1990TurboII-75K

I'm checking into the dalbani.com suggestion for the MP4501 driver. The site does not have a complete description and the price seems low. I'll contact them to see if this is actually the right part.

When this MOP/ECU problem developed, I could not get any Error Codes from the ECU. The TPS on my car is buried under the intercooler and can't be removed without disassembling other things. Therefore I can not easily check it. I have in the past (with bad MOP/ECU) tried pulling the EGO sensor (it's accessible) then starting the car. No Error Codes were output.

Should this sensor cause a EC 15 to come out? Should it be an immediate MIL or CEL on without the EGO sensor plugged in?

I have not tried unplugging the boost/pressure sensor (it's pretty accessible). Should I unplug it then start the car and expect and immediate CEL with EC 13?

HAILERS

I don't own a series five, only series four. On a series four is the engine is idling and I pull the pressure sensor plug off I get a code. Or if I pull the air intake temp sensor off I get a code. If I pull the 02 sensor wire off I get a code IF I drive the car in a closed loop scenario.

I'm slow. What's a EGO outside of what I have as a person? I guess I could have GOOGLED it. Frankly since I own a series four, I know nothing about electrical omp's.

At least this got your post back to the top. I see your delima. If a bad ECU can take out a OMP and a bad OMP can take out a ECU, you can ruin a lot of good parts by *parts swapping*.

1990TurboII-75K

I'm probably showing my age. I worked for Ford Motor Company a long while back and the O2 sensor was known as EGO (Exhaust Gas Oxygen) sensor back in ancient history.

It sounds that the ECU only responds to a sensor failure (being unplugged) while the engine is running and possibly in a particular mode. With the O2 sensor, I know the closed loop control does not occur at idle, but somewhere near 2000 RPM.

For me the easiest sensor to unplug is probably the boost/pressure sensor. So I would have to start the engine, let it idle then unplug the boost/pressure sensor. I should expect an immediate MIL/CEL on the dash and a Error code being logged in a working ECU. Sound right?

HAILERS

Sounds right to me.

I should have know about the EGO.

HAILERS

Sounds right to me. I should have known about EGO.

1990TurboII-75K

The yellow circled parts are the damaged MOP driver parts for my 1990 Turbo II: Toshiba MP4501 and 0.1 ohm power resistor.

micah

Am I supposed to see yellow circles?

1990TurboII-75K

How do you get a picture from here to there? Can I just cut and paste?

1990TurboII-75K

Sorted out the technical difficulties.

1990TurboII-75K

Summary Update on failed S5 MOP (1990 Turbo II): This is additional information
not contained in the FSM regarding testing the electrical stepper motor part of
the MOP assembly. This does not test the MOP position sensor nor the actual flow rate of the MOP.

The reason I'm putting this information together is because after reviewing my
troubleshooting notes of the MOP/ECU failure on my car and realizing that I was
sent in the wrong or a dead-end direction by the 1990 FSM. In fact, by not
correctly diagnosing the MOP stepper motor as the failed part I probably caused
the ECU to burn up it's driver section for the MOP due to low resistance values
the manual did not check.

Refer to the attached MOP Stepper Motor Diagram (below) for connection references and actual measurements.



Problem: The first step in the 1990 FSM for the inspection of the MOP system is
checking the Resistance of each winding in the stepper motor to be within 16-31
ohms. This does check for opens or direct shorts for each individual winding.

These measurements are indicated on the diagram. The FSM states that the MOP is OK. All 4 of those R's are within range: X1=25.8, X2=22.8, X3=19.0 and X4=23.1 but this is NOT an accurate conclusion. The FSM is misdiagnosing the situation.

The following additional measurements need to taken to ensure the MOP stepper
motor is OK from all possible internal problems.

Solution: Check each pair of terminals for either shorts or low resistances
where there should be opens=infinite or high resistances and there are no
connections or resistances=shorts that should not be present.

This list contains all the possible measurements that ensure there are no hidden
problems and the MOP motor is OK.

Rxy = Resistance across terminal x to terminal y. (Example: R12 = 19.0 ohms in
diagram)
Rx:y-z = Resistance across x terminal with the y and z terminals shorted together.
Rxcase = Resistance across x terminal and the external case or ground.
Inf = infinite resistance or very high >100k ohms

These were all my R measurements for my BAD MOP:

R12 = 19.0
R13 = 10.1 R23 = 25.8 NOTE: R13 should be R12 + R23 = 19.0 + 25.8 = 44.8
R14 = inf R24 = inf R34 = inf
R15 = inf R25 = inf R35 = inf R45 = 23.1
R16 = inf R26 = inf R36 = inf R46 = 45.4 R56= 22.8

Loads seen by the ECU MOP driver:
R1:2-3 = 7.5 should be equal to R12 = 19.3 NOT OK
R3:1-2 = 10.1 should be equal to R23 = 26.1 NOT OK
R4:5-6 = 23.0 equal to R45 = 23.0 OK
R6:4-5 = 22.8 equal to R56 = 22.8 OK

R1case = inf All OK
R2case = inf
R3case = inf
R4case = inf
R5case = inf
R6case = inf

The R1:2-3=7.5 and R3:1-2=10.1 loads are the lower than expected resistances that ultimately over heated and destroyed the MP4501 MOP driver IC in the ECU.

Words to the wise, if you suspect MOP problems or have no ECU Error Codes being output do this relatively simple check to ensure the your MOP is working properly otherwise you may permanently damage your S5 ECU like mine.

