P1656 & Clogged Cat

[DieselDavey]

Hello!

Does anyone know if the back pressure from a clogged cat would cause the P1656 Wastegate Solenoid control circut code?

My burb has 173,000 miles, and I suspect it has the original Cat Converter. I've always thought it was clogged due to difficulty towing, but can't get the damn thing loose to install a "test" pipe...

I did all of the tests (vacuum and boost pressures normal), even replaced the Solenoid and the sensor on top of the intake manifold.

During my testing, I did notice that the boost would sometime spike to over 12 PSI... the pressure would always drop back down quickly.

This code is intermittent, and only comes on after a long trip on the expressway (no load).

[tommac95]

Dave-
Just to note ....
I had muself convinced that my cat was clogged (at 175kMi) -- but when i cut it off , i found it was actually FINE. I welded on a new replacement element i'd found , but regretted the waste.

[DieselDavey]

Thanks Tom...

Appreciate the response!

Many others here have told me that probably have a clogged cat... I do have low power when towing...

Every test I could do myself on the wastegate solenoid and the Turbo check out just fine.

Thanks again,

Dave

[Robyn]

Wastegate solenoids are a delicate little device and do fail on a regular basis.
Be sure the vacuum pump is putting out 26"hg at the pump and that the lines are good all the awy to the solenoid and to the actuator.

If the vacuum reading at the pump is less that 26 and the gauge needle wobbles then the pump is bad.

If the pump and line scheck out then replace the solenoid and call it good.
Your issue should be resolved.

The solenoids are about $40 at the Ma general store.

Cats do plug over time but as has been mentioned "Not always"

If you are seeing the effects of a plugged cat then the boost would be very lazy in coming up and the power would be very poor as the engine could not breathe right.

The addition of a good 3-1/2 to 4" exhaust with a cat that is MIA is not a bad choice (if you dont have to do inspections) if you do then a good high flow cat is a great way to go.

The main issue is to keep the outflow as unrestricted as possible.

My dually has a 4 inch system on it minus cat and it flows very well.
With these mods the bottleneck then becomes the turbo wastegate housing with its right angle turn.

The Wastegate solenoid can be aan anoyance.
The addition of a turbo master a good power chip and an exhaust will really wake up the little 6.5. (Pyro and boost gauge are needed then as you are the controls and not the computer)

Best

Robyn

[DieselDavey]

Thanks Robyn,

I've performed all of those tests (you told me how last spring...), all checks out well (vacuum, boost pressures) and I've replaced the wastegate solenoid.

Power does suck even towing a small landscape trailer with 3 Quad runners on board...

I thought a clogged cat might be causing too much pressure from the turbo.... thus the code.

Re-thinking the problem, I guess a clogged cat would hinder the turbo from spinning up as it should... Maybe that would cause a code?

The code comes and goes as it pleases... I've noticed it shows up after a run on the expressway (with or without towing). I don't know how it resets itself.

Thanks anyhow!

Dave

[Warren96]

If the vacum gauge reading, that you hook to the vacum pump, shakes or vibrates when the truck is at idle, that is OK there is no need for lots of vacum at idle. It's when the engine gets to 600 or1000 RPM that you need a steady supply of vacum for boost or EGR. Don't ask me how I know this. By the way does anybody want to buy a new vacum pump?