Sorry, but I need help again
- Thread starter NavyVet88
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Originally Posted by Trav
Time to invest in a bi directional scan tool (not a code reader) and learn how to interpret the data. Honestly, any other way you are on a fools errand, guessing and throwing parts at it and wasting time and getting frustrated. There is no old school or shade tree anymore when it comes to modern vehicles.
^^This. I think you're going to need some more advanced equipment to diagnose this. I recommend hooking up an oscilloscope to the coil pack and injectors, reproduce the problem, and analyze the waveforms.
Time to invest in a bi directional scan tool (not a code reader) and learn how to interpret the data. Honestly, any other way you are on a fools errand, guessing and throwing parts at it and wasting time and getting frustrated. There is no old school or shade tree anymore when it comes to modern vehicles.
^^This. I think you're going to need some more advanced equipment to diagnose this. I recommend hooking up an oscilloscope to the coil pack and injectors, reproduce the problem, and analyze the waveforms.
Originally Posted by NavyVet88
Originally Posted by KrisZ
Did you check for vacuum leaks?
Yes and I did not find any. Doesn't mean I missed a leak, but I did not find one after multiple checks with carb cleaner.
Propane is a better leak finder, are you heat and A/C controls working properly? I have done a few of these that had a cracked hard plastic vacuum line going to the controls.
Originally Posted by KrisZ
Did you check for vacuum leaks?
Yes and I did not find any. Doesn't mean I missed a leak, but I did not find one after multiple checks with carb cleaner.
Propane is a better leak finder, are you heat and A/C controls working properly? I have done a few of these that had a cracked hard plastic vacuum line going to the controls.
Originally Posted by Trav
Originally Posted by NavyVet88
Originally Posted by KrisZ
Did you check for vacuum leaks?
Yes and I did not find any. Doesn't mean I missed a leak, but I did not find one after multiple checks with carb cleaner.
Propane is a better leak finder, are you heat and A/C controls working properly? I have done a few of these that had a cracked hard plastic vacuum line going to the controls.
Both work great. Could it be the map sensor?
Originally Posted by NavyVet88
Originally Posted by KrisZ
Did you check for vacuum leaks?
Yes and I did not find any. Doesn't mean I missed a leak, but I did not find one after multiple checks with carb cleaner.
Propane is a better leak finder, are you heat and A/C controls working properly? I have done a few of these that had a cracked hard plastic vacuum line going to the controls.
Both work great. Could it be the map sensor?
No MAP sensor on these.
More long shot guesses to check...
Have you checked the PCV hose coming off the valve going to the back of the intake manifold? The original design would deteriorate and collapse, and sometimes develop a large hole. There is an updated replacement.
Also make sure the small tube coming off the other valve cover and going to the air intake duct is good.
More long shot guesses to check...
Have you checked the PCV hose coming off the valve going to the back of the intake manifold? The original design would deteriorate and collapse, and sometimes develop a large hole. There is an updated replacement.
Also make sure the small tube coming off the other valve cover and going to the air intake duct is good.
Originally Posted by 01rangerxl
No MAP sensor on these.
More long shot guesses to check...
Have you checked the PCV hose coming off the valve going to the back of the intake manifold? The original design would deteriorate and collapse, and sometimes develop a large hole. There is an updated replacement.
Also make sure the small tube coming off the other valve cover and going to the air intake duct is good.
I'll check those hoses next check I get.
No MAP sensor on these.
More long shot guesses to check...
Have you checked the PCV hose coming off the valve going to the back of the intake manifold? The original design would deteriorate and collapse, and sometimes develop a large hole. There is an updated replacement.
Also make sure the small tube coming off the other valve cover and going to the air intake duct is good.
I'll check those hoses next check I get.
I just had a full on diagnostic ran on the ranger this morning and whadda ya know.....nothing could be found. Long and short term fuel trims were fine, there was no vacuum leaks anywhere either. I'm just going to drive the truck and not worry.
I'm wondering if you have a hot spot on a valve or piston top, causing occasional predetonation. You might be able to pinpoint that by trying a tank of 93 Octane, which would then reduce the occurrence. If a tank of 93 makes no difference, that's not it.
Is this a timing belt motor? a stretched TB in my experience caused occasional misses, especially at idle. Eventually it threw occasional misfire codes, but no mechanic diagnosed it properly - they all suggested wiring harnesses and injectors. I wouldn't have guessed it either, since it was a TB with only 36k on it. By luck, a WP failure drove the replacement, and the problem was gone. I compared the 2 belts and there was a notable difference.
Is this a timing belt motor? a stretched TB in my experience caused occasional misses, especially at idle. Eventually it threw occasional misfire codes, but no mechanic diagnosed it properly - they all suggested wiring harnesses and injectors. I wouldn't have guessed it either, since it was a TB with only 36k on it. By luck, a WP failure drove the replacement, and the problem was gone. I compared the 2 belts and there was a notable difference.
