Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 From my understanding she should read between 3.3 to 3.5 volts on idle , I triple checked for vacuum leaked around the intake , none Anybody any more ideas? Or time to get out the wallet for a new sensor Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 Car has gone from the hunting rpm to idling at 300 rpm, trying to cut out Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 What does it show at the sensor? An analogue meter (one with a needle) is better for reading things like that, the latency in a digital meter makes many do strange things with rapidly fluctuating voltages into them. You might want to check the sensor is getting a good vac signal, and the pipe(s) and hose T's to it are not cracked, blocked or leaking, same for the "Sputnik" damper screwed into the plenum. Did you say it has no FCD? I think the fuel cut raising or removal is done by the modded ECU, correct? Yet to see a dead or faulty MAP sensor on a *JZ. If you have a vacuum gauge (in the sixties *EVERYONE* had one of those, for checking stuff). T it into the MAP sensor hose. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 At the sensor I am getting 0 volts, cannot get any reading Took off the sensor , looks good , Sputnik, no blockages , all vacuum lines are new , on a few weeks, she was working fine post fitting the new lines Put sensor back on , still 0 volts, reset ecu plugged loom back into the sensor , engine on, car idles more stable after the ecu is reset for a min or two, rechecked voltage at ecu on the stable idle, got 1.44v consistently but still 0 volts at the sensor Fcd is incorporated into the modded ecu via a rom chip No vacuum guage unfortunately Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 There are 3 wires to the MAP sensor. One should be ECU ground, one should be %V reference from the ECU. The third will be whatever voltage the sensor outputs, dependent upon the vac / pressure signal to the nipple. That "signal" wire goes to the ecu. You need black lead of meter on the ground wire at the MAP sensor, and the red one on the signal wire. Your wire colour codes will probably differ from the illustration, but the pin locations should be identical. HTH. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 It was the signal wire I tested Pin 62 turbo pressure sensor , black yellow wire Voltage was 1.64 for a few seconds, then fluctuates a lot around 0.3,0,35 then to zero, might spike to 1.64/1.63 , engine on idle Car is overfueling now in idle, stopped rpm hunting Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 http://youtu.be/SeDKyKnNjlQ Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 I can't see how you see volts on the signal wire at the ECU but not at the signal wire on the sensor. The signal wire from the sensor is what delivers the volts to the signal pin on the ECU. If the ECU was receiving bizarre or no volts it would flag a fault code I would think. You are testing with the ECU and MAP sensor both plugged in,aren't you? Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 Sorry my mistake with getting the voltage at the map sensor, really don't want to splice the loom wire Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 It's 1.35v being sent by the sensor to the loom Ecu is feed pin 62 is showing 1.35v too Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 You need to back probe the connector, use something like a straightened paper clip or thick needle. Don't short anything out... You can get proper needle probes for the meter, but they are dear for what they are. http://www.ebay.co.uk/itm/Hantek-Back-Pinning-Probes-Needle-Piercing-Probes-Set-l-/201380859284?pt=LH_DefaultDomain_3&hash=item2ee33c0d94 Some people use T pins, including myself. http://www.spoiltrottenbeads.co.uk/Pack-of-10-T-Pins-for-Macrame-Boards-p302368.html?gclid=CNCCvquiycYCFayWtAodFxcNvw Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 Does the voltage at the ecu signal pin when carefully back probed, go up and down as you rev the engine up and down? If so start looking elsewhere than the MAP sensor. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 Ignore the low voyage at the start was trying to position the earth correctly, this is her revving http://youtu.be/-ab-x0R_FyI Quote Link to comment Share on other sites More sharing options...
Hitbox Junkie Posted July 7, 2015 Share Posted July 7, 2015 dirty throttle body? my car did this and it was down to a dirty throttle body (not supra), cleaned that and now shes golden Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 The MAP sensor seems fine. Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 7, 2015 Share Posted July 7, 2015 here is the map sensor and other sensor readings to cross refferance http://www.mkiv.co.uk/vbb/showthread.php?238522-2JZ-sensor-resistance! Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 The MAP sensor seems fine. Thanks Chris This is really turning into a pickle Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 here is the map sensor and other sensor readings to cross refferance http://www.mkiv.co.uk/vbb/showthread.php?238522-2JZ-sensor-resistance! Thanks , maybe I just don't comprehend but I would is taught my voltage should be around 2.6 mark at idle I really cannot not think of what else would cause her to over fuel Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 7, 2015 Share Posted July 7, 2015 Thanks , maybe I just don't comprehend but I would is taught my voltage should be around 2.6 mark at idle I really cannot not think of what else would cause her to over fuel depends on what you pull on vacuum , off the top of my head I pull -466 so that would/should give me 1.78 v which is pritty close to what you have and depending on how they control the boost cut on you ecu it may will be scaled . you havent messed around with anything near the injector conections have you ? when I changed my injectors i had a boost sort of cut issue which turnt out to be a injector plug with a bad connection same thing as the coil pack clips have Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 7, 2015 Share Posted July 7, 2015 sorry i Just re read the thread you say your idling now and dropping too 300 this will be the ecu learn , from your rich state ! if all is well now what ever you touched before this state could well be your issue Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 7, 2015 Share Posted July 7, 2015 (edited) If your MAP sensor signal voltage is on the low side it would run leaner. I do NOT recommend you try this, but you can inject a voltage into the ECU to simulate the MAP sensor signal, but I really don't think the MAP sensor is (now??) your issue. Maybe a bad connection has come good with fiddling about? I once spent 2 days finding a bad pin connector in the ECU plug on a member's car. It had been to 6 other garages with no fix, so I didn't feel too bad about the bill. I felt even better when a drinking pal's Ford Focus diesel spent months in and out of Ford main dealers with nearly every sensor renewed, the injectors renewed, the metering unit renewed and a new ECU fitted before they found a dodgy intermittent ECU plug contact. Luckily it was under warranty. It would just cut out and die, usually hundreds of miles from home with a load of expensive gear in the back. Edited July 7, 2015 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 I am thinking a doggy connection myself, that I may of fixed unaware Was also thinking of testing the coolant temp sensor , seems to be a common thing to check too , as well as the map sensor Mellonman- this is what confuses me, nothing was touched to warrant these issues , just put on new billet aux wheels and crank pulley, new belt ; car was running fantastic prior to the crank pulley giving up Quote Link to comment Share on other sites More sharing options...
Jellybean Posted July 7, 2015 Author Share Posted July 7, 2015 She seems ok now , still a little rich but maybe due to the ecu reset Small hesitation in turbo 2 transition , she might just need a good run Looks like it was a wiring issue , must of been me in the passenger seat pressing on the ecu cover, maybe it was snagged on a wire Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 7, 2015 Share Posted July 7, 2015 hows your heater matrix ? could of leaked coolent on the ecu connections did they feel oily at all? How did the crank fail with a mass of mess or just your heard is do the squeek thing . must admit it is an odd one but does sound like a connection issue , could be temp sensor thats sort of new the water pump could of caught it ptting the belt on ? Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 7, 2015 Share Posted July 7, 2015 The ECU reset really really isn't as traumatic as people make out. It won't drop to 300(!) rpm because of it, or hunt, or do anything really - it's hard to notice any change on first key-on. There is a guide on here for refurbing your ECU pins, try that horrible job, it worked for me years ago 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.
Note: Your post will require moderator approval before it will be visible.