Jeep going into LIMP Mode

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

Hi Everyone,
Need some help please. My Jeep is going into limp mode after driving about 3 to 5 km (this may vary). It resets itself after shutdown and starting it. If I unplug MAF sensor, Jeep has almost all its power back and its not doing it anymore.

I checked turbo hoses to and from and tighten all the hose clamps. Cleaned MAP sensor. Cleaned EGR Valve.

Decided to buy myself a OBDII scanner, scanned it, came back with MAF sensor faulty.Replaced it, and the Jeep still doing more or less the same thing. Somtimes its just doing in in a shorter time period. Now when I scan it, its showing Turbo/super charger Underboost (P0299).

Took it to the guy that service the Jeep, he did a thorough scan with decent scan equipment, check hoses again, came back with faulty Turbo boost solenoid (think its the one attached to the turbo). Going to take it to someone else for a second opinion.

Any suggestions are welcome.

Thank you in advance

greiswig · **Posted:** Tue Aug 26, 2014 11:57 am

When you say after replacing the MAF it is "doing more or less the same thing," do you mean it is still throwing the MAF sensor bad code? Or it just lacks power?

The P0299 code on my own CRD was an indicator. And if I really put my foot into it, I could get a P0234 code (overboost) which may have caused or hastened my head gasket failure. My guess would be that it isn't the actuator on the turbo that is at fault, but that the variable vanes in your turbocharger are stuck. Mine were completely seized, and yet I could still see movement at the actuator arm when I tested it. The movement was about 1/4", but once I took the turbo apart and fixed the stuck parts, movement was 12-13mm. It is relatively easy to test that and see, but that 1/4" of movement had me fooled: it was just slop in the mechanicals, I think.

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

After replacing the MAF sensor, it just give the P0299 code (underboost). How difficult is it to remove the turbo and clean the vanes.
Will I be able to do it myself?

Thank you

greiswig · **Posted:** Wed Aug 27, 2014 11:24 am

JeeperSA wrote:

After replacing the MAF sensor, it just give the P0299 code (underboost). How difficult is it to remove the turbo and clean the vanes.
Will I be able to do it myself?

Thank you

Well, that depends entirely on you, so I can't really say. Just getting the thing off the manifold is not trivial, and then you have to take the exhaust side apart, assuming stuck vanes are the problem. There are small pieces (especially the little bearings that the actuator plate rides on) that are easy to lose and not magnetic so the also aren't easy to find. Don't ask me how I know this.

If you're a fairly experienced Shade Tree Howler Monkey, then you should be able to do it. The other question that I had was how long the repair might last; depending on your pain threshold, it might be worth it to get a new one. I went the cheap route, but I tried to force graphite into every bearing surface on the variable vanes as best I could, to try to keep it from happening again.

Underboost is a drag as far as performance, passing smog, and mileage. Overboost is much more dangerous to the engine. And trying the "Italian tuneup" listed here as a good way to free up the vanes if you are getting a P0234 is just asking for it unless you've got known good head bolts and torques. (That's more for other readers than for you)

You mentioned that a shop had said the actuator was bad? Hey, it's possible, and that's relatively easy to fix. Does it hold vacuum? If the diaphragm holds vacuum and there isn't something stuck in the mechanism, then it's probably the vanes that are seized. But if it doesn't hold vacuum, the actuator is at least partly at fault. Trouble is, if the actuator has been faulty for awhile, I bet the vanes get an even better chance to get stuck where they sit because they aren't being moved regularly.

HTH,

WWDiesel · **Posted:** Wed Aug 27, 2014 11:10 pm

A suggestion; get yourself a hand vacuum pump kit like a Mityvac http://www.mityvac.com/ and connect it to the turbo vane actuator at the turbo (with the engine shut OFF of course) and spray all the linkages with some good JB or similar penetrating oil and watch all the parts movement as the vacuum comes up. Then unhook the vacuum line, connect it back up and pump it up again and continue this on and off cycle until all parts move freely full travel on each pump up and dump of vacuum.
Done this on mine and it worked great freeing up the vanes... :wink:

Good luck! :SOMBRERO:

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

Thank you, WWDiesel and Greiswig. Im definitely not experienced, just like to fix things myself (or at least try to...)
Ill definitely try this, first the actuator and then the turbo... Ill report back when Im finished!

Thanx again!

papaindigo · **Posted:** Thu Aug 28, 2014 11:00 am

Also try the boost pressure solenid bypass, see CRD tech post, and check for any issues with the vacuum line from the vacuum tower on around behind the engine under the coolant tank

greiswig · **Posted:** Thu Aug 28, 2014 12:37 pm

If you end up needing a hand with the turbocharger part of it, PM me here with a phone # and I'll try to get back to you ASAP.

