Hi all, I've had a problem off & on with my wife's libby throwing an overboost code and it's back. The first time it was happening it ended up being the converter was plugged, they replaced it under warranty and they replaced the turbo at the same time. The next time it started happening the dealer replaced the turbo again, the solenoid & filter, and the computer. It was still acting up and I know it's not the converter this time and I've checked everything obvious that I can think of. Can anyone help with this annoyance please? Is it possible there is an exhaust restriction before the converter? My wife is annoyed with me & the libby over this, she thinks it's a result of the EHM or unplugging the fuel heater, or disconnecting the maf occasionally. Thanks in advance, Tigafila

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'05 CRD Limited: 174k mi Euro Torque Converter, EHM, ORM, Racor fuel filter, Original Rocker Arms, Amsoil everywhere
'98 Dodge Ram 2500 Cummins 24 valve extended cab short bed
'01 Jinma 4wd diesel tractor

Tried replacing the vacuum hose to the wastegate actuator?

If you have a boost gauge, is it actually overboosting? or the ECU thinks so?

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2003 2.8 CRD Cactus Green Renegade
ARB front bar, rear hitch receiver, IPF spotties, HID headlight, 2.25" coil lift, Rancho shocks, daystar rear bumpstop extender, 245/75/16 Maxxis Bighorns.

American KJs don't have a vacuum activated wastegate. We have a VNT turbo that varies the vanes to control boost. overboost code sounds to me like either a MAF or MAP sensor. It did the same thing to me on my TDI Jetta, and the turbo was just fine - its a sensor.

Too bad too, b/c two perfectly good turbos have been wasted.

Ed's idea is sound, but the vacuum line going to the turbo isn't for controlling the wastegate but instead for controlling the variable vanes. The same thing will happen if you unplug it, the vanes go soft and the turbo produces less or no boost.

Try it - you might like it (if you want to trade power for fuel economy)

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L.O.S.T forever!
Silver 2002 Skoda Fabia TDI, 235,000km
Former car: Jeep KJ 2003 CRD

DIESEL - saving millions of liters of petrol every day!

Thanks so much for the great replies. In the beginning I did check the vac hose but I will check it again when I get home (working out of town). Does anyone have a boost guage hooked up so when I hook one up I know what normal is? I have cleaned the map with air during all of this but never with a spray cleaner and not super recently. Is there a recommended spray cleaner? I will double check the map cleanliness also. Does anyone know the normal psi range for boost? Tia, Tigafila

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'05 CRD Limited: 174k mi Euro Torque Converter, EHM, ORM, Racor fuel filter, Original Rocker Arms, Amsoil everywhere
'98 Dodge Ram 2500 Cummins 24 valve extended cab short bed
'01 Jinma 4wd diesel tractor

Up to 23-26PSI at full throttle.

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L.O.S.T forever!
Silver 2002 Skoda Fabia TDI, 235,000km
Former car: Jeep KJ 2003 CRD

DIESEL - saving millions of liters of petrol every day!

Thanks Uffe, I will post results when I get back home. You guys have been very helpful, Tigafila

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'05 CRD Limited: 174k mi Euro Torque Converter, EHM, ORM, Racor fuel filter, Original Rocker Arms, Amsoil everywhere
'98 Dodge Ram 2500 Cummins 24 valve extended cab short bed
'01 Jinma 4wd diesel tractor

For boost on mine I see it spike at 25, but the maximum sustained boost it puts out is 20.

I also had an overboost problem, when it threw the CEL it would go into limp mode & wouldnt recover until you switched off the engine & restarted. Then the cycle starts again, took it to the dealer & they replaced the boost sensor, sa,e problem. Ultimately they replaced the turbo & I have never had the problem again. But they already replaced your turbo....

