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oldsilver

Boost low, egts high and mpg down

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Hi everyone I am new to this forum. I have a 99 dodge 3500 that I have owned since new. I am recently having higher egts, lower fuel mileage and lower boost. My truck has an edge comp box that I run on 3, pusher intake, pac brake, HX35/40 Hybrid turbo from PDR, RV275 injectors, stock lift pump mounted on the frame with 3/8" fuel line and no banjo bolts. 12psi at idle, about 9 at wot. AFE cold air intake and 4" exhaust. So recently I put a new IAT sensor in because my fuel mileage dropped to 9-10 coming back from South Dakota with 10000 pounds where I used to get 15. It raised it to 12 but my boost is still low at about 21-22 psi and my egts go to 1200 real easy. I use this truck to tow my camper and side by sides all over the country and next year I am going to CO and theres no way I can use it in elevation with those egts. I have tried to check for boost leaks and haven't found any. I am aware that I need to get rid of that turbo and exhaust break so I can get a true 4" down pipe but I have had this set up for years and have not had these problems. Looking for help because everybody I call just wants to sell me stuff. I am wanting to do some upgrades this winter for power and reliability, cause reliability is most important to me but I need to fix this problem first. Oh ya I took my elbow off  my turbo and with the truck not running the exhaust break is wide open. Sorry for being so long winded I just can't figure this out. Once this is figured out I would like to do some up grades.

Also just put a crank sensor in about a month ago cause I got a code and I replaced my vp44 at 100000 miles and I have 144000. It was just a rebuilt bosch from Diesel injection service in St.louis

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First off...

11 minutes ago, oldsilver said:

I need to get rid of that turbo and exhaust break so I can get a true 4" down pipe but I have had this set up for years and have not had these problems.

Not true... I've running the same setup with no problem towing much much more weight. Exhaust brake has ZERO impact on the EGT's. I'm also running the same turbo and +75HP Injectors (7x0.0085).

 

11 minutes ago, oldsilver said:

My truck has an edge comp box that I run on 3

What sublevel?

 

11 minutes ago, oldsilver said:

I am recently having higher egts, lower fuel mileage and lower boost.

Classic signs of boost leak... Need to build a turbo cap and pressure test the system and check your boost for leaks or cuts. 

 

11 minutes ago, oldsilver said:

I put a new IAT sensor in because my fuel mileage dropped to 9-10 coming back from South Dakota with 10000 pounds where I used to get 15.

You could of saved a bunch of effort and money and just grabbed a live data tool and monitor the sensor values before changing. In all the years of working on these trucks its extremely rare to hear of anyone replacing the IAT sensor.

 

Image result for mopar1973man towing hay

 

+75 HP injectors, Quadzilla Adrenaline, HX35 turbo, 3" exhaust. Climbing 7-9% grades no issues at all with EGT's. That's only 10,000 pound of hay excluding the trailer.

 

Since then I've upgrade turbos, kept the exhaust brake and upgraded to 4" exhaust. ZERO Impact on EGT's. 

Edited by Mopar1973Man

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I have a cap that I made to go in the rubber air cleaner tube. It doesn't work so well it keeps trying to blow off and it leaks. Do you have any suggestions and is there a common place these trucks like to leak. I ohmed my sensor and according to the numbers I found on line it was bad. I agree with you this setup has done me good in the past. I run my sub level all the way up I haven't had any luck running it lower

Edited by oldsilver

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13 minutes ago, oldsilver said:

Do you have any suggestions and is there a common place these trucks like to leak.

  • Turbo output elbow o-ring
  • Intercooler boots
  • Intercooler
  • Intake horn and grid heater
  • Intake bolts missing or loose
  • Intake gasket blown
  • O-rings on IAT and MAP sensors
15 minutes ago, oldsilver said:

I have a cap that I made to go in the rubber air cleaner tube.

 

Not the way it suppose to be done. It suppose to be attached to the mouth of the turbo.

 

image.jpeg

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I will be honest I'm not sure. It was recommended 13 years ago from a guy I knew a Piers Diesel Research, I went off his advice. I am looking to replace it after I find this problem I'm having. I am even looking to remove my turbo mounted exhaust brake and buy one that welds inline so I can have access to a lot more turbo choices.

I'm looking to do some up grades for reliability ,egts and performance but I would like to find this egt problem first. My turbo and injectors have been in my truck for at least 13 years, I put my comp box in the year they came out, it was replaced once by Edge.

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You have a boost leak, Or something is broken/out of tune. Even with the stuff in my signature I can still pick up and move 10-14k without issue. 

 

0IgCon0.jpg

This was over 7,000lbs of stone in the truck bed.

