Attn wptski
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Post Fiend
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From: South Jersey
Attn wptski
For some reason I couldn't respond to the other post. It sounds like you have a direct correlation between the temperature change and the codes, give the stat a try.
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From: Warren, MI
Attn wptski
Ken:
I changed the thermostat today and the heater is kickn' but I'm still getting P0171/P0174 codes. I took for a short drive and even a P0174 code by itself, it never did that before. I'll get P0171 by itself!
The temperature dropping when accelerating from a light was probably the thermostat but maybe it's the accelerating, stop/go, etc. If I'm driving a steady speed I never get anything. I forget at what point in an engine but vacuum drops when you accelerate. Vacuum lines was one of your earlier suggestions.
That electrical manual is wrong too! There are two units on the thermostat housing, one on each side. As view from the inside, the one the right has only one wire!! The book showed all having two wires. Yes, the IAT had two wires too!
I changed the thermostat today and the heater is kickn' but I'm still getting P0171/P0174 codes. I took for a short drive and even a P0174 code by itself, it never did that before. I'll get P0171 by itself!
The temperature dropping when accelerating from a light was probably the thermostat but maybe it's the accelerating, stop/go, etc. If I'm driving a steady speed I never get anything. I forget at what point in an engine but vacuum drops when you accelerate. Vacuum lines was one of your earlier suggestions.
That electrical manual is wrong too! There are two units on the thermostat housing, one on each side. As view from the inside, the one the right has only one wire!! The book showed all having two wires. Yes, the IAT had two wires too!
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Post Fiend
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From: South Jersey
Attn wptski
Well at least you will be nice and warm now, LOL. The vacuum will drop when the throttle plate is opened and then rebound, the more extreme the change the bigger the drop. The vacuum issue I refered to would be a leak in the intake system after the MAF. If this is the problem then you will have unmetered air entering the engine. Did you ever find the pinpoint tests in you book, is it a Ford book? I don't recall if you cleaned the MAF.
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From: Warren, MI
Attn wptski
[updated:LAST EDITED ON 17-Feb-02 AT 11:09 PM (EST)]Ken:
Yes, I found the pinpoint tests in the back of the Ford book. I did clean the MAF but at that time I didn't have the tamper proof Torx screw driver. I read where it was a #20, if that's it I have a bit now and will be able to do a better cleaning job. All I could do was squirt brake parts cleaner from the opposite end. I can take the back plate off and get a good look at the wires now.
Letting the radiator burp the air out was fun too! Well, the garage floor needed a cleaning anyway :-)
Yes, I found the pinpoint tests in the back of the Ford book. I did clean the MAF but at that time I didn't have the tamper proof Torx screw driver. I read where it was a #20, if that's it I have a bit now and will be able to do a better cleaning job. All I could do was squirt brake parts cleaner from the opposite end. I can take the back plate off and get a good look at the wires now.
Letting the radiator burp the air out was fun too! Well, the garage floor needed a cleaning anyway :-)
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From: Warren, MI
Attn wptski
[updated:LAST EDITED ON 18-Feb-02 AT 06:53 AM (EST)]Ken:
Changing the thermostat seems to have made it worse! I'm getting my P0171/P0174 on my way to work in the morning and that's something it didn't do before. I was sitting listening to the radio like I do and the engine started to flutter for a few seconds, so I tapped the accelerator, it ran smooth then! I didn't get a chance to pull the codes after that happened. I left codes in from yesterday and the MIL came on. Getting confusing now!
Changing the thermostat seems to have made it worse! I'm getting my P0171/P0174 on my way to work in the morning and that's something it didn't do before. I was sitting listening to the radio like I do and the engine started to flutter for a few seconds, so I tapped the accelerator, it ran smooth then! I didn't get a chance to pull the codes after that happened. I left codes in from yesterday and the MIL came on. Getting confusing now!
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From: Warren, MI
Attn wptski
[updated:LAST EDITED ON 18-Feb-02 AT 10:53 AM (EST)]Ken:
If my engine is warming up better and my problem is getting worse should I be looking at the ECT? I could compare the resistance on a cold engine between the IAT and it. I know that they have charts in the book but who knows what the water temerature is?
If my engine is warming up better and my problem is getting worse should I be looking at the ECT? I could compare the resistance on a cold engine between the IAT and it. I know that they have charts in the book but who knows what the water temerature is?
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Post Fiend
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From: South Jersey
Attn wptski
I would do the MAF cleaning, remember the cautions. The air and coolant temperature would be different so I would pull it out and test it with hot water. I hate to keep coming back to this but you should really do the pinpoint tests, they really do work well.
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From: Warren, MI
Attn wptski
Ken:
I pulled the MAF out again and it was a #20 TamperProof Torx. It appeared to be clean but I gave it a couple more shots of brake parts cleaner.
Well, if I compared them when the engine is cold, they both should be the same. It would sure beat pulling the ECT because I can't even get my hand on it to pull the connector off. I have a Radio Shack RMS digital VOM with a temperature probe. I friend loaned me a book that covers Ford fuel injection/emissions up to 1993 and there's charts for resistance/voltage at different temperatures. The IAT was a mile off but the voltages in the Ford manual don't jive!
