Driver side is super clean, driver side has a very faint dark color but not like it is over fueling or running too rich
Fox Xtremely high fuel consumption
- Thread starter PonyGTrider
- Start date
I’m still saying it’s running a bit rich. Not pig rich or anything but those plugs are not showing me the burn is clean.
———————-U P D A T E———————
Well I received the leak down tester I ordered and started taking measurements immediately.
After that I run a new compression test to have freshly taken results.
Both tests were taken with the engine bone cold and here are the numbers and to tell you the truth they don’t make any sense to me, they’re all over!!! But here they are:
Compression test cold, 5 strokes TB wide open:
1 - 170
2 - 135
3 - 145
4 - 130
5 - 130
6 - 145
7 - 140
8 - 135
Leak down test cold, each piston at TDC on compression stroke all of the leakage went thru the pistons rings and didn’t notice any leakage thru the valves.
1- 20%
2- 15%
3- 15%
4- 20%
5- 22%
6- 15%
7- 15%
8- 17%
This engine is a mess as far as my concern.
And what to do from here? Tear it apart deglaze with honing stones, replace rod and main bearings and put new rings? Again there is no blow by whatsoever and feels running strong.
Do this numbers tell you guys anything is causing an extremely poor fuel economy????
Thank you guys!!!!
Well I received the leak down tester I ordered and started taking measurements immediately.
After that I run a new compression test to have freshly taken results.
Both tests were taken with the engine bone cold and here are the numbers and to tell you the truth they don’t make any sense to me, they’re all over!!! But here they are:
Compression test cold, 5 strokes TB wide open:
1 - 170
2 - 135
3 - 145
4 - 130
5 - 130
6 - 145
7 - 140
8 - 135
Leak down test cold, each piston at TDC on compression stroke all of the leakage went thru the pistons rings and didn’t notice any leakage thru the valves.
1- 20%
2- 15%
3- 15%
4- 20%
5- 22%
6- 15%
7- 15%
8- 17%
This engine is a mess as far as my concern.
And what to do from here? Tear it apart deglaze with honing stones, replace rod and main bearings and put new rings? Again there is no blow by whatsoever and feels running strong.
Do this numbers tell you guys anything is causing an extremely poor fuel economy????
Thank you guys!!!!
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DadLife0724
Active Member
I want to put a new set of plugs but before I do that I’ll wait for some comments and suggestion regarding my compression and leak down tests.
So compression and leak down tests need to be done with the engine at operating temperature.
Reason behind it is metal expands when hot so you want everything up to temperature to close up the tolerances. Think ring gap and as the motor heats up those gaps get smaller (how small depends on the setup) and cylinder bore gets smaller. This will all increase or at least should increase the compression numbers and decrease the leak down percentage.
That makes sense, but have you or any of you find out this whole thing goes the opposite?
I’m saying this because comparing the cold compression test I ran looks higher than another test I did not too long ago on a warmed up same engine, or maybe my compression tester is giving me false readings.
So seeing the leak down numbers on this cold engine should I assume that those numbers will get tighter than that? Not that I will go by that, I put everything back warm it up and re-do both tests this afternoon.
And here they are. Leak Down where did they leaked thru and compression tests:
Will this give a better idea if this is causing that awful fuel economy of 9.5 miles to the gallon????? Please comment on this and if this is the cause how would troubleshoot to fix it???
Thank you all for your attention and help!
Something is off in this whole scenario. It just does not track. A 306 getting only 9ish mpg should have a much bigger trail of evidence showing up.
There is some important information missing.
There is some important information missing.
I couldn’t agree more with that statement.
You can ask me what have I done to solve this mystery… I’ve done it! That’s why my frustration.
I don’t have that fact but if I have to guess with good amount of certainty I would say somewhere around 65 - 70k
This goes out just cruising on weekends
So, come clean then.
What information is missing that we have not seen yet?
What was the solution?
