Can anyone help me trouble shoot this? I bought this conversion 2 years ago, and have put 1500-2000 miles on it, and NOTHING I try seems to make any difference. It seems to run great, and has yet to give me any problems other than crappy mileage. No matter what I do, I can't seem to reliably get it above 15 mpg. I have tried going no faster than 55 miles per hour (It runs at approx 2350 rpm at 55 miles per hour) and not going above 2000 rpm when I take off. I use bio-diesel mostly, but I have tried dino-diesel to no effect also. I have street tires on it that are approx the same circumference as 31-10.50s. I have changed my oil to using Mobil1. The engine has approx 87-88k miles on it. The install was done by a gentleman who has done 17-18 of them, and looks very professional, and as I said it has run great for 1500-2000k miles..

Help?

(I'm new here, and if I'm breaking any forms of etiquette, let me know please.)

 

have you tried the basic stuff like air filter, fuel filter and fuel treatment? I know they make seafoam for diesel. you could have dirty injectors or carbon buildup and any good fuel treatment will help.

 

I have that motor in a 91 p/u and get about 27mpg on the hwy. I need a little more information like intake, gearing, exhaust etc. I have a 3" cold air intake (home made), a 3" exhaust, no muffler, intercooled with 32" tires and 4.10 gearing. I don't know what these engines are like with the stock exhaust/intake on them, but I could run a 34" tire with the gears I have and still be in the power band on the hwy. In fact I'm looking to keep the 32's but trying to get some 3.90 gears. The intercooler really made a difference but it takes some imagination to mount. (and it helps if you don't mind your truck having a little of the 'mad max' look!)

 

Redfusion: Yup, tried everything except the fuel treatment. If you think of any other stuff like that, let me know.

91diesel: I still haven't figured out what my ratios are (I'm still new to working on stuff) I have been wondering if cold air up front and improved exhaust would improve things. I have also thought about intercooling, but being new to working on cars, It seemed a little daunting. Did you use the OEM cooler from a 185, or adapt one from another platform? What is your power band, by the way? I thought possibly that the 2350rpms might be to high, and that I might be running outside the optimal range for the engine. And no, I don't mind a little bit of Mad Max...It's a tool, not an ornament.

 

regarding engine rpm of intercooled 1KZ-TE:

at 100 kph it's around 1700 rpm, at 150 kph, it's around 2500 rpm. tires are LT285/75R16 and final gear ratio is 4.30:1

 

Need some more info...
How old are the glow plugs?
How old is the fuel filter?
Do you have any cold start issues?

I definitely think you should do a couple of fuel treatments. One in the tank and one in the intake. This almost always helps. After that you will need to change the parts above. I would also check the diesel forums.

 

I think an intake and exhaust will help with the power/gas mileage alot. the other factor is also the way you drive- I could get 15mpg if I tried! Seriously if you spool up the turbo leaving every stop, that'll kill the mileage. If you don't mind a slight hijacking of your thread, I post some pictures of my set up when I get back from vacation. As far as the IC I used a front mount set up, I don't think the factory ones are very efficient, where does all the hot air go?