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I changed out my boost fooler elbow and got my boost back. I made a test piece to look for boost leaks, I snooped everything and only found a small leak on the fitting going to my boost gauge, There has to be something I am missing

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Posted (edited)

If the boost elbow failed and let full pressure to the waste gate it would open a lot sooner. That would be your leak going down the tail pipe. Thats why @Mopar1973Man suggested pinching the air line to it. Cut the air pressure to it and it wont open.

Edited by dripley
  • Like 1

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286vj2r.jpg

 

Trust me turbo mounted exhaust brake will not affect your towing ability. That is 10,000 pound of hay. I've towed much heavier loads and never had EGT issue even with 3" exhaust.

  • Like 1

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12 hours ago, oldsilver said:

I changed out my boost fooler elbow and got my boost back. I made a test piece to look for boost leaks, I snooped everything and only found a small leak on the fitting going to my boost gauge, There has to be something I am missing

 

Is your boost elbow adjustable? is it possible that the adjustment screw moved?

  • Like 1

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My elbow is not adjustable. I just got back from camping, pulling the hills in Mo at 70 my egts were around 1000 to 1100, the back roads at 55 they were 1200 and on the longs hills they hit 1200 at 70. Still to high and my mileage is crap at 11mpg. I had a little more boost with my new elbow at about 29psi wot, at 70 they were about 26 psi. I have checked and checked for boost leaks and haven't found any. I can't get to the whole intercooler to check it, I guess I could pull it and check it on the bench. The truck runs fine so I wouldn't think it is injectors. I just don't want to start up grading things without finding the problem first.

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Posted (edited)

Check back side of the turbo where big snap ring is on the intake side, that's where I had a pretty good boost leak on mine after having a turbo built, if you do have a leak there you could simply take that snap ring out pull housing off bearing housing be careful not to damage impeller, and just use a small bead of rtv, let it sit overnight to cure before you apply pressure.

I'm guessing you using soap water in the spray bottle to look for your leaks, spray the crap out of everything and pressure-tested.

Do you have a mechanical boost gauge or you're relying on your comp box

Edited by Dieselfuture

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I will check that, I have not checked that spot. I have a mechanical boots gauge(auto meter). I am using snoop, same as soapy water but bubbles at less pressure.

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How is your exhaust brake. Mine failed a few months bank and was partially closed. That ran my egt's up. Found it before i ran enough fuel thru it to notice any lower fuel mileage. If i am reading correctly you have your boost pressure back to normal, correct?

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Its close but its not all back. I took the elbow off the back of the turbo and the exhaust brake is open, unless it is messing up when im driving. My fuel mileage is down to 11mpg with my camper and it used to be at least 15.

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 My EB is in the elbow and it stopped working. That's when I noticed the linkage not moving completely in either direction. Something is gone in the actuator. But it was causing higher EGT's. Probably a loss in power but I caught it pretty quick. I took the actuator off and wired it open.

 My boost is off a couple pounds from a year ago but the EB thing is the only thing other than a blown boot that ever raised my EGT's. The boot caused a lot of smoke but the EB did not.

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You can just put a plug in the housing where boost elbow goes in and see if it helps, another reason for poor mileage could be caused by wore out vp :sofa:

How is your fuel system all upgraded I hope.

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33 minutes ago, Dieselfuture said:

 

You can just put a plug in the housing where boost elbow goes in and see if it helps,

 

I have never had a boost elbow. I relied on the banks tuner to do the fooling since the waste gate opens at 32 or 33 pounds. Though plugging it would see how high it would go. Without fooling it will set the code. I had to drive mine for near 3 years by the boost gauge to keep the code from setting. Got pretty good at it.

 

As far as the VP causing bad mileage, not sure that sofa is big enough to hide behind, but Mikey does not have house to hide behind.

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My injection pump only has about 40,000 miles on it, I hope it isn't wore out but anything is possible. It was a reman from diesel injection service in St.louis. I need to check the back of the turbo like diesel future said. As far as my exhaust brake it seems to be working fine but I am considering taking it off and getting a BD Exhaust flange mounted one anyway. The reason I say that is because the turbo mounted one is handcuffing me on upgrading my turbo. Unless somebody has a better idea with the turbo upgrade, I would love not to buy a new exhaust break but I cant live without it.

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15 hours ago, oldsilver said:

My fuel mileage is down to 11mpg with my camper and it used to be at least 15.

 

Did you by chance have the injectors pop tested to see if the pop pressures are near 310 bar? As injectors wear the pop pressure will fall and the timing tends to get more advanced and spray pattern get crappy.

 

As for the EGT's I still say it going to be a boost leak issue. Another thing it could be is drive pressure leak or exhaust leak before the turbo look for soot marks on the manifold top and bottom for cracks or blown gaskets.

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Ok will do, and I will take the injectors out and have them tested

I looked at the manifold and I didn't see any soot. I just wonder if the intercooler is leaking somewhere that I cant get to

I thought about getting some bigger injectors when I up graded the turbo but I don't want to make more problems for myself.

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