Any internal Computer Diagnostics?

SuperTopo said:
I agree that it’s rare, but they do die. The ECU in my son’s 86 died. I haven’t spent much time trying to diagnose it, the car would only run on the cold start injector, but interestingly the injectors were getting signal, just too weak of a signal. I changed ECU on a whim and boom! The car ran just fine. Putting the original back in and it wouldn’t run. So yeah, rare, but it happens.

So my hypothesis is that the circuit that provides the power for the injectors has an issue that is causing high impedance. So while it does seem to trigger the injectors, it’s too weak.
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Agreed, anything can fail. But I must say the case of your son's ECU sounds a bit odd to me. In the rare event a Bosch ECU does fail, it typically fails completely...as in nothing works at all. In other words no signal, not just a weak signal. But clearly it could happen. ;)
 
87X19 said:
View attachment 78999
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Yep, that is the "test" plug. It is not your issue. Have you pulled the large connector off the ECU in the spare tire well to see what its condition is? As mentioned above, water can travel inside the large bundle of FI wires that runs from the engine bay to the ECU.
 
Thank you for the reply. Yes, I pulled the big ECU plug and tested the connectors. Everything checked out, per the no start procedure, except 0 ohm reading on pin 17. The procedure says to check the wiring on Schematic 17, but I’m not sure how to check it, other than visually. Any additional help is appreciated. Thanks.
 
87X19 said:
Thank you for the reply. Yes, I pulled the big ECU plug and tested the connectors. Everything checked out, per the no start procedure, except 0 ohm reading on pin 17. The procedure says to check the wiring on Schematic 17, but I’m not sure how to check it, other than visually. Any additional help is appreciated. Thanks.
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If I was the one trying to get this car going, this is the first thing I'd do if that car has been sitting for a long time:

Fuel Return question

Hey.......just noticed something !!!!! Might be an illusion or I am not seeing my small screen correctly......BUT...kinda looks like you have all the plugs wires out of order.... Looking at your video #1......and going by the #s you have written on your cap.....they look to be out of order...
xwebforums.com
 
Thanks for the reply, that is a good thread. I think the injectors probably are gummed up from sitting, however I know they are not firing because they are not getting any power by testing the connectors. Since I am replacing all the soft lines anyway, I will probably pull all the injectors shortly.

Does anyone know if there is a way to "hotwire" the schematic 17 section of the harness? Just trying to figure out how to proceed.

Thanks.
 
87X19 said:
I think the injectors probably are gummed up from sitting, however I know they are not firing because they are not getting any power by testing the connectors.
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How did you do this test? The pulses to the injectors are short enough that trying to measure with a voltmeter is not going to be very useful.
 
EDITED to make it more clear......

As Bjorn said, the best method is to use a noid tester. Also keep in mind the injectors are triggered by the ground (negative) side, not 12V. So you should get a constant 12V at the ECU when the key is on and the AFM flapper door is pushed open (you'll hear the fuel pump will run). The negative will flash on and off as the engine cranks to trigger the injectors, but too quickly to record on a DOM....that's where the noid tester comes in.

Sorry if this is redundant to you, I haven't read the entire thread.
 
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I maintain the best way is as I did in the linked post:

Fuel Return question

Hey.......just noticed something !!!!! Might be an illusion or I am not seeing my small screen correctly......BUT...kinda looks like you have all the plugs wires out of order.... Looking at your video #1......and going by the #s you have written on your cap.....they look to be out of order...
xwebforums.com

Noid lights are great, but they won't tell you if the injector is gummed up.
 
You can take the injectors out, leave them on the fuel rain, each one in a small jar and try starting.

I did this and with an assistant to turn the key, you can see the injectors firing and when you open the AFM see the injectors spraying plenty of fuel.

Or without an assistant, use a phone to record a video.

OR

can you hear the injectors click when you apply voltage over the connector? If yes they are probably not gummed up, if you can't hear the click, then the injectors need a clean.
 
Thank you for both replies.

Autozone has the noid lights on their lend a tool program, so I thought about using those. However, the test procedures in the manual say to connect a test light between the injector connectors, which is what I did. Not even a brief flash of light. That would be nice if the test light is just not sensitive enough. Would not explain the lack of ohms on pin 17, but as long as it is getting voltage, I do not care how it works.

