Lack of power in '03 w/HE351, smarty jr,

[CToney]

In late August I was driving my '03 and pulled out to pass and my boost would only hit 26-27 psi. Usually my truck would do 35psi+, (35psi gauge should have 40psi gauge). I thought my small vice grips fell off of my wastegate line as that is what boost pressure would do prior to vice grips being added. I was too busy to investigate things further thinking it was an easy fix I wasn't too worried. The vice grips are in place. To eliminate the chance they were letting air thru I plugged the hole from the boost elbow. The next thing I investigated was a possible boost leak, I found a small one at the intake horn. I fixed the leak but the same problem. Only 27 psi and 1050-1100 F on the pyro. Thinking I was maybe lacking fuel I changed the fuel filters on my FASS. Still no improvement. Today I loaded the performance program on my smarty Jr and boost was the same but pyro would hit 1200 F. I had more power but my boost gauge would not go above 28. My SOP dyno is telling me things aren't right. I shouldn't have a boost leak as my egt doesn't get too hot. I'm thinking my turbo isn't giving me enough air and thus the Jr isn't giving me the fuel to get me to ~37 psi and 1200F.

Can the wastegate break?
What could be causing my low boost and thus low fueling?

I'm thinking I'm going to inspect the turbo a bit more. It really stinks not to have the power I was accustomed to.

 

[Hammer]

You changed the filters on your FASS,do you monitor the pressure?.
You say you checked the turbo wastegate,but did you pull the intake tube and check to make sure you do not have a issue with the charger?
Is the air cleaner new or how long has it been in the truck?
How many miles on the injectors since they were out and last checked?
I will ask this also as I know someone who did this inadvertently,did you make any adjustment to the POD on your Jr?.

Low boost and fueling can be created by many things,its best to start with the easiest stuff and work up.Since you already checked your method of blocking off the gate,I would check the charger for play next and try and make sure you have the gate completely closed if your blocking it.Next I would look for fuel leaks or places air could slip into the fuel system.Star easy first,then keep moving forward,the problem will show itself.......Andy

 

[AH64ID]

If you didn't have the air you would have high EGTs.

One of two things is happening. Your boost gauge is off, or you have a fuel delivery issue. The fuel delivery seems fine sine you are getting an increase in EGTs with SW change. I would verify the boost gauge and no air leak in the gauge line.

If that is accurate it could be a host of things, like a bad MAP or IAT sensor.

 

[CToney]

I don't monitor fuel pressure. I think I'm getting enough since perf setting on jr added more power and egt. Air cleaner is new. I checked compressor today and it looked ok. I'll take off exhaust elbow tomorrow and inspect that too. Injectors were new last fall. I checked pod adjustment on jr. I can steal the boost fooler off of my dads 03. If it changes things that will tell me if my map is bad. I could swap IAT sensor too to check that as well. Truck has low end power just not under full load. I am thinking my wastegate might be open a tiny bit as my cruising boost is a bit lower than normal. I do have another boost gauge I could install as well. One thing at a time and I should get to the bottom of things. Thanks for the help. It's tough to drive without the power that you're used to. Not a big deal back and forth to town but towing or if I have to pass someone it's painful.

 

[AH64ID]

Verify your readings first.

Fuel without air would mean higher EGT's, which is what a stuck wastegate would be. If your wastegate line has been clamped how did it open to get stuck open? If it was failed enough to reduce boost at cruise them you would have a lot more smoke.

Everything sounds like a bad boost gauge, and the low boost is making you think you are low on power.

It's easy to relate lower boost to lower power, even if the power is the same. When i installed my turbo my boost went down, but I was running a bigger tune. The dyno proved power was up, even with lower boost. It didn't feel like power was up as the gauge was lower, but it was.

 

[CToney]

The thing is John that I used to see 1200 F on tow with 35+ psi of boost. Now I only hit 27 psi and 1050 F. Power is down I can't accelerate like I could before. I'll keep going through the list. Eventually I'll find the problem and the lightbulb will go on. Could drive pressure open gate? I'll try to lock the gate manually to see if it was moving.

 

[AH64ID]

Aahh.. You didn't mention EGTs were down too.

You don't have a wastegate issue, you have a fuel issue. I'd start with sensors.

Yes drive will open the gate, but air isn't your issue.

 

[cerberusiam]

The only way drive pressure is going to open the WG is the spring is broke. Normal spring pressure in the actuator is enough to pass 50 psi boost.

