SDgoods Posted January 20, 2013 Share Posted January 20, 2013 (edited) Before you say it, ive searched high and low and have found answers semi-pertaining to my questions and problem... 1973 240z with 81' l28et swap -stock ECCS, mods are: Aeromotive trick flow FPR (set at 30ish psi with vacuum connected) (disconnected sits at 40+) TRE 255lph fuel pump with surge tank Custom fuel feed line, stock feed line used as return line Front mount intercooler Some cheap BOV P/O installed MSA Downpipe with AEM Wideband uego sitting ~6 inches from the stock 02 sensor location 3" custom after the downpipe Aftermarket Coil, NGK spark plug wires. HKS EVC boost controller ** Aftermarket Throttle switch p/o wired in** Test actually had resistance with throttle depressed (bad?) -Turbosmart Boost gauge, Speedhut Tach, AEM Wideband Car idles at 10-11 afrs, theyre pretty inconsistent. Under ANY throttle modulation it directly richens to 10.0 (most likely even less as the gauge only goes to 10), under one specific position at low rpms with the throttle it will hang around 11. WOT is 10- 10.5 and gets leaner as RPMS increase. I've tested all the sensors/circuits. First and foremost, 33-34 on AFM test at 205 Ohms. This is obviously out of the 280-400 ohm range. All of the other AFM tests check out. Can this alone cause the car to run THAT rich even at idle? I should also mention the internals of the AFM look like they were glued and someone didnt want it to be adjusted again. Wondering if I should try to break/ heat up the glue and adjust afm? Or could this in itself be causing my whole problem? -Notable mention, the air regulator seems to not be working as it appears the p/o didnt wire it in from the fuel pump relay as it is an aftermarket fuel pump. Therefore the AAC is not working correctly, ( might explain idle AFR's, not any other condition though) Car pulls 20 in/hg no problem once warm. Is this one circuit in the AFM causing all my problems? AAC/AFM joining together to cause it? Any help would be greatly appreciated before I go spend $180 on an MSA AFM Thanks Edited January 21, 2013 by SDgoods Quote Link to comment Share on other sites More sharing options...
billseph Posted January 21, 2013 Share Posted January 21, 2013 You didn't make any mention of checking the CHTS circuit or sensor which is the biggest raw fuel curve adjustment in the system...lots of threads mention a faulty sensor, or circuit to cause extremely rich conditions. Some say that with the CHTS unplugged that the car will die out from so much fuel being dumped into the system, but mine will run with it unplugged...with it unplugged the ECCS thinks its like -40 something degrees Fahrenheit. Since you're rich all across the board I'd say to verify the resistance at the ECU end first, then all the way back to the sensor (by cyl. 5 spark plug) if it doesn't check out (all in the FSM). Quote Link to comment Share on other sites More sharing options...
loy Posted January 21, 2013 Share Posted January 21, 2013 Yeah when I have the CHTS unplugged mine would run pig rich. There's not much to the inside of the AFM. The Throttle position switch should open when the throttle is depressed. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 21, 2013 Share Posted January 21, 2013 Weird that you know the resistance range that the AFM pins should show but you don't set your fuel pressure to the stock setting. Are you working from the FSM or just from threads on the internet? 4 psi, plus the +, might not be huge but it's certainly not helping your rich condition. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 21, 2013 Author Share Posted January 21, 2013 (edited) Weird that you know the resistance range that the AFM pins should show but you don't set your fuel pressure to the stock setting. Are you working from the FSM or just from threads on the internet? 4 psi, plus the +, might not be huge but it's certainly not helping your rich condition. It is to the stock setting, It's 30psi with the vacuum line connected. If i do the setting per vacuum line disconnected (was it high 30's low 40's i forget) , with it connected it then drops to low 20's. I'm working from the FSM for the tests but have gathered information from various threads to help. You didn't make any mention of checking the CHTS circuit or sensor which is the biggest raw fuel curve adjustment in the system...lots of threads mention a faulty sensor, or circuit to cause extremely rich conditions. Some say that with the CHTS unplugged that the car will die out from so much fuel being dumped into the system, but mine will run with it unplugged...with it unplugged the ECCS thinks its like -40 something degrees Fahrenheit. Since you're rich all across the board I'd say to verify the resistance at the ECU end first, then all the way back to the sensor (by cyl. 5 spark plug) if it doesn't check out (all in the FSM). The sensor itself I did test (I actually only did it at one temperature, around 120 degrees and it tested out) So I will do it through the curve. Im fairly certain I also did the whole circuit to the ecu but i will do it again to make sure. Its been a month or two but I disconnected the connector when it was running and caused the motor to die. Edited January 21, 2013 by SDgoods Quote Link to comment Share on other sites More sharing options...
cgsheen Posted January 22, 2013 Share Posted January 22, 2013 On the stock ECCS, a non-working A.A.C. will definately cause a Rich condition - it needs that bypass air at idle. We noticed that on my Son's L28ET swap. It ran Rich by a couple of points (was in the mid-12's at idle). Connecting a vacuum supply brought it back into the 14's. His VCM was disconnected and he needed it to pass emissions at idle, so we just hard-wired it to vacuum... Doesn't sound like that's your whole problem, but it may help. On mine, I don't need no stinking A.A.C. Quote Link to comment Share on other sites More sharing options...
