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nwoods 05-02-2021 03:13 PM

Recommended Repair Procedure for P3497 (Cylinder Deactivation System - Bank 2) ?
1 Attachment(s)
2006 WK with the 5.7L, about 155,000 miles on chassis, but only 1,000 miles or maybe less on a fresh complete rebuild down to and including the pistons and bearings. I do NOT know if the MDS solenoids were replaced in the rebuild. The engine was rebuilt due to dropped valves, and it was performed by a shop prior to my purchase.

Driving home from Mojave yesterday, 3 hours or so on the road, and the CEL came on and at one point during stop and go traffic, it stalled on me. It started right back up and at no point did I feel any juddering, reduced power, misfire, or anything of the like.

I also sometimes have an airbag seat sensor warning light on my dash, and it was illuminated when the CEL came on. My OBDII reader can clear codes, but the P3497 code comes back immediately. The airbag light is off. I can access "advanced OEM mode" with my code reader, but I cannot access live data for some reason (works on other cars).

I spent several hours this morning reading through previous threads on this, and identified a number of potential issues, but they don't really seem to pertain to me. One suggestion was to add Risolone engine treatment, but I am very hesitant to do that on a fresh new build, especially on an engine that uses hydraulic valve lifters. I am reasonably confident 5W20 oil was used and the shop said they used Mobile 1 synthetic, so I don't suspect its an oil viscosity issue.

There is a potential that it could be O2 sensors, but I am not sure how to test this theory.

One thing I have noticed is that this engine idles irregularly. With the air on (which is constant here in SoCal), it surges on idle. It runs okay, but doesn't hold a steady RPM. Seems to rhythmically cycle between 500 rpm and 1,000 rpm or so. It doesn't do this all the time, but it does do it when its warm....which is a lot of the time.

I am not a mechanic, but thanks to the wonders of youtube, I have pulled out, rebuilt, and installed an engine before (on a Montero), and I have installed new (rebuilt) cylinder heads on my son's 4.7L V8 in his WJ. I have decent collection of tools, and can follow directions, I just have no diagnostic or practical knowledge to work with.


jtec 05-02-2021 03:34 PM

Set Condition:
O2 sensor readings on Bank 2 side indicate a lean condition while in 4 cylinder mode.

Possible Causes

nwoods 05-03-2021 10:02 AM

I reached out to the shop that rebuilt the motor. They confirmed the MDS solenoids are new.
Logically, I think the oil weight is okay, I think the MDS solenoids are okay, I think the oil passages are okay (less that 1,000 miles on rebuild).... I do have lifter noise when I first start the engine, it very quickly goes away once oil circulates (within a few seconds).

I think the surging or lunging in the idle speed is very directly related to whatever is going on with this error code. Could it be a bad O2 sensor? Or, if the O2 sensor is reading properly, what else would throw the mixture off? I pulled off the air plenum yesterday and noted that the back side of the butterfly valve in the throttle body had a lot of carbon build up on it. I sprayed throttle body cleaner liberally in there and tried wiping it out with a rag, but I think I will need to remove the throttle body to get to the interior side of it. I assume there is a sensor there, similar to a MAF sensor? Could that be the problem? Its not throwing a code for it......

Argh! I hate it when things are diagnostically indistinct!

Really stumped as to what to do next.

SKALA308 05-03-2021 11:08 AM

Frustration problem. There is no sensor behind the throttle body, other than the MAP sensor at the back of the inlet manifold. An ageing/faulty MAP sensor will cause problems, unfortunately as will most of the other host of sensors.

nwoods 05-04-2021 03:10 PM

Bump....really looking for help here on this one. Not sure where/how to troubleshoot this. Where do I start?

Rick_H 05-05-2021 12:26 AM

Not that it's your main concern right now, but one of the most common causes of airbag lights coming and going are the connectors underneath the front seats. Try re-seating them.

It wouldn't be a Hemi if the throttle body wasn't filthy. It often manifests on mine with a hunting idle, or it stalls when getting off the gas. I guess the throttle gets so gunked up the PCM can't settle on what it thinks is a rational position for the throttle that still allows it to idle. I usually disconnect the battery and remove the throttle body to thoroughly clean the bore and back of the throttle plate with a cloth dampened with a solvent of some sort at least once a year. It usually helps idle quality immensely. There's a warning in my service info to never spray throttle cleaner directly into the throttle body, which is why I remove it and clean it manually with dampened cloths. I suppose it could run back into the gears that drive the plate and dissolve grease in there. I think some people do it anyway, I guess it works for them. I'd probably need a new throttle body if I tried it. I doubt that the throttle/idle issue has anything to do with your code, it's a problem many of us have and don't get an MDS code.

