bad performance

Hello,

Sounds like it could be a timing issue to me, I would check that first before doing any parts changes. Do you know how to check that?

This guide can help

https://www.2carpros.com/articles/engine-has-low-power-output

Tom

yes, it feels like kind of a timing issue, but I was under the impression that was all electronically controlled by the PCM and non adjustable. Also wouldn't that set a code?

Can there be a problem with the VVT without setting a code? It's VVT, no timing settings.

Hi,

Well not really, the ECU will pick up a problem generally. How did the shop or whoever verify that the catalytic converter had good flow through it. It sounds like a restriction if no lights on and developing no power. The VVT failing would have other issues present It sounds like a restriction somewhere.it could also be the fuel filter clogged up. How did the problem come on, overnight or slowly with time?
Tom

They drill a hole in front of each converter and connect a gauge to test pressure differential. This vehicle doesn't have an external fuel filter only the one on the fuel pump and that's fairly new. The problem existed with the old fuel pump and even after changing it. I bought the van with this condition and did a tune-up and fuel pump first and have been researching the problem since. It only had 157,000 miles when I bought it. I make deliveries with it and put the rest of the miles on, all highway.

Hello,

Very interesting. Which model do you have the 1500,2500,or 3500? When you have the van in park and you give it gas does it take a while to have the rpm's rise how responsive is it? Does it shoot right up or take time like when your driving? I'm trying to verify it's the motor and not the transmission or the brakes dragging. after a drive go out and feel your tire's rims to see if they are hot. Are there any engine noises, any ticks or anything like that?
Tom

It is a 3500. In park it has a slight hesitation on acceleration but not as bad as under a load. All the brakes are new as of last summer. I am certified in brakes. Engine seem fairly quite, no unusual noises.

Good morning,

Slight hesitation, so the rpm's do in fact go up slowly in park? I'm still not convinced we're not looking at the transmission in the wrong gear making it feel like the engine doesn't have power. If it is starting off from stop and not in first gear it would feel like it's the engine at fault. Try to put the shifter in 1 position and see if it takes off slowly. In first get the rpms to 2,500 rpm's then floor it and see if it takes off to 3,500 rpm's quicker or more normal. I've found some technical service bulletins on this condition of no power, one pertains to detergent gasoline and clocking injectors and another having to do with the catalytic converters and there is one dealing with the transmission that's seem to address what I think we are seeing. Give me a few minutes and I'll get them posted up for your review. I'd like to confirm there are no lights on the dash lit correct?
Tom

Hi Mbowtie,

There are a whole bunch of TSB's listed for this rig, to many to post but I've gone through them some do speak about no power. Is there anything else no right with any electrical things? Check all the fuses in the van just to be sure one bulletin is about shifting and it starting in the wrong gear a blown fuse is related so check them all. I'm attaching part of the one dealing with Tier One fuel detergent which I think is Shell maybe Mobil gas. At he end of this I'll put the one that is the Catalytic issue which says the ground wire for them can have a bad crimp so go through and test to see if they are grounded good, also when the shop tested them did thy check there electrical function that if fact they are sending a good data signal. There's also Calibration and relearning issues which seem a bit suspect relating to the transmission gearing. Has the rig had any servicing at all since this begun did the previous owner mention. Google these two TSB numbers and you can read them. There is mention of after market Calibration issues. Looks like the systems do need to be re-calibrated at times and needs to be done at the dealer (classic). It might not be a bad idea to call the local dealership about factory calibrations. When and why there are needed. You may get some insight too. If the CAN system and ECU aren't all on the same page our symptoms very well could arise from that and have no codes present or dash warning on.
Let me know if any of these things makes sense to you.
Tom
2carpros

GM TSB power loss
#18-NA-102 and # 07-06-04-019F
TSB
Models: 2016 and Prior GM Cars and Gasoline-Powered MST Light Duty and HD Trucks
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Technicians may encounter a concern where the catalytic converter has come apart or has set a P0420 and/or P0430.

