being home. My haltech would change timing at will, If i wanted it to run some what right i would have to play with the trigger angle sweeping it all the way one way then back then back to where i had it. I ended up breaking a piston because i couldnt figure it out until it was too late. I took apart the cas and changed the trigger wheel from a z31 into the rb cas. The problem is that the wheel is bigger than the stock one so i had to mod it some. I got it installed into the cas and put it on the rb25 and took it for a spin,power was night and day difference. The timing was right and i didn't have to mess with the angle anymore and the idle was even better. The only thing that was affected by the stock wheel was the ignition the fuel was just fine on my haltech. Not sure if this helps but in my case the cas did work and it worked ok. I didnt notice that it was changing timing when ever it wanted because according to the haltech it was still where i wanted it. Might want to talk to microtec and see if they ever had an issue like that. Maybe even change to a different trigger wheel see if it helps.

[KDeiwert]

This is very intersting. I have been searching around, and have seen a number of AU skyline guys litterally telling people "good luck" in getting the Microtech to work with the RB's CAS. The above post points to this as well.

[240z4u]

This is very intersting. I have been searching around, and have seen a number of AU skyline guys litterally telling people "good luck" in getting the Microtech to work with the RB's CAS. The above post points to this as well.

I asked scotty to post up about this scenario... I think that is what happened. Sorry your having such bad luck Shocker.

Evan

[Shocker]

Hey shocker a buddy asked if i could chime in i can offer some info on the stock cas and problems i ran into with the haltech i have. My rb25 would run ok with the stock rb cas idle good, start good but once i got into boost it would run like crap sometimes and then others it would run just fine. I found with my haltech e6k that i had to advance the timing to make it retard and vise versa. I wasnt sure why because according to haltech the e6k shouldnt have any problems with the stock cas trigger wheel. The stock wheel has progressivly bigger windows in it with the smallest being home. My haltech would change timing at will, If i wanted it to run some what right i would have to play with the trigger angle sweeping it all the way one way then back then back to where i had it. I ended up breaking a piston because i couldnt figure it out until it was too late. I took apart the cas and changed the trigger wheel from a z31 into the rb cas. The problem is that the wheel is bigger than the stock one so i had to mod it some. I got it installed into the cas and put it on the rb25 and took it for a spin,power was night and day difference. The timing was right and i didn't have to mess with the angle anymore and the idle was even better. The only thing that was affected by the stock wheel was the ignition the fuel was just fine on my haltech. Not sure if this helps but in my case the cas did work and it worked ok. I didnt notice that it was changing timing when ever it wanted because according to the haltech it was still where i wanted it. Might want to talk to microtec and see if they ever had an issue like that. Maybe even change to a different trigger wheel see if it helps.

Thank you for this bit of information.

So basically you verified the haltech was telling you it was at XX timing, when really it was at XX timing in the bad? Swapping out the trigger wheel for the z31's solved this issue? Did you modify the housing of the 25 CAS? or kinda find a way to Frankenstein them together?

Was haltech aware of this issue and informed you of it? Or is this something you discovered on your own.

I feel there is a huge disconnect between some of our RB parts in relation to after market items made for them. AEM had an even worse issue with the RB CAS and not many understood why. SkylinesAU are so saturated with Power FC's I feel these issues are never really brought to the table so no one really knows they might exist until well, you burn a few motors...

Thanks Evan for having your buddy post, if he doesn't mind coming back on to answer a few more questions I'd greatly appreciate it.

[eh?]

I feel there is a huge disconnect between some of our RB parts in relation to after market items made for them. AEM had an even worse issue with the RB CAS and not many understood why. SkylinesAU are so saturated with Power FC's I feel these issues are never really brought to the table so no one really knows they might exist until well, you burn a few motors...

Thanks Evan for having your buddy post, if he doesn't mind coming back on to answer a few more questions I'd greatly appreciate it.

