1988 Bronco II computer codes

OK so today I go out in the am to start the bronco at 55 degrees.
It always starts fast and does a little surging and then to fast idle. This time it ran rich ( black smoke ) and shaky the whole 15 minutes I ran it. Engine light eventually came on. I felt the radiator hose as it warmed up and I think the thermostat is working like it should, but I could feel some warmth in the hose about 2 or 3 minutes after I started it. ( I am getting an OE 195 soon, and it will be tested in hot water first ). I shut the bronco down and let it sit until late afternoon. I removed the original ACT sensor. It had a light black film on it so I carb sprayed it clean and put it back in. I started it up and it went to fast idle as usual but did not put out any black smoke at all for the 15 minutes I ran it. It idled down to 850 and was smooth. Is the car confused or just me !!

IIBRONCOS said:

OK so today I go out in the am to start the bronco at 55 degrees.
It always starts fast and does a little surging and then to fast idle. This time it ran rich ( black smoke ) and shaky the whole 15 minutes I ran it. Engine light eventually came on. I felt the radiator hose as it warmed up and I think the thermostat is working like it should, but I could feel some warmth in the hose about 2 or 3 minutes after I started it. ( I am getting an OE 195 soon, and it will be tested in hot water first ). I shut the bronco down and let it sit until late afternoon. I removed the original ACT sensor. It had a light black film on it so I carb sprayed it clean and put it back in. I started it up and it went to fast idle as usual but did not put out any black smoke at all for the 15 minutes I ran it. It idled down to 850 and was smooth. Is the car confused or just me !!

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Is it still good? Might have been a bad connection at the ACT sensor or maybe it was just dirty and cleaning it did the trick.

It seems that the warmer weather we have been having has had a positive effect. After running over 10 minutes the check engine light still comes on. I will be putting in the 195 degree thermostat some time this weekend.

OK so the ( tested in hot water on the stove ) 195 degree thermostat is installed. I started it and it did the usual hunting up and down for about 15 seconds, and then went to about a 1500 rpm idle. It did have 1 rich running event with black smoke for about 15 seconds. It warmed up to operating temperature in about 12 minutes. After about 17 minutes the CEL came on. Do I need to clear the codes out of the computer to reset it ?

Seems like a long warmup time in 55deg weather, 5 to 8 minutes, maybe 10 min. at the longest.
Have you checked the Fan clutch, before cold start fan should be hard to turn, won't spin at all.
After start up let engine run for 1 minute then shut it off
Now see if fan will spin, should be easier to turn and spin a bit when pulled or pushed
If it is still hard to turn then fan clutch is locked, which is not a big deal, just takes longer to warm up engine because of higher air flow in engine bay.
And better than never locking, lol, that will cause rising engine temps at idle.

Does the Rich black smoke event happen just after starting or after a few minutes of running?

Thinking you may have fuel leaking into intake after shut down, so flooded startup.
Check vacuum hose on the Fuel Pressure Regulator, if diaphragm leaks raw fuel collects in this hose and is sucked into intake after startup

Could be you need to clear the codes but I would get the codes first, just to see whats there.
Info on that here: http://www.therangerstation.com/tech_library/OBD_I.shtml

With jumper in place to read the codes, wait until the codes start to pulse the CEL or meter then pull out the jumper wire, that will clear the codes, shut key off then turn it back on, computer will reboot and codes should be cleared.

The Bronco has a fixed flex fan that spins with the engine speed.
The black smoke is random but it usually takes a couple of minutes of run time before it will happen. The FPR is new and there is no fuel in the vacuum line. It always restarts fine and no black smoke on a restart. I will try clearing the codes. I could try blocking the radiator intake with cardboard to speed warm up.

I cleared the computer codes before I did a cold start up today, and it is 75-80 degrees outside. Upon initial start up it did the usual searching up and down for about 15 seconds and then went to a 1200 rpm idle for a minute and then went to 1500 rpm's. The rpm's came down to 1200 and then after 10 minutes it was at 850 rpm's. There were no rich running symptoms this time. I was hoping for no CEL, but after 15 minutes of running the CEL came on.

And what is the code for that CEL?

I don't know the code yet. I am going to try and do it tomorrow.
I will report what I find. Thanks.

IIBRONCOS said:

I cleared the computer codes before I did a cold start up today, and it is 75-80 degrees outside. Upon initial start up it did the usual searching up and down for about 15 seconds and then went to a 1200 rpm idle for a minute and then went to 1500 rpm's. The rpm's came down to 1200 and then after 10 minutes it was at 850 rpm's. There were no rich running symptoms this time. I was hoping for no CEL, but after 15 minutes of running the CEL came on.

