I have not, I did raise the injector size to lean it out but then it was running great before so I really wanted to fix the problem before tuning so I went back to the original tune and just changed the offsets for the BOSCH III's. Also I need to adjust for cranking as it cranks for a good 5 seconds before it fires, I saw a thread I subscribed to on this and need to check into this.
I see Minimum MAP for PE and it shows 91.88 Kpa this is the only thing I see related to MAP and PE.
ok...just wanted to see if you changed that. I got myself into trouble (dropping out of PE) by lowering it too much until Rbob figured out that was the cause.
Here is the secondary ignition waveform first one is at idle and the second one is at WOT under load.
I am certainly a newbie using a lab scope but does not look right comparing wave forms in manual and reference waveform on this scope and the duration appears to be very low.
Check your scope connections. The pattern pictured in this post looks like the pickup isn't setup right or you've got poor connection. The sample pattern from General Disorder is more like what you should be seeing.
Yes WOT cylinder 1 only. I have noticed the Fire kV and rpm during parade getting lost.
Here is another I think looks much better at 10kV scaling and 1ms. If this looks like the right setting I can start switching cylinders. I will certainly look into a USB scope if it will help here.
This waveform looks more correct though I see what looks like lean AFR and either some pick up noise on the burn line or detonation. If the time scale was lower, it would be easier to make out.
I think I see the problem with the funky waveform. Try setting the voltage scale to 15 or 20KV to shrink the vertical(voltage) axis. Then reduce the time scale. This will produce a more viewable scope trace. What's weird is the secondary waveform, as far as I can tell from these screen shots looks to be lean by the climbing burn line, but your plugs are definitely rich. The noise on the burn line looks like detonation. Increasing the voltage axis to 15KV and stretching the waveform out with a quicker time scale will make things more visible. I think I see oscillation at the end of the burn which would tell me your coil has plenty of juice. Have you verified timing is in fact correct using a dial back timing light? As far as parade KV viewing, it's not much good unless you have a large enough screen to show all 8 cyls with enough resolution to do any good. Better with a small screen to view one at a time. I have the Modis ultra with a 7 inch screen. Then, I have an old Sun with a big old CRT screen. It's old and almost nothing on it works but it still works great for ignition waveform viewing on anything that still has wires.
One thing that will cause black plugs along with lean O2 readings is a coil that won't support normal combustion. Do you have a tester coil available? Also, you might want to try disconnecting the exhaust just in front of the mufflers if you can and see if the engine accelerates normally. The back pressure results you got might be skewed if the engine can't accelerate.
After reviewing your log, your system voltages are way too low (at least what the ECM is seeing). ECM seeing around 11V at the battery terminal and 12.7 volts at the fuel pump relay. Check your alternator voltage at the main battery terminal on the back side. If it's normal (13.5 to 14.5V), then you have a huge voltage drop some place and you'll have to start probing around the various 12V nodes on the car to see where the voltage drop is occuring... i.e., the ignition switch, 12V junction blocks, etc... Probably start at the ECM and work your way upstream probing all the connections all the way back to the alternator... fuse block, ignition switch, junction blocks, etc...
If the alternator is not putting out the right voltage at the main terminal, then probably need to have it checked out or replaced.
Need to get this ironed out before worrying about tuning. Incorrect system voltages at the ECM is a recipe for all sorts of driveability issues.
Check your ECM grounds as well. That can also cause problems.
Your BLMs are all over the place too and you appear to be stuck in BLM cell 4 (the idle cell), but I don't want to attack that yet... no tuning around malfunctions!!
what injectors are you running now? EArlier post indicated you swapped out injectors along the way...
That's goes hand in hand with the voltage concern... your injector voltage offsets need to be correct as well before getting into any kind of tuning....
Getting 14.2 to 14.5 Volts at the battery so must be wiring to the ECM not getting full voltage. I did check all grounds at the ECM already thinking it was an electrical issue. I'll test all wiring with power to the ECM and see what I am getting there.
Yeah you really want 14.5 ish at the ECM. The problem is a lot of the injector pulse width's, etc are based on the voltage and if it's different at the injectors than it is at the ECM, you get incorrect fueling.
B1,c16 and a6 ignition power are the ecm power wires.
Thank You below is what I have with key on engine off and there is 12.5 volts at the battery.
B1 - 11.25 Volts
C16 10.75 Volts
A6 10 Volts
Will try with running but it likely does not matter.
More testing with engine not running and note I have an electric fan and water pump that is always on with key on:
B1
Key on fan and wp on 11.25
Key off 12.48
Key on no fan 11.88
Key on no fan no wp 12.2
C16
Key on fan and wp on 10.75
Key off 12.44
Key on no fan 11.77
Key on no fan no wp 12.18
A6
Key on fan and wp on 11.25
Key off 0.00
Key on no fan 11.44
Key on no fan no wp 11.86
It is early am so I did not test while running. Looking at the electric water pump power supply it does not appear to have a relay so I will add one!
