Low Boost Pressure, Turbo Replaced

taroo · **Joined:** Sun Apr 27, 2008 2:14 pm **Posts:** 291

gmctd wrote:

?
That chart is to ABSOLUTE manifold pressure, beginning at 30"HG abs = 15psi BARO or 0psi gage, what you would see on ur (hopefully installed) BOOST gage at idle
- 60"HG abs would be 15psig BOOST
- 90"HG abs would be 30psig BOOST

Scalar, 30"HG = 15psi

Those orange peaks are not much above 70"HG abs, well below 30psig BOOST

ECM uses "HG ABSOLUTE to accurately compensate for changes in altitude thru-out the KJ's grazing ranges, world-wide

Hint: Next time ur watching Bambi the weather-girl, cover your eyes so her obvious attributes don't confuse your brain while she's talking hi-pressures and lo-pressures and falling or rising inches, and note her associated numerical references to the barometer - it all should then become clearer to you

And, thanks for that very informative chart - we needed that, eh................

Ohh...can run a chart anytime. I have a ScanTool connected to my laptop that will collect/chart/graph/log. It is from a company called AutoEnginuity. https://www.autoenginuity.com/ I have had it for years.

gmctd · **Posted:** Fri Jan 02, 2015 6:13 pm

No prob, dude - education is what these forums are all about -an educated Diesel owner-driver won't be misled by the various damage-likely myths and misconceptions so prevalent on the 'web

I have AE ENHANCED, just don't know how to use it all, so keep 'em coming

No matter what you do to the emissions components, ECM has got ur back - really bad elimination would be bypassing the BPS, such that ECM couldn't pull vacuum to reduce BOOST - mortally damaging

Previous Diesel engines used cast-iron heads which could easily survive NOx-forming combustion temperatures
- the BOSCH CRD ECM will likely pull fuel when zero EGR is sensed via incorrect MAP input
- if you choose to defeat the emissions componentry additional caution is required because of the KJ's aluminum head

Otherwise, having been exposed to that chart for the first time, it all appears copasetic to me, including the BOOST levels - I would need to run the same on my mostly-unmodified (GDE Hot-tune, correct PROVENT install, flow-master exh, all oem emissions components intact) KJ to compare differences

P'raps I'll get out the DELL\AE scantool and learn some new stuff

canonoch1 · **Joined:** Sun Mar 10, 2013 2:59 am **Posts:** 77

i checked to FCV to see if it was sticking closed but it is wide open. I'll be away tomorrow Sunday morning i will unplug it and test drive. I am thinking of picking up a boost gauge. I will let you al know when I do. I have a email into Stigan's looking for help from them. We'll see

gmctd · **Posted:** Sat Jan 03, 2015 11:21 am

canonoch1 wrote:

i checked to FCV to see if it was sticking closed but it is wide open. I'll be away tomorrow Sunday morning i will unplug it and test drive. I am thinking of picking up a boost gauge. I will let you al know when I do. I have a email into Stigan's looking for help from them. We'll see

Good move on the BOOST gage - I could not find any reference on the STIGAN website for the turbo you have - their posted pics do appear to indicate waste-gate and VVT\VGT availability

WWDiesel · **Posted:** Sat Jan 03, 2015 2:25 pm

Just a thought fellas! Is it possible that he may have a EGR valve problem and the EGR valve is malfunctioning and allowing the dumping of some of the boost back into the exhaust manifold via the EGR feed line? A simple and thin temporary block off plate bolted in the EGR feed line from the exhaust manifold would rule out any backflow leakage...
:idea:

gmctd · **Posted:** Sat Jan 03, 2015 3:42 pm

Good tho't, but with new EGR, and is vacuum-opened, would not suspect early failure

WWDiesel · **Posted:** Sat Jan 03, 2015 4:01 pm

gmctd wrote:

Good tho't, but with new EGR, and is vacuum-opened, would not suspect early failure

I thought the EGR was electrically operated by the OBC? It could still be hanging part way open if it is a euro vacuum operated unit... vacuum opened, spring closed?

papaindigo · **Posted:** Sat Jan 03, 2015 4:16 pm

On the 05 and 06 domestic KJ CRD the EGR is electrically controlled by the ECM (per the FSM and of course it has to be or GDE's tune could not alter EGR operation). I'm pretty sure that's also true for 05+ export KJ CRDs but am not positive. Earlier export KJ CRDs (not sure of what years) however had a vacuum controlled EGR.