I've always wondered with the amount of popped RB's if the CAS was really the problem while the pistons are being blamed. I've opened up two totally stock RB25's to find evidence of knock in cylinders 5&6. There's no reason the stock CAS needs 360+ slits, other oem cas worked fine with 10x less. With the aem I am able to see timing sync errors in realtime, is it possible to see that with the microtech?

[KDeiwert]

Thank you for this bit of information.

So basically you verified the haltech was telling you it was at XX timing, when really it was at XX timing in the bad? Swapping out the trigger wheel for the z31's solved this issue? Did you modify the housing of the 25 CAS? or kinda find a way to Frankenstein them together?

Was haltech aware of this issue and informed you of it? Or is this something you discovered on your own.

I feel there is a huge disconnect between some of our RB parts in relation to after market items made for them. AEM had an even worse issue with the RB CAS and not many understood why. SkylinesAU are so saturated with Power FC's I feel these issues are never really brought to the table so no one really knows they might exist until well, you burn a few motors...

Thanks Evan for having your buddy post, if he doesn't mind coming back on to answer a few more questions I'd greatly appreciate it.

From my limited time exploring the Nissan forums, I think that I have seen this same disconnect with the RB/SR engines and the aftermarket manfactures. Granted, I come from one of the most saturated communities out there, DSMs. I think the biggest problem is that because there are so few shops here in the US, heck, even worldwide, that build these engines, the documented F-ups and list of parts that create issues are few and far between. This is very sad to me, because the RB series motors are in my oppinion, some of the strongest in the world.

FWIW, I have been very impressed with the members of this community. Everyone seems very helpful and ligitimitally concerned with solving problems, not just b*tchin up a storm like I am use to on some other forums. Good stuff guys.

[Shocker]

I've always wondered with the amount of popped RB's if the CAS was really the problem while the pistons are being blamed. I've opened up two totally stock RB25's to find evidence of knock in cylinders 5&6. There's no reason the stock CAS needs 360+ slits, other oem cas worked fine with 10x less. With the aem I am able to see timing sync errors in realtime, is it possible to see that with the microtech?

The way to sync up the microtech to the ecu is to have the car running around idle with no load. Get the timing like out and take a reading off the crank, have someone in the car watch the timing on the ECU and match the engine timing with the timing the ECU is reading.

EX. Ecu is reading 17 degrees, at the engine with the light your reading 16 degrees off the crank. Advance the CAS 1 degree to 17 degrees at the crank, you are now in sync with what the ECU thinks the timing is at.

Eh? have you been able to successfully get your CAS to function well and properly with the AEM unit? Which CAS are you using the Mitsu, or the Hitachi?

FWIW, I have been very impressed with the members of this community. Everyone seems very helpful and ligitimitally concerned with solving problems, not just b*tchin up a storm like I am use to on some other forums. Good stuff guys.

Thats one thing I love about this forum. Its also why we are aloud to have our own classifies section in the RB section.

[Carl H]

yikes!from what it looks like and people citing different sources the cas could be the culprit here...this is one of the unexplanable issues that standalones have on the nissan engines that i choose to stay dear and near to the stock ecu for tuning.that and a friend of mine had a microtec that he had installed on his rx7 that when he set to injector test mode, stayed in injector test mode and would not come out...microtec didnt even know what was up.it sounds like it might be new trigger wheel time....

[240z4u]

Shocker, glad to help.

Scotty did this writeup on hybridz.org in Jan of last year; http://forums.hybridz.org/showthread.php?t=128944

Shows the cas dissasembly etc.

Keep on it man, I would have already driven the car into a large body of water.

[eh?]

The way to sync up the microtech to the ecu is to have the car running around idle with no load. Get the timing like out and take a reading off the crank, have someone in the car watch the timing on the ECU and match the engine timing with the timing the ECU is reading.

EX. Ecu is reading 17 degrees, at the engine with the light your reading 16 degrees off the crank. Advance the CAS 1 degree to 17 degrees at the crank, you are now in sync with what the ECU thinks the timing is at.

