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got a multimeter....need to know how to check electricals........any suggestions?

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Old 05-13-11 | 04:05 PM
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IN got a multimeter....need to know how to check electricals........any suggestions?

i need to know how to check the following and what they should be reading:

1991 s5 TII-

air flow meter

boost sensor

tps

omp

injectors

and anything else that could cause my car not to start or run very very very rich...thanks
Old 05-13-11 | 06:16 PM
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Stop making threads and pay someone to fix your car, or sell it!
Old 05-13-11 | 06:38 PM
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if you don't know how to use a multimeter, a RX7 is not for you
Old 05-13-11 | 06:44 PM
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I hear mazda released this book that tells specs and how to repair the car. Damn if only we knew what that book was called.
Old 05-13-11 | 06:45 PM
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Get the FSM(Factory shop manual) it tells how to do all these checks and the proper values you should be reading. It is exspensive unless you can find the pdf's somewhere online, but it can be a lifesaver for the RX7 owner.
Old 05-13-11 | 06:50 PM
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Originally Posted by nate91242
I hear mazda released this book that tells specs and how to repair the car. Damn if only we knew what that book was called.
Might one of these be that book.

http://www.mazdatrix.com/m-1.htm
Old 05-13-11 | 07:16 PM
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(cough) see sig below (cough)

edit: google "electrical troubleshooting" - we all started with knowing nothing.
Old 05-14-11 | 12:23 PM
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i can do without the smart *** comments guys. i know how to use a multimeter.

i know how to check the injectors, but the rest is not covered in the repair manuals. all it says is take it to a dealer. all i need to know is the specs. maybe somebody out there is KIND enough to help a FELLOW RX7 OWNER.
Old 05-14-11 | 01:52 PM
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It isn't our fault that you took on a task over your head and outside of your knowledge. You make a new thread every week about the same bullcrap and expect us to fix your car over the Internet. Everything you need is available on this website or linked from it, either you too dumb or lazy to find the resources yourself.
Old 05-14-11 | 03:59 PM
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Originally Posted by blackrotary23
i know how to check the injectors, but the rest is not covered in the repair manuals. all it says is take it to a dealer.
The specs are in the FSM fuel and emissions section. You're just not looking hard enough.
Old 05-14-11 | 05:17 PM
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Originally Posted by blackrotary23
i know how to check the injectors, but the rest is not covered in the repair manuals. all it says is take it to a dealer. all i need to know is the specs. maybe somebody out there is KIND enough to help a FELLOW RX7 OWNER.
That may be all the Haynes manual says, I can't remember as I haven't opened mine in years.

Originally Posted by RotaryRocket88
The specs are in the FSM fuel and emissions section. You're just not looking hard enough.
He is right the specs you seek are in the FSM. It is the manual the dealers use. Have you looked in the links in pfsantos's sig? Download those PDF's and look at them.
Old 05-16-11 | 05:36 PM
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ok, i checked everything out with a multimeter and everything checks out fine. \

what is happening is when i go out to start the car, it takes a while to get started. then it spits fuel smoke out the pipe and runs with my foot on the pedal. i can keep the car running at 1000 rpms with my foot on the pedal, if i take it off, it dies and is hard as hell to start again. when i get it running for the first time of the day, it runs kinda like it needs a tune up or something. it takes a couple of seconds to get some hp out of the car while driving it. i am getting boost anywhere over 3000 rpms and no less. once i let my foot off of the pedal, it will stall and wont start again unless i push start it and pop it in first gear then it runs the same as i described above.

could fuel pressure, air flow meter, or fuel pump solenoid resistor cause this to happen?
Old 05-16-11 | 06:18 PM
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If it was the air flow meter, the car would just start, get to about 500 rpms then die. So I would say no go on that idea. Fuel pressure, maybe, get a pressure tester and find out. Fuel pump solenoid resistor, maybe, check it for proper resistance.

I would also check for vacuum leaks, and check that the water thermo sensor is connected properly (by properly I mean that BOTH pins are making good contact, not just the plastic piece hooked up.) I would also check the compression.
Old 05-16-11 | 08:17 PM
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Originally Posted by texFCturboII
If it was the air flow meter, the car would just start, get to about 500 rpms then die. So I would say no go on that idea. Fuel pressure, maybe, get a pressure tester and find out. Fuel pump solenoid resistor, maybe, check it for proper resistance.

