Off the chart MAP sensor reading on S5 TII N370/N374
09-22-07 | 11:15 AM
#1
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
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From: SoCal
Off the chart MAP sensor reading on S5 TII N370/N374
I got a S5 TII motor rebuilt and have been trying to get it to start, it's got some wierd readings from the MAP sensor, instead of 1.9V, I'm getting 50V or 60V+ reading and can hear something ticking around the solenoids... Any one experienced this? Already tried different N374 ECUs and N370 MAP sensor, reset the code, no error. But still get the same off the chart reading from the MAP sensor if I were to test it, then it trips the code 13 again. HELP!
09-22-07 | 11:44 AM
#5
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
You can't get 50-60 vdc out of a twelve volt system.
If reading 0.50vdc or 0.60vdc, then remove the plug off the boost sensor. Put the meter neg lead on a known gnd and the positive lead on the BROWN/WHITE wire in the plug. IT must read from 4.5 to 5vdc. IF it reads only 0.60vdc you've a large problem with the ECU.
Try this if you see only 0.50vdc........remove the plug from the afm and then read the voltage on the brown/white wire on the boost sensor plug. IF it is now 4-5vdc, then the afm is killing the ref voltage output from the ECU. IF the voltage remains low with the afm plug off......tough luck. Bad ECU. Won't ever start without the five volts dc ref voltage.
IF you have noticed SPARK, the above does not apply and your not reading the meter right or the meter is kaput. Because the five volts dc ref voltage also is required for spark, therefore if you have spark the ref voltage is goos and most lilkely the ECU is probably good.
JUST IN CASE: The key has to be ON to do the above things suggested.
If reading 0.50vdc or 0.60vdc, then remove the plug off the boost sensor. Put the meter neg lead on a known gnd and the positive lead on the BROWN/WHITE wire in the plug. IT must read from 4.5 to 5vdc. IF it reads only 0.60vdc you've a large problem with the ECU.
Try this if you see only 0.50vdc........remove the plug from the afm and then read the voltage on the brown/white wire on the boost sensor plug. IF it is now 4-5vdc, then the afm is killing the ref voltage output from the ECU. IF the voltage remains low with the afm plug off......tough luck. Bad ECU. Won't ever start without the five volts dc ref voltage.
IF you have noticed SPARK, the above does not apply and your not reading the meter right or the meter is kaput. Because the five volts dc ref voltage also is required for spark, therefore if you have spark the ref voltage is goos and most lilkely the ECU is probably good.
JUST IN CASE: The key has to be ON to do the above things suggested.
09-22-07 | 11:50 AM
#6
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
lol! Just double checked, thanks for catching that! You're right, it's .06V (60.4mV) instead. But not changing when I apply vaccum to the MAP sensor (3.9inHg), also trips the error code 13 again everytime I do that with some solenoid ticking or flickering...
09-22-07 | 12:02 PM
#7
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
You can't get 50-60 vdc out of a twelve volt system.
If reading 0.50vdc or 0.60vdc, then remove the plug off the boost sensor. Put the meter neg lead on a known gnd and the positive lead on the BROWN/WHITE wire in the plug. IT must read from 4.5 to 5vdc. IF it reads only 0.60vdc you've a large problem with the ECU.
Try this if you see only 0.50vdc........remove the plug from the afm and then read the voltage on the brown/white wire on the boost sensor plug. IF it is now 4-5vdc, then the afm is killing the ref voltage output from the ECU. IF the voltage remains low with the afm plug off......tough luck. Bad ECU. Won't ever start without the five volts dc ref voltage.
IF you have noticed SPARK, the above does not apply and your not reading the meter right or the meter is kaput. Because the five volts dc ref voltage also is required for spark, therefore if you have spark the ref voltage is goos and most lilkely the ECU is probably good.
JUST IN CASE: The key has to be ON to do the above things suggested.
If reading 0.50vdc or 0.60vdc, then remove the plug off the boost sensor. Put the meter neg lead on a known gnd and the positive lead on the BROWN/WHITE wire in the plug. IT must read from 4.5 to 5vdc. IF it reads only 0.60vdc you've a large problem with the ECU.