Eh? have you been able to successfully get your CAS to function well and properly with the AEM unit? Which CAS are you using the Mitsu, or the Hitachi?

Thats one thing I love about this forum. Its also why we are aloud to have our own classifies section in the RB section.

I have the mitsu CAS and I was one of the first to complain about the timing problem. My car just wouldn't run after 30 mins of driving. It actually died on me while driving. However aem issued out modified CAS wheels for free to everyone and now I have zero issues with timing. Autronic also makes modifed cas wheels for the RB, so there definitely is a problem with the CAS and aftermarket computers

The initial timing procedure is about the same for the aem but there's more too it. The Cas doesn't move and you must adjust the aem to match. There's another value you must check for that they specifically tell you to check. If the value the aem is expecting doesn't show, you've got to change it to match. It's kinda complicated and I'm sure it has to do with timing synchronization.

[Shocker]

yikes!from what it looks like and people citing different sources the cas could be the culprit here...this is one of the unexplanable issues that standalones have on the nissan engines that i choose to stay dear and near to the stock ecu for tuning.that and a friend of mine had a microtec that he had installed on his rx7 that when he set to injector test mode, stayed in injector test mode and would not come out...microtec didnt even know what was up.it sounds like it might be new trigger wheel time....

Very scary indeed, question is how do you go about testing that the CAS is the issue? Rebuild the engine again with a trigger wheel? Then find out its an ECU issue and not a CAS issue after its too late?

This scenario scares the sh*t out of me. I wish trouble shooting an issue such as this wouldn't cost anything, but for me now its been two built motors.

I suppose if there was some DET monitoring it would help, granted you know what to listen for. If only the plugs would show the damage being done as it happens rather than having to wait and pull my head to look at my melted quench wells, pads, and destroyed cylinder walls.

I just don't know which route to take in terms of insuring a properly running engine. New ECU make? Send this one in to be checked/fixed if thats the case? Trigger wheel? Bad CAS? Watching my money and time burn like this makes me deathly sick inside.

I just wish there was a definitive answer out there, I'm sure there is, the problem is finding it.

[240z4u]

I am getting ready to dodge a flying shoe...

Have you considered going back to nistune or something of that nature?

The cas is a problem, if its what cooked your motor I am not sure.

Evan

[scottymizt]

Thank you for this bit of information.

So basically you verified the haltech was telling you it was at XX timing, when really it was at XX timing in the bad? Swapping out the trigger wheel for the z31's solved this issue? Did you modify the housing of the 25 CAS? or kinda find a way to Frankenstein them together?

Was haltech aware of this issue and informed you of it? Or is this something you discovered on your own.

I feel there is a huge disconnect between some of our RB parts in relation to after market items made for them. AEM had an even worse issue with the RB CAS and not many understood why. SkylinesAU are so saturated with Power FC's I feel these issues are never really brought to the table so no one really knows they might exist until well, you burn a few motors...

Thanks Evan for having your buddy post, if he doesn't mind coming back on to answer a few more questions I'd greatly appreciate it.

yes the timing was at one thing and actually be totally different, I couldnt find anything on my problem i ended up just figuring it out myself. I didn't have to mod the housing all i did was take the metal bushings out of the sensor and move it up a little. Yes the trigger wheel solved my problem. here is a lil info that i wrote on hybridzhttp://forums.hybridz.org/show...t=casthe z31 trigger wheel has 5 small windows and one big one for the home window.

[Shocker]

yes the timing was at one thing and actually be totally different, I couldnt find anything on my problem i ended up just figuring it out myself. I didn't have to mod the housing all i did was take the metal bushings out of the sensor and move it up a little. Yes the trigger wheel solved my problem. here is a lil info that i wrote on hybridzhttp://forums.hybridz.org/show...t=casthe z31 trigger wheel has 5 small windows and one big one for the home window.

