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Help diagnose '93 Escort OBD code 172

Our '93 Escort 1.9L with 98K miles has had the check engine light on for a while. The memory codes scanned 122 (TPS signal low) and 172 (running lean). I cleaned the TPS connector and reset the codes. That seems to have fixed the code 122, but the code 172 keeps coming back within ten miles of driving (three times so far).

I assume that checking the fuel pressure will be the next step. Can someone advise me where I can buy a Schrader to 1/8NPT adapter to connect my pressure guage to the fuel line? Beyond that, I can imagine cleaning the fuel injectors and checking more carefully for vacuum leaks.

But I have a suspicion that I'm taking the code too literally. Is it likely to be a falty sensor mimicking lean conditions? Are there any inexpensive parts that I should change as a shot in the dark?

Your advice as to how to proceed with the diagnosis will be appreciated.

TIA, Blake

Reply to
Ninja
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The first thing I'd do is put a really good digital dvom (one with a graphing bar) or analog vom on the tps signal. It might be biased low but take a while to set a code. Does this car have a MAF?

Reply to
Steve Austin

After owning several 1.9L escorts, I've seen the main problems as bad O2 sensors. You may want to try this first....

Reply to
CraigFL

Thanks for the suggestion. I may have to go buy the book to know what the correct TPS reading should be, but I do like the idea of visibility on the problem.

And yes, the car does have a MAF. How might that come into play?

Reply to
Ninja

Thanks to Steve and Craig for their suggestions. I put a new oxygen sensor in, and that took care of my code 172 problem. Oddly, the engine seems to run rougher now, but it passed smog check, and that's what really counts.

Reply to
Ninja

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