Yeah you really want 14.5 ish at the ECM. The problem is a lot of the injector pulse width's, etc are based on the voltage and if it's different at the injectors than it is at the ECM, you get incorrect fueling.
exactly!
the other thing I would advocate is changing the tune to have it reference the battery (keyed ignition) voltage for managing the injector offsets. In stock form, it's looking at the fuel pump voltage. Since the injectors are powered off the keyed ignition, it makes more sense for the ECM to base voltage-driven PW corrections off the keyed ignition, not the voltage at the fuel pump relay.
That secondary waveform trace is much more useful. Have to take into account the scope being used with the LCD screen, poor resolution. It's hard to be sure how much of the hash is detonation and how much is just the scope. Firing KV looks about right, the burn line is fairly level. The hash that I'm concerned about towards the end of the burn line could be detonation or a valve sealing issue. I'm not sure if it may also cause by excessive bask pressure or charge contamination. There tends to be more hash at WOT anyway because of higher cylinder pressures. What are your lifters set at? Assuming their hydraulic, should be 1/2 turn in for the street. Be sure to get them at definite zero first. The coil wiggle at the end means there is plenty of juice in the coil. You photo cut off the left hand portion of the screen. I don't know if you can see the primary coil driver start coil charging. It was visible in the other traces, though a bit distorted by the settings. Looks like the ignition is healthy. I think this was already discussed, but any possible cause of charge contamination: EGR, excessive back pressure, contaminated or old fuel. Valves not seating correctly(valve lash setting). Injector spray pattern, contaminated injector pintles. Fouled injector pintles would help explain the rich looking plugs along with normal AFR readings, although all the plugs looking pretty even would be odd.
Again, crack the exhaust before the mufflers just to be sure. Of course on the other end of things, be sure there is no restriction to inlet air.
Thanks for the feedback. I can try removing the other exhaust I already tested with the passenger side off.
Just tested voltage with engine running at idle with coolant fan and water pump disconnected and B1 and C16 are both getting 14.3 volts and A6 is at 13.8 volts.
Voltage with engine running at idle with coolant fan disconnected and water pump connected and B1 and C16 are both getting 14.2 volts and A6 is at 13.3 volts.
Voltage with engine running at idle with coolant fan and water pump connected and B1 and C16 are both getting 13.8 volts and A6 is at 12.8.
Not sure why TunerProRT is showing 10.9 to 11.5 Volts.
You have to do a voltage drop test with a load in the circuit. You can't check the voltage open circuit. If there's a poor connection, the meter doesn't provide enough resistance to measure what the ECM will actually see under load.
you measured those directly at the ECM connectors?
Yes I did.
I could leave connected and verify under wot to see if it drops.but the live data in my scan still showed the lower voltage at idle. I did rev the motor with no load and there was little change.
I should be able to do more testing tomorrow morning I thought about driving it to a more remote road and let it cool down then unplug the fan and water pump and try a quick test this way.
You have to do a voltage drop test with a load in the circuit. You can't check the voltage open circuit. If there's a poor connection, the meter doesn't provide enough resistance to measure what the ECM will actually see under load.
GD
assuming he back probed the ECM connectors with the connectors still attached to the ECM, that seems like a valid measurement, no?
I could leave connected and verify under wot to see if it drops.but the live data in my scan still showed the lower voltage at idle. I did rev the motor with no load and there was little change.
I should be able to do more testing tomorrow morning I thought about driving it to a more remote road and let it cool down then unplug the fan and water pump and try a quick test this way.
Thanks again fior for all the help!
did you back probe the connectors or disconnect them and then measure? though not sure how you'd be able to disconnect them and have the engine still run...
I did back probe while engine running of course. I also back probed and checked with harness disconnected for the non running tests. Using the same scope in DMM mode.
I could also also do the secondary test on all of the other cylinders now that I have a good setting to work with.
see if you can disconnect an injector plug while running and then measure the voltage terminal on the harness to see what the ECM is sending to the injectors.
If that's the case, I would try another ECM. They are cheap and it reporting 2v lower than what's going into it makes it suspect. A few tenths of a volt drop is normal, but 2 whole volts is unacceptable in my opinion.
If you've probed as far back to the ECM as the connectors and are still getting a "difference of opinion" with what the ECM is reporting, then likely the issue is within the ECM itself.
This definitely crossed my mind and not a bad idea to have a spare for how cheap they are.
I went out for a quick run and left the air cleaner off and it was way worse so this may be a lean issue. I would think I would see this in with the wide band AF meter???
I bumped up the fuel pressure a little and ran the scope in DMM mode on B1 and the lowest it went down to was 13.8 and highest 14.1 volts. Felt a little better with more FP but still not there.
If you've probed as far back to the ECM as the connectors and are still getting a "difference of opinion" with what the ECM is reporting, then likely the issue is within the ECM itself.