Bottom line though is yes a stuck EGR can mess up boost. Dealer always wants to replace EGR although it's not often "really" bad and ignoring the fact that it's not all that hard to remove, clean, reinstall. The latter however requires a "real" mechanic or DIY person not just a parts replacer.

gmctd · **Posted:** Sat Jan 03, 2015 4:50 pm

No, my bad (at my age, I think it must be the Rip Van Winkle effect) - IIRC it is a linear stepper motor, no vacuum connection - still, would not think a new one would fault this early in the game to give same black-smoke symptom as original unit

And, yes, a vacuum-operated EGR (or anything else) would be spring-loaded, usually normally closed, with vacuum on the diaphragm pulling the valve open - PWM solenoid valve would allow incremental opening (where do we see that, elsewhere on this engine?)

A vacuum-operated waste-gate or VVT setup would use exhaust gas energy\volume to open the waste-gate or force the vanes open, usually no spring required - noted exception is the Ram Cummins turbo, with a very strong spring forcing the wastegate open, such that it takes a very strong arm to close it without vacuum assistance - the orange silicone-rubber diaphragm often punctures, rendering it useless, whereupon the IP cuts fuel such that the big six blows no black smoke, but is totally powerless

WWDiesel · **Posted:** Sat Jan 03, 2015 8:45 pm

All that stated good! Now back to original possibility, install a temporary thin block off plate in the EGR feed line to the EGR valve to eliminate any possibilities of loosing boost through a defective EGR valve!!!
It can always be removed later if needed for vehicle inspection purposes if required??? :wink:

WWDiesel · **Posted:** Sun Jan 04, 2015 4:09 pm

From another post, you may find this to be of interest:
It does happen....
I stand by my suggestion... :wink:

Kurt-06-CRD wrote:

Here's the rest of the story.
Get rid of your EGR system and life will be good. My NEW EGR valve had a very slight leak, it cold pass a very small amount of air when on the bench. Rather than replace it again, I blocked it off and installed the GDE tune. The car now runs great, no CEL, no smoke, better power, better fuel economy and clean engine oil.
I was thinking this vehicle might need to go but now I see running it for many, many more miles!
kurt

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=43&t=80230&p=853780#p853780

gmctd · **Posted:** Sun Jan 04, 2015 5:01 pm

WWDiesel wrote:

From another post, you may find this to be of interest:
It does happen....
I stand by my suggestion... :wink:

Kurt-06-CRD wrote:

Here's the rest of the story.
Get rid of your EGR system and life will be good. My NEW EGR valve had a very slight leak, it cold pass a very small amount of air when on the bench. Rather than replace it again, I blocked it off and installed the GDE tune. The car now runs great, no CEL, no smoke, better power, better fuel economy and clean engine oil.
I was thinking this vehicle might need to go but now I see running it for many, many more miles!
kurt

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=43&t=80230&p=853780#p853780

Problem being: the EGR valve opener\closer is a linear stepper motor
- like a solenoid, the 'shuttle' travels in and out, linearly - it is either on or off
- unlike a solenoid, ECM pulses the coils which create incremental linear movement as slight as 0.001" per step
- this is like a stepper motor, but with linear travel rather than rotary travel

Now.........modern quality-control testing is not per-batch quantity, but e pluribus unum: only one per batch quantity
- increased unit-for-test is related to failure rate per quantity: more unit failures = more units tested

