Hi, All

I'm new to PSDs and to the board, too. Did a search on cruise controls and didn't find what I need.

I just got my 96 on the road - 7.3 turbo PSD, Auto, long bed, 31.5's, dual 5 inch stacks, EDGE programmer. and it has about 200K on it. Starts easily and is extrEEEmely strong. Well, compared to my old DUDge 360 gasser.

First, it only gets about 14 at 60 cruise, flat road on the Ohio interstate. I'm disappointed with that, since many others have said they get or exceed 20 MPG. I'd like to figure out what to do to get more out of it. BTW, at 60, it's cranking 2000 RPM. I'm not sure what rear end gears it has but 2 grand aint all that hateful so I would imaging it has something longer than 4.11s.

Anyway, with the cruise set, the engine surges between 2000 and 2200 RPM and it does this all the time. The speedo sets rock solid on 60. Now, I am familiar with cruise controls and automatics and I don't believe this thing is normal. My other vehicles don't surge at all, especially on flat level roadway.

Does anyone have any thoughts on my 2 problems ?

Roger
Central Ohio

 

Whoever told you that they get or exceed 20mpg is flat out full of *****. With the exceptio of 1 or 2 trucks most peak at 18, but some only get to about where you are. Throw a trailer on and some go down below 10. 14mpg is about right for the way your truck is set up. If you are running 2000rpm at 60mph then you have 4.10 gears, as that was a very common gearset then. If you want better mpg then you need to go down to a 3.55 gearset if you can find one. Over 2000rpm you're getting into the engine power band, but peak economy is below 2000rpm.

For your surging, have you ever done anything to beef up the transmission? I sure hope you have since you put on the crap Edge programmer. A 200k E4OD running with a chip with a REALLY crappy trans tune (like yours) is asking for death. The fact that the speed isn't changing, but the rpms do tells me that its starting to slip. What does your fluid look/smell like? What is your trans temp? Surely you have a full set of gauges. If you don't well......I guess your truck got to 200k, so it had a good run.

 

I forgot to say that it is 4WD and for the most part, the 4WD seems to work well. At times I have a bit of trouble shifting HI to LO on the transfer case but can manage most of the time.
Someone on the SD board suggested the TC might be locking and unlocking but being new to this type of truck, I'm in the dark on that.
I haven't been able to hear anything moving, locking/unlocking due to the noise level from the twin stacks. There is no muffler or cat so it sounds like a class 9 semi - loud. In fact, on a long trip, it gets old. I learned about that when I had a Corvette with side pipes. They let out at the back edge of the door, right under your ear.
The truck has about 200,000 miles on it and I don't know if there was ever any service done to the tranny. The gal I got it from had it for several years and did nothing to it. And she was not able to locate the fella she bought it from to ask any questions. I guess I should do a title search to try and locate him.
I haven't looked at the dipstick to see what the fluid looks like and it's in the shop now so I won't have access to it for a few more days but I will look into that. However, what I've experienced in automatics slipping, this one doesn't feel like it's slipping. It pulls extremely well and the surging seems only to be at hiway speeds.
If the TC is locking/unlocking is there anything I can do or should look for to remedy other than pull it ? What are your thoughts on putting some LUCAS in ? What about the "lock line" and (possibly) forcing it to lock ? Would that tell me anything ? I understand that the lock command comes from the engine control computer so I'm wondering if there might be a bad sensor or the computer itself is bad.
What is the difference between the EDGE and other chips/programmers ? And why is the EDGE so bad ? I have to admit that I know nothing about programmers other than to know that they exist and everyone seems to have his own opinion on them. Tell me more about your opinion of the EDGE other than to say that it's a piece of crap. At this point I have no opinion on it nor do I take offense at your comment about it.
The only gauges on the truck are boost and EGT. Boost runs below 5 most of the time unless I put my foot in it and then it only gets up to about 10. EGT is typically 5-700* until I start up a hill or pull a load and then it might rise to about 1000. I've never seen it over 1100. I do know that 1200 is the limit of what I should see for any extended period of time. I do plan to get a transmission temp gauge and a REAL water temp gauge.
Any other gauges you suggest I install ?

