Hi everyone. My 99 7.3 has the edge evolution programmer on it. For over a year now I have done everything I can think of to figure out why it doesn't run like it did when I bought it. On race mode I cant even go up the summit empty without hitting 1200+ EGT and only 10-12 psi boost. This used to be maybe 1000 EGT and 18-20 psi boost. I have no leaks in my intake/intercooler system, no leaky uppipes, pretty much brand new turbo (has done this since the turbo was brand new), intercooler was recently taken to the radiator shop to get cleaned and made sure no leaks and proper flow, also brand new fuel pump and the HPOP was recently rebuilt. Any suggestions would be great!! Thanks in advance!

 

Well lets start ruling stuff out. High egts is basically just an improper mixture of air and fuel. Is it a re-manufactured/new stock turbo, or an aftermarket? If so did u re tune for this? Whats the current condition of your injectors? How many miles on the truck? Have you checked the Air intake temp sensor? Are you running any codes? What are you running for exhaust?

 

Stock reman turbo. Did not retune anything did the same thing before and after the turbo replacement, new turbo made it slightly better like a couple psi of boost. Injectors i put new o-rings not to long ago but as far as I know they're all firing properly, not running like it has a misfire or anything. No codes air intake sensor has just been hanging in the engine compartment since I got it. K&N intake 4 inch exhaust all the way out and about 280,000 miles.

 

Id replace the AIT sensor just to be sure, theyre pretty cheap. Also when did u first start noticing this? Was it right after the new turbo was put in? Does it feel like it has less power?

 

It does feel less powerful. Especially when pulling something and the EGTs want to light the engine compartment on fire. I noticed this after I replaced the transmission and the PCM. It sat for months while I fixed everything and the finally got it driving again and then it seemed like it had no power compared to what it was before.

 

Someone more informed then me might be able to diagnose it on the pcm end, might be an incompatible pcm, but thats just a thought. I would very thurougly go through the intake tubes and filter and make sure varmints etc didnt leave anything in them while it was sitting. Other then that it may also be an issue with the wastegate not building pressure correctly.

 

PCM should be okay got the same code PCM. Intake tubes are clear and the wastegate came with the turbo. May have to try that AIT sensor. Only like 10 bucks might as well.

 

Yeah Id give it a shot. I was trying to rule out, cheap easy things that could fix it. Hopefully someone else will chime in with more suggestions. Are you pushing out alot more smoke then before?

 

Whoa... you may want to slow down with the wrench and spend more time with the eyeballs.

PCM, "brand new" reman turbo, O-rings, programmer, fuel pump, HPOP, intercooler cleaning... and an AIT on top? I'd hold off on that AIT sensor in regards to solving low boost.

Fact 1: You don't "tune" the turbo. You tune the fueling, and the turbo simply reacts to the exhaust backprssure. Low fuel = slow turbo. High fuel = fast turbo. Exhaust leak = no turbo.

Is that a K&N element in a stock air box, or a K&N air box and element?

Am I to understand the problem has existed since the remanned turbo was installed, but the previous turbo performed better? Or am I seeing you say the turbo replacement bumped the boost a couple of PSI? Tunes/programs confuse the matter, there's no way to tell what to expect. Stock tune is the troubleshooting tune of choice, because many of us know what to expect from that - plus it's pretty fail-safe.

With 12 PSI boost, here are your usual suspects, working backwards:

• Stuck Exhaust Back Pressure Valve
• Leaking exhaust components between the turbo exhaust housing and the engine block - including the manifold interface with the engine.
• Intake leaks, including the intake plenums on the engine.
• Wastegate opening prematurely, capping the red line sometimes helps.
• Clogged intake filter.
• The turbocharger is In the center of all that.

What tests are you conducting to verify absence of a boost leak? No soot anywhere under the hood (not just the up pipes)?

 

I'm an absolute newbie here (see the name) but just rebuilt and replaced the turbo, uppipes, and a few other parts. Hammering it on the interstate, I was seeing 11 psi despite all the fixes. No signs of leaks anywhere, and I felt fairly confident in the work. Until I taped a piece of TP on a stick and stuck it in the back of the engine compartment by the baby's butt at the turbo outlet. I'd managed to tighten the ring clamp up around both but it didn't seat properly. Soooo, if your toilet paper test (cost me two sheets) comes out looking like a flag in a storm, you may have the exact same problem as I do. Oh yeah, and deadhead, I was hitting 1150* getting on the highway.


If you find that is the problem, it took me less than two hours to resolve. It wasn't easy, but after the uppipes were unbolted at the manifold and the clamp was loose on the turbo, things slipped into place. If you've got a skinny teenager nearby, it may help out. Again, I'm the new guy...but high EGTs and no visible leaks elsewhere with 11-12 psi, yeah, that's familiar.

 

Pumps out some black smoke but not like it used to.

I haven't just thrown parts at it yet. Everything that has been replaced needed it. Except for the HPOP rebuild maybe but I wanted to freshen it up with the miles and the issues. When in stock I get the same results but worse. The K&N is not in any box hasn't been since before I bought the truck. Preformed worse with the old turbo. I have no EBPV. Exhaust doesn't leak, can't find soot anywhere. The intake has no leaks, pressurized it to about 15 psi with the air compressor sprayed every boot there was with soapy water no bubbles. I've ran it with the red line off made no difference. Filter can be off and go around the block runs the same. Clean it several times still same thing.

 

I may have to try the TP trick. Can't find any soot and can't feel any gaps or anything out of place but you never know.

 

X2 with Randomnewguy and Tugly's bullet point #2. Getting the dowel pin aligned in the baby's butt is a classic problem, first thought I had when you said high EGT/low boost/new turbo. It can bolt up and seem ok, but with those symptoms it's the first thing to check. Did you re-use the OE uppipe donuts?

 

New uppipe donuts. I'll triple check that connection tonight

 

My intake leak had nothing to do with the CAC boots or the IC - it was the plenum seal that gave way. I hope it's that alignment pin - the fix is free.

Since you are eliminating most of the possibilities I've given, there is one on the list you're not gunna like - the turbo.