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14mpg!! and serious turbo lag

12K views 18 replies 13 participants last post by  rtc1184 
#1 ·
Hey guys im very new to 12 valve engines but 14 mpg seems pretty low to me for any diesel motor and if im wot or half throttle it doesnt matter at take off you cant see behind the my truck for all the black smoke but it seems very slow to me and doesnt start building boost for 5 sec at least very laggy to me to say the least, it seems to me like the truck is flooding bad hence all the black smoke. I have only had the truck for 4 days now and the previous owner told me that it has hx-40 turbo, 215hp injectors, and he said they adjusted the timing he didnt say if it was retarded or advanced though, oh yea and the fuel plate is stock and in the stock position has never been touched so im told....anyways i was just wondering if maybe the timing could be off and what could be causing all the smoke at take off? Thanks for any help guys itll be greatly appreciated
 
#2 ·
I'm gonna guess that if he did a different turbo and different sticks, your truck may be in the same condition as the "slow spooling/bogging" truck.

Does it still have its AFC? How many miles? What is the truck (signature)? What boost/fuel pressure/pyro do you get?

What conditions do you drive in? 50? 60? 85? Taxi-like stop and go? Auto or manual? Rear end? Tires?
 
#3 ·
I'm sorry I should have included more info, im assuming it still has afc he never told me any different the truck has 258k miles right now the max boost im getting is 32lbs normal driving anywhere from 0 to 10 but I have glowshift gauges so not sure how much they help, ive heard they are not very good gauges lol Im not sure on the fuel pressure either how can i test that? Exhaust temps flunctuat anywhere from 600-800 regular driving and i think the hottest ive ever noticed it was 1000 thats post turbo by the way. Mostly drive on highway 60mph and some city 25-50mph id say 60% is highway driving though. Truck is automatic, im not sure about the rear end gear ratio, stock tire size also thanks for any suggestions
 
#12 ·
...hottest ive ever noticed it was 1000 thats post turbo by the way...
That's dangerous. Post turbo 1000º equals anywhere between 1200º-1300º+ ACTUAL egt.

Get that pyro pre-turbo if you wanna know your true egts...
 
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#5 ·
Fuel filter is brand new...I know this is a complete newbie ? but i have to ask and trust me i feel like a complete for asking but what do you mean trick out my afc?
 
#10 ·
spike... do you have any idea what your talking about ?
 
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#15 ·
i am pretty new at this but; i had a leaking fuel return line. when i went to fix it i found the fuel pick up hose had several cracks and sucking air. fixed it and my mileage and power went up and black smoke went way down... this was my experience. hope it helps!
 
#17 ·
read the beginners thread posted previously. def put the egt probe pre turbo for accurate results. learn the truck, as it may take some time but will help in the long run. sounds like the smoke screw may be turned way in or the afc is gutted. 32lbs on a hx-40 isnt too high. should be somewhere in s the 35-38lbs of boost range. also i dont believe the plate is in. i have a stock hx-35 5spd 215pump no plate and afc slide all the way forward and it dont smoke that much. if your plate is in then you are not getting a whole lot of fuel. hmmm something dont add up with your situation and what the previous owner told you.
 
#18 ·
Yes i agree with you rtc1184 im starting to regret buying from this guy because I hate getting lied to, he also told me that when he had the fuel turned all the way up on the truck it pushed 50lbs of boost easy is that possible with an hx-40? and i agree on the pyro it has a prob already in the manifold for a guage i just need to hook it up i guess to get some more accurate readings
 
#19 ·
well yes you can get 50lbs out of it, but HIGHLY not recommended. that is way outside of its map. 40lbs ish is plenty high. also if he pushed 50lbs on it, then he is likely to have blown a head gasket or messed the turbo up if he did it on a frequent enough basis.

read about the pre-boost screw and starwheel. that alone will help you alot. i think it could be as simple as tuning your afc. i would take the afc and inspect it personally. see if there is a plate in it. take pictures, we are more then happy to help you and explain things, if they havent been answered a million times.

i highly doubt you have 215hp injectors! your pump is a 215pump.

put your egt probe pre-turbo and put it in the elbow that the turbo is on. remeber there is a divider in the middle of the manifold on so put the probe toward the back(or closest to the firewall side)
 
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