1988 ford code 18
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1988 ford code 18
My son's 1988 F250 351 that has a code 18 KOEO. I posted this problem earlier but will make the situation a little simpler.
This engine now idles and starts perfectly cold or hot, but won't rev above (guessing ) 1500 rpms unless you probe the negative coil wire with a grounded incandescent test light. With the test light connected it runs perfectly.
Is this telling me that something in the computer or TFI module has something wrong in the circuitry?
The engine falters without the test light because it looses spark at the aprox 1500 rpm mark.
This thing is driving me crazy.
Anybody got an Idea. I think I'll pull the PCM and check for burns and bad capacitors.
HELP
Thanks
Jack
This engine now idles and starts perfectly cold or hot, but won't rev above (guessing ) 1500 rpms unless you probe the negative coil wire with a grounded incandescent test light. With the test light connected it runs perfectly.
Is this telling me that something in the computer or TFI module has something wrong in the circuitry?
The engine falters without the test light because it looses spark at the aprox 1500 rpm mark.
This thing is driving me crazy.
Anybody got an Idea. I think I'll pull the PCM and check for burns and bad capacitors.
HELP
Thanks
Jack
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Joined: Oct 2016
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From: Houston/Sugar Land
There is no KOEO code number 18. 18 will come up after the KOEO codes and it is for Continuous Memory. Here is what it means (M) Ignition TACH signal erratic - Ignition Systems
This is from rla on this site about the code in CM
Code 18 (CM): IDM circuit failure or SPOUT circuit grounded.
Verify the IDM signal is getting to Pin 4 of the computer (PCM).
The IDM signal is derived by the Ignition Suppression Resistor
This is from rla on this site about the code in CM
Code 18 (CM): IDM circuit failure or SPOUT circuit grounded.
Verify the IDM signal is getting to Pin 4 of the computer (PCM).
The IDM signal is derived by the Ignition Suppression Resistor
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From: Houston/Sugar Land
Another article I found.
ok, you are misunderstanding this system. You have power on the positive side,with the key on, Then the computer has a driver in it that grounds the coil to fire it, this is the wire with a resistor in it, It is not getting power from the computer, it is getting its ground from it. if you disconeect the #1 wire, there will be no power on the the #2 wire, here how you diagnos this, If you have power on the positive side,#1, then you put a test light on the neg side and crank the motor. If it flashes, then you need a coil, if it doesnt, then you need a ignition module or an ecm, It is very common for the ignition module to go out on these, not very likely its a computer.Tim
ok, you are misunderstanding this system. You have power on the positive side,with the key on, Then the computer has a driver in it that grounds the coil to fire it, this is the wire with a resistor in it, It is not getting power from the computer, it is getting its ground from it. if you disconeect the #1 wire, there will be no power on the the #2 wire, here how you diagnos this, If you have power on the positive side,#1, then you put a test light on the neg side and crank the motor. If it flashes, then you need a coil, if it doesnt, then you need a ignition module or an ecm, It is very common for the ignition module to go out on these, not very likely its a computer.Tim
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Thanks Sandymane.
When you speak of wire #1 and #2, I suppose you are talking about the plug on the TFI module.
I was wrong about the test. We got the code 18 with engine running if my old memory is correct. Been about 3 weeks now since test.
Thanks for all the help. I'll try to get back to it tomorrow if I get time.
Thanks again
Jack
When you speak of wire #1 and #2, I suppose you are talking about the plug on the TFI module.
I was wrong about the test. We got the code 18 with engine running if my old memory is correct. Been about 3 weeks now since test.
Thanks for all the help. I'll try to get back to it tomorrow if I get time.
Thanks again
Jack
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
Thanks Sandymane.
When you speak of wire #1 and #2, I suppose you are talking about the plug on the TFI module.
I was wrong about the test. We got the code 18 with engine running if my old memory is correct. Been about 3 weeks now since test.
Thanks for all the help. I'll try to get back to it tomorrow if I get time.
Thanks again
Jack
When you speak of wire #1 and #2, I suppose you are talking about the plug on the TFI module.
I was wrong about the test. We got the code 18 with engine running if my old memory is correct. Been about 3 weeks now since test.
Thanks for all the help. I'll try to get back to it tomorrow if I get time.
Thanks again
Jack
If you are unsure about how you got the code, you could run the diagnostic codes again. Engine Running codes should only be addressed when all KOEO codes have been eliminated. ..... Engine should be at operating temperature when doing test (if possible).
Ford OBD Diagnostic two digit codes. https://www.therangerstation.com/tec...gitcodes.shtml
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I made a little progress yesterday.
