TGCTD

Since a fair amount of us are driving stock trucks,i think some would be interested on what i learned this week about the stock turbo. Since i work for a DC dealer i road test other CTD rams besides my own that i bought new in 2002. About a week ago i was driving a customers truck and noticed it had a noticable differance in acceleration than mine did. With his permission from the passenger seat he allowed me to mash the go pedal to the floor to see how it performed. It performed better than mine did and i wanted to know why. ???You see since mine was new i usually drove mildly,with only seeing 3/4 to WOT occasionally. when i did mash the pedal to pass someone etc. the engine would reach about 2200-2500 rpm and flatten right out. accelleration would cease until i let off the throttle a bit. Not knowing any better, i thought this was normal because it pulled well when driving normally. I decided to investigate this and found that i had a DTC(diagnostic trouble code ) stored in the Cummins ECM. The DTC was code PO234 (turbo boost limit exceeded) and that it did not turn on the MIL (malfunction indicator light). Turns out that a TSB existed for this code. The TSB called for replacing the MAP sensor,which i did,and it did not fix the problem. I decided to watch the boost while i mashed the pedal to the floor and what i found was my boost was hitting 38-39 PSi when the truck was falling on it's face. Well as it turns out max boost is around 34-35 psi. After that the ECM starts to pull fuel and timeing causing the symptoms to occur. Through coversations with the DC STAR center and some Cummins special tools supplied to us for diagnostics I found the waste gate was not moving.(I was told that you won't see them move if trying to use your hand like on most models) Turns out the Turbo had to be replaced as a assembly. Now the truck pulls great!! What a unbelievable difference this made. So what i learned is giving the engine extra boost without fooling the ECM that it wants it does no good for power increase. Modifying the turbo to produce more boost with out adding a power box of some kind is fruitless. Anyone experiencing similar symptoms should have DTC's and your actual boost pressures checked.

PourinDiesel

Most people on this site that modify or run a modified turbo or different turbo usually run a "boost fooling" device.
It attaches the map sensor on an ISB or IAT/MAP sensor on an 03. These devices are usually provided in a fueling box like Edge, TST, Bluechip etc.
This only lets the ECM see safe boost pressures hence no codes and no defueling.

--Justin

TGCTD

Yes, that i s why i said for people with stock engines without some kind of power box. Ie people experiencing power loss with a unmodified engine. :P

KatDiesel

No offense or anything but a stock fueled truck will not make 38 to 39psi worth of boost.

Was this "boost level" verified using a gauge or scantool?


I am going to guess you read boost from a scantool (DRBIII?), if so its adding 14psi for atmospheric pressure. 39 - 14 = 25psi, which a stock fueled truck can make, and yes the ECM will see it as overboost at that level.

TGCTD

Katdiesel you are correct. It was read with a DRB III and you are right the 38-39 psi was read as the DRB III shows atmospheric pressure at Key on. Actual boost should not exceed in the neighborhood of 19-20 psi or an overboost condition will occur. Today is the first time i was able to take the truck on an extented ride and i do not remember this truck pulling a smooth torque band like it does now. I just mentioned this because i didn't notice for a very long time that the the truck was accelerating more poorley than it should. The MIL light never came on ,but a code was stored a long time ago. I just started to wonder if this was a common problem or not,seeing that there is a TSB for the Map sensor for this condition.

frostie

A friend of mine with an 02 just put a $30 air pressure regulator to the boost sensor. He limited the pressure to 20 PSI but was able to actually get 30 PSI boost due to the computor thinking it was only getting 20 PSI allowed it to keep fueling. Quite simple and pulled very good ;D

TGCTD

Now that is pretty ingenious! How did he make the adjustment. I am thinking he turned down the atmospheric pressure at idle ??? Did he install the reg. in-line before the MAP?

BigBlue

I've been able to push 23 psi on my truck without setting off any code without my comp on. I even checked the codes in the computer. None.

KatDiesel

[quote author=BigBlue link=board=4;threadid=19905;start=0#msg187924 date=1064278331]
I've been able to push 23 psi on my truck without setting off any code without my comp on. I even checked the codes in the computer. None.[/quote]

Without the COMP on, as in "on the truck" or just turned "off"? The "boost module" portion works with the COMP off and or the EZ data plug unplugged.

How did you check the codes in the computer? I can garentee its in your ECM what boost level you have hit. No it wouldn't showup with the key on key off method.

BigBlue

It was with the Comp UNPLUGGED. If the codes there, then the computer must not care to much cause the truck runs great with the Comp unplugged. Heck, it runs better with the Comp unplugged than it does with the Comp plugged in and turned off. I've had two different Comps on my truck and each time, the truck seemed to run better with it unplugged than it did with it plugged in and turned off.

427AC

[quote author=frostie link=board=4;threadid=19905;start=0#msg187492 date=1064201059]
A friend of mine with an 02 just put a $30 air pressure regulator to the boost sensor. He limited the pressure to 20 PSI but was able to actually get 30 PSI boost due to the computor thinking it was only getting 20 PSI allowed it to keep fueling. Quite simple and pulled very good ;D
[/quote]I would like all the info on this mod. can you get part numbers and the rest of the details? Pictures would be really cool

427AC

who has the details on the presure gauge mod? I would like to see more abut this. Any pictures would be great.