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It was in the low 30's here yesterday, probably about 50 in the garage when I started my BII.
At start, fast idled to 2000 rpm for about 20 seconds then came down to about 1600, about another minute down to 1200. At that point I backed out of garage and took off. It took probably 5 miles before the "old engine" quieted down and was running smooth as can be. Sort like me, it needs a good warm up before it can really get to work.
I think mine has to fully warmed up before it will idle down to 800, if it is cold enough outside I don't think it ever gets there by idling in the driveway or at least not in the amount time I'm willing to let it sit and idle.

It seems that my issues with a herky-jerky idle on a cold start have gone away (knock on wood). The last two things that made a difference were, getting the radiator filled to the top when cold and filling the overflow tank to a 1/3 (this coincided with a 90% of cold idle issues) and fixing a small vacuum leak at the brake booster grommet and line. I'm guessing there was enough of an air pocket at the ECT to give false temp readings to comp until the tstat opened up and coolant flowed past the ECT??? Could totally be a coincidence.

JerryC said:

It was in the low 30's here yesterday, probably about 50 in the garage when I started my BII.
At start, fast idled to 2000 rpm for about 20 seconds then came down to about 1600, about another minute down to 1200. At that point I backed out of garage and took off. It took probably 5 miles before the "old engine" quieted down and was running smooth as can be. Sort like me, it needs a good warm up before it can really get to work.
I think mine has to fully warmed up before it will idle down to 800, if it is cold enough outside I don't think it ever gets there by idling in the driveway or at least not in the amount time I'm willing to let it sit and idle.

It seems that my issues with a herky-jerky idle on a cold start have gone away (knock on wood). The last two things that made a difference were, getting the radiator filled to the top when cold and filling the overflow tank to a 1/3 (this coincided with a 90% of cold idle issues) and fixing a small vacuum leak at the brake booster grommet and line. I'm guessing there was enough of an air pocket at the ECT to give false temp readings to comp until the tstat opened up and coolant flowed past the ECT??? Could totally be a coincidence.

Click to expand...

Well judging by your warm up times mine seems to be in the ballpark. I filled up the cooling system with the flush tee cap off to push any air our when I filled it. I started it at 75 degrees and it only searched for about 5 seconds and then went to fast idle. It tool a good 10 minutes before it came to 800 rpm. It did not have any rich black smoke events. After the warm up I put the scanner on it KOEO test. This time it did not have the 8 flashes like the first test. Here is what I could determine from the flashes. The first 4 single flashes could be 2 sets of 2 ? I did get a CEL light before and after the test.
1
1
1
1
1
1111
1
1111
1

IIBRONCOS said:

. After the warm up I put the scanner on it KOEO test. This time it did not have the 8 flashes like the first test. Here is what I could determine from the flashes. The first 4 single flashes could be 2 sets of 2 ? I did get a CEL light before and after the test.
1
1
1
1
1
1111
1
1111
1

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I cant figure those out, that's why I bought the scan tool

OK so I got the Innova 3145 scanner and extension cable. I warmed up the Bronco II. This scanner is easy to use. It came up with KOEO 11. It also has 3 continuous codes. The first one is 18, loss of tachometer input/IDM circuit failure spout circuit grounded.
The second is 41, HEGO ( HO2S ) sensor signal out of range always lean. The third one also is 41, no HO2S switching detected.
Has anyone else had these codes and know what the fix is ?
Thanks for your help.

IIBRONCOS said:

OK so I got the Innova 3145 scanner and extension cable. I warmed up the Bronco II. This scanner is easy to use. It came up with KOEO 11. It also has 3 continuous codes. The first one is 18, loss of tachometer input/IDM circuit failure spout circuit grounded.
The second is 41, HEGO ( HO2S ) sensor signal out of range always lean. The third one also is 41, no HO2S switching detected.
Has anyone else had these codes and know what the fix is ?
Thanks for your help.

Click to expand...

O2 (oxygen) sensors are in your exhaust and are used to get a proper fuel/air mixture. Yours is staying lean, meaning the computer will try to add more and more fuel to the mixture. That explains your black smoke.

There are a few things that could cause the sensor to read lean:
1) A large vacuum leak
2) An exhaust leak near the O2 sensor
3) Damaged wiring between the O2 sensor and computer
4) A malfunctioning O2 sensor

Most people in your shoes replace the O2 sensor(s) and pray that fixes it. I would start by inspecting the engine for cracked or missing vacuum lines.
If that looks good, check for damage to the exhaust before or nearby the sensor. And finally visually inspect the wires between the oxygen sensor and the computer. If all of that checks out, then I'd be tempted to just replace the sensor and hope that's it.

The engine running issues ( surging and periods of rich running ) are only at cold start up until the engine warms up. Am I right that cold start up is open loop and the computer does not get readings from the sensors ? When the engine is at operating temp it runs very good. Could the computer be at fault and not working correctly in open loop ? Your help is much appreciated.