If looking for ECM voltage issue, don't forget the ECM grounds. ECM voltage is the difference between power and ground. Absolutely correct that you have to load the circuits for a useful voltage drop test. A 55w headlamp bulb draws about 5 amps. It's about right for 14-16ga power and ground circuits. I use a 3156 bulb( about 2.3 amps) for 18ga. I have one of each with test leads attached. Be careful how you connect to the ECM connector terminals not to deform or overheat them.
Whatever is happening to cause reduced power, you should be able to see it in basic engine performance testing. Cam and ignition timing, spark KV, air fuel ratio, compression, intake or exhaust restriction. If you can verify that each of these are okay, the engine should run normally.
That is was worse with the air cleaner off is strange, looking at the dark plugs. There seems to be a combustion issue, something causing the fuel/air mix not to burn completely.
One of the first things I tested was all of the ECM grounds, but just checked to see that I had a low Ohm reading. So what your stating here is to do a voltage drop test on both the positive and grounds at the ECM? Would I use the battery for my starting point for each? Then I would need to drive it to see what kind of a drop I am getting under WOT when the issue is happening.
I did also run a jumper cable from battery ground to the ECM ground for testing but this did little to the voltage reading .01 volts higher.
I can try to pull the other banks exhaust off or maybe just pull the O2 sensor, I have 2 O2 bungs so I can also still run the O2 on the other bank.
Cam timing should be right I did not touch it when doing a head gasket change and it ran great before and after this. Ignition timing have messed with a lot with no major changes, if I go too far advanced it does pull timing so it is changing. Spark KV is fine according to the scope. A/F is rich 10:1 according to Innovate LM2 Wide Band A/F ratio meter, and I raised the injector size in the tune to lean it out and it was at 13:1 it felt stronger here but still laying down at WOT. Ran with no air filter with worse results so this does not appear to be a restriction. I ran with the even bank disconnected with no change so need to check the odd bank here for a possible restriction.
With the engine running, to check the grounds, put the positive probe on the ECM ground at the ECM connector and the other probe on the (-) battery terminal. If you get more than a few millivolts, your grounding point isn't good enough. Run through all ECM ground wires with that test.
Just did the ground test and on ECM grounds A12, D1, and D6 I get -0.01mV maximum during test it goes to -0.00mV for current value then toggles back and forth from -0.01mV to -0.00mV. On ECM ground D7 I get a minimum of -0.02mV then the same toggle back and forth from -0.00mV to -0.01mV.
10 mV is probably ok. Your grounds seem adequate IMO... The wires themselves have amount of resistance per foot anyway and you'll never overcome that.
Nothing in terms of sensors or expected voltage inputs is so sensitive that ~10mV offset is going to throw the vehicle operation into chaos. I'd worry if you got up to say 1/2 a volt or something like that.
For example, the O2 sensor ground ties into the main ECM ground... (it's not really the ground of the O2 sensor... the ECM only uses it as a reference). Ground offsets in the hundreds of mV becomes a large percentage of the O2 sensors 0-1V operating range.
I messed this test up. I was using the scope and hooked the regular ground lead to the battery ground instead of the one off the channel 1 lead. I noticed this as it was still connected when I went to try a different ECM, this other ECM responded the same way. So I re tested and the voltage drop on A12 is 1.49 Volts, D1 is 760mV, D6 is 1.14 Volts, and D7 I have down as 1.21mV but may be a full 1.21 Volts.
I did however notice with the different ECM my voltage was up to 12.5 volts for battery reading and 13.5 volts for fuel pump so this did change but may not matter once the grounds are straightened.
I messed this test up. I was using the scope and hooked the regular ground lead to the battery ground instead of the one off the channel 1 lead. I noticed this as it was still connected when I went to try a different ECM, this other ECM responded the same way. So I re tested and the voltage drop on A12 is 1.49 Volts, D1 is 760mV, D6 is 1.14 Volts, and D7 I have down as 1.21mV but may be a full 1.21 Volts.
So it appears this is the issue.
yeah those ground offsets would definitely be problematic.
Went through and cleaned and tested all grounds in the engine area and still having the same voltage drop.
Started testing all of the original ground wires in DMM mode with my scope and I am seeing .3 Ohms on all of them from one end to the other, then from battery negative to ECM I get the same .3 Ohms. So I decided to try my regular DMM and I get 0 Ohms testing with it. Previously I had 4 ohms with the scope from ECM ground to battery ground but this was with the battery positive lead connected so I decided to pull the battery positive lead and test again with my regular DMM I get 1.8 Ohms on all grounds with the positive lead connected.
So I am getting more resistance on the ECM ground leads with the battery positive lead connected when testing from ECM ground to battery ground.
I was going to change all ECM ground wires tonight but I do not see much of a problem with the original ones.
I will try the voltage drop test again with my regular DMM and see what kind of numbers I get with it.
