Afshin Posted July 8, 2007 Share Posted July 8, 2007 Well non-load and rpm dependent makes temperature sensor, O2 sensor and AFM less likely culprits (but of course life is full of unexplainable surprises). You already went thru the TPS and it usually does not cause so much poor running anyways. Perhaps the ECU is not getting the right rpm signal, in other words at 2000 rpm it is thinking you are at 1000 RPM and not sending in the extra fuel. I believe on the NA set up the ECU gets the rpm signal from the positive lead of the coil (as opposed to the electronic ignition in the turbo). You should check that circuit. Also if you are using a MSD, as you know they change from multiple spark at low rpm to single spark at high rpm. The MSD feeds the coil and any problem with the unit could lead to faulty signal to the coil and hence faulty rpm reading by the ECU and then no increase in fuel delivery. Since the MSD has 2 circuits for feeding the impulse to the coil, one could be faulty (low RPM) while the other high RPM circuit is functional. SO if the MSD is on disconnect it!! If it is not on, then check the circuit from the coil to the ecu (? Pin 18 on the ECU). That’ all I can think of for now. Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted July 8, 2007 Author Share Posted July 8, 2007 Afshin & Clifton- The ignition was OK, the input signal for MSD box & N/A ECU is on the negative coil lead. I took the dizzy of and made it turn by hand & the noid light on the injector harness pulsed. But I tried a 4th ECU & it ran better unbelieveably last night. It still was a little lean off boost, but ran smooth and very, very strong. When I had it sitting @ idle it all of the sudden dies-WTF? So I hooked up the meter as CLifton had suggested, & drove the car about 3 miles. Sure enough there was a voltage drop when the car went lean from 1000 to 1500 from AFM. The wiper on the AFM was ever so slightly bent, so I straightened it a little. Improved the cars performance in that range greatly. But I thought to myself "why did the other AFM act the same way?" After a closer inspection the wiper on AFM #2 was bent in almost the exact same spot!?! So after this, I test drove the car again, it was pretty dark outside. I tried to pull out of the driveway & the motor shuts off! I could only restart the car with all the lights off. Checked the in car voltmeter & it said the alternator was charging at 14 volts. Pulled it into the garage & checked the battery voltage with the motor off- 10 volts. The battery had become discharged. Charged the battery overnight & drove it this morning-WOW! The importance of battery voltage.....the car hauls the mail now! I think I had several bugs causing the problem, but I appreciate you guys as well as the others that posted (Warren, Rags, etc.) giving me ideas. I have not posted much here before, even though I have been a member for over a year, but I will definitely post more. The Hybrid members rock! Quote Link to comment Share on other sites More sharing options...
Daeron Posted July 9, 2007 Share Posted July 9, 2007 I will reply in the form of an epilogue: Analog multimeters are always best for testing devices such as the AFM on the early Z FI.. sometimes digital meters (even the best ones) can miss a bad spot in the potentiometer, that will always flicker a cheap analog needle. Quote Link to comment Share on other sites More sharing options...
Afshin Posted July 10, 2007 Share Posted July 10, 2007 Glad you got her to run, must be having a blast. Well now it’s time to ditch the stock EFI, really!!! I’ve gone through a few EFI mods and each time the gain was huge. You won’t believe how much more power and how well the car will run when you update. I first updated to the Z31 set up and then updated that to reprogrammed chip and Z32 ECU set up, each time with noticeable gain. I then upgraded to a SDS system which has been absolutely wonderful. It’s almost criminal to have a set up like yours with stock EFI. Also the connectors and harness have a limited lifetime and gremlins will keep reappearing (that was actually one motive for switching from the Z31/32 set up, to get rid of the old harness and intermittent problems). Quote Link to comment Share on other sites More sharing options...
Clifton Posted July 10, 2007 Share Posted July 10, 2007 That's great you figured it out and got it running good again. Nothing is worse than trouble shooting. Quote Link to comment Share on other sites More sharing options...
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