2010 Impala 3.5L VIN K Cam Crank correlation wave form

Florin Technician Ontario Posted   Latest   Edited  
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Driveability
2010 Chevrolet Impala LT 3.5L (K LZE) 4-spd (4T65-E)
P0300 — Random/Multiple Cylinder Misfire Detected
Crank / No Start

Hello, friends, I have a head scratcher here with crank and no start symptom. Fuel pressure checks ok 55-60 PSI, good spark, Checked compression on front cylinders and is arround 200PSI, also performed relative compression with scope at battery and looks good. Scoped fuel pump and has good pattern. I scoped also Cam and Crank for potential incorrelation but couldn't find a good known pattern to compare with.

Customer states that before it wouldn't start anymore it was making some loud noises in the engine compartment and it was initially running rough.

The only DTC in the ECM was P0300.

I would appreciate if somebody could provide a good known cam crank pattern so I can see if we have a timing issue.

Thank you.

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Israel Technician
Florida
Israel
 

If you got good spark, good compression and good fuel pressure, the next step I would do is check for fuel contamination. Pull a sample and see if it eats through a styrofoam up and see if a small amount leaves an oily residue after burning (pour a small amount on the floor and use lighter to burn). I have seen people put diesel in these things. I have never seen a bad waveform not set a circuit…

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Florin Technician
Ontario
Florin
 

Thank you for the tips, by the way I just put about 15 liters of fresh gasoline since the tank was almost empty and that was the first taught. I will however check the tsb as per your advice.

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Ray Diagnostician
Ontario
Ray
 

Look thru your scan data pids for sensors that could be out of range, such as the ECT, etc. Israel Campillo has some good tips. The capture is 05-2013 Impala 3.5 cmp ckp from rotkee​.​com

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Florin Technician
Ontario
Florin
 

Thank you for your advice, I will try to pay closer attention to the pid's on the scan tool. However I found in Pico wave form library something that looks different than the one you show me and that one looks way different than mine which makes me think of jumped timing, corroborating also with customer statement of bad noises from engine compartment while engine was still running. There are no…

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Israel Technician
Florida
Israel
   

if you added fuel to a contaminated tank, you just contaminated that new fuel, unless there was very little left. Make sure you clean the spark plugs or put new ones. I have had contamination foul the plugs, and even after fresh fuel it would not start. Do a compression test. If timing is off, compression should be lower than normal. If compression is low across the board, I would go for timing.

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Florin Technician
Ontario
Florin
 

Hi, sorry but I forgot to mention that I tryed also to start eliminating the tank and the pump and adding fuel from a pressurized injection cleaner device with fresh fuel. Also spark plugs look very good not fouled or wet. I have to still check the compression on the rear cylinders, but according to relative compression they were almost same as the front ones. One thinh I noticed that I didn't…

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Ray Diagnostician
Ontario
Ray
 

This capture is a 2011 Impala 3.5 cmp ckp from the Pico waveform library.

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Thanks
Stephen Technician
Tennessee
Stephen
 

I think an in-cylinder pressure capture would be the fastest way to see if the timing is bad enough to cause a no start. An ignition sync is a good aid to in-cylinder captures.

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Florin Technician
Ontario
Florin
 

Thank you for the advice I will do that next step.

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Ray Diagnostician
Ontario
Ray
 

You can scope the secondary to see if the spark plugs are fouled, which could be caused by bad fuel. In this capture, the left spark plug spark voltage shows a fuel fouled spark plug.

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Florin Technician
Ontario
Florin
 

Thanks again for the advice, I performed the in cylinder compression test and found good compression at all cylinders, but the sync I didn't do with ignition since there are wires, but I picked the firing time of every injector and found out that injection event was always at the exhaust stroke and I think this is enough to blame a jumped timing or bad cam reluctor. I will shortly upload all the…

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Ray Diagnostician
Ontario
Ray
   

Ported injectors fire during the exhaust stroke. 08 Chrysler 3.5 CH A ckp CH B running compression CH C injector is firing on the closed intake valve and when the intake valve opens, the air/fuel mixture is drawn into the cylinder, during the intake stroke.

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Florin Technician
Ontario
Florin
 

Ok then I gues I missinterpreted this situation, i might have forgoten this part of theory, thank you for opening my eyes. I will try tomorrow to put a new set of spark plugs in and try again with the secondary ignition trigers. Thank you

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Stephen Technician
Tennessee
Stephen
 

I meant to use a pressure transducer in the plug hole to check valve timing. Is that what you did? It sounds like you did a relative compression test.

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Jordan Technician
Nevada
Jordan
 

Did you use an ignition sync channel on the relative compression test? A V6 engine can have low compression on one bank but due to the firing order it can look normal on relative compression.

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Florin Technician
Ontario
Florin
 

for the relative compresion test I used an injector trigger at cyl 1, but I also performed compresion test in each cylinder and compresion stays between 189 and 210 approx in all cylinders with not big difference between the banks.

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Ray Diagnostician
Ontario
Ray
 

You should use an ignition sync with the relative compression and the in cylinder compression to see how far the ignition is advanced or retarded with the compression strokes.

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Caleb Diagnostician
Indiana
Caleb
 

Great tip Jordan. This engine is cam in block though.

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Jordan Technician
Nevada
Jordan
 

Ahhh! Good point, I was assuming overhead cam.

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Randall Technician
Pennsylvania
Randall
 

Florin, I see no mention of injector activity? Pulse width, noid light, or verified clicking. Also if the plugs are not getting fuel fouled or at least “wet”, are the air intake and exhaust open? Back in the day I would try to start them on propane. Randy

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Timothy Owner/Technician
Wisconsin
Timothy
 

I believe you stated that you had tried an alternate fuel source? Have you tried ether? It should try on that, regardless of whether the fuel is contaminated. If it tries on ether, than you know it's fuel.

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Matthew Diagnostician
Kentucky
Matthew
 

You need to pull a spec on the compression second if that’s good then we can assume the valve time is good enough on the intake at least from a cranking standpoint exhaust can be pretty far out but engine should still start but run poorly, and if fuel supply is adequate and ignition is timed correctly It should theoretically start. is the coolant level low. maybe Get on the intake and verify…

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John Technician
Ontario
John
   

If timing checks out, be sure to inspect exhaust back pressure for any restriction. The p0300 may indicate it was running poorly and the catalyst is now damaged

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Enrique Diagnostician
California
Enrique
 

I would also suspect a plugged exhaust, 200 psi sound kind of on the high side. remove the upstream O2 sensor and check backpressure

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