SuperTopo - You are correct, and the reality is I will have to clean the injectors.

Please keep the suggestions coming, they are really appreciated.
 
Alex, good point on testing the injectors independently. I can do that just to check condition.

Thanks.
 
SuperTopo said:
I maintain the best way is as I did in the linked post:

Fuel Return question

Hey.......just noticed something !!!!! Might be an illusion or I am not seeing my small screen correctly......BUT...kinda looks like you have all the plugs wires out of order.... Looking at your video #1......and going by the #s you have written on your cap.....they look to be out of order...
xwebforums.com

Noid lights are great, but they won't tell you if the injector is gummed up.
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Agreed. The noid light suggestion was regarding the comments on "no signal to the injectors". That should be confirmed first, because if there isn't any signal then the condition of the injectors doesn't matter (yet). :)
 
In my experience it is fairly rare for all four injectors to get 100% gummed up to the point of zero fuel flow. More common is one or two are really dirty, or all of them are slightly dirty but still allow a little fuel spray, or such. In other words, there's enough fuel getting into the engine for it to at least try to fire up. That's not to say the engine will actually run or run well, but it will pop and fart trying to start. Unless perhaps the little filters at the top of each injector has filled up with crud from the tank. In which case you will find crud throughout the entire fuel system. And the internal screen in the pump will be clogged as well.

Usually if I find there's absolutely no fuel getting to the combustion chambers then it is due to another problem, not dirty injectors. For example no electrical impulse to them, a failed pump, completely clogged main fuel filter, fuel tank pick up plugged, etc.

You can always spray some starting fluid into the intake and see if it wants to fire.

This discussion reminds me of a theory I heard at a EFI training clinic many years ago. The thought was it is impossible for electrical fuel injectors to clog. Because the constant back and forth, in and out movement of the needle in its little seat will constantly clean the orifice, preventing contaminants to build up there. To some extent there is a bit of truth to this; the needle/seat is one of the last parts of the injector to cause a failure - unless it gets physically damaged. However it can happen. And there are other parts of a injector that can clog and cause failure. So the theory wasn't completely true.

Speaking of things I've heard. The chief engineer at one of the larger fuel injector cleaning/rebuilding companies in the US told me he believes almost EVERY old fuel injector can be saved. One exception is if the ceramic insulator at the tip has been physically damaged. Otherwise they have the ability to clean or replace every component in a injector and make them as good as new.
 
Dr.Jeff said:
Speaking of things I've heard. The chief engineer at one of the larger fuel injector cleaning/rebuilding companies in the US told me he believes almost EVERY old fuel injector can be saved. One exception is if the ceramic insulator at the tip has been physically damaged. Otherwise they have the ability to clean or replace every component in a injector and make them as good as new.
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That sounds a bit like "triggers broom". If you don't know it, google it and enjoy :)
 
Dr.Jeff said:
In my experience it is fairly rare for all four injectors to get 100% gummed up to the point of zero fuel flow. More common is one or two are really dirty, or all of them are slightly dirty but still allow a little fuel spray, or such. In other words, there's enough fuel getting into the engine for it to at least try to fire up. That's not to say the engine will actually run or run well, but it will pop and fart trying to start. Unless perhaps the little filters at the top of each injector has filled up with crud from the tank. In which case you will find crud throughout the entire fuel system. And the internal screen in the pump will be clogged as well.

Usually if I find there's absolutely no fuel getting to the combustion chambers then it is due to another problem, not dirty injectors. For example no electrical impulse to them, a failed pump, completely clogged main fuel filter, fuel tank pick up plugged, etc.

You can always spray some starting fluid into the intake and see if it wants to fire.

This discussion reminds me of a theory I heard at a EFI training clinic many years ago. The thought was it is impossible for electrical fuel injectors to clog. Because the constant back and forth, in and out movement of the needle in its little seat will constantly clean the orifice, preventing contaminants to build up there. To some extent there is a bit of truth to this; the needle/seat is one of the last parts of the injector to cause a failure - unless it gets physically damaged. However it can happen. And there are other parts of a injector that can clog and cause failure. So the theory wasn't completely true.