Recommendation/Instructions
If you believe the catalytic converter has failed with no apparent reason, it is recommended to inspect for a poor crimp for the coil grounds terminal on the engine block for the bank with the concern.
Technicians should inspect the ground for possible corrosion or damage at ground terminal ring, fasteners and grounding surfaces.
If no corrosion or damage is found, tighten the ground bolt to the proper torque
Warranty Information
For wiring repairs covered under warranty, please refer to latest version of bulletin 10-00-89-005 for warranty information on wire/connector repairs.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

It has been a really long time since seeing a condition like what I suspecting on this, 1 the timing isn't correct and 2 the transmission isn't gearing correctly, but as for the first one on timing, way back in the day when all cars had timing chains we would get every once in a while a no power condition with high mileage cars the timing chains would stretch. When that would happened we would have no power and everything looked fine. This has a chain and I suppose it could be the case. A last resort check but I'm feeling like a timing issue n this but it's the computer doing it from either bad data going into the system or the system itself not calibrated or a module to module communication issue. The CAN system. Scanning that should also probably be done.
Tom

Do I have to go to a transmission shop for that ?

By the way; my 0 to 60 is 14.5.

Hi,
0 to 60 mph in 14 seconds is no racer, lol. What does the engine sound like, does it sound like its working hard or is it just a slow take off but the engine sounds normal. Its hard to explain but an engine pushing through a restriction or off the wrong gear has a different type of sound. Can you upload a video of a typical take off up to 60 mph? I want to hear the shift change if possible and know what rpm's its at during that the first gear shift up. For that test don't floor it all the way just most of the way. When the gas pedal is to the ground a switch gets triggered that overrides the normal operation. I want to know the rpm's and sound without that switch triggered.
Idk if a transmission shop is needed at this time but maybe, I would call AutoZone and see if there scanner will do a CAN scan and if not ask them who in your area will and go from there. I will do more research on this Calibration thing and get back to you in a little while. If you let me know what town your in I can probably get in contact with places near there to explain what we have going on so its not a square one thing with you trying to do that. It will probably save you time and money.

Here is how you can do a can scan

https://youtu.be/InIlnsjOVFA


Tom

The engine does kinda sound like it's laboring, but also it kinda surges up to speeds when floored. I'll try to get a video, I live in Toledo, OH. I appreciate your efforts and time you've invested in my problem, thank you.

Hello,

It's my pleasure to be helping out, here at 2CarPros this is what we are here for. Keeping people on the road safe and sound without going broke dealing with the dealerships or shops. Yes, that surge when floored is expected. Try this test, as mentioned before when the gas pedal is pressed to the floor the last bit hits a kick down switch that wont kick down unless it's all the way. So if you are getting on the highway or a place like that press the pedal almost to the floor but not quite, you should be hearing the engine labor going about 35 maybe 40 mph. With your symptom you wont be taking off all that fast, at that moment, press the pedal all the way. Then transmission should kick down to a lower gear the engine should rev super high and you should accelerate quickly. We're seeing if one, does it kick into a lower gear and two, do the rpm's shoot straight up to a high rpm? If it kicks down but the engine doesn't have a quick rpm rise our problem is in the engine. If it doesn't kick down and the engine labors with no quick rpm rise then its a transmission issue.
Let me know,
Tom

Seems like it is downshifting but maybe not enough. I have the tachometer on the odometer.

I can run it right up to the rev limit. But it takes awhile to get there.

Good Morning,

Thanks for the video.
Being a delivery van and going in and out of the rig all day, water getting in the car is probably common for you. On some vehicles, the IP to body harness connector, which carries the APP signal to the ECM/PCM, is located in the left hand kick panel area and if the kick panel is not sealed properly, water enters and causes a short in the APP circuits. Locate the IP to body harness connector, which should be located in and around the left hand kick panel area. Check to see if there is a water leak into the area.

I got the good headphone out and could hear pretty good. The second one did seem to show that the transmission is kicking down properly. How much cargo are you moving around with that, is is bulky and light or are your loads heavy?

Tom

That was taken empty. But my normal cargo is bulky and light.

It starts great, runs great and even gets good mileage 13.8, just has no ponies. GM 6.0 LS engine is supposedly 300 horsepower. This one can't get out of its own way.

Hmm, The mileage not being bad? it being a bigger heavy vehicle with a fair amount of wind resistance on it. Maybe its just the normal way those are. If there was a problem with restriction, function or something like that your mileage would be bad. I've never driven one to know whether they normally have good pickup or not. Something to consider also wold be the gear ratio in the rear end. If it has a rear end in there to get better mileage it wouldn't have any get up and go. Maybe we should look into that?
Tom

As I mentioned earlier, my wife has the identical van but hers shifts and gits when you step on it.