Try this if you see only 0.50vdc........remove the plug from the afm and then read the voltage on the brown/white wire on the boost sensor plug. IF it is now 4-5vdc, then the afm is killing the ref voltage output from the ECU. IF the voltage remains low with the afm plug off......tough luck. Bad ECU. Won't ever start without the five volts dc ref voltage.
IF you have noticed SPARK, the above does not apply and your not reading the meter right or the meter is kaput. Because the five volts dc ref voltage also is required for spark, therefore if you have spark the ref voltage is goos and most lilkely the ECU is probably good.
JUST IN CASE: The key has to be ON to do the above things suggested.
It does have spark (from spark plugs and wires) but seems weaker compare to my old Corolla GTS, which is kinda questionable...
Ignition to ON, yes.
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09-22-07 | 12:10 PM
#8
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
ECU Ground and wiring
Does it matter if the ECU is mounted on those metal bracket on the car? or the ground wire should be sufficient? This is a N374 JDM ECU, second one, and I noticed two Green wires, 2L and 2B, but 2B is thicker...
09-22-07 | 03:55 PM
#11
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
The ECU can sit on a foam rubber pad and work. There is no chassis gnd.
The brown/red wire should read more than what you stated. I reckon you looked at the FSM and know what it should read. I forgot..
The buzzing is the BAC doing its thing. It has a duty cycle and buzzes. Normal.
Pins 3a, b, c, d are all gnds on the ECU. YOu might pull the plug off and with a meter check each one. Make sure the key is OFF when doing that. Check at the harness plug. They should all read less than one ohm.
They all come together somewhere on the engine. On a series four it's on the rear rotors top. On a series five it's somewhere else. If the 3a, b, c, d read high, then figure out where the gnd on the engine. If they read less than a ohm or.....even two, then they are probably gnd'd on the engine somewhere.
I've no idea why the rear primary won't come on. It should have batt voltage at its pin on the ECU when the key is to ON. Is this the case?
Tell you what. That boost/pressure sensor. Disconnect it and try to start the car. It is NOT a player in starting the engine. BUT might be the cause of the rear primary not coming online......somehow. Never hurt to try. Also see if the rear primary will work if that boost sensor is disconnected.
The brown/red wire should read more than what you stated. I reckon you looked at the FSM and know what it should read. I forgot..
The buzzing is the BAC doing its thing. It has a duty cycle and buzzes. Normal.
Pins 3a, b, c, d are all gnds on the ECU. YOu might pull the plug off and with a meter check each one. Make sure the key is OFF when doing that. Check at the harness plug. They should all read less than one ohm.
They all come together somewhere on the engine. On a series four it's on the rear rotors top. On a series five it's somewhere else. If the 3a, b, c, d read high, then figure out where the gnd on the engine. If they read less than a ohm or.....even two, then they are probably gnd'd on the engine somewhere.
I've no idea why the rear primary won't come on. It should have batt voltage at its pin on the ECU when the key is to ON. Is this the case?
Tell you what. That boost/pressure sensor. Disconnect it and try to start the car. It is NOT a player in starting the engine. BUT might be the cause of the rear primary not coming online......somehow. Never hurt to try. Also see if the rear primary will work if that boost sensor is disconnected.
09-22-07 | 05:30 PM
#13
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
Thanks, HAILERS. I just gave it a try without the MAP sensor connected, still no start. The MAP reads N370 with E1T10775. I have 3 of them with 3 different 4 digit number next to N370, and all 3 behaving the same.
The reading for 3A~D are all around 1Ω:
3A: 0.8~0.9Ω
3B: 0.8~0.9Ω
3C: 0.8~1.2Ω
3D: 0.8~1.1Ω
The reading for 3A~D are all around 1Ω:
3A: 0.8~0.9Ω
3B: 0.8~0.9Ω
3C: 0.8~1.2Ω
3D: 0.8~1.1Ω
Last edited by GTPilot; 09-22-07 at 05:40 PM.
09-22-07 | 06:12 PM
#14
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
How do you know the rear primary isn't working???
