Engine/Transmission (1994 - 1998) Fuel Mileage down

[nfox]

My friend has a 96 auto with 47,000 miles and a few mods, and he has noticed lately his in town mileage dropped 4 miles to the gallon and when he steps on it, it smokes black way more than it ever has since he has owned it, He said it starts like it always has, he said his boost pressure and egt are fine. His auto transmission is giving him fits, is there any way possible that cuold be draggin on the motor and killin his mileage? Any thoughts would be greatly appreciated!!!

 

[JohnE]

Summer air temperature is my quess.

My mileage is down in summer, too. The last I checked it was only 22. 5 with almost all freeway driving. Normally, I average 22 mpg.

My best mileage is in long winter driving trips.

 

[illflem]

The black smoke indicates to me that his timing may have slipped.

It happens.

 

[nfox]

Mileage drop

My buddy just checked his mileage and 200 highway miles he used 18 gallons of fuel, and he has 3. 54 gears, his highway mileage was always 18 to 19mpg. He pulled the dipstick and checked the engine oil to see if there was any diesel fuel in the crank case and the oil was right at the full marked and smelled just like engine oil. Checked air cleaner and k+n was clean and no blockage in the airbox or tube going to turbo? The is no fuel leaks. Tommorow he is going to the local dealership and they are going to check the timming to see where it is set at and set the valves, if that is all right what should we look at next? If one of the injector tips fell off how the motor sound and run? All thats been done to the pump is they set the gov lever as high as it would ride up on the stock camplate. Any other suggestions would be greatly appreciated. Sorry for the long post.

 

[nfox]

Low Milage

My friend got his pickup into the dealership thursday morning and they adjusted the valves and pull the intake hose off of the turbo and the the fins on the cold air side the tips are bent over and you can see where it has been rubbing the compressor housing, OUCH!! He wants to go up a step in injector size from the stock 180 injectors, what would you recomend?

 

[shendren]

i would solve the problem first before i started adding injectors, etc.



how was the timing?



why were the blades bent on the turbo?

 

[jimk]

Re: Low Milage

Originally posted by nfox

My friend got his pickup into the dealership thursday morning and they adjusted the valves and pull the intake hose off of the turbo and the the fins on the cold air side the tips are bent over and you can see where it has been rubbing the compressor housing, OUCH!! He wants to go up a step in injector size from the stock 180 injectors, what would you recomend?

I would look in the classified section and buy a good used turbo, and a set of 215 injectors or dds. Check all of the hose clamps on the inner-cooler lines. I like to run 17 degrees timing or a little more, he will probably wont 15. to 16

Before the power if increased consider the automatic, will it stand a increase in torque? The automatic when properly modified will work and last a long time. good luck Jim

 

[nfox]

bad Mileage

The dealership checked the engine timing and it is at 13* and went over and looked at his turbo and i didn't see any bent fins ,but one fin has a crack from top to bottom. They are going to pull the injectors and pump and have them checked out. The truck has no fuel leaks and it is not going into the crankcase, where else could it be going? His pyrometer probe is located about 6" down from the turbo in the downpipe and when i rode with him for the first time i noticed when he stepped on the go pedal is was nothing to see 35 psi of boost and the egt's would be at 1300*, how hot would the egt's been if his probe was in the manifold where is should be mounted? He said the few times he pulled the sled with his truck, the egt guage would read 1500*, OUCH!!:--) Do you think from egt's running that high that his engine compression could be low? Please chime in. Oo.

 

[FreeBMW]

i have hear that probes in the downpipe can read 300deg COOLER that ones located in the manafold.





FYI Cummings says that 1250f in the manafold is the absolout max that is 100% safe.



The max i have ever seen on a dyno 1/4mile run 1st through 5th at WOT was 1420 and that was only for a few sec.







IMO he is lucky all he lost was the turbo...