Okay,

We should try to see if the have different rear end ratios then just to see. How about the mileage she gets with hers? Yours not having horrible mileage makes me wonder because if there is a failure or something not right it would show up in a loss of mileage.

Yes my thoughts exactly, hense me doing this research.

If you count the bolts around the rear differential we can identify which one it is and its ratio.

Mine is 3:73 and hers is 3:42.

Well,

That would be part if it. The only other thing I could think of that would make the engine work harder (especially on take off).and sound wise it definitely does make feel like its struggling to go is if your radiator fan clutch is locked up. If you try to spin it it should have some resistance but move freely, its centrifugal so at idle it allows the motor to develop its power then as the rpm's increase it will start to engage. This gets the motor to hit its torque power level then it will put resistance on the motor.It's worth taking a look at that too.
Tom

Yes, I can hear it release when it reaches operating temperature in the mornings. Bet you never expected to be hit with a crazy challenge like this aye Tom? LOL

Lol.

Well, we have gone through a lot of possibilities. No light on, no codes , no noises is pretty blind for sure but soon as you mentioned the mileage isn't off and the second video showing that the rig is kicking down and the engine is gaining rpm's at a level that a van with wind resistance that's telling me most likely nothing has failed and it would be a performance setting. Which there still can be a calibration issue or computer input to tell the computer which gear it should be in. Now we know the rear ends are different maybe the PCM doesn't know that. If there was resistance or things of the sort the mileage would be horrible. I think the tact we should take is to see if the calibrations that can be done would be something that would let the PCM know which rear end is in it. Someone very well could have changed the rear end to get better mileage and not done what would be need to tell the PCM of the change. Make sense?
Tom

It used to be a church bus before I got it. I doubt they put that much thought into it. But yes it makes sense. About the differential; those are the numbers per RPO sticker on each van, not sure if that's what is actually in there.

A quick call to the dealer with the VIN should get us the info to see which rear end was in it from the factory and what the PCM thinks in in there.

I'm a Chevrolet man of the 1970's and 1980's so I'm not real familiar with these LS engines yet. With no distributor, how do you check for worn timing chains without disassembling the engine?

Hello,

Well that's a good question, in the old days you would be looking at the rotor for change here the cams so the valve cover comes of. The other symptoms of the chain and guides being bad would be noise and misfire. I don't think its the issue, I think you should take a good look at the timing chain cover and try to see any form-a-gasket or anything to lead us to believe it was taken apart or if the cover is still factory with the factory installation. Then let me know maybe we have to pay attention to the actuator.

But here, this is the system that matters for a timing issue the actuator maybe is suspect
Camshaft Position (CMP) Actuator System.

The camshaft (CMP) actuator system is an electro-hydraulic operated device used for a variety of engine performance and operational enhancements. These enhancements include lower emission output through exhaust gas dilution of the intake charge in the combustion chamber, a broader engine torque range, and improved fuel economy. The CMP actuator system accomplishes this by, changing the angle or timing of the camshaft, relative to the crankshaft position. The CMP actuator simply allows earlier or later intake and exhaust valve opening, during the four stroke engine cycle. The CMP actuator cannot vary the duration of valve opening, or the valve lift.
During engine "off", engine idling conditions, and engine shutdown, the camshaft actuator is held in the park position. Internal to the CMP actuator assembly is a return spring and a locking pin. During non-phasing modes of the camshaft, the return spring rotates the camshaft back to the park position, and the locking pin retains the CMP actuator sprocket to the camshaft. For the Gen IV small block engines, the park position for the CMP actuator and camshaft is, 8.5 degrees before top dead center (BTDC), which is equal to 17 crankshaft degrees BTDC, to the next cylinder in firing order. The engine control module (ECM) can only command the CMP actuator to retard the valve timing from the park position, or advance the valve timing back to the park position. The total range of valve timing authority is 31 degrees of camshaft rotation, which is equal to 62 degrees of crankshaft rotation. The control range is from the park position of 8.5 degrees camshaft, or 17 degrees of crankshaft BTDC, to 22.5 degrees camshaft, or 45 degrees crankshaft, after top dead center (ATDC).
CMP Actuator System Operation
The camshaft position (CMP) actuator system is controlled by the engine control module (ECM). The ECM sends a pulse width modulated, 12-volt signal to the CMP actuator solenoid to control the amount of pressurized engine oil, into the CMP actuator. A low reference circuit, or ground wire between the CMP actuator solenoid and the ECM completes the electrical circuit. The frequency of the pulse width modulated signal is fixed at 150 Hz. To regulate the pressurized engine oil into the CMP actuator, the solenoid uses electromagnetic force on the solenoid pintle to pulse the oil control spool valve. The pressurized engine oil is sent to unseat the locking pin, and to the vane and rotor assembly of the CMP actuator, to either retard or advance the valve timing. The ECM will control the amount of ON time applied to the solenoid, through the 12-volt signal from the ECM.
The ECM uses the following inputs before assuming control of the CMP actuator, and to calculate the optimum valve timing.