When we got the truck it idled real rough and wouldn't rev up at all unless I unplugged the alternator. Put on another 2G alternator and then it would idle smooth for what ever reason. Then changed alternator to a 3G and it would rev up to about 1500 rpms then start loosing spark. Yesterday I found an old TFI module in my pickup glove compartment. I put it on the F250 and now it runs like new on the road for about 10 miles and then won't restart, probably until it cools off. Probably why the old module was lying around instead of being on a vehicle .I'll try again this morning when the sun comes up.
I don't like parts changers and don't choose to be one myself. I like to figure things out. I was a machinist for 45 yrs and am a beginner at this.
Making progress.
Thanks for all the help
Jack
When we got the truck it idled real rough and wouldn't rev up at all unless I unplugged the alternator. Put on another 2G alternator and then it would idle smooth for what ever reason. Then changed alternator to a 3G and it would rev up to about 1500 rpms then start loosing spark. Yesterday I found an old TFI module in my pickup glove compartment. I put it on the F250 and now it runs like new on the road for about 10 miles and then won't restart, probably until it cools off. Probably why the old module was lying around instead of being on a vehicle .I'll try again this morning when the sun comes up.
I don't like parts changers and don't choose to be one myself. I like to figure things out. I was a machinist for 45 yrs and am a beginner at this.
Making progress.
Thanks for all the help
Jack
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Fleet Owner
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Did you use thermal paste on the back of the module? If not it will overheat in short order. When the engine dies and will not restart are you still getting spark? Have you verified the fuel pump is good?
Code 18 KOER indicates the SPOUT circuit is open. Is the SPOUT plug installed? It is usually a small gray plug with two wires near the ignition module.
Code 18 KOER indicates the SPOUT circuit is open. Is the SPOUT plug installed? It is usually a small gray plug with two wires near the ignition module.
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I went to my son's house this morning to get the pickup and it fired right up. Made it about five miles and it went dead at an intersection. Pushed it out of the road. I'll go back in a couple hours and drive it home and put the new TFI module on and hopefully I'm done for now.
Jack
Jack
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We can now drive it far enough for every thing to warm up and have found that the coil quits after about 5 miles. We hooked up an old coil and it fired right badk up. We have now changed the coil and spark plug wires, cap and rotor. It starts quick ,idles perfect but cylinders continually drop on the road. Would like to check fuel pressure. We borrowed 2 pressure gauges from Advance Auto and neither one had the adaptor that would fit the ford schrader valve.
Guess I'll try to find one that will fit before I move on. After that I will check the function of the MAP sensor. I guess that could be part of the problem. Any I will get to learn how to check it instead of just replacing it.
Jack
Guess I'll try to find one that will fit before I move on. After that I will check the function of the MAP sensor. I guess that could be part of the problem. Any I will get to learn how to check it instead of just replacing it.
Jack
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In most there are only one in their kit that fit Fords. I guess people take them and the parts stores never check the returns. Before you take another home check the fit in the parking lot and return if it is missing so you save time and frustration. You can always check pressure in the parking lot and take it back in when finished to save a trip back.
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Thanks Sandymane, I did check the last one before I left the store. I actually tested the fit on right front tire of the car I was driving as I think they are the same size.
I really like watching a guy that goes by Scanner Danner on youtube. He is really sharp but there is a video of a 1988 f150 kicking his butt. These things can be real tough to figure out because something not apparent can mess up something else. I am now just getting code 11. Now I can do a KOER test that might tell me something else.
Thanks for hanging with this Old amature .
Jack
I really like watching a guy that goes by Scanner Danner on youtube. He is really sharp but there is a video of a 1988 f150 kicking his butt. These things can be real tough to figure out because something not apparent can mess up something else. I am now just getting code 11. Now I can do a KOER test that might tell me something else.
Thanks for hanging with this Old amature .
Jack
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I am now finally getting NO codes, engine off or running, except the #11 which is a great sight to see
. The engine runs fine idling but the coil misfires pretty bad when revved up. Could this possibly be the distributor hall effects or do they just quit altogether ?
Thanks for any ideas
Jack
. The engine runs fine idling but the coil misfires pretty bad when revved up. Could this possibly be the distributor hall effects or do they just quit altogether ?Thanks for any ideas
Jack
Lead Driver
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From: Houston/Sugar Land
Here is a very good article about the Hall effect and other possible electrical information you may find helpful. Electronics are foreign to me so I have plenty of articles;
https://www.fordforumsonline.com/thr...-systems.3764/
https://www.fordforumsonline.com/thr...-systems.3764/