crank relearn

[odd boy]

here it is. I have some additional information for you, the actual AFR is 17.5!!!!. I multiplied by 1.23 = 17.5/14.63 but nothing happened, then I put back as it was.

Note that the log file here is for the stock one when the AFR is 17.5.


my case.efi

[Blacky]

Are you saying the measured AFR (using a wide band) was 17.5?

If the PCM is commanding 14.63 (as per the log file) and the result is 17.5, then the engine is either getting too much un-metered air (i.e. intake manifold leak or exhaust leak) or the engine is not get less fuel than the PCM "thinks" it is delivering Possibly one or more blocked injectors or injectors that are not flowing what they say they are.

P.S. The jagged spark data is exactly what I would expect when the PCM trying to maintain constant idle under difficult circumstances (i.e. starved of fuel).

If you want to see how badly the engine runs without the PCM using the spark to control the idle, set tables: B5935, and B5936 to zero.
You will most likely find that the idle speed hunts up and down over ever increasing rpm ranges until finally it gets too low and stalls.

Regards
Paul

[odd boy]

Are you saying the measured AFR (using a wide band) was 17.5?

yes that is right

If the PCM is commanding 14.63 (as per the log file) and the result is 17.5, then the engine is either getting too much un-metered air (i.e. intake manifold leak or exhaust leak) or the engine is not get less fuel than the PCM "thinks" it is delivering Possibly one or more blocked injectors or injectors that are not flowing what they say they are.

Injectors were sent for cleaning 3 days ago and there is no difference. the headers are brand new

P.S. The jagged spark data is exactly what I would expect when the PCM trying to maintain constant idle under difficult circumstances (i.e. starved of fuel).

What is the next step? The fuel pressure was checked and found 60 Psig

[Tordne]

If you're saying that you are commanding 14.63:1 and are getting 17.5 then I think you should resolve that matter first as this is obviously of concern.

[odd boy]

I have different way to explain what is going on (I'm thinking loudly), I run the cyl test (thorough the scan tool) and I'm questioning the performance of cyl#6. Then I followed the old method of testing the performance of a cylinder/injector/coil.

I did the following:

1. I started with checking the power of the injector and the coil (by using fuse tester), the power was found okay.

2. I unplugged the power connector of the injector, very very small difference was noticed.

3. I put the connector back, but after shutting of the engine.

4. I put a new coil to make sure that the problem is not from the coil, then I started the engine and the result was "NO DIFFERENCE"

5. I unplugged the spark plug cable from the coil and again "no difference"

Do you think the cyl is week and the engine needs to be disassembled?

[joecar]

How did you use a fuse tester to check for power to injector and coil...?

What if power to either one is below battery voltage...?

A voltage drop like this (due to lose/corroded/broken connection/wire) would prevent the injector/coil firing correctly.

You have to use a DMM... there are cheap ones available for $20.


Also, to test that the injector circuit is firing, use a noid light (has the same impedance as an injector)... these are about $10.

You can feel with your finger resting on the injector that it is firing... or use a mechanics stethoscope (but you'll hear all the injectors);
problem is you can't easily tell if the spray pattern is good without removing the injector/rail assembly (and then you have to be careful not to blow up).


Also, to test for spark, use a spark tester (looks like a spark plug with a ground clamp)... these are about $25.

If spark is good, there is no need to replace the coil ($$$).


You need to do four tests before proceeding:
1. compression test: the suspect cylinder will compare lower; compression gauge is cheap $30... can tell you if it's rings or valves;
2. leakdown test: again, bad cylinder will compare lower; leakdown tester is more expensive $80+.
3. cooling system pressure test (tester is $100...goto radiator shop).
4. test for combustion gasses in coolant using a test kit $20... also observe presence of bubbles in radiator fill neck.

Those 4 tests will dictate your next actions.

If there is a problem, is it due to:
- weak spark (why?);
- weak injector spray (why?);
- insufficient airflow in/out (loose/broken rocker, bent pushrod, blockage (rag... I have seen this before)... why?);
- loss of compression (valves, springs, rings, other... why?);


Also, are you sure it is only one cylinder...?


By taking time to diagnose it, you will save time/money/effort.