(goldfish) Posted July 2, 2009 Share Posted July 2, 2009 I would say that both systems measure crank angle as neither are driven from the cam. Just the the 81 system is more accurate because of the gear slop and such, but seems to be more prone to failure. Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted July 2, 2009 Author Share Posted July 2, 2009 I would say that both systems measure crank angle as neither are driven from the cam. Just the the 81 system is more accurate because of the gear slop and such, but seems to be more prone to failure. See thats what I thought but hugh says it measures cam angle... Quote Link to comment Share on other sites More sharing options...
hughdogz Posted July 2, 2009 Share Posted July 2, 2009 Please allow me to clarify myself. In a four-stroke motor, for all the cylinders to fire the crank has to undergo two revolutions, while the camshaft (and distributor rotor) goes around just one time. Since the CAS in the distributor (and camshaft) rotates only once, while the crankshaft rotates twice I believe it is a cam angle sensor. If you want to classify a sensor based upon how it is physically connected rather than what it is measuring, you could call a speedometer a crank angle sensor!! The crank-shaft connects to the flywheel, flywheel connected to the clutch => transmission => speedo cog => speedo cable => speedo. Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted July 3, 2009 Author Share Posted July 3, 2009 So what do the high reving high performance modern engines use for a CAS? Do they use a distributer CAS? Quote Link to comment Share on other sites More sharing options...
hughdogz Posted July 3, 2009 Share Posted July 3, 2009 So what do the high reving high performance modern engines use for a CAS? Do they use a distributer CAS? I'm not sure...I just work with old Datsuns!! I think Z32's use a CAS mounted on the cam, but I wouldn't exactly call them modern anymore...we're up to Z34's now. But, the more I think about it, not only is the extra gear a potential issue, but for one engine cycle, you can measure 720 degrees of crank timing while only having 360 degrees of cam timing available. All else equal, there is 2x the resolution for a crank mounted sensor. Sometimes you need both. Unless you're building a super-duper motor for racing, the distributor CAS will do for street use and is already there...otherwise you'll have to deal with mounting a CAS which is probably not that difficult. Again, the hard part is configuring the ECU to your application. There are just as many "nuts and bolts" electronically as there are physically. I hope you have good tech support or else be able to use someone else's configuration if they are so kind to share it...I couldn't have configured the Wolf myself (without Ron and KTM's help). Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted July 3, 2009 Author Share Posted July 3, 2009 Well it seems like euro cars hide it in the back of the engine on the transmission... and alot of 90's cars mount it on the cam... Im still trying to understand why people switch out to a 300zx CAS... Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted August 6, 2009 Author Share Posted August 6, 2009 I know you guys wont believe me on this because I dont even believe this... But i noticed in another thread it is recommended to clean the ecu plugs, So I cleaned them. Now the car is pushing 22 PSI!!! On a stock t3!! I couldnt believe it when it happend! And it wasnt just boost spike, it happend more than once! Now Im wondering if this turbo is truely a t3 and how my motor is even holding 22 psi... Quote Link to comment Share on other sites More sharing options...
skib Posted August 6, 2009 Share Posted August 6, 2009 a stock T3 is capable of hitting 22psi, but after about 15 its just blowing hot air so to speak. (hughdogz will have a better worded answer to what Im talking about in the morning lol) Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted August 6, 2009 Share Posted August 6, 2009 You really need to figure out why the wastegate isn't working right. The engine won't stay together long. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 7, 2009 Share Posted August 7, 2009 The stock wastegate is controlled by a preset spring pressure, not the ecu, unless I'm greatly mistaken. Every system on a mass production car I've personally experienced don't use the ecu to aid in regulating boost pressure. Assuming you're using the s130 gear, I imagine it couldn't be any more 'advanced' than the z31 stuff. I can't say for sure on Nissan vehicles, but GMs, specifically the Turbo Sunbird, Syclone and Typhoon, for sure use the ECM to control boost. I am running one of these ECMs (with custom code) on my L28, and the ECM controlled boost control solenoid works mint, when the wastegate isn't pushed open by the exhaust pressure. LOL (simple spring fixed that problem). I also know Subuarus use the ECM to control boost pressures. I'm sure I could find many more too. I have seen a few cars that are set up without any electronic ECM controlled boost control Solenoid, such as the '89(ish) Toyota Supra, and a few others that are not coming to mind currently. Just pointing out that there are some vehicles out there with ECM controlled boost. It's nice, with a bin switcher, you can have two "tunes" set up on a single chip and switch between a "low boost" bin and a "high boost" bin, on the fly. