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Thought I'd better post this right away in case anyone else is thinking about buying a A/F meter for this car. Don't do it yet.

Today I discovered that the SRT-4 computer conditions the O2 signal so that the range is from 2.5 to 3.5 volts. From the FSM, "The O2 sensors produce voltages from 0 to 1 volts (this voltage is offset by a constant 2.5 volts on NGC vehicles)." I installed a new A/F meter and it read full rich all the time, even with the key in the "run" position and the engine shut off.

I've already asked Darren Dawes if he will tackle this problem.
 

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thanks for the heads-up. and people thought this was going to be a regular turbo engine. :roll:
 

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NGC vehicles? Looks like one for the list, Grunge.
 

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Mike, what wire did you connect it to? I have the M/M and I want to verify for you to see if its the correct wire. I am not to fond of the manual. It does a poor job on describing the fuel injection/ emittion setup. I was looking for a description of the TIP throttle inlet pressure sensor and I could not find any. It was not even in the back of the book.

Also, Im yet to find the obdii fault codes in teh book. :(
 

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Discussion Starter #6
I'm a little disappointed in the FSM too. I was hoping for more information also, but mostly it's just telling us how to change parts.

They are using the same 4-wire O2 sensor that Mopar has had since the late 80's. There are 2 white wires, 1 black wire, and 1 gray wire (these are the wires coming out of the sensor, not the car's wiring harness). The larger white wire is the heater, the smaller white wire is the heater ground. The black wire is the signal, and the gray wire is the signal ground, although there is 2.5V on that wire also on the SRT-4. The black wire is the one you want to monitor. It goes to the black/dark green wire on the harness.
 

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diodes.

silicon junction gates always cause a contstant voltage drop. typical diodes drop 0.7 volts. Zener diodes come in many different voltage drops, and are made for this specific purpose: creating a desired and precise drop in DC voltage. drop by radio shack or find an electronics surplus store online that may have a 2.5V Zener diode.

Jer
 

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PostPosted: Mon Mar 24, 2003 10:31 am Post subject: diodes.

silicon junction gates always cause a contstant voltage drop. typical diodes drop 0.7 volts. Zener diodes come in many different voltage drops, and are made for this specific purpose: creating a desired and precise drop in DC voltage. drop by radio shack or find an electronics surplus store online that may have a 2.5V Zener diode.

Jer
:?: ?????? yea somebody explain what hes talking about cuz that looks russian to me
 

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:lol: Not Russian, German!

A zener diode is a device that limits voltage. For example, if you have a 5V zener diode in a circuit that has anywhere from 1V up to 7V, the zener will basically pass any voltage over 5V to ground. Works great on a MAP sensor circuit. For another example, if your ECU cuts the engine out when it gets 4.7V from the MAP, you can install a zener so that the MAP will never put out more than 4.6V, i.e., you've bypassed the overboost cutout.

I thought about using a zener for the a/f meter, but I'm going to see what Darren Dawes suggests first.
 

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Germanium and silicon diodes are the commen ones. Silicon drop voltage by .7 whre as fermanium drop it by .3 The numbers do vary.

Diodes are not only used to bias(set a voltage) a system, but they are also used to isolate circuits from each other in a dc system.


TO make it easier, a diode is nothing ore than an electrical check valve. voltage goes one way but not the other. Before voltage is allowed to go through the diode, it has to reach the .7 volts or .3 volts(depending on what you have). So picture the diode needing .7 volts before it turns "on" allowing voltage to go though.
 

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Exhaust Depot said:
Germanium and silicon diodes are the commen ones. Silicon drop voltage by .7 whre as fermanium drop it by .3 The numbers do vary.

Diodes are not only used to bias(set a voltage) a system, but they are also used to isolate circuits from each other in a dc system.


TO make it easier, a diode is nothing ore than an electrical check valve. voltage goes one way but not the other. Before voltage is allowed to go through the diode, it has to reach the .7 volts or .3 volts(depending on what you have). So picture the diode needing .7 volts before it turns "on" allowing voltage to go though.
Damn Impressive ED!!! Here I was thinking u only knew about boost and fast vehicles.

Well said for the electronic newbies :!:
 
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