NON-VVT L92, First Drive, Ran Hot

[7.5in.300BLK]

Ok, here's the latest. Excessive crankcase pressure seems to be a plaguing bane in my rear. I now have been able to use a ball valve to get the pcv into a 5 in mg vacuum. I need to find a permanent solution, probably an AER vacuum regulator. I feel like the overheating issue might be due to insufficient low rpm flow from my stock water pump (brand new ACDelco Mechanical Water Pump 19253263, Summit Part Number: ADO-252-901, thermostat: GATES 34198S). After another cooldown and oil change, I got my O-scope out and checked the injector and coil control circuits.

Injector 2(Dead):
https://drive.google.com/file/d/1dGz...ew?usp=sharing

Injector 6(Not Dead):
https://drive.google.com/file/d/1SRh...ew?usp=sharing


The coil was getting a signal, I just didn't take a picture of it because I was also trying to keep my crankcase pressure from popping my seals again. I think tomorrow I'll backprobe the ECM to see if the injector control signal is dropping off there. That should put all of that to rest.

Otherwise, here is latest log of the latest cold start: https://drive.google.com/file/d/16c2...ew?usp=sharing

[7.5in.300BLK]

I?m pretty sure that is correct.

I missed this, and I wondered if that might be the case. If it is, then what is actually what?

[7.5in.300BLK]

Did you do any wiring on the harness? Is it possible you got some injector control wires swapped? In any case, I'd still be looking for power at the injectors.

The only wiring modification I did was removing the phaser wires from the cmp harness and hooked the L92 cmp connector to the LS3 cmp sensor. Otherwise all the wiring is unchanged.

[7.5in.300BLK]

Ok, it's been a long day.

I hooked up the oscilloscope, took the back cover off the ECM x2 connector, and probed pins 17, 18, 19, 20, 37, 38, 39, and 40. Each had a clean injector signal on it. So I went back over and probed 2, 4, 6, and 8, all were getting the signal. I then unplugged all the right bank injectors and got no response from the engine. Then it hit temp and the bank 2 lean went away. I cleaned up the ground behind the power steering pump. I loosened and retorqued the exhaust manifolds. I took the fuel rail off and checked to see if the injectors were clicking. I did a leak down test on the entire engine, none had more than a 12 psi differential from 100 psi. I have solid compression in the whole engine. Bank one runs fine enough to tune, and I could start tuning after it warms up and stops running lean, but it just doesn't make any sense.

[edcmat-l1]

Ok, here's the latest. Excessive crankcase pressure seems to be a plaguing bane in my rear. I now have been able to use a ball valve to get the pcv into a 5 in mg vacuum. I need to find a permanent solution, probably an AER vacuum regulator. I feel like the overheating issue might be due to insufficient low rpm flow from my stock water pump (brand new ACDelco Mechanical Water Pump 19253263, Summit Part Number: ADO-252-901, thermostat: GATES 34198S). After another cooldown and oil change, I got my O-scope out and checked the injector and coil control circuits.

Ok, it's been a long day.

I hooked up the oscilloscope, took the back cover off the ECM x2 connector, and probed pins 17, 18, 19, 20, 37, 38, 39, and 40. Each had a clean injector signal on it. So I went back over and probed 2, 4, 6, and 8, all were getting the signal. I then unplugged all the right bank injectors and got no response from the engine. Then it hit temp and the bank 2 lean went away. I cleaned up the ground behind the power steering pump. I loosened and retorqued the exhaust manifolds. I took the fuel rail off and checked to see if the injectors were clicking. I did a leak down test on the entire engine, none had more than a 12 psi differential from 100 psi. I have solid compression in the whole engine. Bank one runs fine enough to tune, and I could start tuning after it warms up and stops running lean, but it just doesn't make any sense.

You have a mucked up motor sir. Put the o-scope down and do a compression and leak down test. I'm betting your dead cylinders really are dead.

[DanN]

Did you check for power on the pink? The injectors don't use an external ground - the ECU triggers them to fire with the ground. They should have constant 12 with the ign on.

[7.5in.300BLK]

Did you check for power on the pink? The injectors don't use an external ground - the ECU triggers them to fire with the ground. They should have constant 12 with the ign on.

14.6V on the pink. I checked them at the same time I was checking for signals.

[7.5in.300BLK]

You have a mucked up motor sir. Put the o-scope down and do a compression and leak down test. I'm betting your dead cylinders really are dead.

Hey edcmat,
I did a compression test before I even started checking anything else. I had 180 psi on all the cylinders. I also did a leak down test. I?|I post the results at the bottom of this. If you really think my engine is messed up, please let me know your thoughts on how you?ve come to this conclusion. The last thing I want to do is pull the motor again, tear it down to find nothing wrong.
Cylinder
Observed Pressure
Leakage % = (100 - psi)
1
91 psi
9%
2
88 psi
12%
3
92 psi
8%
4
92 psi
8%
5
90 psi
10%
6
91 psi
9%
7
90 psi
10%
8
89 psi
11%

[Dustindavisusmc]

Name is Dustin I have almost the exact same problems and the exact same issues... I have a L92 2008 Cadillac .. I changed out the vvt and phazer . Fresh motor you have my attention.