About that boost/pressure sensor. Have you pulled the plug off the sensor and rang out the brown/red wire from the plug to the ECU plug????? It's a brown/red wire on a series four and I *think* the same color on a series five. Does it ring from end to end and is not shorted to gnd? Might be a problem doing this since it splices off and goes to the boost gauge in the instrument cluster. Should ring to the ECU though for sure.
About that boost/pressure sensor. Have you pulled the plug off the sensor and rang out the brown/red wire from the plug to the ECU plug????? It's a brown/red wire on a series four and I *think* the same color on a series five. Does it ring from end to end and is not shorted to gnd? Might be a problem doing this since it splices off and goes to the boost gauge in the instrument cluster. Should ring to the ECU though for sure.
09-22-07 | 06:50 PM
#15
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
How do you know the rear primary isn't working???
About that boost/pressure sensor. Have you pulled the plug off the sensor and rang out the brown/red wire from the plug to the ECU plug????? It's a brown/red wire on a series four and I *think* the same color on a series five. Does it ring from end to end and is not shorted to gnd? Might be a problem doing this since it splices off and goes to the boost gauge in the instrument cluster. Should ring to the ECU though for sure.
About that boost/pressure sensor. Have you pulled the plug off the sensor and rang out the brown/red wire from the plug to the ECU plug????? It's a brown/red wire on a series four and I *think* the same color on a series five. Does it ring from end to end and is not shorted to gnd? Might be a problem doing this since it splices off and goes to the boost gauge in the instrument cluster. Should ring to the ECU though for sure.
3W (Front): http://www.youtube.com/watch?v=4Kglh5wGDLo
3Y (Rear): http://www.youtube.com/watch?v=hQxwkB_P5AQ
Last edited by GTPilot; 09-22-07 at 07:00 PM.
09-23-07 | 02:14 PM
#17
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
Tell you what. I've used LED's like the ones from RadioShack as shown in this article......http://www.teamfc3s.org/info/article...odes/main.html
I'd tie the postive terminals together and insert in a 12vdc source (cigar lighter connector) and then, at the ECU, put the other wire of the LED's into the backside of the wires going to the secondary injectors. Now those LEDS don't pull much of anythoing in current and are safe to use if looking to see if the injectors are firing or not.
I'd have huge doubts about using any other type of light to look at the output of the fuel injectors. I'm not saying that is the problem. Might be, might not.
I did that with the LED's to see just when the fuel injectors cut fuel and if it was a true statement that the front rotor fuel injector cuts off under certain conditions while the rear rotor fuel injector remains operating. And sure enough under CERTAIN conditons this is true. But most of the time if you let off the throttle both fuel injectors stop putting out.
Actually I forget just which injector cuts off while the other remains working when you let off the pedal. No memory here. It's stated (which injector cuts out) in the Training Manual that NZCONVERTIBLE made available to us.
I've still no idea why the rear injector isn't putting out and just why your boost/pressure sensor is not putting out a valid signal to the ECU. Have you been checking this output at the ECU or the boost/pressue sensor? Ohm out that wire from the boost/pressure sensor to the ECU plug and make sure the signal isn't broken.
Hummmm. Since this boost/pressure signal on a TURBO car is picked off and sent to the boost gauge,maybe that is where the problem lies. Maybe disconnect the plugs on the back of the instrument cluster to see if the output of the boost sensor gets closer to a valid signal. But then again, a boost/pressure signal isn't required for STARTING.
This idea is close to dumb......try disconnecting the tps and try starting. Like I said, close to dumb idea, but try it.
And I don't know what the TEST LIGHT was you used, but try two of the LED's like in the article and see what happens. I used them with no harm done and would expect the same for anybody else.
I'd tie the postive terminals together and insert in a 12vdc source (cigar lighter connector) and then, at the ECU, put the other wire of the LED's into the backside of the wires going to the secondary injectors. Now those LEDS don't pull much of anythoing in current and are safe to use if looking to see if the injectors are firing or not.
I'd have huge doubts about using any other type of light to look at the output of the fuel injectors. I'm not saying that is the problem. Might be, might not.
I did that with the LED's to see just when the fuel injectors cut fuel and if it was a true statement that the front rotor fuel injector cuts off under certain conditions while the rear rotor fuel injector remains operating. And sure enough under CERTAIN conditons this is true. But most of the time if you let off the throttle both fuel injectors stop putting out.