When you say the problem comes back immediately after you clear it, I assume you mean it comes back as soon as you drive it and meet the criteria for the engine to go into cylinder deactivation mode, and not as soon as you start the truck, right? Because if it comes back before actually going into 4 cylinder mode, that would be real strange.

If the problem was the O2 sensor, I think you'd have seen other codes before this one, which is kind of an unusual one. The fact it's only seeing lean conditions in MDS mode makes it seem as though it sees no A/F problem during normal operation, eliminating a defective O2 sensor as the issue.

The code description jtec posted listed several possible causes. From the code description, it looks like the PCM is detecting signs that the valves on the deactivated cylinders aren't staying fully shut, allowing air to flow through those cylinders, meaning the MDS lifters either aren't collapsing at all, or aren't fully collapsing when the MDS solenoids are activated. The PCM has disabled the injectors, so it's just pumping air into the exhaust stream, causing the O2 sensor to read a ton of unburned oxygen. You said the MDS solenoids are new, and presumably so are all the lifters with the rebuild. But the other two possibilities of low oil pressure or a restricted oil passage are cause for concern on an engine that was just rebuilt due to a rapid unscheduled disassembly of the valve train (and pistons, apparently).

If you have any warranty on the vehicle and/or rebuilt engine, I'd get the company behind that warranty involved immediately, before you run out of miles or do something they can claim absolves them of any liability. The engine may have to come apart to find/figure this one out. If you don't have any warranty, I'd probably take it to a good shop that still does actual engine work if it were me, because this sounds like the kind of problem that firing the parts cannon at could get very expensive, and still never find the real issue. Maybe it could be a defective MDS solenoid that appears to the PCM to be working properly, but in fact isn't fully opening. You could swap the Bank 2 and Bank 1 sensors and see if the problem moves, but they aren't exactly easy to get to. I do recall reading or hearing that when when something goes kaboom inside a hemi, metal usually manages to find its way into the screens on the MDS solenoids. Which means metal likely wound up in those passages when the engine blew. Did they get it all out when they rebuilt the engine?

jtec 05-05-2021 08:04 AM

were there ANY other codes?

As we sort thru the ideas, add a bottle of RISOLONE a oil detergent to engine oil.
Code reappears as soon as cleared, with engine OFF key on........ OR engine running?
Can you see live data with the scanner?

Appearing with KOEO would have me thinking wiring to MDS, meanwhile I will ck TSB's and notes- time permitting.

nwoods 05-05-2021 10:29 AM

Thanks guys, with regards to the codes, no not really. There are only two codes, both P3497 (1 of 2) and (2 of 2).... There are 4 MDS solenoids, two on each side of the block....Perhaps both for Bank 2 are bad?

When the codes come back immediately, what I mean is that to clear the codes I have to turn the engine off with the key in the accessory on position, with the OBDII reader plugged in. Then I clear the codes, turn the ignition key all the way off, and if I cycle the ignition back to On, one click before engaging the starter, the engine goes through its checks and the CEL comes on and stays on when I go ahead and turn the key the rest of the way to start the engine. The CEL stays steady on as the engine is running. Cold engine or hot. Doesn't seem to make a difference.

I have noticed that the engine is now somewhat reluctant to start. I've only had this truck for a few weeks, but it initially started right up, now since the CEL came on, I have to keep the key turned for a few cycles before it will start, and the idle is irregular.

I will remove the throttle body today and give it a much more thorough cleaning, and see what happens.

With regards to Rislone, there are half a dozen different additives that they make, but one thing is certain, the MDS system is very sensitive to oil viscosity. None of Rislone's documentation provides viscosity information. I would image some of their products thicken it (such as their High Performance Engine Treatment), and others may thin it out (Hyper lube zinc with ZDDP), but its impossible to tell from their product data which is which. Also, the senior contributor to Bob the Oil Guy's forum is a chap named MolaKule, and he tested Rislone and had this to say:

My engine is essentially new, it doesn't need anti-wear additives to solve this issue, it shouldn't have any sludge build up at this point that would cause any issues.