If I can compare them on a cold engine I'd have to pull the PCM connector on the firewall and read back to the ECT. Since that would break the circuit to the PCM and maybe the ground too, I'd have to provide a ground somehow. I could do that by grounding that signal return wire on the IAT connector.
Those pinpoint check are great and I wish that I could perform them but I don't have the breakout box they refer to which I assume is a "Y" cord to use at the PCM connector at the firewall. Am I right about that? Can that be purchased from a Ford dealer? It might be list in the "tools" required section in the front of the Ford manual I have.
I pulled the MAF out again and it was a #20 TamperProof Torx. It appeared to be clean but I gave it a couple more shots of brake parts cleaner.
Well, if I compared them when the engine is cold, they both should be the same. It would sure beat pulling the ECT because I can't even get my hand on it to pull the connector off. I have a Radio Shack RMS digital VOM with a temperature probe. I friend loaned me a book that covers Ford fuel injection/emissions up to 1993 and there's charts for resistance/voltage at different temperatures. The IAT was a mile off but the voltages in the Ford manual don't jive!
If I can compare them on a cold engine I'd have to pull the PCM connector on the firewall and read back to the ECT. Since that would break the circuit to the PCM and maybe the ground too, I'd have to provide a ground somehow. I could do that by grounding that signal return wire on the IAT connector.
Those pinpoint check are great and I wish that I could perform them but I don't have the breakout box they refer to which I assume is a "Y" cord to use at the PCM connector at the firewall. Am I right about that? Can that be purchased from a Ford dealer? It might be list in the "tools" required section in the front of the Ford manual I have.
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From: Warren, MI
Attn wptski
Ken:
My friend with a 91 Bronco said that his PCM connector has a removable cover plate where you can access the pins. If so, I can do pinpoint tests. I hope that mine is like that too!
My friend with a 91 Bronco said that his PCM connector has a removable cover plate where you can access the pins. If so, I can do pinpoint tests. I hope that mine is like that too!
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Post Fiend
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From: South Jersey
Attn wptski
I would compare them to the specifications, in my 2000 manual it has a chart, 194' = 2.8k, 176' = 3.8k and 50' = 58.8k ohms. I would be careful using the ohm meter, only measure the sensor with it disconnected. I don't believe they use the block as ground, they have a signal return. I didn't think a basic BO box would be that expensive, did you check your local parts store for one, they might also loan them. I'm not sure about an access cover but you need to be very care that you don't short out the PCM or apply voltage to a curcuit when testing.
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From: Warren, MI
Attn wptski
Ken:
That other book listed like 58K at 50 deg. also and when I checked the IAT, I got 30.9K at 48/49 deg. Just to double check I got a thermometer used for A/C work and it showed the same temperature too! This book gives votage and resistance at a certain temp but the Ford manual only gives a voltage and the two didn't list the same readings for voltage. That's why I'd like to compare the ECT and IAT.
I'll have to ask at the auto parts store about the breakout box.
That other book listed like 58K at 50 deg. also and when I checked the IAT, I got 30.9K at 48/49 deg. Just to double check I got a thermometer used for A/C work and it showed the same temperature too! This book gives votage and resistance at a certain temp but the Ford manual only gives a voltage and the two didn't list the same readings for voltage. That's why I'd like to compare the ECT and IAT.
I'll have to ask at the auto parts store about the breakout box.
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Post Fiend
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From: South Jersey
Attn wptski
My Ford 2000 manual lists both resistance and voltage, I also confirmed the values from another source. If you have an IAT that is sensing that the air is warmer than it really is, which would be less dense air, then the less dense air would require less fuel. But in your case then this would mean that the air is denser than indicated and is not receiving enough fuel, which would be a lean condition. Can you pull the IAT and test it at room temperature, it might be at the bottom of is limits. Again this is just guessing at the problem.
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From: Warren, MI
Attn wptski
Ken:
I don't know what chart I was looking at in the Ford manual but I found another one that's exactly the same as in the other non-Ford and the same as your values! Voltages and resistance values are the same too!
It seems that some DTCs almost point to a sensor exactly and the ones like I'm getting point to nothing exactly!
Yeah, I could check the IAT at room temperature. It's easy to pull. It wasn't raining, I'd do it right now.
Speaking of rain I have another post about a water leak too in my Ranger. I got tape all over the cowl holes and wiper arm drive openings. It's not the time of year where one can drag out the garden hose :-)
I don't know what chart I was looking at in the Ford manual but I found another one that's exactly the same as in the other non-Ford and the same as your values! Voltages and resistance values are the same too!
It seems that some DTCs almost point to a sensor exactly and the ones like I'm getting point to nothing exactly!
Yeah, I could check the IAT at room temperature. It's easy to pull. It wasn't raining, I'd do it right now.
Speaking of rain I have another post about a water leak too in my Ranger. I got tape all over the cowl holes and wiper arm drive openings. It's not the time of year where one can drag out the garden hose :-)