Guest bastaad525 Posted August 16, 2003 Share Posted August 16, 2003 Jersey where exactly in the line did you tee in the pressure gauge? it has to be after the FPR right? Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 17, 2003 Share Posted August 17, 2003 It needs to be before the FPR... after the FPR there is 0 pressure. (put it between the pump and the FPR somewhere) Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 17, 2003 Share Posted August 17, 2003 okay now I"m confused, how is there 0 pressure after the FPR? I mean between the FPR and the fuel rail. Isn't the pressure before the FPR useless?? It will show how much pressure the pump is putting out, but not how much pressure is getting to the injectors, right?? You poking fun at me again Drax? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 17, 2003 Share Posted August 17, 2003 Lol! Drax is right. AFTER the FPR is the return line. BEFORE the FPR is the injectors and fuel rail. The pump is putting out the pressure, the regulator is passing enough fuel to the return to keep the proper pressure in the injectors. The easiest place to measure the fuel pressure in a stock system is in the pressure line going to the rail. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 17, 2003 Share Posted August 17, 2003 Thank you Sleeper Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 17, 2003 Share Posted August 17, 2003 Sorry bastaad, I wasn't poking fun at you! I guess I could have explained the "why" as well. Quote Link to comment Share on other sites More sharing options...
Jersey Posted August 17, 2003 Author Share Posted August 17, 2003 525 - i put it right between the fuel filter and the hard line, on the passenger side of the engine bay. I still can't figure out how the ECM advances timing. I know it has to send some sort of signal to the CAS but not sure how and/or if there's any way to measure or test it. If the CAS was bad, i would think that the Z wouldn't run at all, right? Need to figure out if one of those photo diodes are just for advancing....or something like that My cousin just found a '83ZXT that i'll be picking up this week to get it running for him. If i don't get this figured out by then, at least i'll have a chance to see if all my problems really IS the ECM. Until then...back to the drawing board! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 17, 2003 Share Posted August 17, 2003 If the FPR is bad, is this something I can get from any auto parts store and expect it to work right, or is it something you should really pick up from Nissan directly? Also, is there a difference between the turbo and the n/a FPR's? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 17, 2003 Share Posted August 17, 2003 525 - i put it right between the fuel filter and the hard line, on the passenger side of the engine bay. I still can't figure out how the ECM advances timing. I know it has to send some sort of signal to the CAS but not sure how and/or if there's any way to measure or test it. If the CAS was bad, i would think that the Z wouldn't run at all, right? Need to figure out if one of those photo diodes are just for advancing....or something like that My cousin just found a '83ZXT that i'll be picking up this week to get it running for him. If i don't get this figured out by then, at least i'll have a chance to see if all my problems really IS the ECM. Until then...back to the drawing board! All the CAS does it tell the ECU where the motor is mechanically. Advance is done electronically internal to the ECU. All you set with the distributor is the initial advance with the TPS closed. The ECU does the rest by timing the signal to the coil. Yes, if your CAS was bad, the car would not run at all. Have you tried what I suggested earlier with your timing? Watch the timing mark when you open the TPS. I don't mean by opening the throttle, I mean by pulling the connector off. If it doesn't move, your TPS may not be working. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 17, 2003 Share Posted August 17, 2003 I'll have to try that too. Never checked the timing, but I have noticed that when I pull the TPS plug off the idle changes, but not always... On another note, is it possible that disconnecting one or more of these sensors while the car was running, could send the ECU into a sort of 'safe' or 'panic' mode? I ask, because I seemed to have noticed a pattern with my car and the '4500rpm brick wall' I sometimes run into The car will be running fine, and I was messing aroudn with different things, say, unplugging the tps while the car is running. Then go for a drive and the car will not want to pull above 4-4.5k at all, even after I reconnect whatever I disconnected. Then I'll unplug all connections to the ECU, resetting it, and then the car runs perfect. I've now noticed this pattern twice. Maybe, any time you do something to the car like disconnecting one of the sensors, you automatically need to reset the ECU? Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted August 17, 2003 Share Posted August 17, 2003 bastaad - I found this info on a web site the other day. A variety of symptoms can be expected when one of these sensors or its wiring or ducting goes awry. GM says the engine will crank up and die. Bosch talks about starting problems both hot and cold, hesitation, stalling (especially under load), rough idle, and low power output. Nissan gives stalling, poor idle, black smoke, and switching to the fail-safe mode as evidence of air flow meter problems (in some models, this mode will be manifested by the inability to exceed 2,000 rpm). Generally, contamination of the sensing element, which slows response, will result in stumble. Regardless of those corporate opinions, the most logical effect of a bad signal (or no signal) is stalling, sagging, or missing at transient throttle. If this is far out of range, it may cause the computer to go into its limp-in mode, also known as LOS for "Limited Operating Strategy." In other words, driveability and performance will be pretty bad. Diagnosis isn't so easy because lots of other things can cause those same symptoms -- problems with ignition, compression, fuel pressure, etc. Something that's often overlooked is ripped duct between the sensor and the throttle body, which admits unmeasured or "false" air and leans out the mixture. A PCV system with a valve that's stuck wide open or a hose that's cracked can do the same thing, and a plugged air filter can mean trouble, too. So, at the risk of repeating what I've preached for years, don't automatically blame the engine management electronics or fuel injection set-up just because it's there. Actually, the trouble is most likely elsewhere because these systems are generally quite dependable. That's not to say you'll never encounter a failed air flow/mass sensor. For instance, older GM MAF's have a poor reliability record (the higher-frequency 10kHz Hitachi unit used on late model GM cars has a much lower failure rate). Here is the link http://www.autosite.com/garage/encyclop/ency13e.asp Quote Link to comment Share on other sites More sharing options...
