cgallamore Posted May 17, 2011 Share Posted May 17, 2011 cleaned egr coolernew turbo filtercleaned and lubed vgt linkagechecked air going to vgt, removed hose, appears to have plenty of air pressure.egr vaulve shaft is shiny, appears to be doing as should.comes and goes without ryme or reason, sometime i think rough roads help, but not every time????when it makes 33psi boost it is great, fire breather, good engine brake, hurts the feelings of large car owners.at 25 psi boost, it sucks, poor power, piss poor engine brake, builds exhaust temp very quik. brown exhaust smoke.humitity, altitude, temp,rain, day, night,it runs good and bad in all situations.never knowhow long either way is going to last, 5 min, or 5 days.can be running fine pulling a hill, downshift and it goes to hell, or maybe pulling hill running bad and downshift and it comes to life.no codes lights or alarms. the only thing i can see is boost change, its either 25psi runs bad, 33 psi runs great.engine brake works great at 12 to 14 psi boost. is shity at 5 psi.have been paying very close attention, near consuming, trying to nail down a common cause. no results.... Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/ Share on other sites More sharing options...
rhasler Posted May 17, 2011 Share Posted May 17, 2011 Just a guess, maybe the boost relief valve is sticking? Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77923 Share on other sites More sharing options...
cgallamore Posted May 17, 2011 Author Share Posted May 17, 2011 Just a guess, maybe the boost relief valve is sticking?where is it?how do i check it?is it a mackpro thing?i think i have had this problem all along. i allways watch important gauges, old school oil press. water temp. exhaut temp. when ex temp would start to climb i adjusted how hard i was pulling to keep it down. we have talked about lack of boost with engine brake. and engine brake sometimes good or bad. now i think this boost issue ties in???? Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77924 Share on other sites More sharing options...
rhasler Posted May 17, 2011 Share Posted May 17, 2011 where is it?how do i check it?is it a mackpro thing?i think i have had this problem all along. i allways watch important gauges, old school oil press. water temp. exhaut temp. when ex temp would start to climb i adjusted how hard i was pulling to keep it down. we have talked about lack of boost with engine brake. and engine brake sometimes good or bad. now i think this boost issue ties in????There should be a metal tube running from the intake manifold/mixer housing over to the exhaust pipe behind the turbo. The BRV is just past the mixer housing and has a hose attaching it to the metal tube running to the exhaust pipe. Usually the seat in the end of the valve will start to unscrew. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77929 Share on other sites More sharing options...
cgallamore Posted May 17, 2011 Author Share Posted May 17, 2011 There should be a metal tube running from the intake manifold/mixer housing over to the exhaust pipe behind the turbo. The BRV is just past the mixer housing and has a hose attaching it to the metal tube running to the exhaust pipe. Usually the seat in the end of the valve will start to unscrew.i remember mackpro checking that when he ran the overhead, ill check it again, just tighten the screw??????? JB weld ???? Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77930 Share on other sites More sharing options...
rhasler Posted May 17, 2011 Share Posted May 17, 2011 i remember mackpro checking that when he ran the overhead, ill check it again, just tighten the screw??????? JB weld ????Check for a broken spring. The screw should be peened in place to keep it from coming out, but they still seem to wear in which case you would replace it. 1 Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77933 Share on other sites More sharing options...
cgallamore Posted May 17, 2011 Author Share Posted May 17, 2011 Check for a broken spring. The screw should be peened in place to keep it from coming out, but they still seem to wear in which case you would replace it.thanks..... Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77934 Share on other sites More sharing options...
fjh Posted May 17, 2011 Share Posted May 17, 2011 thanks..... If the spring idea don't work my best guess is the egr valve sticking! They can and will stick and not code out Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77937 Share on other sites More sharing options...
cgallamore Posted May 17, 2011 Author Share Posted May 17, 2011 If the spring idea don't work my best guess is the egr valve sticking! They can and will stick and not code outthe correct way to check egr is to unplug it ???????????? Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77956 Share on other sites More sharing options...
