Rough idle

[Ski]

I took my bronco down to the local Advance and they found 3 codes for me. P1351, P1359, and P0133. Doing some research turned up that P1351 is "Ignition Diagnostic Monitor Circuit Input Fault", P1359 is "Spark Output Circuit Fault", and P0133 is "Upstream Heated Oxygen Sensor Circuit slow response Blank 1" This is all nice but what do they mean????

 

[wwatsonh]

I took my bronco down to the local Advance and they found 3 codes for me.  P1351, P1359, and P0133.  Doing some research turned up that P1351 is "Ignition Diagnostic Monitor Circuit Input Fault",  P1359 is "Spark Output Circuit Fault",  and P0133 is "Upstream Heated Oxygen Sensor Circuit slow response Blank 1"  This is all nice but what do they mean????

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Check out fordfuelinjection dot com. It has tons of info about codes, etc. Some of the info is hard to find, but you'll probably be able to find what you're looking for.

Will

 

[Ski]

Well I went to the site you stated and found some good info. Alot of info about EFI in general and some tech tips. A very good site. However it didnt reall cover anything with ignition or misfire probs. Someone I work said it could also be a "knock" or "tap" causing the computer to over compensate with an adjustment in the timing. Is this true? My engine seems to run strong and smooth other than the surging at low speeds and rough idle. Let me try to 'splain. it runs smooth just idles up and down at a low speed if I try to maintain that speed. In park it will idel rough, but not under a load. Am I being clear?????? confusing

 

[Seabronc]

I'll bet that the slow O2 sensor response is probably responsible for the idle problem. If sensor is reacting slow to changes the computer makes the computer is probably over compensating based on input it expects from that sensor. Once it adjusts the sensor finally reacts but the computer has already gone to far so it starts adjusting in the oposite direction and since the sensor is slow the computer goes too far in the other direction, ( just conjecture on my part, but the computer depends on the inputs being accurte and timely in order to properly control the engine). As far as the sensor it is talking about, you should have one either in the exhaust manafold or very close to it, I'm not sure on the 96 exactly where it is located.

Good luck,

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[Broncoholics]

Could be leaking valves. Old Broncos used to run leaded gas. Now that unleaded is all you can get it eats away at the head and causes the valves to recess up in there creating leaks. I added case hardened valve seats and my low idle miss was gone. I though it was all ignition, spent lots of cash to find it was a valve. A compression test didn't find it either. I had to do a air leak down test and could hear the water bubbling in the engne galley.

 

[Ski]

I'll bet that the slow O2 sensor response is probably responsible for the idle problem. If sensor is reacting slow to changes the computer makes the computer is probably over compensating based on input it expects from that sensor. Once it adjusts the sensor finally reacts but the computer has already gone to far so it starts adjusting in the oposite direction and since the sensor is slow the computer goes too far in the other direction, ( just conjecture on my part, but the computer depends on the inputs being accurte and timely in order to properly control the engine). As far as the sensor it is talking about, you should have one either in the exhaust manafold or very close to it, I'm not sure on the 96 exactly where it is located.

Good luck,

I will try the O2 sensor however, what would cause the ignition/misfire codes? It certainly doesnt sound like its missing.

 

[Seabronc]

I will try the O2 sensor however, what would cause the ignition/misfire codes?  It certainly doesnt sound like its missing.

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I'm not sure, but it is possible since the slow sensor has an effect on how the computer adjusts the timing and the SPOUT is the path for the adjustment.

Good luck,

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