Happy motoring

 

[nfox]

Bad Mileage

The dealership pulled the pump and injectors staurday afternoon and monday morning they are going to a diesel shop to get checked out. I took a look at his injectors and they are really sooted up bad on the tips i could barely see any of the spray holes. One injector looked like it had some metal flakes on the tip of it, what could that be from? Will know more in a couple of days when the diesel shop tears into his pump, injectors,turbo. Later

!!

 

[shendren]

i'll bet the soot is from the timing. i'll bet his mileage problem is from the timing. crank it up to 15. 5. and the sooted injectors goes away and his mileage increases 3mpg... ... .

 

[nfox]

My buddy got his injection pump to the diesel shop and they ran it on there test bench and saw that there was a 60% variance between the fuel coming out of the pump lines. They tore the pump apart and got the problem corrected and rebuilt his stock turbo and sold him a set of 370 injectors. He just got the truck back from the local dealership on saturday afternoon on august 30 and took it for a test drive and the first thing he notice was the cruise control didn't work, nor did the o/d in the transmission. The second thing he mentioned was it pops out the exhaust when he fires the truck up. Then another thing he said it has a slight cough or stumble when he hits the accelerator pedal. Could the problem be a timing issue or being it's a 180hp pump that it will need bigger delivery valves to run the 370's? Any ideas are well appreciated!!

 

[JohnE]

Did the pump shop also reset the governor lever and adjust the plate position?



Where did the dealer set the timing and by what method?

Sounds to be the 370 stumble though.

With a blanced pump and new injectors the fuel deliver part is mostly corrected. Mileage should be better once things clean up



No cruise or O/D.

Dealer forgot to hook-up the TPS, maybe?



Make sure your buddy uses copious amounts of injector cleaner to clear the soot. Give it a week and recheck.

 

[nfox]

He is running the stock camplate at factory specs, and has just raised the gov lever as high as it would go without the screw falling out. Far as timing the dealership supposedly set at 19* and it does not sound very noisy at all. I think he should talk to the pump shop and see if they have any idea whats going on. Any ideas would be very helpful.

 

[JohnE]

why?

Why did he raise the governor lever as high as possible? It kinda sounds as though it is dropping past the main fueling curve (lower ½" of the plate) into rack stop wild abandon.

Even a full forward position stock plate has less fueling than a #4 plate at full back position. At 3,200 RPM I couldn't hit 35# of boost and 1300° EGT pre-turbo with #4 fully back and a blocked wastegate.

Either something is fishy or you left off some important data.



Governor springs or stock?

Stock auto or rebuilt?

Blocked wastegate?

What was doen to increase the fueling?



Depending on how the 19° is measured it may be quieter.

 

[nfox]

I have rode in that truck a couple of times and in 1st gear foot to the floor it will turn 3500rpm no problem, and when he pulled the sled at the fair he was making 48 psi of boost and egts at 6" in the downpipe were at 1600*. Now his transmission is slippin real bad and when he flips his lockup switch the transmission shudders really bad. I wasn't around when they put the twin ram manifold on and then they raised the gov lever as high as it would go. Sounds fishy to me also. Oo.

 

[nfox]

fuel milage down

My buddy said the tech at the dealership said they set the timing at 17*, who knows for sure, when my friend left with his truck the other night, he put it in gear and stepped on it, took off it popped out the exhaust 3 times and when he got to stop sign down the street stopped and took off same thing popped 3 times out the exhaust and away he went. He also mentioned that when the truck gets warmed up it doesn't do it as bad. Any suggestions?

 

[illflem]

Sounds fishy, it's illegal to set the timing to other than the Cummins specs, doubt if any dealer in the country would do it.

 

[nfox]

Timming

My buddy went to at diesel shop about 50 miles from where we live and they checked the timing and it was at 9*. So they reset the timing to 16* and it ran great for a day or so and now the truck will barely run and move itself, so back to the diesel shop to see what they figure out on it next for a problem.

 

[DMC]

Nfox



You might want to tell your buddy, if he keeps standing on that motor when its cold he will soon need a headgasket.



I guess he may as well get that transmission rebuilt to handle all of that power as well.







Good Luck



Don