Actually I forget just which injector cuts off while the other remains working when you let off the pedal. No memory here. It's stated (which injector cuts out) in the Training Manual that NZCONVERTIBLE made available to us.
I've still no idea why the rear injector isn't putting out and just why your boost/pressure sensor is not putting out a valid signal to the ECU. Have you been checking this output at the ECU or the boost/pressue sensor? Ohm out that wire from the boost/pressure sensor to the ECU plug and make sure the signal isn't broken.
Hummmm. Since this boost/pressure signal on a TURBO car is picked off and sent to the boost gauge,maybe that is where the problem lies. Maybe disconnect the plugs on the back of the instrument cluster to see if the output of the boost sensor gets closer to a valid signal. But then again, a boost/pressure signal isn't required for STARTING.
This idea is close to dumb......try disconnecting the tps and try starting. Like I said, close to dumb idea, but try it.
And I don't know what the TEST LIGHT was you used, but try two of the LED's like in the article and see what happens. I used them with no harm done and would expect the same for anybody else.
09-23-07 | 03:28 PM
#18
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
I've also made something similar for retrieving error codes. The numbers are read differently between S4 and S5, but I was able to get some codes and confirming by disconnecting known good sensors and such. Sure enough everytime something happens, it trips the error code for the MAP sensor (code 13). I started to think that there may be something wrong with the harness itself, pinched, slightly cut, or grounded due to a cut somewhere. But thought those should have been picked up by the error code check. The test light I used was merely a regular test light the car stereo installers use, pretty much just the same as a LED as a test light, but I'll stop using it just in case.
There are two wires binded together with the same color Brown/Black, but this is a NA to Turbo conversion, so I'm not absolutely sure where it's connected by the previous mechanics worked on it but will try to find out.
From threads that I researched in, the rear injectors are usually the ones that get shut off when anything happens, including overboost. So I had suspicion on if the MAP was giving high readings and causing that to happen, but even disconnect it, doesn't seem to do much. I also heard that S4 design is more forgiving, when some things are not working properly, the ECU goes into safe mode, where as S5, just nothing would run if anything critical that's not in line.
Tried starting without the TPS, no difference...
Other than the budget thing, I'm just very tempted to get another harness to be installed. This is using a JDM harness adn JDM ECU, and I've seen people recommending using the US harness and ECU, but don't think that matters that much.
There are two wires binded together with the same color Brown/Black, but this is a NA to Turbo conversion, so I'm not absolutely sure where it's connected by the previous mechanics worked on it but will try to find out.
From threads that I researched in, the rear injectors are usually the ones that get shut off when anything happens, including overboost. So I had suspicion on if the MAP was giving high readings and causing that to happen, but even disconnect it, doesn't seem to do much. I also heard that S4 design is more forgiving, when some things are not working properly, the ECU goes into safe mode, where as S5, just nothing would run if anything critical that's not in line.
Tried starting without the TPS, no difference...
Other than the budget thing, I'm just very tempted to get another harness to be installed. This is using a JDM harness adn JDM ECU, and I've seen people recommending using the US harness and ECU, but don't think that matters that much.
Last edited by GTPilot; 09-23-07 at 03:30 PM. Reason: typo
09-23-07 | 08:52 PM
#19
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
Here's the thread where I got straightened out on how the front rotor has fuel cut when the pedal is lifted just a touch while driving along at a steady speed. ROTOMAN came up with the information. Several people have mentioned this in the past and I was sure that was not right, but the two LED's showed me it is a fact. This does not help you though. Just FYI.
I'd try the USA harness like you say.
Two wires both brown/black on the boost sensor are gnd wires. One is just reinforcing the other.
I'd almost bet money that if you ohm'd out the brown/red wire to the ECU ....it won't.
I'd try the USA harness like you say.
Two wires both brown/black on the boost sensor are gnd wires. One is just reinforcing the other.
I'd almost bet money that if you ohm'd out the brown/red wire to the ECU ....it won't.
09-23-07 | 10:36 PM
#20
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
I forgot to add the link: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/1-5k-2-2k-rpm-surge-686904/
I just read about fifteen thousand post about N374. Lots of problems with that ECU and claims that a chip they bought fixed it to front rotor injector won't fire to Works Like a Charm. B.S.
