When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Sooo... I bought this tool... (with the tool connected to the positive pole on my battery...) all 8 cylinders (engine off) show the same result... The left side of the fuel-injector connector gets a light, when I probe it.. the right side of the injector connector shows no light, when I probe it.... AGAIN.. the same behavior across all 8.
Compression check next.... give me 2 hours....
If you probe the pink wire the test light will light…that is the 12 volt feed !!…the control wire or ground is the striped wire..that should NOT light as in my picture below and as I said if it does you have a short to ground !!..I guess you’re OK if the control wire does not light !!…and just remember a compression test will not reveal some defects in the valve train !!
Keep the test light connected to the ground ( control) side of the connector as you have and pull and twist the harness at several locations and see if the light illuminates. If it does, you have located the short.
Keep the test light connected to the ground ( control) side of the connector as you have and pull and twist the harness at several locations and see if the light illuminates. If it does, you have located the short.
...already did this... pulled very hard on the wiring loom.... made no difference.
If you have spark, compression and fuel the cylinder should fire. Since you have a situation that takes time to develop, you said it runs for awhile and then misses, I think you should look at the injector signal and spark while the engine is running and missing to see if it's being lost after running for a while. It may be a driver issue in the PCM that as it heats up the circuit fails until it cools down. It then starts to work again after it cools down a bit.
If you have spark, compression and fuel the cylinder should fire. Since you have a situation that takes time to develop, you said it runs for awhile and then misses, I think you should look at the injector signal and spark while the engine is running and missing to see if it's being lost after running for a while. It may be a driver issue in the PCM that as it heats up the circuit fails until it cools down. It then starts to work again after it cools down a bit.
This is a GREAT idea but unless one has a scope checking for spark or injector dropping out is impossible…also there are a few things that his compression test may not pick up such as a sticking valve or maybe a worn cam lobe…going in cylinder with a pressure transducer would be the only way to pick this up unfortunately…hope you didn’t get a lot of snow in Jerz ??
This is a GREAT idea but unless one has a scope checking for spark or injector dropping out is impossible…also there are a few things that his compression test may not pick up such as a sticking valve or maybe a worn cam lobe…going in cylinder with a pressure transducer would be the only way to pick this up unfortunately…hope you didn’t get a lot of snow in Jerz ??
Got 10 inches or so. Spent a few hours in at 10 degrees snow blowing it. For the spark plug you can just pull the wire out of the coil and hold it close the the coil top and you will see a steady spark. If it drops out it's very easy to see. Same with the injector, just put the light probe on the PCM side and it will pulse every time the injector fires. Again easy to see if it stops or stays on.
Got 10 inches or so. Spent a few hours in at 10 degrees snow blowing it. For the spark plug you can just pull the wire out of the coil and hold it close the the coil top and you will see a steady spark. If it drops out it's very easy to see. Same with the injector, just put the light probe on the PCM side and it will pulse every time the injector fires. Again easy to see if it stops or stays on.
Don’t know if this misfire is under load or at idle…we don’t even know what his bank 1 O2 sensors is doing…when my upstream O2 was stuck lean a few weeks ago I had fuel trims like that…they were maxed out !!…I really didn’t see misfires unless I put a load on the engine…E brake on and letting the clutch out slowly…it took a lot to make all 4 cylinders misfire !!
...already did this... pulled very hard on the wiring loom.... made no difference.
Can you do me a favor and graph your upstream O2 sensors…with the fuel trims you had that was the FIRST thing I would want to look at…I feel like an idiot !!…I know you replaced your sensor but it would be great to see what it’s doing graphically !!…what O2 sensor did you use ??…I changed 3 new B1S1 sensors 3 weeks ago…1 Delphi and 2 Bosch before I put in a Denso that finally worked…never assume a new part is good…this is what my scan tool showed when the sensor was stuck lean…it “looks” like it’s switching normally but if you look at the scale (lower left is bank 1 upstream) it is only switching between 78-135mv…extremely lean…that is why the PCM was adding all that fuel…it was a “false” lean condition !!...I bet your downstream bank 1 will be over 900mv's like mine is in the picture.
Don’t know if this misfire is under load or at idle…we don’t even know what his bank 1 O2 sensors is doing…when my upstream O2 was stuck lean a few weeks ago I had fuel trims like that…they were maxed out !!…I really didn’t see misfires unless I put a load on the engine…E brake on and letting the clutch out slowly…it took a lot to make all 4 cylinders misfire !!
He said "ALSO... I should point out.. it is (the bad idle, miss, DTC. gas smell...) NOT continuous or immediate. Upon starting from cold it will run for a short amount of time (minutes...), then go bad. Then after a few minutes it will smooth out for a short period of time.. then repeat."
So he should be able to take a look at it. Although he might not be able to see the injector pulse with a light if the pulse is too narrow. He does need to look at the O2 sensors because they can also help diagnose what's happening.
Since you have a compression gauge, why not perform an engine running compression test? A standard cranking compression test is a good test for cylinder sealing whereas the running test will be a better indicator of cylinder efficiency. Install your gauge in the cylinder, ground the plug wire to prevent damage and disconnect the injector. Start and run engine at idle releasing the gauge pressure at 3 to 4 second intervals. Open and close the throttle quickly and record readings. At idle, the cylinder should show 50% to 75% of normal compression readings, a fast throttle opening should read 80% of normal compression. Check additional cylinder readings and compare with #1 cylinder. This test gives a better indication of cylinder efficiency and quickly reveals possible valve carbon or sticking, broken or faulty valve spring, worn cam lobes or lifters, and restrictions in the intake and exhaust. I cannot picture the intake manifold on the engine. Is there any vacuum or fuel purge system hoses connected to the #1 intake runner that could affect the air intake? Have you checked the intake for possible leaks?
I wanted to finish out this thread.. I hate it when people announce problems and never reveal the solution to their issue.
The symptoms are listed on the initial post.
The solution? I did 2 things which I know is bad science but one of these solved the issue. I replaced the O2s and I had a small crack welded up on the passenger header (see attached [pics).