Units on dealer parts shelf can be shown to be at various valve openings, anywhere from fully open to fully closed and all points in between
- only those pre-tested units will be fully-closed
- this is not important at this stage because at key-on, after installation, ECM excercises the unit, then fully-closes it
- ECM will then "step" the valve open depending on sensed requirement for EGR as engine starts

Point being, bench-testing of a new purchase does not duplicate bench-testing with a new unit installled, then pulled from the engine for bench-testing
- ECM will have stepped the valve fully closed at key-off
- leak-test at bench-test should be performed from that point
- testing requires inspection for any carbonated soot that could block valve closing rendering test non-functional, invalid
- exceptions, as usual, are not the rule

canonoch1 · **Joined:** Sun Mar 10, 2013 2:59 am **Posts:** 77

i haven't had the time to mess with it any further yet. I will pickup a boost gauge for it as soon as I can. And thanks for the graph and chart

canonoch1 · **Joined:** Sun Mar 10, 2013 2:59 am **Posts:** 77

so tonight I pulled the vacuum actuator off the Stigan's turbo since I still have our original turbo and compared the two. The original total rod length is shorter then the Stigan's. I am thinking I may try installing the original vacuum actuator this weekend. should probably only take a couple of hours and a couple dozen clips to connect the rod to the vane arm :ROTFL:

gmctd · **Posted:** Thu Jan 08, 2015 1:53 am

canonoch1 wrote:

so tonight I pulled the vacuum actuator off the Stigan's turbo since I still have our original turbo and compared the two. The original total rod length is shorter then the Stigan's. I am thinking I may try installing the original vacuum actuator this weekend. should probably only take a couple of hours and a couple dozen clips to connect the rod to the vane arm :ROTFL:

That could be a good start:
- first, note if the STIGAN has a return-spring in the actuator - it should not for KJ service - exhaust energy blows the vanes open
- then, compare total vane movement stop-to-stop on each turbo with the actuator linked, mark it down
- compare total up\down actuator-link movement stop-to-stop on each turbo with the actuator linked, mark it down
- remove the links, measure total actuator up\down movement in each, mark it down
- links removed, measure total vane movement in each, mark it down

These finite limit dimensions (you did write them down as measured, right?) should give you enuff data to initially-adjust the replacement, getting you within the ball-park for final adjustment

canonoch1 · **Joined:** Sun Mar 10, 2013 2:59 am **Posts:** 77

here is a pic of the 2 vacuum actuators the one on the left is the Stigans on the right is the original Garrett.

gmctd · **Posted:** Fri Jan 09, 2015 12:57 am

Looks you need to adj the STIGAN shorter by almost 3/8", figgerin' on those being 1/4" squares

Also looks like they both are spring-loaded - if so, see if the tension is similar

But, you can also sub the Garret actuator onto the STIGAN, just fer grins'n'giggles, see how it responds

Nice shot, btw...........

canonoch1 · **Joined:** Sun Mar 10, 2013 2:59 am **Posts:** 77

thanks, was kind of figuring of trying the original to see what happens

canonoch1 · **Joined:** Sun Mar 10, 2013 2:59 am **Posts:** 77

well i put the Garrett actuator on this weekend and jeep runs better although still not completely happy with it yet. I need to install a boost gauge and get a hold of a CRD service manual and read up on the turbo

gmctd · **Posted:** Mon Jan 12, 2015 1:23 pm

canonoch1 wrote:

well i put the Garrett actuator on this weekend and jeep runs better although still not completely happy with it yet. I need to install a boost gauge and get a hold of a CRD service manual and read up on the turbo

Good - one step at a time, but the Boost gage is most important, now

You'll also need to blow all that previously-stored black soot outta the soot trap and exhaust pipe, either with some good power runs, or about 10mi at hiway speeds should do it

Low Boost Pressure, Turbo Replaced

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