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

Thank you Papaindigo. Will do, Greiswig, thanks again.

greiswig · **Posted:** Fri Aug 29, 2014 11:40 am

Thumbs up on what other people were suggesting above: do the simple things first, like checking vacuum lines. I jumped ahead to the vanes being the issue because of my recent experience, but you may be lucky.

In that same vein, tell us how you checked your boost hoses? I think the only real way to do it is to block off the inlet and outlet and pressure check the hoses along with the intercooler. There is a thread here showing how to do that with common PVC plumbing parts.

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

I removed the link between the electronic actuator and the turbo, it moved freely and got between 20 to 30mm movement. Decided to loosen the hot side of turbo anyway, and spray some Mr Mussle oven cleaner into it. Moved the link every now and then and closed everything up after 2 hours. No difference, so maybe I have to start from scratch again, with the hoses... or I have to replace the electronic boost actuator, bad thing is, have to replace the turbo, cause it comes as 1 unit!

Greiswig, I removed the hoses, inspected them put them back and did a soap test. So maybe the next step is to do the pressure test.

greiswig · **Posted:** Tue Sep 02, 2014 10:05 am

Yes, I would pressure test the hoses and intercooler as a system, at about 10psi to start.

Good luck with the oven cleaner. It has a lot to go through to reach the vanes if they are binding in their individual holes. Didn't work for me, at least.

20-30mm is a lot more than my actuator moves. The range that you give tells me you might be estimating? Mine moves just under 12mm as measured with the turbo off the vehicle and using a MityVac.

gmctd · **Posted:** Tue Sep 02, 2014 11:54 am

If you are seeing ~1" actuator link movement, possibility the internal linkage is broken - you should feel some resistance while moving the link because it is rotating a ring which pivots the vanes - it should not move "freely" - wide open position of the vanes would result in no-to-little power - this, of course, based on your interpretation of ease of movement.........................

greiswig · **Posted:** Tue Sep 02, 2014 1:28 pm

Just re-ran this experiment yesterday for someone else: without the vacuum actuator attached, the little arm moves very freely on mine...easily moved with a single finger, but it feels a little gritty. Just like you would expect.

With the vacuum actuator attached, it takes a pretty hard pinch between the bottom of the actuator arm and the top of the vacuum chamber to get it to move much on mine. The diaphragm on that actuator must be pretty stiff.

gmctd · **Posted:** Tue Sep 02, 2014 4:01 pm

Also, since it seemingly resets after power-down, could be:
- dirty Boost Solenoid Filter, just down and behind the air filter housing - looks like a plastic in-line fuel filter for lawnmower, easily replaced
- heat-deteriorated vacuum hose, vacuum reservoir to Boost Pressure Solenoid, or BPS to vacuum actuated servo
- broken return-spring in the vacuum actuated servo, allowing diaphragm freedom of movement
- ruptured diaphragm

Again, ~1" travel is too much

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

Hi guys, thinking about it now, there was absolutely no resistance in the movement of the small arm. Not even a gritty feel! So ja, guys, internal linkage might be possible... any suggestions on how I can determine if it is and if there is any repairs I can try?

Gmctd, the other options you have given we can rule out. The Jeep got a electronic boost actuator and I cant find any kind of filter.

George, yes it seems anyway I have to take off the turbo to make sure of the internal link...so then I have to clean the vanes thoroughly. Thats if its possible to fix the link...

gmctd · **Posted:** Thu Sep 04, 2014 10:25 am

Ok, my bad - you should ignore my input, figgerin' from the 05-06 pulse-width-modulated vacuum-servo'ed systems - I know how the later stepper-motor type systems function, but have never seen one, so even the limit-to-limit linkage-travel figure is bogus....................

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

Gmctd, no probs, thanks for the info. Im not sure about the linkage travel. With the MAF sensor unplugged, there is still a little bit of boost at 2500 rpm. So I assume the link have to be in place?
Im anyway going to take of the circlip again today, just to make sure theres really no resistance. At 150 000 km, I assume again, there have to be some resistance caused by carbon build-up...

greiswig · **Posted:** Fri Sep 05, 2014 10:26 am

Boost being there doesn't mean the linkage is working. My vanes were totally frozen in one position, so boost was perfect for midrange. But it's like the broken analog clock that is exactly right twice a day.

If you have disconnected the actuator from the arm and the arm just flops around freely and can spin a full circle, it sounds like it is broken. If you accidentally tried to force it to work and a number of the vanes were stuck in place, I could see where that might be the weak link that breaks.

JeeperSA · **Joined:** Thu Jul 17, 2014 3:38 am **Posts:** 22

Ive checked the linkage again, and it seems fine. The gritty feel is there and I can actually hear the ring move inside. The travel is about between 10 to 15 mm. So maybe it is the Electronic actuator...I think the best will be to take it to another shop, see what they come up with and if the same, then I have to buy a turbo/actuator...

Thank you guys, Ill report back...

Jeep going into LIMP Mode

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