Napheus wrote:
I signed up for a GDE tune, and am looking forward to getting this done shortly. However, I have an issue I need to sort out before I get the tune. My wife primarily drives the CRD. I occasionally take it to work because it is 26 miles one way and its good to stretch her legs a few times a month. The last time I drove it, I noticed a decrease in mileage. Typically when I am on the interstate, after getting up to speed, I reset the evic and play a game where I try to see if I can maintain the MPG displayed above 30. Even with winter fuel I have been successful at doing this. Last time, mileage was only showing 25-26. This is concerning to me. I have no codes other than the CEL for MAF from running ORM and also running EHM since before 1000 miles on the odometer. Currently at 57000 and some change. Also, changed the fuel filter as it was due and to rule out a plugged filter which I have experienced issues with one time previously.
I want to make sure I am running at the mileage levels I was at prior to doing the GDE. I'm almost tempted to get a second ecu with the tune and leave the current one installed until I get the mileage back up. It would seem like a waste to "only" return to the mileage level I was at before the tune because a sensor was bad/fouled/erroneous. I did hit a deer in October to the tune of $7500 damage on the passenger side, but even after I picked it up from the body shop, it ran well and handled the same as it always did prior. Now I am wondering if some arcane sensor was caused a premature death due to this incident.
Pardon me if I overlooked any other posts referencing sensors, but I was wondering if there is some clarification of sensors that has been done? I have seen multiple posts where MAP and MAF have been interchanged incorrectly it would seem and is confusing to not only new guys but even people that have been here some time it seems are confused. This is what I think I know;
MAF is on top of the air filter, and when disconnected throws CEL, renders EGR inoperative.
MAP is the blue Bosch sensor on the back of the manifold, drivers side that gets clogged with soot and oil when the EGR and PCV are fully operational. I have witnessed this buildup and cleaned mine as well. This measures air pressure correct?
I have seen reference to a "Mercedes logo" sensor. I am assuming this is a sensor on the side of the airbox, semi hidden behind the hose to the intercooler or a radiator hose if I recall correctly. Purpose of this sensor and what sort of problems? Does this measure air temperature? I thought I saw a mention of this but nothing definitive and I can't find it again.
Any other sensors I might have missed?
Again, I just want to know what to look at before I tune the ecu but don't realize the full potential of the tune. I notice some have had issues with brakes dragging and that certainly is something I will address; I've tried to compile a list of electrical and mechanical things to look at as well. I'm going to pull my intercooler hoses off and fully inspect them, I don't recall there being a wind storm at the front of the engine when idling before, but I don't drive it very often and am only going by what strikes me as odd compared to the other times I've performed maintenance on the CRD. It is possible the replacement intercooler could be leaking which causes the wind storm at the front. Or it could be my imagination. The clutch fan could be on its way out as I've read in another post, causing excessive drag too. In the event there isn't anything mechanical or fuel related, I would suspect faulty or failing sensors may be the culprit. Suggestions?
What is your operating temp at? Ensure you do not have a boost leak as well. I only ask, because due to a failed thermostat and a boost leak I was way down on mileage (25 highway calculated).
I was operating at 154* F according to scangauge and VH (viscous heater) was constantly running. All this added up to bad MPG's
Boost leak was from the factory intercooler and looked like it was a factory defect and had probably been leaking since it left the assembly line:
kapalczynski wrote:
Original problem was while in cruise control or even manually controlling throttle up a steady slight incline, jeep would surge between medium boost, little boost, medium boost, little boost,etc. Also was only reporting 25mpg hwy (30 on the lying mpg display)at 65mph.
I tracked down my issue to a boost leak in the intercooler. It appeared to be a factory defect as there was no damage to the intercooler, it was NOT leaking form the plastic end caps or seals and was leaking from one of the aluminum cross tubes at the joint with the metal part of the end cap(bad sauder/weld).
*Interesting to note, after cleaning my MAP sensor (coated with oil/soot sludge buildup) i expected to see a large ammount of buildup in the intercooler (90k miles on vehicle), but only found a very thin coating of slick black oil (about a teablespoon after it all drained down to a corner overnight).
I just finished the new intercooler installation and the mpg display is looking better (though it used to be off 5mpg at hwy and about 2mpg in city and may still be). The surging is completely gone and she drives so SMOOTH. Power was about the same, but quicker boost response from non/low boost state.
OLD INTERCOOLER
PRESSURE TESTING
MAP SENSOR - In case you were curious this when when I got the vehicle around 89k miles. Also, vehicle had nearly died(felt like I had NO boost and black smoke out the tailpipe) 2 different times before cleaning this. I haven't had a issue since the cleaning (8 months now).
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