Originally Posted by meep
I'm wondering if you have a hot spot on a valve or piston top, causing occasional predetonation. You might be able to pinpoint that by trying a tank of 93 Octane, which would then reduce the occurrence. If a tank of 93 makes no difference, that's not it.
Is this a timing belt motor? a stretched TB in my experience caused occasional misses, especially at idle. Eventually it threw occasional misfire codes, but no mechanic diagnosed it properly - they all suggested wiring harnesses and injectors. I wouldn't have guessed it either, since it was a TB with only 36k on it. By luck, a WP failure drove the replacement, and the problem was gone. I compared the 2 belts and there was a notable difference.
No, he said he has a 3.0 V6. It has a timing chain. Pushrod, cam-in-block engine with a short chain.
I'm wondering if you have a hot spot on a valve or piston top, causing occasional predetonation. You might be able to pinpoint that by trying a tank of 93 Octane, which would then reduce the occurrence. If a tank of 93 makes no difference, that's not it.
Is this a timing belt motor? a stretched TB in my experience caused occasional misses, especially at idle. Eventually it threw occasional misfire codes, but no mechanic diagnosed it properly - they all suggested wiring harnesses and injectors. I wouldn't have guessed it either, since it was a TB with only 36k on it. By luck, a WP failure drove the replacement, and the problem was gone. I compared the 2 belts and there was a notable difference.
No, he said he has a 3.0 V6. It has a timing chain. Pushrod, cam-in-block engine with a short chain.
I had a bad fuel pressure regulator in mine (94 4.0)-- the diaphragm had ruptured. These start small, sometimes. You can plug off the vacuum line to it for diagnostics-- will mess with your fuel trims but run ok. Raw fuel in the vacuum line says it's totally gone.
Originally Posted by exranger06
Originally Posted by meep
I'm wondering if you have a hot spot on a valve or piston top, causing occasional predetonation. You might be able to pinpoint that by trying a tank of 93 Octane, which would then reduce the occurrence. If a tank of 93 makes no difference, that's not it.
Is this a timing belt motor? a stretched TB in my experience caused occasional misses, especially at idle. Eventually it threw occasional misfire codes, but no mechanic diagnosed it properly - they all suggested wiring harnesses and injectors. I wouldn't have guessed it either, since it was a TB with only 36k on it. By luck, a WP failure drove the replacement, and the problem was gone. I compared the 2 belts and there was a notable difference.
No, he said he has a 3.0 V6. It has a timing chain. Pushrod, cam-in-block engine with a short chain.
Copy that and thanks - I'm not as familiar with this engine family. I'll keep my dollar in the hat for carbon buildup. Those compression numbers seem high to me for an engine of that era. My old 283 which was close to 11:1 had around 145-155. No way a regular octane engine should be up there, unless my memory is just totally off, which it could be.
Originally Posted by meep
I'm wondering if you have a hot spot on a valve or piston top, causing occasional predetonation. You might be able to pinpoint that by trying a tank of 93 Octane, which would then reduce the occurrence. If a tank of 93 makes no difference, that's not it.
Is this a timing belt motor? a stretched TB in my experience caused occasional misses, especially at idle. Eventually it threw occasional misfire codes, but no mechanic diagnosed it properly - they all suggested wiring harnesses and injectors. I wouldn't have guessed it either, since it was a TB with only 36k on it. By luck, a WP failure drove the replacement, and the problem was gone. I compared the 2 belts and there was a notable difference.
No, he said he has a 3.0 V6. It has a timing chain. Pushrod, cam-in-block engine with a short chain.
Copy that and thanks - I'm not as familiar with this engine family. I'll keep my dollar in the hat for carbon buildup. Those compression numbers seem high to me for an engine of that era. My old 283 which was close to 11:1 had around 145-155. No way a regular octane engine should be up there, unless my memory is just totally off, which it could be.
Park outside and hope for a astroid to hit it. I would rather have a issue to find/fix than this phantom car problem. Ever thought of FAQing the MIT brothers Click and Clack? I think they were on NPR on Saturday morning and do a good job helping people.
https://www.cartalk.com/
https://www.cartalk.com/
I'm beyond wanting to say that I am done with worrying about this issue. I am going to check the gap in every spark plug tomorrow after church and see if by some miracle I can find one that is out of spec and it be the fix. If that shows nothing, I'm going to drive it until the truck won't let me drive it anymore.
I thought surely that with all of the other possibilities eliminated I would find low or no compression in a cylinder, but the compression was fine in all.
I thought surely that with all of the other possibilities eliminated I would find low or no compression in a cylinder, but the compression was fine in all.
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