I would also check for vacuum leaks, and check that the water thermo sensor is connected properly (by properly I mean that BOTH pins are making good contact, not just the plastic piece hooked up.) I would also check the compression.
the engine has good compression. i tested it and it is reading 80-90. i disconnected the resistor and it pretty much acted like the fuel pump got cut off so i think it is working. the water thermo sensor is brand new. i actually have 2 of them and they both work just fine. i also have had 2 different wire harnesses in the car and they both connect very good. the only other things i have not replaced on the car so far are the fuel pressure regulator, solenoid resistor, and air flow meter. i ordered an aftermarket fuel pressure regulator and i am going to take off the stock one and run a straight line to the new regulator and adjust it to spec. as for the vacuum leaks....there are NONE. i made sure of that first thing. everything is sealed up tight. i can get it started when it is cold but it take a few tries. once it gets warm to normal temp it wont start for **** unless i pop the clutch, then it will run all of half ***. it seems to me like it is a fuel problem seeing how everything under the hood checked out to be fine with the multimeter. i have a new fuel pump, filter, and injectors are reading 14-15ohms (high imp)
Old 05-17-11 | 12:41 PM
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how are the spark plugs?
Old 05-17-11 | 04:08 PM
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Originally Posted by texFCturboII
how are the spark plugs?
plugs are brand new.
Old 05-17-11 | 06:08 PM
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How are things checking out at the ECU?
Old 05-17-11 | 07:26 PM
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ecu is good. i have checked all of the electricals. that is why i think it might be a fuel issue. or my air flow meter is checking out alright, but it still could be off by a bit adjusting the fuel to rich at all times but still making it to where the car will still run.
Old 05-17-11 | 09:55 PM
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No, I mean how did all the injectors, AFM, Water Thermo Sensor, Crank Angle Sensor, TPS, etc. check out at the ECU? Did you backprobe all those sensors AT THE ECU?
Old 05-17-11 | 09:59 PM
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no i did not nor am i familiar on how to do so.
Old 05-17-11 | 11:12 PM
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Thats going to give you a good idea as to what signals are actually making their way to and from the ECU, hence working properly.

1) Get physical access to the ECU. It's located in the passenger footwell behind a metal kickplate. You are going to have to remove some plastic around the bottom of the door and the foot to do so, then peel the carpet back.
2) Remove the kickplate, and voila, there is your ECU.
3) Now grab the Fuel and Emissions section of the Factory Service Manual, get to the part of that section that talks about the Emissions Control Unit. You should find a list there that says what each pin is, whether or not it is an output/input, and what voltage it should be showing and when.
4) Also listed is a diagram saying which pin is which. Find the pins for the TPS, the AFM, the injectors, the boost sensor, the coil packs, the water thermo sensor, the crank angle position sensor, fuel pump resistor.... anything vital to the starting and running of the car.
5) turn the ignition to "on"..... do not start it, but turn it to "on" so that everything has power.
6) "backprobe" meaning insert the probe of the multimeter into the rear of the pin, while the big plugs are still connected to the ECU. Compare the voltage you read there to the values given in the FSM. To gain access to some of the pins, you may have to completely unbolt the ECU so you can maneuver it easier.
Old 05-18-11 | 03:59 PM
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Originally Posted by texFCturboII
Thats going to give you a good idea as to what signals are actually making their way to and from the ECU, hence working properly.

1) Get physical access to the ECU. It's located in the passenger footwell behind a metal kickplate. You are going to have to remove some plastic around the bottom of the door and the foot to do so, then peel the carpet back.
2) Remove the kickplate, and voila, there is your ECU.
3) Now grab the Fuel and Emissions section of the Factory Service Manual, get to the part of that section that talks about the Emissions Control Unit. You should find a list there that says what each pin is, whether or not it is an output/input, and what voltage it should be showing and when.
4) Also listed is a diagram saying which pin is which. Find the pins for the TPS, the AFM, the injectors, the boost sensor, the coil packs, the water thermo sensor, the crank angle position sensor, fuel pump resistor.... anything vital to the starting and running of the car.
5) turn the ignition to "on"..... do not start it, but turn it to "on" so that everything has power.
6) "backprobe" meaning insert the probe of the multimeter into the rear of the pin, while the big plugs are still connected to the ECU. Compare the voltage you read there to the values given in the FSM. To gain access to some of the pins, you may have to completely unbolt the ECU so you can maneuver it easier.
i dont have a fsm, but i will try to find the info online. you have been very helpful and i thank you very much. in the past 2 months, i have had trouble finding somebody to actually give the step by step instructions to what i should do to figure out if everything is working correctly. once i find the info, i will post the information i find at the ecu readings. thanks!
Old 05-18-11 | 11:46 PM
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Well, I gotta say, that every bit of this information is available here, at this exact site.... you just gotta look for it. I've been guilty of doing what you do before, and despite my high post count I have A LOT left to learn. Everything I have learned I have learned from this website.... just search my friend, you aren't the first person to have the issue you have now. The FSM is available in the FAQ in the 2nd gen section, btw.

The vast majority of people that post here or frequent this forum have been here for years, hence the attitudes you will receive. Many are veteran shade-tree mechanics that know a whole crap ton about these cars and many others and just working on cars in general. They don't respond positively to questions that have been asked over and over and over. I cut my teeth on an 89 turbo II, and really learned on a 86 n/a. I'm still learning a lot. So don't give up, keep learning; it's simply nuts, bolts and plumbing, be it electrical or of the liquid variety; it isn't rocket science. It's here, search for it and you will catch a lot less flack.
Old 05-21-11 | 12:56 PM
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well, i backprobed the ecu and everything is checking out according to the spec chart. i put an aftermarket fpr on and adjusted it to stock pressure. still i am getting the same feedback from my car.it will fire up when it is cold, run kinda funky, wont idle.

when i let my foot off the pedal, it stalls and will not start back up. i think my air flow meter might be bad although it is reading correctly.
Old 05-21-11 | 02:33 PM
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Have you checked compression?


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