* Engine speed
* Manifold absolute pressure (MAP)
* Throttle position angle
* Camshaft position sensor (CMP)
* Crankshaft position sensor (CKP)
* Crankshaft/camshaft correlation
* Engine coolant temperature (ECT)
* Closed loop fuel control
* Engine oil pressure (EOP)
* Engine oil level
* CMP actuator solenoid circuit state

CMP Actuator Solenoid Circuit Diagnostics
The engine control module (ECM) monitors the control circuit of the camshaft position (CMP) actuator solenoid for electrical faults. The control module has the ability to determine if a control circuit is open, shorted high, or shorted low. If the control module detects a fault with the CMP actuator solenoid control circuit, DTC P0010 will set.
CMP Actuator System Performance Diagnostic
The engine control module (ECM) monitors the performance of the camshaft position (CMP) actuator system by monitoring the calibrated desired position, and the actual position of the camshaft, through the 4X signal of the CMP sensor. If the difference between the actual and desired position is greater than a calibrated angle, for more than a calibrated amount of time, DTC P0011 will set.

This truck isn't turbo is it? What about the size of the tire? Are they the stock size or the same as the comparison van

Here is why I ask about Turbo because it must be and we have been chasing our tails looking for everything besides the obvious. Is this your motor in the attachment below?

Let me know,

Tom

God no! I kinda wish it was a turbo, just a factory LS 6.0 best of my knowledge. Got OEM size tires. But the CMP actuator system you describe I haven't heard it called that before, I know it as VVT (variable valve timing) and that was one of my original questions. You originally felt that wasn't my issue.

I would try a new MAF sensor it sounds like the metering if off telling the computer the engine is not taking in air like it should. Also service the throttle bore as well. Here are two guides to help walk you through:

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

and

https://www.2carpros.com/articles/throttle-actuator-service

Please run down these guides and report back.

As mentioned earlier I am not getting any codes set or check engine light. It seems like both of those conditions would definitely trigger a code and an MIL

Good morning,

I curious about your combustion efficiency, with a good burn and everything working right you should be getting water drips out of your tail pipe. Take a look at that, let me know if you have a clean burn with water coming out of the pipe or if you have black carbon build up on the inside of the exhaust pipe. Also don't remember if you said whether or not the clutch fan is locked up or not. I think you just said you could hear it not that you went out and feel how much resistance it had not running. Ken does have something with the MAP. Does you scanner have live capabilities? If so we might be able to get some direction at watching that while driving.
Let me know.
Tom

Yes I get drops of water, and also some black carbon but not a lot. Yes, my fan clutch is working, and yes, I can read limited live data. I have a Blue Driver code reader. It's pretty good after market unit.
https://www.bluedriver.com/products/bluedriver-scan-tool

Okay, that's interesting to have both because the water is showing the engine is working good or has perfect combustion but having the carbon on there is saying that something is wrong with combustion and its loading up. It usually is one or the other. Are you having better or worse take off when its cold as opposed to it being warmed up? I wondering if there is something happening with the engine temperature changing the condition.of the burn. Can you send me a freeze frame of the live data for the oxygen sensors to see the catalytic function when your pushing the engine. We have to have a problem there in the catalytic's with all we have gone through and if the MAP is truly working fine, Ken does have a good point with that possibility, we have to have them partially clogged.
Tom

Well, there is no freeze frame data saved when there is no MIL and since it never sets any codes there is no data saved. I'll try to send live data image. The first one is at 60 mph and the second one is WOT.