Hi all,
I retrieved fault code 1-1-3 and am experiencing hesitation when getting going but on the highway when it's opened up a bit it runs ok. I think because if one injector is faulty at low rpm's there isn't enough fuel but when on the highway the working injectors produce enough fuel to satisfy the combustion needs. This is what i am thinking but i'm looking for some educated guesses. Where do i start? i can't drive the car very easily and with the weather in boston and no garage to protect myself i can't dive too deep into this. Should i just buy some new injectors from fcpgroton and replace? injector seals? O2 sensor? What would you guys do? as a last resort i will bring it in to the shop.

Thanks,
Chris

I got the same 1-1-3 code yesterday on my '92 745 Turbo (LH 3.1) with rough idle. The Bosch Fuel Injection & Engine Management manual recommends to run through fuel injector cleaner in a full tank of gas (which I did and I also cleared the OBD codes). So far, fault code has not reappeared and idle is back to smooth.
ALTNRG

Also, the Bosch Fuel Injection & Engine Management manual recommends using detergent fuels that promote fuel injector cleaners.
ALTNRG

In one of your earlier threads on the subject, kpwall made the suggestion to remove power to reset the ECU - then drive to see if the same code(s) return. I could not find a response from you on this. Remove fuse 6 for a few seconds and replace, if you have not yet tried this.

I don't believe anyone will recommend or suggest you replace all the injectors just because that primitive OBD hints at injector failure. Possibly you might be advised to swap the fuel pressure regulator as a cheap parts-change guess to cure a recurring 113, if you have no means to check fuel pressure yourself. Also read about resoldering or replacing your fuel injection relay. Anything that interferes with fuel delivery, not just clogged injectors, might set 113 after a while.
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Art Benstein near Baltimore

Sorry Art, I already cleared the fault and it came back as well as running worse than before. It's not the fuel relay i already tried a know good one. Also, i pulled the vacuum line to the fuel pressure regulator and it did not smell badly of fuel.

Thanks,
Chris

Well, LH injectors are awfully expensive and not that prone to fault. If you still suspect the injectors, look at the plugs to see if they give a clue to one or more cylinders burning poorly. Make sure all the injector solenoids are operating by listening. You can remove the electrical connector of a suspect to test for a difference in engine sound.

There's another check of injectors I used in conjunction with a fuel pressure gauge: The OBD provides a test cycling of the injectors in "mode 3". I connected one at a time (engine not running) cycling it with the OBD while watching the residual pressure drop. Goodness was indicated by roughly equal response from each injector.

I'd get LH injectors from the junk yard - that's how reliable I view them. But those injector cleaning service sites make you wonder otherwise.
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Art Benstein near Baltimore

Thanks for your help Art!

I'll let you know when i figure it out

Chris

I forgot to ask if you've checked your O2 sensor. Assumptions, you know. Everything that computer knows about your engine comes from there.
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Art Benstein near Baltimore Crrrrazy Ray's!

I can't take credit for this, but I want to share it with others. So before you work on the injectors, AMM or Oxygen sensor, try cleaning the ground connectors on the intake manifold. As I write, it has worked for me.
ALTNRG

The one item that all the codes in the vehicle had in common is the ground for the computer.

Injectors need a good ground to pulse according to the computers signal. How does the computer know the injectors are not firing properly? The only thing that can be measured is the current drawn by the injector as it fires. Ohms Law applied. If resistance is up or down, more or less current is drawn, computer thinks injectors are bad.

If the O2 sensor is compensating for a rich or lean mixture, what is causing the mixture to go lean or rich? A poor ground increases or decreases resistance for the injector so it opens for a longer or shorter period, resulting in a rich or lean mixture. O2 sensor compensates, computer issues code for problem.

How does the computer know the idle switch is not grounding? It can only compare it to another ground, which happens to be via an internal route, which also happens to be the ground for every other ground the computer needs. Since the switch on my vehicle checked as 0 ohms to ground with the switch disconnected, the only item common to all three was bad computer ground.

What I did was:

Removed, cleaned and reattached the two ground points for the computer on the manifold.

With battery disconnected, removed the connector to the computer and the computer from the auto and sprayed the connectors with electrical contact cleaner, air blasted dry, reinstalled and reconnected.

Removed and cleaned the grounding "loops" near the computer connection.

During that same disconnected battery time, removed and cleaned the battery negative to block connection and the ground strap between the Valve cover and body at the right rear of the engine.

Have not seen an engine code or light since.

Your suggestion to clean up those grounds cannot be overemphasized. I've read several accounts of success after fixing either the crimps on the eye rings or just simply loosening and retightening the fuel rail bolts where they are attached. I believe it is prominently placed in the 700/900 FAQs. One provides the return current for the injector drive and the other the ground reference for sensors, such as the temp sensor, so you can imagine the havoc played with the sensor input voltage if the fuel rail was being lifted off ground during each injector pulse along with the accompanying coil collapse spike.

The LH2.4 ecu injector driver transistor does not have any smarts attached to measure injector current - it is just an open collector - so the ecu doesn't really know whether the correct load is being sunk. But the effects of the reference ground being part of that load make the procedure you suggest a winner.

The idle switch is a yes/no input, pulled to 5V when no, and fairly immune to ground shift, but not to noise. The TPS, even though snap action on the closed-throttle side, can be noisy and intermittent. I had a scope on that pin on one car while clicking it on and off with the pedal; the switch was all over the map, sometimes making, often not, even though the mechanical "click" was distinct.

I guessed something like that might be the result of some overzealous throttle-body cleaning some time in its past, if not just wear over 15 years.

I'm not sure exactly how I could suggest making a similar find without the aid of a scope-- maybe luck with an LED test light, or an audible tester (I use a Sonalert piezo buzzer with a set of clip leads for a lot of that sort of hands-free diagnostics) of some sort.
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Art Benstein near Baltimore Crrrrazy Ray's!