Speaking of things I've heard. The chief engineer at one of the larger fuel injector cleaning/rebuilding companies in the US told me he believes almost EVERY old fuel injector can be saved. One exception is if the ceramic insulator at the tip has been physically damaged. Otherwise they have the ability to clean or replace every component in a injector and make them as good as new.
Click to expand...

I guess we all have different experiences. I've had to free up the injectors on several X1/9s over the last 20 years. This has always been on an X1/9 that has been sitting for a couple of years. If the car was running last month and today it won't start, I'm with you that the injectors being dirty is unlikely to be the issue. With cars that have sat for years the problem has not been "dirty" injectors, but "stuck" injectors. You actually need to physically free up the needle, it's stuck. So it may be rare to you, it's been anything but rare to me when dealing with cars that have sat for years.
 
SuperTopo said:
With cars that have sat for years the problem has not been "dirty" injectors, but "stuck" injectors.
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That's a good distinction - dirty vs stuck. I guess I was thinking more in terms of clogged ones (from being very dirty). I have seen a few "stuck" ones, but usually the whole injector is very trashed by that point so I just replace them.

Have you found many cases where all four were completely stuck and therefore there was no fuel going into the engine at all? That's something I don't recall finding before.
 
Dr. Jeff/ng-randolph, you two were correct, using a test light, per the manual's testing procedure, was not a valid test. I put a noid light on the injector plug and got the faint glow.

SuperTopo/Alex - also correct. I pulled off the intake, extracted the injectors, and got no spray out of the injectors when cycling the engine. I was getting the clicking sound, so I cleaned the injectors using a 12v battery and an adapter setup to an aerosol injector cleaner. Put the new lines on, tested the injectors before installing them in the runners, and all looked good. Once buttoned up, the engine fired up fairly quickly, and seems to run well.

Thanks to all for your help.

Unfortunately, it appears the water pump is leaking (heavy drip) out the weep hole. This is an AC car, so from the threads I have read, it sounds like I am in for a challenge. Any of you experts have a recommended thread for the water pump swap out on an AC car? Starting to feel like I should have just dropped the engine and done all the parts swapping on the bench.

Thanks.
 
87X19 said:
Unfortunately, it appears the water pump is leaking (heavy drip) out the weep hole. This is an AC car, so from the threads I have read, it sounds like I am in for a challenge. Any of you experts have a recommended thread for the water pump swap out on an AC car? Starting to feel like I should have just dropped the engine and done all the parts swapping on the bench.

Thanks.
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This is not too bad of a job. It is possible (or so I've hard) to remove and replace only the impeller side of the pump, but there is a good reason to remove the entire pump from the block: This allows you to measure (and adjust as needed) the impeller to housing clearance. On a 1500 with A/C, the bracket holding the A/C compressor to the block blocks access to one of the water pump-to-block screws, so the A/C compressor and its bracket have to be undone. No need to undo A/C hoses etc. or remove the compressor entirely. Replacing the water pump is a bit of work, for sure, but not difficult.
 
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87X19 said:
Dr. Jeff/ng-randolph, you two were correct, using a test light, per the manual's testing procedure, was not a valid test. I put a noid light on the injector plug and got the faint glow.

SuperTopo/Alex - also correct. I pulled off the intake, extracted the injectors, and got no spray out of the injectors when cycling the engine. I was getting the clicking sound, so I cleaned the injectors using a 12v battery and an adapter setup to an aerosol injector cleaner. Put the new lines on, tested the injectors before installing them in the runners, and all looked good. Once buttoned up, the engine fired up fairly quickly, and seems to run well.

Thanks to all for your help.

Unfortunately, it appears the water pump is leaking (heavy drip) out the weep hole. This is an AC car, so from the threads I have read, it sounds like I am in for a challenge. Any of you experts have a recommended thread for the water pump swap out on an AC car? Starting to feel like I should have just dropped the engine and done all the parts swapping on the bench.

Thanks.
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Stuck, not clogged, injectors strike again!

Try running the car for bit before replacing the pump, sometimes they quit leaking after the pump gets some runtime if it's sat for a long time. Sometimes not...
 
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