Jersey Posted August 18, 2003 Author Share Posted August 18, 2003 Sleeper - yes, sorry i didn't mention about the TPS. I pulled the connector off when it was running and watched timing - no change at all. I did meter it and it does have continuity between the two pins when the throttle is closed and breaks when throttle slightly touched. Also, after the Z is warmed up and goes into it's "warm" mode, the injectors go into their slower pulse mode and soon as i touch the throttle and the TPS connection gets broke, the injector ticking becomes fast. So it seems to be working correctly but it does not change timing one bit plugged or unplugged. 525 - have you confirmed that these ECM's can be reset? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 18, 2003 Share Posted August 18, 2003 I dont know if there is a way to prove one way or the other, the same as no one seems to know for sure if they 'learn' and run better the longer they are run, i.e. reset it by disconnecting the wiring harness and cutting power, causing the car to run at 'baseline' then taking it for an extended drive, a couple guys on here have said that the car 'readjusts' and will run better. All I know is thrice now when the car has really started to act up, and I"ve disconnected and reconnected the ECU, the car has returned to running 'normally'. Quote Link to comment Share on other sites More sharing options...
Jersey Posted August 19, 2003 Author Share Posted August 19, 2003 Thanks for the reply and info 525. Quote Link to comment Share on other sites More sharing options...
fl327 Posted August 19, 2003 Share Posted August 19, 2003 Everytime I get a stumble or the car wont run right on WOT, I reset the ecu and reset a few minutes later. It usually runs normal afterwards. The only time it didnt run right afterwards is because I needed a new fuel filter. But I do the cleaning of efi connectors and reset the ecu before I go into any other alternatives, since It is free and easy to do. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 19, 2003 Share Posted August 19, 2003 I reset the ECU several times today, to try to solve this 'new' miss problem I'm having, and it didn't seem to have any effect at all. Quote Link to comment Share on other sites More sharing options...
Guest trey11691 Posted November 14, 2008 Share Posted November 14, 2008 im haveing the sputtering problems to but way worse! 1988 300zx NA. i did a tune up, (plugs, cap, button.. etc.) a month later the car started actin strange. on cold start up i have to throttle it to get it goin after a few seconds of 2000 rpm it idles. ill drive it a few mile with no problems, then the car will just loose power, rpms drop it idles extremely rough i give it gas and it will spit and spudder ad bog down. eventually the rpms will come back up if im lucky. it dies sometimes at redlights. if the rpms wont go up im stranded the car will spudder and spit and i cant go over 15mph, and it will backfire sometimes. if i kill the engine and crank it, and hit the throttle right when it cranks up the rpms will shoot up. sometimes they will bogg back down if i can keep it at about 4000rpm for about 15-20 seconds, the engine will clear up and run fine for the next 10 minutes or so. i have changed the coolant temp sensor (was never even hooked up i had to buy a pigtail) and unscrewed a bolt from behind #1 injector on right side, it leaks, and i have no change in car.i think and have been told the plugs are "fuel filling" the car is flooding itself. i dont no wat could be causeing it al. tomoro i will check fuel preasure and i few other sensors. im good with cars but wat could cause such terrible running? please if you can tell me anything i would love to have your openion. oh and it did this when i was lettin someone test drive it, needless to say, i havent heard back...... Quote Link to comment Share on other sites More sharing options...
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