rickyellow zee Posted April 30, 2013 Share Posted April 30, 2013 I have idle and start up issues. The car is a 280z with L28et swap. It seems that my car runs the same with or without the chts plugged in. I have continuity from plug to ecu connector and i checked the snsor itself. All things checked out ok. Still the idle is lumpy and it struggles to start.I thought this would be a chts issue. Any help is appreaciated. Quote Link to comment Share on other sites More sharing options...
Domzs Posted April 30, 2013 Share Posted April 30, 2013 If you have problem with cold start , check your air regulator valve to see if it opens when cold and closes when hot ( or power applies to it ) . Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 It does open up. When the car is warmed up the idle drops to around 500-700 rpm from 1000rpm...a little low in my opinion. As it is the aac and the egr are not hooked up but are capped off. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 30, 2013 Share Posted April 30, 2013 have continuity from plug to ecu connector and i checked the snsor itself. All things checked out ok. CHTS problems would be there always, not just at start. If you want to know that CHTS circuit is correct, you have to measure resistance at the ECU/ECCS connection and compare the number to the resistance versus temperature chart in the FSM. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 I have done that and things are as they should be. The car should run like shit with the chts unplugged right? Maybe tge car is running closed loop when it ignores tge chts? Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 Btw sorry for the typos. damn cell phones are hard to type on. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted April 30, 2013 Share Posted April 30, 2013 Also a car will not run properly if it is just a chts problem. Normally when I am idling and I pull it, the car automatically dies. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 So it should die. Its clearly not running properly. ideas? Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 30, 2013 Share Posted April 30, 2013 (edited) Describe your EMS. Is it the stock 280ZX turbo system, or modified 280Z, or Z31, or other? Edit - also curious - if you did this, "measure resistance at the ECU/ECCS connection and compare the number to the resistance versus temperature chart", why did you say that you did this, "I have continuity from plug to ecu connector and i checked the snsor itself"? Did you actually get a resistance in ohms, from the pins at the connector? Edited April 30, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
cgsheen Posted April 30, 2013 Share Posted April 30, 2013 You need to test every part of the ECCS system, go through the troubleshooting steps in the FSM. If the CHTS resistance checks out, check the connectors and wiring all the way back to the ECU, then troubleshoot the rest of the components and wiring. Quote Link to comment Share on other sites More sharing options...
cgsheen Posted April 30, 2013 Share Posted April 30, 2013 It does open up. When the car is warmed up the idle drops to around 500-700 rpm from 1000rpm...a little low in my opinion. As it is the aac and the egr are not hooked up but are capped off. The AAC capped off / not operable will cause a lower RPM and enrichen your idle. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 Ok. it will lower idle but that doesnt explain why my car runs the same with the chts unplugged as it does pluggged in. I tested the chts at the ecu plug and used my multimeter as per the fsm. I did it properly i assure you. Then tested at the sensor, same readings. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 Car is running stock 280zx turbo ecu. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 30, 2013 Share Posted April 30, 2013 Ok. it will lower idle but that doesnt explain why my car runs the same with the chts unplugged as it does pluggged in. I tested the chts at the ecu plug and used my multimeter as per the fsm. I did it properly i assure you. Then tested at the sensor, same readings. That's kind of what I thought. Not the best way to do it. You can get continuity over a short-circuited wire. Or you can get continuity to the connector but have a bad connection to the sensor. Continuity doesn't tell you as much as resistance. Quote Link to comment Share on other sites More sharing options...
cgsheen Posted April 30, 2013 Share Posted April 30, 2013 Ok. it will lower idle but that doesnt explain why my car runs the same with the chts unplugged as it does pluggged in. I tested the chts at the ecu plug and used my multimeter as per the fsm. I did it properly i assure you. Then tested at the sensor, same readings. The CHTS isn't the only component in the system. I'm saying - if the CHTS and wiring test good back to the ECU, something else is your problem. Troubleshoot the rest of the system like you did the CHTS - you're on the right track, but don't get fixated on one thing. (general knowledge part of this post - the ECU polls the CHTS to know when the engine is cold and when it's warmed up. at a certain CHTS temp (listed in the FSM), the ECU will try closed loop mode operation. in closed loop the ECU will start to poll the O2 Sensor and make injector pulse calculations based on the CAS, temp sensors, AFM, and O2 sensor values under certain operating conditions (that would normally be thought of as "cruise" conditions - these are also listed in the FSM). Otherwise it's always running on it's "base map". there is no "limp mode" - unless you consider it's base map a limp mode - the stock ECU isn't that smart...) Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 That's kind of what I thought. Not the best way to do it. You can get continuity over a short-circuited wire. Or you can get continuity to the connector but have a bad connection to the sensor. Continuity doesn't tell you as much as resistance. So sorry maybe I didnt explain myself correctly. I measured the resistance using an ohmmeter. It checked out. I also checked continuity of the wire for shits n giggles. Also tested the sensor itself with an ohmmeter. Thanks for all the help thus far. I am grateful. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 The CHTS isn't the only component in the system. I'm saying - if the CHTS and wiring test good back to the ECU, something else is your problem. Troubleshoot the rest of the system like you did the CHTS - you're on the right track, but don't get fixated on one thing. (general knowledge part of this post - the ECU polls the CHTS to know when the engine is cold and when it's warmed up. at a certain CHTS temp (listed in the FSM), the ECU will try closed loop mode operation. in closed loop the ECU will start to poll the O2 Sensor and make injector pulse calculations based on the CAS, temp sensors, AFM, and O2 sensor values under certain operating conditions (that would normally be thought of as "cruise" conditions - these are also listed in the FSM). Otherwise it's always running on it's "base map". there is no "limp mode" - unless you consider it's base map a limp mode - the stock ECU isn't that smart...) The car does go like a bat outta hell when in gear and the pedal is mashed. Its just idle and start up that Im having an issue with. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 30, 2013 Author Share Posted April 30, 2013 I will check the AFM tonite when I get home. The 02 sensor is new and I do get the green light at the ecu. That tells me the ecu is reading the 02 sensor right? Quote Link to comment Share on other sites More sharing options...
Domzs Posted April 30, 2013 Share Posted April 30, 2013 If your AAC valve is capped off , what controls the idle ? What problem do you have with start up , long crank ? Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted May 1, 2013 Author Share Posted May 1, 2013 At start up it cranks and cranks until i give it some gas. sometimes it sputters out and dies and sometimes it barely keeps idle. my afm cover is off and if i turn the pot(sweeper) it richens out the mixture and the idle cleans up. lumpiness is gone until i let go of the afm sweeper(I belive its a potentiometer?). Tgats my start up woes. once the car is warmed up its alright except for the low idle. Quote Link to comment Share on other sites More sharing options...
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