As John pointed out, you have a fueling problem if the EGT's are down.

 

[CToney]

I did say 27 psi 1050-1100F instead of usual 35 psi 1200F. I get more fuel on perf but no more boost. 1200F. But if MAP isn't reading properly on tow both boost and pyro would be low. Hopefully it's a cheap and easy fix...

 

[AH64ID]

A cheap OBDII reader is the ultra gauge, thou it won't tell you rail pressure on the 03.

Timing is more advanced on SW3, more timing means less boost for the same fuel, or same boost for more fuel. Knowing the difference in SW2 and SW3 that isn't surprisig if you have something limiting fuel.

 

[lpennock]

A cheap OBDII reader is the ultra gauge, thou it won't tell you rail pressure on the 03.

Ultraguage won't read boost pass 24psi so while cheap it isn't real good for looking at boost issues.

 

[AH64ID]

24 psi is 100% fueling, and above the OEM wastegste setting. If 24 is being seen then the boost reading isn't the issue.

No OBDII reader can read higher, it's an OBDII limitation of 37psia or 24psig at sea level.

If it's reading high and defueling for an overboost there should be a code.

 

[lpennock]

Actually there are a couple obd readers that can read above 24. Edge CTS can and Diablo predator (and I would guess Trinity). The computer can read boost to about 42psi (57 psi absolute).

 

[AH64ID]

While they may hook into the OBDII port they are not reading OBDII data. OBDII data cannot transmit readings above 256kpa, or 37.xx psi.

 

[lpennock]

Believe what you want but when I was designing a boost fooler I got boost reading on gauge pid to 35psi and absolute pid to 49 (my base baro is 14.1psi because of my altitude).

 

[AH64ID]

It's not what I want, it's a simple OBDII limit.. Nothing more or nothing less, hard to argue with design limits.

The reason certain readers can go higher is become they are setup to read the Cummins PID's, not the generic OBDII readings. OBDII is limited on all readings irregardless of sensor capability, we just happen to be below the limit on just about every reading.

 

[lpennock]

Actually we are both correct. I went an looked up J1979-2006.

PID 0b has a range of 0-255 kPa, 36.98 psi. This matches what you are saying; however, according to the spec if pid 4f is supported it is to be used as a scaling factor for the value returned in 0b. So according to the spec the maximum value is much higher than 37psi.

For example pid 70h, Boost pressure control, lists the valid range as 0-2047.96875kPa which makes the maximum value 297psi. Without doing the scaling math I would bet this pretty close to the scaled map max.

The fact the scangauge is only supporting MAP 37 psi just means it didn't fully follow the standard by using pic 0b as a scaling factor.

 

[CToney]

One problem with living North of the 49th, things are not usually cheap. Nor do we have the selection of items you guys can get. For diagnostics having a gauge that could plug into the obdii port to measure boost, IAT and rail pressure wouldn't be a bad investment. You don't know what you're talking about until you measure it. Any suggestions for a gauge? What are they worth?

 

[lpennock]

Actually we are both correct. I went an looked up J1979-2006.

PID 0b has a range of 0-255 kPa, 36.98 psi. This matches what you are saying; however, according to the spec if pid 4f is supported it is to be used as a scaling factor for the value returned in 0b. So according to the spec the maximum value is much higher than 37psi.

For example pid 70h, Boost pressure control, lists the valid range as 0-2047.96875kPa which makes the maximum value 297psi. Without doing the scaling math I would bet this pretty close to the scaled map max.

The fact the scangauge is only supporting MAP 37 psi just means it didn't fully follow the standard by using pic 0b as a scaling factor.

I did additional research on J1979 and pulled a copy of the 2002 spec from Library of Congress. In that spec MAP doesn't have the scaling factor defined and 4F is a reserved PID. So it appears that MAP was extended sometime between 2002 and when the 04.5 HPCR was released. So it looks like we are both correct as I did my data logging on a 06.

Guess we both learned something here.

 

[lpennock]

One problem with living North of the 49th, things are not usually cheap. Nor do we have the selection of items you guys can get. For diagnostics having a gauge that could plug into the obdii port to measure boost, IAT and rail pressure wouldn't be a bad investment. You don't know what you're talking about until you measure it. Any suggestions for a gauge? What are they worth?

Depending on the year of your truck the Ultraguage (see finding in previous post) would be reasonable and inexpensive but wouldn't do data logging. Edge CS or CTS would give you full logging capabilities that can be handy when trying to look at WOT conditions.