Mike Posted May 17, 2011 Share Posted May 17, 2011 LOL......Hey Bigen......say ya got low boost.......sounds like another doctor visit. I had it once and doctor gave me the patch and now i'm like a new pony. Hope ya get it straightened out. mike Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77965 Share on other sites More sharing options...
fjh Posted May 18, 2011 Share Posted May 18, 2011 the correct way to check egr is to unplug it ????????????If you unplug it it will code out!The valve is controled by the flow in the mass flo tube the valve really only goes where its told to go the computer does not know if its getting there or not!It would show up on the advance display in diagnostics as not reaching target but won't throw a code for it!put the block plate in, that 68 made ya and try it!If it is the egr valve your floating boost will be gone! Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-77989 Share on other sites More sharing options...
cgallamore Posted May 18, 2011 Author Share Posted May 18, 2011 If you unplug it it will code out!The valve is controled by the flow in the mass flo tube the valve really only goes where its told to go the computer does not know if its getting there or not!It would show up on the advance display in diagnostics as not reaching target but won't throw a code for it!put the block plate in, that 68 made ya and try it!If it is the egr valve your floating boost will be gone!thankssounds like a plan.im in salt lake now, i am sceered to tear into it out here. if bolt breaks im screwed....i think 68 is on the french riviara this week, not gona bother him till he gets back to work.when i seen how hot mrs. mackpro is, i thought maybe he was packin like john holmes. but i figured it out HE'S RITCH..... Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78009 Share on other sites More sharing options...
rhasler Posted May 19, 2011 Share Posted May 19, 2011 thankssounds like a plan.im in salt lake now, i am sceered to tear into it out here. if bolt breaks im screwed....i think 68 is on the french riviara this week, not gona bother him till he gets back to work.when i seen how hot mrs. mackpro is, i thought maybe he was packin like john holmes. but i figured it out HE'S RITCH.....Sounds like all those EGR problems paid off for someone! Somewhere in the back of my head I hear Dave Chappelle....I think fjh is probably on the right track, especially if '68 checked that boost relief valve out recently. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78012 Share on other sites More sharing options...
fjh Posted May 19, 2011 Share Posted May 19, 2011 Sounds like all those EGR problems paid off for someone! Somewhere in the back of my head I hear Dave Chappelle....I think fjh is probably on the right track, especially if '68 checked that boost relief valve out recently. yup that guy made enough money to take a Vacation! Why don't ya drop up my way Chuck I need a vacation! How bout you Rass ? you could use a week in the Sun couldn't ya! Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78035 Share on other sites More sharing options...
rhasler Posted May 19, 2011 Share Posted May 19, 2011 yup that guy made enough money to take a Vacation! Why don't ya drop up my way Chuck I need a vacation! How bout you Rass ? you could use a week in the Sun couldn't ya! Why yes, yes I could! Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78050 Share on other sites More sharing options...
fjh Posted May 19, 2011 Share Posted May 19, 2011 Why yes, yes I could!See Chuck No Problem there! Were here for ya BUD ! Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78054 Share on other sites More sharing options...
Mackpro Posted May 24, 2011 Share Posted May 24, 2011 thankssounds like a plan.im in salt lake now, i am sceered to tear into it out here. if bolt breaks im screwed....i think 68 is on the french riviara this week, not gona bother him till he gets back to work.when i seen how hot mrs. mackpro is, i thought maybe he was packin like john holmes. but i figured it out HE'S RITCH.....Back from vaction for a few days then off for 5 more days of fun. I married a much younger girl and Ms Mackpro is a Princess (so she thinks) so thats where all my money goes. I think I replaced the boost pressure relief valve on yours, if not I know I have had it off atleast twice and checked it, Im sure I screwed it in farther and peened the end over so it wouldn't back out. Im leanin toward EGR valve or turbo actuator. Gotta go put more suntan oil on Ms Mackpro Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78315 Share on other sites More sharing options...