Just wanted to post a quick update. I cleaned the map and that did nothing, I believe they replaced it the last time when they threw 2 turbos, a computer, and anything else they could think of. I checked all vacuum lines for the turbo all ok but I didn't expect to find much because if I'm not mistaken a bad vacuum line would cause less boost not more. It will throw the code/go into limp mode with maf connected or disconnected. I could not get it to act up with my scan tool on it and after I took the scan tool off I couldn't get it to do it for a while.....strange. I can't find a tap for a boost guage hook up so I guess I'll have to make one to tap in after the intercooler unless there's an easy spot I'm missing. Any other ideas beside what I have checked? Thanks again for the help, Tigafila

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'05 CRD Limited: 174k mi Euro Torque Converter, EHM, ORM, Racor fuel filter, Original Rocker Arms, Amsoil everywhere
'98 Dodge Ram 2500 Cummins 24 valve extended cab short bed
'01 Jinma 4wd diesel tractor

I think the best spot is in the intake plenum after the intercooler hose. Remove the boost hose and stuff some cloth or paper towels in there to protect the inside of the intake when you drill and tap (remember to be able to get it OUT again!). This way you can catch the metal fragments and get them all out of the intake with no problem.

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L.O.S.T forever!
Silver 2002 Skoda Fabia TDI, 235,000km
Former car: Jeep KJ 2003 CRD

DIESEL - saving millions of liters of petrol every day!

Any chance the wiring harness is rubbing where it comes off the engine and goes behind the fuel filter assy? I recall some model years having a vulnerability there... Since we're groping for an explanation, I'm guessing a wiring problem could possibly fake out the ECM into thinking bad thoughts about the MAP?

FWIW!

Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

An exhaust restriction would cause under-boost not the other way around. Some VGTs such as those in the VW TDI have had problems with soot building up around the vanes causing them to stick at either high or low boost angles. The cure was found to be getting the motor hot and running at WOT once or twice with every tank of fuel. I don't know but at least its a starting point.

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Manure green 2005 CRD sport4x4, GDE Hot tune, Cat Gut, OE skids, Draw tight hitch, Duramax lift pump, 160K on multiple varieties of fuel, XM radio, Escort live with Redline, fog light mod, GPS, Icom IC7000 all band radio call sign KC9QPF, Grabber AT2s on Soft 8s, FIA grill blanket.

msilbernagel good thought I will double check it, thanks. Nursecosmo actually I found out the hard way when the first converter (particulate filter) plugged it will actually cause an overboost code. I think it's because the turbo starts making boost and up to a point it can flow, but then the boost overwhelms the restriction. I purchased some pvc fittings to tee in to the boost hose after the intercooler to get an accurate reading, now I just have to get my truck running so I can check the CRD out. Thanks again everyone, Tigafila

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'05 CRD Limited: 174k mi Euro Torque Converter, EHM, ORM, Racor fuel filter, Original Rocker Arms, Amsoil everywhere
'98 Dodge Ram 2500 Cummins 24 valve extended cab short bed
'01 Jinma 4wd diesel tractor

Tig, it is physicaly impossible to overboost if the exaust is restricted. Our Jeeps use a VGT type turbochager, if it is overboosting it is because of a controler or vane problem. Look here http://en.wikipedia.org/wiki/Variable_g ... rbocharger

If the dealer told you that you have a "particulate filter" they are just yanking your chain. The CRD doen not have a particulate filter, it just has a standard old oxydation catalyst, the so-called "dumb" cat. It's sole purpose is to burn off any hydrocarbons not used up in cumbustion. They are extreamly hard to plug unless you never let it warm up or dont drive it for more than a mile at a time, and even then you would have to really be making a lot of smoke out of the tailpipe.

It sounds like they really have no idea what is wrong with your Jeep and I would go to another if they have already replaced two turbos because of an imaginary cat problem.

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Manure green 2005 CRD sport4x4, GDE Hot tune, Cat Gut, OE skids, Draw tight hitch, Duramax lift pump, 160K on multiple varieties of fuel, XM radio, Escort live with Redline, fog light mod, GPS, Icom IC7000 all band radio call sign KC9QPF, Grabber AT2s on Soft 8s, FIA grill blanket.