Help!!! Cummins isx 500

Here is my .0002 on this,,,, vgt turbo variable geometery turbo, the vanes and actuator have to be timed if not it will run like a dog been there done that. Even new turbos will be wrong.

 

Hard to say for sure, but sounds like you have changed and tried everything else, the vgt is the only other thing i can think of. The only other option i can think of would be the ecm.

 

I second the ECM. Would be nice if u could get a loaner to try first though

 

On '07 emissions engines this is true. For an '06, there is not special timing procedure.

are there any fault codes? i imagine with all of this going on there has to be something. also, did they check the fuel pressure while under load when this problem occurs? the fuel gear pump might not be able to keep up....

do you notice any rough idle or does happen only under load or at take off?

 

I would absolutely have the fuel pressure tested while the truck is under load. I have had mechanics hook up a gauge before and sit in the cab while we take it for a rip. You need to know if the pressure is high enough, and if it is fluctuating or not.

Also, it very well could be the turbocharger. ISX turbo's are probably the worst for reliability I have ever seen. Most last about 300,000 miles, some make it more, some less, but the average seems to be about 300,000 miles. VG turbo's are an immense pain in the rear, and very costly.

Personally, if I owned the truck, I would get PDI to replace the stock exhaust manifold with there after-market one, and then they can put on a plain jain turbo with no VG.

Watch out for the head gasket. My dad's 2006 ISX started leaking oil at the rear, the common problem on these engines. After that he started losing turbo boost, would never go over 28 PSI, normal for him is about 38-40 PSI. Went on like that for a month, then one day a few weeks ago she just started smoking white like crazy and there was anti-freeze in the oil, she was cooked. It's in for a full in-frame now and the real kicker was, only 1 piston was burning coolant, the other 5 were in great shape. The truck had 1,150,000 KM on it (714,576 miles)

Needless to say, the ISX is a junk engine in my opinion. It eats way to much exhaust. Exhaust has microscopic pieces of carbon in it, which are like sand to an engine and precision parts. Would you body perform well if you ate your own excrement? Of course not.

Cummins parts have been getting worse and worse. They use cheap metal, and not enough of it. I am extremely unimpressed with there pistons and connecting rods, there good for paperweights on your dispatchers desk. It reminds me of how Dodge advertises there pickup trucks with a "FREE CUMMINS DIESEL, NO CHARGE UPGRADE TO DIESEL" That is hands down the worst engine in existence, there's a reason that piece of crap is free. It's in the right pickup though, Dodge is the worst out of the big 3 and it's been proven time and time again, cheap junk, just like Cummins.

The best thing you can do short of ripping it out for a single turbo Cat transplant, is remove the EGR valve, cooler, VG turbo, factory exhaust manifold and intake manifold. Replace all of these with after-market solutions, and that is as good as an ISX will ever get.

 

As I said, be very mindful of a head gasket failure.

Oil at the back of the head is exactly how my dad's problems started. After a while, started losing boost, and the head gasket let go. Now it's in for a $25,000 in-frame.

The problem with the ISX is to do a head gasket, your 75% of the way to an in-frame, so if your engine is already old, and you do a head gasket, there's a good chance something else will pop less then a year down the road, and now your paying all that labor twice instead of once.