cgsheen Posted January 22, 2013 Share Posted January 22, 2013 Not to niggle, but - everyone seems to refer to fuel pressure as a static figure. It's really not. The FPR is supposed to maintain a 36.3 PSI (250.1 kPa, 2.55 kg/cm squared) differential between fuel pressure and manifold pressure. That means you subtract the manifold vacuum or add the boost pressure to get the proper fuel pressure required at any given time. How much vacuum are you running at idle? Subtract that from 36.3 to see what your fuel pressure should read... 1 Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 22, 2013 Author Share Posted January 22, 2013 Manifold vacuum? It pulls 20 inches hg. So subtract that from 36? Regarding the aac, the vcm was missing so i bought one, hooked it all up to find out the air regulator isnt opening, I read in fsm regulator circuit is through the fuel pump relay, this car having an aftermarket fuel pump makes me think the p/o didnt wire it in. Also that would only affect my afrs at idle. I will get the fuel pressure working correctly and test chts corcuit again. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 22, 2013 Author Share Posted January 22, 2013 Vac disconnected from fpr at 36psi, with connected it sits at 24psi and idles (cold) at 12.5 afr. Im going to a car meet so ill see whr it does when its warm Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 22, 2013 Author Share Posted January 22, 2013 When warm idle is inconsistently thrughout the high 10's and 11's. Wot throttle is a little leaner and leans out as rpms increase. Regular drivig ANY throttle it directly goes pig rich and pegs the wideband at 10. The lower fuel pressure helped with idle and wot a little. Testing more circuits tomorrow Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 The CHTS circuit is fine. However I found some other things- The head temp sensor was slightly out of spec at several different temperatures and I'm going to replace it but I don't think its causing my automatic pig rich condition with any throttle movement, which leads to the next finding... The throttle switch appears to be from a 240sx, showing continuity at full closed and OL at very little throttle input. I adjusted it to its extent so the OL didnt happen until maybe 1/4 or 1/3 throttle. Can anyone clarify that it's not supposed to go OL until full throttle (as per FSM "throttle depressed", doesn't say WOT or half throttle or anything. Any input on me just making a plate that allows a greater amount of adjustability or should I just get an actual ET throttle switch and connector? Also, 2+ ecu grounds have resistance at pin 107 and a couple others. Ill have to dig a bit further into that... Quote Link to comment Share on other sites More sharing options...
loy Posted January 23, 2013 Share Posted January 23, 2013 Are you looking at the service manual? It's suppose to go open as soon as the throttle is depressed. You should have a automatic 240sx tps, one with a wire a pigtail coming out of it, since you're on a stock ecu. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 Are you looking at the service manual? It's suppose to go open as soon as the throttle is depressed. You should have a automatic 240sx tps, one with a wire a pigtail coming out of it, since you're on a stock ecu. Im going off the FSM. Ok then it was working correctly if it goes open as soon as its off idle... Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 Theres no pigtail, its a connector wired in to the stock wiring that directly connects to the throttle switch Quote Link to comment Share on other sites More sharing options...
cgsheen Posted January 23, 2013 Share Posted January 23, 2013 Manifold vacuum? It pulls 20 inches hg. So subtract that from 36? Regarding the aac, the vcm was missing so i bought one, hooked it all up to find out the air regulator isnt opening, I read in fsm regulator circuit is through the fuel pump relay, this car having an aftermarket fuel pump makes me think the p/o didnt wire it in. Also that would only affect my afrs at idle. I will get the fuel pressure working correctly and test chts corcuit again. The Interweb says 20 inches hg = 9.8 PSI, so ya, at 20 inches hg vacuum the fuel pressure should be about 26 PSI... I'll have to look at the FSM again I guess... I have in my mind the A.A.C. is directly controlled by the VCM, which is directly controlled by the ECU (as is the Fuel pump relay - doesn't matter if there's an aftermarket fuel pump, you still want it controlled by the ECU through the fuel pump relay I would think. You may not want the fuel pump modulator...) Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 You are correct about the vcm controlling ecu through vacuum however the air regulator is what allows the air to get to the aac when vacuum is applied to it. The vcm only applies vacuum to te aac diaphragm, it doesnt supply bypass air Directly Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 Vcm controlling aac not ecu** Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 I found a constant 13 volts while the car is running at the air regulator connector, regardless of engine rpms and throttle position Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 23, 2013 Share Posted January 23, 2013 I found a constant 13 volts while the car is running at the air regulator connector, regardless of engine rpms and throttle position That's a good thing. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted January 23, 2013 Author Share Posted January 23, 2013 That's a good thing. But its not opening, and the regulator ohm test checks out at around 70 ohms. Now that fuel pressure is correct (and the AAC presumably not working) it idles at 11-12 AFRs. Im getting 13 volts to the connector, the test doesn't say anything besides the ohm check on the regulator. Is it safe to assume an internal component is bad in it? Also, my idle isnt my biggest concern right now. cruising around any throttle shoots to extremely rich. Quote Link to comment Share on other sites More sharing options...
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