2008 driveability issues

does it have a MAF sensor if does check related air box and snorkel to throttle body for rips cracks or could unplug sensor see if it improves in limp in mode running off map n rpm take vacuum gage reading at idle then raise engine to 3000 rpm read vacuum does it drop if so plugged exhaust.

cleaning was very diy, i took a tire valve stem remove the injector oring , push the valve stem onto the injector, unscrewd valve cap removed valve core, drilled small hole in valve stem cap so that carb cleaner straw can go thru it screw cap on,valve stem squirt carb cleaner while engergizing injector.I know it sounds a little hokey but i did visually watch the stream improve as i did this a few times
aditionally this problem seems to affect the whole left bank , i would think it would be pretty unlikey that all injectors on just the left side.
i pulled all plugs , all plugs on left side are snow white lean , performed a compression test all cylinders 150 160 psi
so at this point i know mechanically the eng is ok
i cant help but think that i must have a massive vacuum leak that is only affecting the left bank ,
i will trying a smoke test in the next day or so, but i am not sure where to attach smke machine to eng , i dont not have avacuum brake booster so i can not attach there.
I was thinking about tapping a fitting in the snorkel, and then capping it when im done. Also if i hook up through the snorkel will smoke be able to get past the closed throttle plate

I have run into this after customer did same thing. They ended up plugging up fuel injectors . Fuel filter did not stop everything. Also you can have pressure and not volume. There is a quick easy test I can post tomorrow I don’t remember it off top of my head

i did have lower than normal fuel pressure 47 psi koeo after replacing fuel pump i had 55psi koeo , and when running needle fluctuation was less

i look foward to your volume test
thanks

How about a simple vacuum gauge on the intake manifold? It should show low vacuum with a leak. Some people claim it can tell you everything, i don't think so, but it should tell you something.

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You don't have a vacuum leak. You said that when you raised the rpm's off idle that the fuel trims still stayed +20 something percent positive. Is that right? If so, you don't have a vacuum leak, and I wouldn't expect that to cause your low power issue.

I just skimmed the responses, so I apologize if I say something that someone else did or that I missed. What scan tool are you using? Are you able to record data on a test drive? You can probably pick out your problem by selecting the correct data and analyzing it. If you can record data let me know and I'll tell you what PIDs to record.

i have a zurich zr 13 i dont know if it can record data while driving , i will check when i get home .i have been ubable to get a definitve answer as to where to hook up a vacuum gauge on a 2008 6.0 , earlier models had more vac ports , i do not have a vacuum booster. I am abffled as to why this affecting the entire left bank, i have pulled all plugs and all 4 on the left bank are snow white lean.I have performed a compression test all 150-160 psi . Another member suggested that my cleaning of the injectors could have actually blocked them , i am unsure as why this would be as i visually observerd the injectors go from a steady stream to a more conical spray pattern
As i said i will check if the scanner i have has recording capabilities

thanks ed

it looks as though my scanner will record , i have not tried it yet.
i did figure out where i can hook up a vac gauge i am getting 16 inches at idle, which i suppose it is not to bad considering it is running so poorly
it is still baffeling that 1 bank is so lean
i did swap injectors from side that is running poorly to the side that is operating properly, so i know that clogged injectors is not an issue

i dont have a problem doing a road test and recording data , but shouldnt i be able to see changes at idle, i can see data that suggests that it is running lean and trying to add fuel even at idle
any help is appreciated thanks ed

I think the point of the road test is to see the engine response under different loads and rpms, but Andy knows more than me and knows better what be wants to see.

On the vacuum gauge is the needle steady? When you snap the throttle what is the low and high numbers? At steady high rpms what is vacuum and is it steady?

I agree that something common to the bad bank is the culprit. A breathing problem on one side, a bad ground that is common to say injectors on one side, a pcm on one side.