[edcmat-l1]

Hey edcmat,
If you really think my engine is messed up, please let me know your thoughts on how you?ve come to this conclusion.

You've said you have multiple cylinders that are dead until the engine has some heat in it and then they magically come to life. You also said you have a problem with excess crankcase pressure. The combination of those 2 things would lead anyone with ample experience with these engines to determine you have real engine issues.

When these engines are right, in healthy condition they do NOT have excess crankcase pressure. That alone is a sure sign something bad is wrong.

[7.5in.300BLK]

You've said you have multiple cylinders that are dead until the engine has some heat in it and then they magically come to life. You also said you have a problem with excess crankcase pressure. The combination of those 2 things would lead anyone with ample experience with these engines to determine you have real engine issues.

When these engines are right, in healthy condition they do NOT have excess crankcase pressure. That alone is a sure sign something bad is wrong.

I guess my next question would be what constitutes excessive back pressure. I?m quickly realizing that of everything I thought I knew, I actually know very little. If I put the oil fill cap upside down on the oil fill neck, it does not blow off. My idle vacuum is a constant 15 in mg with not flutter or fluctuation. I thought my issues with my crankcase pressure was a PCV issue. When I set the vacuum 5 in mg, which doesn?t take much there is nothing coming out of the dipstick tube or filler neck. So what is considered excessive and when is it considered bad?

[7.5in.300BLK]

Name is Dustin I have almost the exact same problems and the exact same issues... I have a L92 2008 Cadillac .. I changed out the vvt and phazer . Fresh motor you have my attention.

Ground wires behind the power steering pump are the grounds for both banks of ignition coils. There are 3 total, one is larger, and 2 are tied together. I'm not sure which goes to which. I just clipped all 3 and gave them new heat shrink terminals. Fires right up now, no misfire, no lean, no bottoming out o2 sensor.

[7.5in.300BLK]

You've said you have multiple cylinders that are dead until the engine has some heat in it and then they magically come to life. You also said you have a problem with excess crankcase pressure. The combination of those 2 things would lead anyone with ample experience with these engines to determine you have real engine issues.

When these engines are right, in healthy condition they do NOT have excess crankcase pressure. That alone is a sure sign something bad is wrong.

Hey edcmat,

Thank you for your help. I appreciate you taking the time and your insight on the issues. I'll keep an eye on the engine, but after replacing the terminals for the grounds behind the power steering pump, it seems to be running right for now.

[7.5in.300BLK]

Did you check for power on the pink? The injectors don't use an external ground - the ECU triggers them to fire with the ground. They should have constant 12 with the ign on.

Hey Dan,

You've been right here with me, and I greatly appreciate all the time you've put into this. I really did learn a lot from this little ordeal. I'm not sure exactly what the issue within the wiring was, but it had something to do with the ground terminals behind the power steering pump. Turned out to be a spark issue and one of those wires was the ground for the right bank. I clipped the old terminals off, cleaned up the wire, and replaced them with heat shrink terminals. Thank you, so much, for everything. You put some legitimate effort into my problem. You're the kind of guy that makes these forums a community for people to help and be helped.

[DanN]

Ground wires behind the power steering pump is the ground for both banks of ignition coils. There are 3 total, one is larger, 2 are tied together. I?m not sure which goes to which. I just clipped all 3 and gave them new heat shrink terminals. Fires right up now, no misfire, no lean, no bottoming out o2 sensor.

CONGRATS!

Bad ground strikes again. I'm pretty sure that bigger ground ls likely the one that goes to the PCM main ground; if that one is bad, all bets are off. The PCM doesn't supply 12V power to anything - only ground triggers to the coils, injectors, relays, etc. I should have picked up on that. GM factory ground splices are fu-u-ug-ly.

[DanN]

Hey Dan,

You've been right here with me, and I greatly appreciate all the time you've put into this. I really did learn a lot from this little ordeal. I'm not sure exactly what the issue within the wiring was, but it had something to do with the ground terminals behind the power steering pump. Turned out to be a spark issue and one of those wires was the ground for the right bank. I clipped the old terminals off, cleaned up the wire, and replaced them with heat shrink terminals. Thank you, so much, for everything. You put some legitimate effort into my problem. You're the kind of guy that makes these forums a community for people to help and be helped.

Hey man - I'm right there with you! I'm still pretty green tuning wise, but it's communities like this that make learning possible. I would be fully ~LOST~ without the guys here.

I do diagnostics and troubleshooting for living (by phone) for products we make for the RV industry; but not on this type of stuff. But the one thing I always try and keep in mind is to check the basics first. I couldn't tell you how many times I've fixed "problems" by suggesting the customer apply the park brake or turn the ignition on. HAHAHA

I'm glad you got it sorted, and I appreciate the shout-out!