Great bit of information in that thread, I just skimmed through it but it seems like it might help a great deal!

Now I wonder how my ECU would respond to the AEM trigger wheel alone, instead of the z31 since the AEM trigger wheel is designed for the RB/Z32 CAS.

This really got my attention...

That is exactly correct. One wheel/pattern (the 24 teeth) is a resolution wheel. The other (the one tooth) acts as a reset to TDC. It counts teeth there after in 60* increments to fire the cylinders.

I only know megasquirt closely, but it should be the same for AEM.

The 360 tooth wheel cannot be used because at 7000-8000 rpm, it causes too many "interrupts" (computer verbiage) that delay the system and cause errors and misfiring.

hmmm. Thoughts on my thinking?

[scottymizt]

i didnt see that evan posted my link before sorry The aem wheel is made for it and the microtech should see it no problem. It's just the various side of the windows in the rb wheel that confuses the aftermarket computers. I am modding another cas for my rb20 that is in my sonoma, i am putting a megasquirt 2 on it and i wanna keep the stock harness and everything.

[Shocker]

i didnt see that evan posted my link before sorry The aem wheel is made for it and the microtech should see it no problem. It's just the various side of the windows in the rb wheel that confuses the aftermarket computers. I am modding another cas for my rb20 that is in my sonoma, i am putting a megasquirt 2 on it and i wanna keep the stock harness and everything.

This could be my issue right here, worth a shot to try. I suppose you could free rev the engine and watch the ECU timing VS a timing light through the entire RPM band to confirm its working properly.

It would almost be worth it to modify one cas with the AEM trigger wheel, and use an OEM CAS and compare. Free reving certainly should do no damage to an unloaded engine.

If the timing is varying on the microtech in relation to the engine that's the problem.

I have two working RB25 cas's one Mitsu and one Hatichi.. stupid Mitsu has those anti removeal screws on it....hmm too bad I'm a long way off from another running motor....

[scottymizt]

This could be my issue right here, worth a shot to try. I suppose you could free rev the engine and watch the ECU timing VS a timing light through the entire RPM band to confirm its working properly.

It would almost be worth it to modify one cas with the AEM trigger wheel, and use an OEM CAS and compare. Free reving certainly should do no damage to an unloaded engine.

If the timing is varying on the microtech in relation to the engine that's the problem.

I have two working RB25 cas's one Mitsu and one Hatichi.. stupid Mitsu has those anti removeal screws on it....hmm too bad I'm a long way off from another running motor....

the mitsu one is the one i think that is easy to mod, both can be taken apart just the one comes apart easier. I just used a flat blade screw driver and pushed down really hard and turned it, the screws came right out. Good luck man i'll post my results when i try to get the megasquirt to work with the rb cas.

[Shocker]

the mitsu one is the one i think that is easy to mod, both can be taken apart just the one comes apart easier. I just used a flat blade screw driver and pushed down really hard and turned it, the screws came right out. Good luck man i'll post my results when i try to get the megasquirt to work with the rb cas.

Thanks for the tip, the Mitsu is my back up I believe. I'll try to take it apart. AEM doesnt even list their trigger wheels online so I'll have to call.

I really wish I could test this now, instead of having to wait months.....

Good luck with your Mega in the process.

[Carl H]

doesnt the aem wheel use the ford 36-1 style wheel?

[craz4240]

I am getting ready to dodge a flying shoe...

Have you considered going back to nistune or something of that nature?

The cas is a problem, if its what cooked your motor I am not sure.

Evan

From what I have read I would throw the microtech out the window,man what terrible luck..too bad the rb25 ecu is 16 meg and not 8 like the rb20 cause myself on this build am running stock ecu with carl h tune,with consult,innovate datalogger just to make sure everything runs like stock. good luck my man I really feel for you and this build.

[Shocker]

doesnt the aem wheel use the ford 36-1 style wheel?

I think its 24-1