My gut tells me that this issue is an electronic, sensor based problem.

EDIT: I did recently remove both seats to clean the car. I will double check the connectors

jtec 05-05-2021 10:49 AM

please post the code numbers.

The info in trouble tree suggests an OIL issue, pressure, viscosity, cleanliness the RISOLONE is an old stand by of mine, a detergent that can be left IN no need to change oil after X miles with it. YES the engine was rebuilt as far as thoroughly cleaning the engine IDK - cant hurt as we look into this.... right now I think its a come back to the engine rebuild shop.

The MDS and VCT are an achilleas heal - an unneeded overly complicated rube goldberg - just because you can do something is no reason to do it.. KISS.

I will check the possibility of TSB's and class notes BUT not looking as a DIYer.

nwoods 05-05-2021 11:04 AM

2 Attachment(s)
What is VCT? Which Rislone product?

Here are the codes:

nwoods 05-05-2021 11:15 AM

Also, you asked about live codes. My code reader has this capability (I can do this on my other vehicles), but for some reason this does NOT work on the Jeep WK.

jtec 05-05-2021 11:26 AM

1 Attachment(s)
VCT variable cam timing same POS using oil pressure and solenoids to change cam timing


SKALA308 05-05-2021 02:06 PM

Just some info. Only from 2009/10 did the WK come with VVT or VCT as jtec called it.
I would say could be the lifters for cylinders 4 and 6 (bank 2) are not functioning correctly either due to a lifter fault, oil pressure or a faulty MDS solenoid. No easy fix, will have to strip down to some extent.

Rick_H 05-05-2021 05:19 PM


Originally Posted by nwoods (Post 41264815)
When the codes come back immediately, what I mean is that to clear the codes I have to turn the engine off with the key in the accessory on position, with the OBDII reader plugged in. Then I clear the codes, turn the ignition key all the way off, and if I cycle the ignition back to On, one click before engaging the starter, the engine goes through its checks and the CEL comes on and stays on when I go ahead and turn the key the rest of the way to start the engine. The CEL stays steady on as the engine is running. Cold engine or hot. Doesn't seem to make a difference.

This monitor should only run when the engine is transitioning from 8 to 4 cyl mode. Meaning the code should only ever set when the engine activates MDS, which requires you to be cruising in a higher gear at a steady speed. It should never set KOEO or immediately after startup, or even just puttering around at lower speeds. The fact that you're seeing it before ever meeting the conditions for MDS engagement makes me wonder if your scanner is really ever getting the code cleared in the first place.

Try clearing the code again, then cycle the key off, then turn it back on (without starting the engine) and run a new scan for codes. It should have no codes stored. If you can't get this code to clear so that you can run a scan with no codes present before starting the engine, you're going to have to source a scanner that can actually get the codes cleared before proceeding. There is no way this code should set before even starting the engine, I suspect your scanner isn't really clearing it. If this code really is setting with the engine off, then you're going to need more help than you can get on a forum, because you've got something really bizarre going on.

It is possible that it's just a clogged screen on one or both bank two MDS solenoids, but you need to figure out what's going on with the codes before deciding to R&R the intake to mess with the solenoids. And I still recommend getting the engine rebuilder involved before doing that if there's any sort of warranty at all, because I suspect this is going to come down to an issue with the rebuild - even if that's just some missed debris clogging a solenoid.

And for my money, if it were my Jeep, I wouldn't be putting anything in the oil at this point. There's a chance this is going to come back on the rebuilder, and putting an additive in the oil on a fresh rebuild is just inviting them to blame the problem on you.

jtec 05-05-2021 06:02 PM

sorry for late reply, I found NO TSB's or foot notes for the code you aee dealing with.

Rick_H's post above mirrored my concern about the resetting of the code KOEO - the set condition blah blah the o2 sensors see a lean condition see post 2 above........ had me thinking HOW with KEY on engine off could it meet conditions... IIRC There was no mode 10 in 2006,

some thiughts.
use a different scanner to clear codes. checp easy
trouble shoot the #4 MDS solenoid for a short to voltage or ground PCM to solenoid

BUT I do not think a esy trouble shoot, do you have full trouble tree for the code? .

sorry GTG

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