Look forward to you finding the solution, and the path that leads you to it. Cheers
Sandy


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i will perform those vacuum gauge tests when i get home from work today
i look foward to seeing what PIDs Andy wants me to monitor

One thing I wouldn't mind seeing you try that is quick and easy, is trying to drive to O2 sensors rich with propane. It can be done at idle. Just take a propane bottle of some type and feed some propane into the engine. The oxygen sensors should all go rich. Is this something you can try?

i can do this , although i am not be able to get to it before friday.
would i introduce propane through the intake before the maf sensor by removing air box lid

You can do the test like that. If the sensors on both banks go high, we'll move on.

ok thanks
like i said i may not be able to get back to untll friday due to my work schedule
thanks for your help

Andy is there a risk of explosion if the MAF has a hot wire element? I don't mess with cars for a living but i am a licensed gas fitter and electrician. I know enough to be scared of both. Lol

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ok iwas ready to perform your propane test , but i decided let me check aprk plugs one more time so removed all plugs checked gaps checked for cracked insulators etc all looked good, then i decided to check spark ,using a spark tester i found that i have no spark on any cylinder on the left bank. I was so sure it was going to be something cmputer related i overlooked the basics. Now as they say when it ran it pours , i discharged my battery when cranking and testing each cylinder with a test light , no problem i will just get my battery charger and charge it up, battery charger not working.So i am off to get a charger so i can begin diagnostics, Any insight would be greatly appreciated i am assuming it has to be something common to left bank poor connection bad ground etc, this being a 2008 i am sure someomne has run into this scenario before, Anyway off to get a charger

thanks ed

Well got a new charger , charged battery and begin testing
Since all cylinders are not firing on bank 1 (confirmed with spark tester works on bank 2 not working on bank 1).I found something on line on how to test gm cop coils, i performed this test at the main coil harness not esch individual coil ,
pink wire should be 10-12volts......12v ok
black wire ground should be 10-12volts.......12v ok
brown wire low refrence signal...........should be 10-12 volts ...12v ok
green wire trigger wire should read 5-8 hertz i got no reading on this wire

thqt being said i checked continuity between pcm and this grn wire , wire actually changed color to red/wht in harness it went to #20 in pcm connector 1 and i had continuity.
At this time i assumed that i had an issue with the pcm
I thought where does the grn wire on bank 2 go so i checked continuity from there expecting it to possible go to connector 2 however it actually had coninuity to the same terminal #20 connector 1 as bank 1 , i tried the same test on on the grn wire looking for 5-8 hertz again i got no such reading . I thought what if a ran jumper from bank 2 grn wire to grn wire bank 1 maybe they bwould all start working, when i did this the eng just shook and misfired more.

at this time i thought what is swapped the entire coil assy all 4 from one side to the other , coils from bank 1 that were inop are now working properly and coils from bank 2 that were working are now inop.

I am a little confused sine both grn wire go to the same terminal at the pcm connector, i dont know if there is another way to determine the trigger signal other than a hertz reading as this test was inconclusive

the chart that i found for pcm breakout ..says battery positive voltage
i was unable to read any voltage at this terminal grn wire at either bank yet bank 2 is working
even tried a cop coil tester ( looks like a mini fly swater) you just hold it on coil and it will light up on a working coil lights up on bank 2 not on bank 1
i would be happy to try any other tests or if anyone ahs a link to wiring harnes diagrams

Why do you say the black wire/ground should have 12v? Sounds like a bad ground.

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the instructions that i was following described the proceedure to test these circuits, i thought the same thing the first time i did the test i used a test light hooked up to battery pos , so the the light illuminated when i probed the black wire , so considering how the test light is hooked up , the black wire is a ground, the instructions were to hook the dvom red lead to pos and the the blk lead to the black wire , doing it this way it does read 10-12v i guess it makes sense

what i dont understand is why the bank 1 and 2 seem to have the same readings
the instructions called for a reading in hertz on the trigger wire , i did not get a good reading on this circuit which is why i still have a problem,

what also dont understand is that the grm/wht wire on the bank 2 and the grn wire on bank 1 have continuty to the same pin on the pcm connector, on top of that when i check continuity from grn/wht to grn wire Using the (beep function) i get no beep but i do get resistance reading of 1875 ohms

i know i am close but i am missing something on bank 1

here is the link to cop diagnostics

easyautodiagnostics.com/gm/4.8L-5.3L-6.0...test-the-cop-coils-2

Ok i read the test. Now the 12v on ground make sense. The only thing i would prefer is using an incandescent test light on ground (black wire) and feed wire. This will load the circuit and be a better test. Just be careful to not load the computer module. The high current could fry the pcm.

As for the hz test. What kind of meter do you have? Try it in a wall outlet if you feel comfortable doing so and you should get 60hz. Make sure the meter can go down to 5hz. Some meters don't have the range.

A wiring diagram would answer the question on the signal wire being shared. An ohm test to signal just measures the component resistance, and i don't think it's helpful.

I would expect each coil to have a dedicated signal wire? Unless it is some type of data cable. Doubt it.

Your are almost at the end!


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