1990TurboII-75K

Does anyone understand why with a failed MOP driver in an S5 Turbo II N370 ECU does not display any Error Codes? I have tried unpluging O2 and MOP motor and boost/pressure senors and there were no immediate MIL/CEL on the dash display nor stored in memory? Does this mean there is something else wrong with the ECU? Has anyone experienced this same condition? How do you known the ECU is working?

RRTEC

iTrader: (13)

In my experience I always replace both parts, then toss the Old ones out..... Great info on the thread though.. Top notch.b

1990TurboII-75K

I had some input regarding the MOP electrical testing that I described before. In order to clear things up and make a useful tool. I created the table below with all the measurements and expected values for anyone's use. It is complete and will not lead you down the wrong path like the 1990 FSM.

dellenrules

My car is running in LIMP MODE. I changed out my oil metering pump believing that was the problem, but it wasn't and I'm still having that issue. Everything starts up fine. when my care reaches about 3200rpm it kicks into LIMP MODE and my check engine light comes on. It is code 20. it doesn't appear next time i start the car. I placed a brand new oil metering pump in my car and it didn't change anything. Any ideas would be helpful.

1990TurboII-75K

Looking at the FSM Error Codes below and the diagnostic for the MOP position
sensor. I would look at the connector and harness wires to the MOP position
sensor. Make sure they are clean and solid connections. Check the MOP sensor
at the connector according to the FSM. I would also use the chart above to
check your MOP stepper motor to ensure that it was OK too.

One thing to be aware of is that the FSM does not check for internal shorts in
the MOP stepper motor. So use the MOP Test Table above to be sure.


The Codes - from the 1990 Service Manual (86-88 do NOT match!)

Code - Input Device - Fail-safe operation mode
----------------------------------------------
20 - Metering Oil Pump (MOP) position sensor - Basic Fuel Inj and fixed timing
27 - MOP (General) - Basic Fuel Injection and fixed timing
37 - MOP (General) - Basic Fuel Injection and fixed timing

Code - Output Device
--------------------
26 - MOP (Step Motor)


I'm not quite sure why there are (4) EC's for the MOP system. It seems that
Mazda wanted it thoroughly checked but I don't see the distinction between
27,37 and 26 codes. What are each of them diagnosing?

Captain Jean-Luc Picard

I dont understand why this is such an issue. Everyone here has told you that both the OMP and ECU can go out at the same time (OMP takes ECU with it), so instead of hounding for more answers, simply pick up another ecu and omp, plug them both in, and go on with life.

I know it is nice to know the "why" along with the "what" whenever possible, but I think you're looking for answers noone has ever researched that deeply. We find out that we need parts X and Y, and we replace parts X and Y without further diagnosis as to which part killed the other, which resistor inside part X actually failed, etc.

RotaMan99

1990GTU, do you have electrical engineering background?

HAILERS

Ohm out all the wires in the OMP system from point to point and at the same time check for shorts to ground on each wire. Disconnect the plugs at each end of the wire your ohming out so you don't pick up some device attached to one end or the other.

And go to the FSM OIL section and follow the instructions to the best of your ability. Don't grow up to be a parts swapper.

Captain Jean-Luc Picard

And if you have a flat tire, you probably ship it off to the manufacturer's lab to study the cause behind the failure rather than getting a new tire and going on your merry way.

rubyg7631

the best way to find a short is with an inductance meter,impedance meter or an audio generator adjusted to 1000 cicles and an osciloscope conected in paralel to this setinngs can detect a short of 1 turn on the winding you cannot find so small short with an ohm meter.

HAILERS

One bad unit can destroy another. Just replacing one of the two can/will cause the destruction of the other. Gee whiz golly, now you've two blown units and now your going to put another one in and screw it up. Your not a mechanic, your a parts swapper and nothing more or less. You probably take alternators to the Pepboys to figure out if they're good or bad. Parts swapper. Low as it gets.

NZConvertible

Dude, STFU unless you have something useful to add instead of idiotic comments like that. If everyone shared your narrow-minded attitude half the technical info on this forum would never have been posted. The info being provided could save someone from damaging another ECU and is adding to the community's knowledge. These parts are only going to get harder to find as people just keep swapping in replacements.

Captain Jean-Luc Picard

Which is exactly why the OP was told more than once at the start of the thread that both parts are already defective and should be replaced together with other working units to resolve the issue. But instead of listening to that simple, apparently experienced advice, we have all this "but...but...how...what if...but..." going on.

Actually if you count up the man hours he has in posting, troubleshooting, and worrying about the mode of failure of parts that have already failed, he could probably have saved money (money is time) by simply acquiring good used replacements and gone on with his business.

Also, you dont know me, so you can keep your inaccurate personal opinions to yourself. Or better yet, you know what you can do with them...not sure if I can post the phrase here so to avoid further drama I will leave it at that.

NZConvertible

I can't understand why you're even bothering to post. Instead of whining like a bitch, you should be thankful there are people who like to put their time into researching this kind of stuff. You obviously didn't notice that his last few posts weren't questions but info useful to others. I bet you don't complain when you come here and read info that's useful to you that somebody else spent their time gathering.

Who said anything about a business? He's working on his own car. The phrase "time is money" doesn't apply to personal free time (unless you're a sad bastard who has none).

HAILERS

[QUOTE=Captain Jean-Luc Picard;7685460]Which is exactly why the OP was told more than once at the start of the thread that both parts are already defective and should be replaced together with other working units to resolve the issue. But instead of listening to that simple, apparently experienced advice, we have all this "but...but...how...what if...but..." going on.

In my post above, I quoted DELLENRULES question at the top of my post, and answered him. So what you just wrote makes no sense what so ever. But then again, I don't expect much out of you anyway.