I vaguely remember a post about the boost wire and the injector wire being pinned wrong for the ECU. I cannot find what I *THINK* I read in the past. Seems like it was within the last year but I can't find that thread/post.
I'm betting that the boost sensor wire is not going to the right pin on the ECU and same with the injector wire.
I just read about fifteen thousand post about N374. Lots of problems with that ECU and claims that a chip they bought fixed it to front rotor injector won't fire to Works Like a Charm. B.S.
I vaguely remember a post about the boost wire and the injector wire being pinned wrong for the ECU. I cannot find what I *THINK* I read in the past. Seems like it was within the last year but I can't find that thread/post.
I'm betting that the boost sensor wire is not going to the right pin on the ECU and same with the injector wire.
09-23-07 | 11:20 PM
#21
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
HAILERS, I'm along the same line with you. It just doesn't make sense when I'm testing voltage it would trip the error code, and always the MAP sensor code. I'll try to get the ohm reading and see what happens, but have to figure out which wires they are, looks like the color changed by the time it go to the ECU... You've been a great help!! THANKS!!
09-24-07 | 12:01 PM
#22
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
I've made a grave mistake. I should not have mentioed a brown/red wire as the signal coming out of the boost sensor. That would be a series four car.
The output signal from YOUR series five is colored Green/Yellow and stays that color from the boost sensor plug to the ECU plug. It goes to the sixteen pin plug on the ECU. Bottom row, fourth wire from the right. Sorry 'bout that wire color thing.
If you don't have long meter leads, you can get a roll of common auto wire and wrap it around the probes so you can reach the plug at the ECU and also at the same time the elect plug at the boost sensor.
That N374 sounds odd from the threads I read. Some had the same problem you have and other said it flat did not work and then others like RETED say it works just fine and dandy. I can't help but think it has something to do with the harness b/t the ECU and the sensor/injector plugs.
I can't find the thread but I definetly remember a guy posting how he found the wires for the boost sensor in the wrong location and the same with the fuel injector plug. But I don't remember if it was a diff ECU pinout or wiring harness pinout. Just cannot find that thead. Certainly are a lot of threads complaining about the N374. One guy even bought a chip from????? that fixed his problem of the rear injector not working. Puzzleing (sp).
The output signal from YOUR series five is colored Green/Yellow and stays that color from the boost sensor plug to the ECU plug. It goes to the sixteen pin plug on the ECU. Bottom row, fourth wire from the right. Sorry 'bout that wire color thing.
If you don't have long meter leads, you can get a roll of common auto wire and wrap it around the probes so you can reach the plug at the ECU and also at the same time the elect plug at the boost sensor.
That N374 sounds odd from the threads I read. Some had the same problem you have and other said it flat did not work and then others like RETED say it works just fine and dandy. I can't help but think it has something to do with the harness b/t the ECU and the sensor/injector plugs.
I can't find the thread but I definetly remember a guy posting how he found the wires for the boost sensor in the wrong location and the same with the fuel injector plug. But I don't remember if it was a diff ECU pinout or wiring harness pinout. Just cannot find that thead. Certainly are a lot of threads complaining about the N374. One guy even bought a chip from????? that fixed his problem of the rear injector not working. Puzzleing (sp).
09-24-07 | 10:17 PM
#23
Thread Starter
Where did the boost go??
Joined: Jun 2004
Posts: 104
Likes: 0
From: SoCal
Confirmed, HAILERS. That's the same one that kept tripping off the error code 13 every time I touch it.
I also think that it's something to do with the pin out on the ECU. but the weird thing is that the car ran fine for about half a year...never had the problem. then the motor blew all of the sudden... wish we can get the pin out diagram or table for the N374 ECU, it would clear out all the questions... anyone living in Japan or going to Japan?? =)
I also think that it's something to do with the pin out on the ECU. but the weird thing is that the car ran fine for about half a year...never had the problem. then the motor blew all of the sudden... wish we can get the pin out diagram or table for the N374 ECU, it would clear out all the questions... anyone living in Japan or going to Japan?? =)
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