Mike Posted May 24, 2011 Share Posted May 24, 2011 Back from vaction for a few days then off for 5 more days of fun. I married a much younger girl and Ms Mackpro is a Princess (so she thinks) so thats where all my money goes. I think I replaced the boost pressure relief valve on yours, if not I know I have had it off atleast twice and checked it, Im sure I screwed it in farther and peened the end over so it wouldn't back out. Im leanin toward EGR valve or turbo actuator. Gotta go put more suntan oil on Ms Mackpro Sure looks like she has whip marks on her arm. And where is the arrow pointing on her backside? mike Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-78333 Share on other sites More sharing options...
cgallamore Posted June 7, 2011 Author Share Posted June 7, 2011 Back from vaction for a few days then off for 5 more days of fun. I married a much younger girl and Ms Mackpro is a Princess (so she thinks) so thats where all my money goes. I think I replaced the boost pressure relief valve on yours, if not I know I have had it off atleast twice and checked it, Im sure I screwed it in farther and peened the end over so it wouldn't back out. Im leanin toward EGR valve or turbo actuator. Gotta go put more suntan oil on Ms Mackproi think ive nailed it down, its altitude. checking this trip to make sure but apears to be related to alt. above 10,000ft. boost is below 20 psi.12,000ft. boost gauge reads get out and push.could this be ecu program issue???????? Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79252 Share on other sites More sharing options...
Mackpro Posted June 7, 2011 Share Posted June 7, 2011 i think ive nailed it down, its altitude. checking this trip to make sure but apears to be related to alt. above 10,000ft. boost is below 20 psi.12,000ft. boost gauge reads get out and push.could this be ecu program issue????????I'll send in a E-service to mack about it. I think there is a download but I also hear it hurts you down around normal altitudes. I'll see what they say. Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79255 Share on other sites More sharing options...
Mackpro Posted June 7, 2011 Share Posted June 7, 2011 Mack sent me a new engine data file for your truck, next time your in we'll install it. they say no side affects at lower altitude. Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79261 Share on other sites More sharing options...
slpwlker Posted June 7, 2011 Share Posted June 7, 2011 My Cat does that out in Colorado. It pulls even heavy it is slugish but when I am giving these legal weight guys hell up the mountains I realize it isn't just me. I've changed air filters,Fuel filters,pulled my hair out till I got to lower altitude and figured It didn't like being upwards of 12k feet. Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79262 Share on other sites More sharing options...
cgallamore Posted June 7, 2011 Author Share Posted June 7, 2011 My Cat does that out in Colorado. It pulls even heavy it is slugish but when I am giving these legal weight guys hell up the mountains I realize it isn't just me. I've changed air filters,Fuel filters,pulled my hair out till I got to lower altitude and figured It didn't like being upwards of 12k feet.took me a while to figure its not random, it does okay sometimes, sometimes acts stupid as low as 6000ft.what nailed it is eastbound 70 in co.come out of the tunnel with no jake brake every time. Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79272 Share on other sites More sharing options...
slpwlker Posted June 7, 2011 Share Posted June 7, 2011 What was funny we where grossing about 126k going up to the mine in Climax and it pulled like a raped ape up and over loveland. I flew up that pass. Got to the mine got empty. Coming back is when it decided to go nuts on me. I could barely pass loaded trucks. Took it to pete the next morning and had the air filters changed and a cab air bag. Did better but as we headed east it got better and better. Next time we got out there it started doing it again then that was when it dawned on me. Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79275 Share on other sites More sharing options...
fjh Posted June 8, 2011 Share Posted June 8, 2011 Mack sent me a new engine data file for your truck, next time your in we'll install it. they say no side affects at lower altitude.Let Us Know if this data file thing works Chuck I got a customer that has a similar issue.Thanx Quote Link to comment https://www.bigmacktrucks.com/topic/19104-low-boost/#findComment-79312 Share on other sites More sharing options...
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