Or is this just an Epic Troll?
gkomo
now i can hopefully expect to receive the shaft
I think he means he’s done everything he can think of and the problem is still there, and is out of ideas.
I wish this was a troll but it is not.
This is for real and I still have not find what the heck is going on.
Now I’m debating to either leave it as is or take everything apart.
Talking with a friend of mine he said from my compression results that cylinders 1 4 and 5 are on the low side and the computer is over fueling trying to compensate for their under load. It makes some sense but not sure.
I did perform a cylinder balance test and according to the computer all cylinders are contributing fine.
So, if you were me what would you do, leave it as it is or take it apart hone it, put new rings and replace all the rod and main bearings?????
Now speak up! I will be reading you all Thank you
If you are wiling to tear it down then go for it. Honing the cylinders and then custom gaping some good rings on the stock pistons will for sure help. Take the heads to a shop and have them clean them up (deck, lap the valves, check the springs, and put new valve seals on them). I would also suggest a new oil pump and timing chain of which get high quality on both.
As for the ECU trying to compensate for the three cylinders being of lower compression but the cylinder balance test shows good then I doubt that. If the ECU even has this strategy it would have to show an imbalance to try and correct.
What is bothering me is that the compression tests are not jiving with the leak down test if the test equipment is known to be accurate and the tests were performed correctly. I know you had the motor at operating temp but I do not know how you did the testing. Biggest thing there is you have to make sure that both valves are close during the leak down test.
So here I would expect either Cylinder 1 to have less compression than Cylinder 4 or Cylinder 4 to have more compression than Cylinder 1
Cylinder 1 - 31% with 130 psi
Cylinder 4 - 17% with 130 psi
And here I would expect either Cylinder 1 to have less compression than Cylinder 5 or Cylinder 5 to have more compression than Cylinder 1
Cylinder 1 - 31% with 130 psi
Cylinder 5 - 21% with 120 psi
Those two examples are completely opposite of each other so needless to say it bothers me. Maybe I am reading into this completely wrong but its not what I have typically seen. Typically the less the leak down % is the higher the compression is.
As for the ECU trying to compensate for the three cylinders being of lower compression but the cylinder balance test shows good then I doubt that. If the ECU even has this strategy it would have to show an imbalance to try and correct.
What is bothering me is that the compression tests are not jiving with the leak down test if the test equipment is known to be accurate and the tests were performed correctly. I know you had the motor at operating temp but I do not know how you did the testing. Biggest thing there is you have to make sure that both valves are close during the leak down test.
So here I would expect either Cylinder 1 to have less compression than Cylinder 4 or Cylinder 4 to have more compression than Cylinder 1
Cylinder 1 - 31% with 130 psi
Cylinder 4 - 17% with 130 psi
And here I would expect either Cylinder 1 to have less compression than Cylinder 5 or Cylinder 5 to have more compression than Cylinder 1
Cylinder 1 - 31% with 130 psi
Cylinder 5 - 21% with 120 psi
Those two examples are completely opposite of each other so needless to say it bothers me. Maybe I am reading into this completely wrong but its not what I have typically seen. Typically the less the leak down % is the higher the compression is.
Yeah I’m tempted to take everything apart deglaze the cylinder walls by honing them and get some good file to fit rings.
On the other hand being only 3 cylinders on the low side I was thinking what if the 1st and second ring gaps got stuck aligned can you just re-position them and put them back in? Probably it is not worth the effort and better start with a new set of rings for all….
Yeah I was intrigued by the non sense between the leak down/compression tests but it is what I got putting every piston at TDC. The problem could be the cheap leak down tester I ordered, the percentage gauge needle was sticking up and was hard to calibrate so I had to take it apart and lubricate some brass gears and pins and ran a bit smoother but still I had to calibrate the meter almost for each cylinder may I created inconsistent reading because of that. On the other hand all the measured leak percentage was bleeding thru the rings not thru the valves so I know the valves were closed.
At this point I’m willing to go the extra mile if that will solve the pathetically poor fuel economy if those three cylinders are causing it.
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