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 7, 2009 Share Posted August 7, 2009 My bet is that your wastegate isn't able to bypass enough exhaust to keep the boost levels set where you're wanting them to be. You'll have the same issue of not being able to control the boost pressure over 12psi with your new set up unless you switch over to a larger external wastegate, or change turbo set ups entirely. With the new management, injectors, etc. you'll be able to safely handle that 15psi, but because your wastegate is too small you'll be pushing higher and higher levels of boost as you add more fuel and air to create a larger volume of exhaust which your wastegate will still not be able to vent, therefore building even more boost. Looks like the next step is going to be a new turbo Looks like you've got the disease! Unless I missed it in the thread where it was changed, he is running the OEM turbocharger, which is more than capable of keeping boost pressures down in the single digits. If there is a problem with the wastegate and/or actuator not allowing the flapper to open enough than boost can spike, or go higher than it should, also excessive carbon build up around the wastegate opening can do the same, but that usually only comes after severe neglect, and rarely in a situation where the car is actually being "driven" to the point where the wategate will be opened. In some cases, the owners of the cars drive so gingerly, that carbin is allowed to build up on the wastegate flapper, due to essentially "non-use". This is rare though, and just mention it as more of a point of interest. In this thread it was also mentioned that there is a gauge with a built in boost controller and the boost spikes seemed to appear after the install of the controller, as I'm reading it. I would recommend removing the additional solenoid and connecting the wastegate actuator back to the intake and verify that the wastegate is indeed working correctly, then and only then, you can trouble shoot the boost spiking issue. Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 8, 2009 Share Posted August 8, 2009 Hold on here... we haven't even solved a basic boost control issue and we're jumping right into programmable ECU's? Yikes! To me, it looks like we're trying to run before we can crawl? The AEM boost controller is pretty basic and should be easy enough to sort out. The stock ECU has no control over the wastegate, so if you're suddenly getting 22psi after cleaning the ECU plugs, then something else coincidental is going on. As others have suggested (many times) and so far appears to have yet been done, start by reconnecting the wastegate actuator directly to the manifold, and verify that it manages the stock boost level ok. If not, then obviously that has to be solved first. If everything checks out ok with that, reconnect the AEM boost controller solenoid, and verify that the vacuum lines are hooked up properly... port 2 connects to the actuator, and port 3 connects to the manifold. The gauge (controller) port also connects to the manifold. There are two settings you have to program on the Tru-Boost... duty cycle (on/off percentage for the solenoid, because that's all that a boost controller does is turn a solenoid on for a certain percentage of time and off for a certain percentage of time, rapidly blocking and unblocking the pressure sent to the wastegate actuator to make it look like less pressure is pushing on it) and spring pressure (boost pressure when the controller starts cycling the solenoid). Thats the thing... the controller is set at 12 but yet it still pushes 14.4. I have checked what the controller is set at numerous times and it still says 12, and if i set it back to 10 psi it still pushes 14.4. You do not set it to an actual pressure level like 12psi, so don't enter 12 and expect 12psi of boost. Start with the spring pressure set to one, and a duty cycle of 10% (which means that the pressure to the actuator is blocked 10% of the time), and increase the duty cycle in small increments until you see a pressure level you want. Once you're happy with the boost level, and it's stable, increase the spring pressure as high as you can without getting boost spikes. This will keep the wastegate closed for as long as possible before it has to start regulating boost and will help the turbo spool up quickly. This will always be several psi lower than the boost level you are trying to achieve. If your duty cycle is set to 10% and you're still getting 14psi of boost, then the spring pressure is probably too high. Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted February 6, 2010 Author Share Posted February 6, 2010 Bringing this back from the dead... If anyone was wondering what the problem was 1. Boost selenoid was setup for external wastegate and 2. Vacuum leak in afm hose between AFM and turbo... Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 6, 2010 Share Posted February 6, 2010 Holy Necropost Batman! I was reading the last page here and was thinking 'sounds like the wastegate is hooked up backwards' and as I got to the bottom---apparently it was! Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted February 10, 2010 Author Share Posted February 10, 2010 Im still trying to understand why people switch out to a 300zx CAS... By the way I have figured this out as well... I am a nice person and am willing to share... The reason the 300zx CAS is better than the 280zx CAS is because it has an extra unique notch on the trigger wheel that indicates top dead center. This small marking is VERY useful in programming standalones. Quote Link to comment Share on other sites More sharing options...
S130Z Posted March 16, 2010 Share Posted March 16, 2010 (edited) Edit: Sorry, still getting the hang of the new layout, didnt realize there was more than one page. Edited March 16, 2010 by S130Z Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.