Not able to get OBD1 fault codes by following instructions

1993 BMW 320I
150,000 MILES • 2.0L • 6 CYL • 2WD • MANUAL
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CHRISTOPHER SA
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Hi again,

I have come across two sources that talk about how to get fault codes by pressing the accelerator pedal down and releasing it 5 times when the car ignition is in the on position but without the engine being turned on.

I spent quite a bit of time trying to get the fault codes to come up and was not able to do so. Any thoughts on what else I can do, short of taking it to a BMW specialist?

Here is the link I found the info on (better than the other one I mentioned - of the two, as it has more fault codes written up):

http://www.bmwe36blog.com/bmw-on-board-diagnostics.html

I am trying to do this because my car is getting about 11.34 miles per gallon instead of 35.8mpg.

I have changed the oil filter, air filter, cleaned and refurbished the fuel injectors with a Mr. Injector refurbishment kit and replaced the car's computer (DME unit) - though it was a used unit from Europe (and the problem was present with the old unit). I have not been able to check yet if there is a spark going to each spark plug.

On the number 1 cylinder, where the right hand bracket is that holds down the ignition coil, in the top corner of the bracket the screw hole in the engine block has no thread, leaving that bracket looser than it should be. I am wondering if that has anything to do with it.

Note: When refurbishing the injectors, I rigged up a circuit and switch (that also had a fuel injector plug attached) which I hooked up to my car battery that activated the injectors when I pressed the switch. When doing this I also forced carburetor cleaner through the injector to clean out any gunk. All injectors worked fine when activated and the spray became uniform in all of them.
Oct 10, 2019 at 3:31 PM
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DANNY L
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Hello, I'm Danny.

Here is something you can try first. This is our obd1 code gathering for BMW's. Get back to me after performing this to see if it works.

https://www.2carpros.com/articles/bmw-obd1-1995-and-earlier-code-definitions-and-retrieval-procedure

Hope this helps and thanks for using 2CarPros.

Danny-
Oct 10, 2019 at 4:49 PM
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CHRISTOPHER SA
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Hi Danny,

The instructions in the link you gave is exactly the same as in the link I put up! And the instructions didn't work. No check engine light came on blinking the codes. I tried quite a few times.
Oct 10, 2019 at 11:16 PM
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DANNY L
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Hello again.

Did it just say no codes found/no codes or just nothing at all happened (no communication)? Those are the only BMW obd1 code resources we have. Let me know and we'll go from there.Thanks again for using 2CarPros.

Danny-
Oct 13, 2019 at 5:14 PM
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CHRISTOPHER SA
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Nothing at all happened.
Oct 14, 2019 at 12:32 PM
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DANNY L
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Hello again.

You say you forced the injectors to spray with a 12v source externally from the ECM/PCM? If so, Do you know if the ECM/PCM is providing proper signal voltage? Have you checked the injector spray pattern with a scan tool while/with engine running?
Let me know. Thanks again for using 2CarPros.

Danny-
Oct 15, 2019 at 9:30 PM
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CHRISTOPHER SA
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Here are the answers to your questions:

"Do you know if the ECM/PCM is providing proper signal voltage?" No.

"Have you checked the injector spray pattern with a scan tool while/with engine running?" No. Not even sure how you can do that.

Oct 17, 2019 at 12:30 AM
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STRAILER
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It sounds like you either have a ECU that is out or the wiring to the diagnostic connector is bad. here is a guide to help test the wiring with the connecting wiring diagram below so you can see how it works and which wires to test:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what happens.
Oct 20, 2019 at 12:44 PM
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CHRISTOPHER SA
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When you talk about a diagnostic connector are you talking about the OBD1 connector in the engine compartment on the right side near the strut tower? And how could a bad diagnostic connector cause my fuel consumption to increase so much?

As a note, I have gone ahead and ordered a new oxygen sensor. Also, I looked at the driveability section of the Bentley manual and it had some indicators as to what I need to look for.
Oct 21, 2019 at 8:15 PM
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STRAILER
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We need the connector under the hood to work so we can get the codes if any. Do you have the tools to get the codes? BMW takes a special tool or this guide can help:

https://www.2carpros.com/articles/bmw-obd1-1995-and-earlier-code-definitions-and-retrieval-procedure

Please run down this guide and report back.
Oct 22, 2019 at 11:34 AM
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CHRISTOPHER SA
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Hi Ken,

I don't have the scan tool to plug in to the diagnostic connector and the information in the guide is what I tried to do and was not able to get any codes to flash via the check engine light.

I have been searching for a scan tool and the only one that I have been able to find was a Peakes scan tool that is no longer made. Do you have any sources for these scan tools?

I understand now about the connector. I will be thoroughly cleaning the DME/ECU connector in the next day or so with the relevant cleaners. I will also do the OBD1 connector while I am at it.
Oct 23, 2019 at 6:43 AM
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STRAILER
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CHRISTOPHER SA
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Hi Ken,
I have one of those adapters and it came with an OBD II C110 reader. It didn't work on my car though, giving an error message saying it couldn't communicate with the computer. So I am looking at a Peake Research tool - https://www.ebay.com/itm/Peake-R5-FCX3-Scan-Reset-tool-for-BMW/123947878747 instead.
Oct 24, 2019 at 3:13 PM
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STRAILER
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Okay sounds good. let me know what happens.
Oct 26, 2019 at 11:33 AM