Roger
Central Ohio

 

[QUOTE=powerstroke73;3229704] If you want better mpg then you need to go down to a 3.55 gearset if you can find one. QUOTE]

You will be happy that you were getting your 'bad' mileage compared to slugging along with the 3:55's ~ especially with a load.

 

You should never let your EGTs get beyond ~1250F because the turbo fins flatten out from the excessive heat.

 

[QUOTE=Pagnew;3229879]

If you're getting up to 20k GCW then yeah its gonna suck. My truck with 3.73s pulls well, but even still I'd prefer to go down to 3.55s as the towing change isn't going to be drastic, but should be good for 1-2mpg at highway speed. Sure 4.10s are going to pull a house down, but unless you're towing REAL heavy every day they're a complete waste.


Now back to the OP, there is a manual TC lockup switch that overrides the PCM and sends a constant voltage to the TC telling it to lock. If you suspect that is your issue then wire it up quick and head down the road. You'll know quick if thats the problem. As for your service issues, why are you even wasting time trying to track down previous owners? You own the truck now, and anything they did was probably done a long time ago. Own up and change all the fluids. Thats the first thing I do whenever I buy a truck, every single fluid comes out and gets changed. This way I KNOW when it was done last and that it was done right. Hasn't let me down yet.

As to why the Edge is bad is because its an off the shelf programmer. You can chose to believe me or not, but I've run the Edge Evo and I was one of the beta testers for the Juice/Attitude for the 7.3L. I've also got a 4pos flip chip from DP Tuner, so I have direct comparison. I ran the Juice/Attitude both with and without the EVO. Overall the engine ran louder (read excessive rattle from advance ICP tuning) and made ok power over stock, but was sadly disappointed with the trans shift scheme. The other thing is that if you don't like the programs then tough crap. My DP chip is custom tuned to the mods I have and what I want to do with the truck. My DP in the 80econo mode is stronger than the EVO set on 100hp with the Juice/Attitude stacked on level 5/5. My 120hp race setting blows it away. The best thing is if I mod the truck more or decide I want newer/different programs, or just tweak my current ones its a simple deal.

Now if you are seeing only 10psi at WOT with the truck chipped then either your gauge line is kinked, you have a boost leak, or the truck is getting NO fuel. Stock trucks get 17-18psi at WOT, chipped should see up to about 28psi. Your EGTs sound about right.

 

Umm....yeah you can go beyond 1250*F without any issue. Now you can't sustain those temps, but you can easily run above 1250 for 30sec or slightly longer. I've seen 1400* on more than 1 occasion, like pulling the 5mi grade to the Tower City exit on I-81 with a trailer in tow on my 120hp race setting.

Think of it this way, when you use a torch the flame is 1600*+, but yet it doesn't melt or cut steel right away does it. You must sit and hold it on the steel, it then begins to glow, THEN it starts to melt/deform, and then it cuts. Same thing applies to the engine. The parts must be heat soaked first before any damage can occur. 1250*F is still the max temp you can sustain and run at indefinetly.

 

Per POWERSTROKE73 -If you're getting up to 20k GCW then yeah its gonna suck. My truck with 3.73s pulls well, but even still I'd prefer to go down to 3.55s as the towing change isn't going to be drastic, but should be good for 1-2mpg at highway speed. Sure 4.10s are going to pull a house down, but unless you're towing REAL heavy every day they're a complete waste.

Sorry - I need to get OT to respond

Disagree -the 3:55's are not worth it - especially for only a 1~2mpg gain on the highway. Any kind of a precieved gain will be lost anyway when accelerating from a stop or passing. And with a load - it certainly doesn't get any better.

Now, if you do any kind of decent off-roading, again, you'll be disappointed...your truck is 4X4 ...stay with the gears you already have. Keep the truck versatle. Otherwise get a two wheel drive truck if you don't need an off-roader,want better mileage, and are going to keep it on the highway.

Changing to a 3:55 would be the true complete waste for a 4X4 version

 

i agree on leaving the gears alone...I mean honestly you just bought a diesel truck....i really hope u didn't buy it on the hope of getting 20 mpg, and i hope u didn't buy it just to drive it around, IMO u should pull the sh** out of that truck because thats wat it's built for...and ur getting 14 which is great if u ask me...ours gets 10-12...pullin a heavy load more like 6-10

 

I get damn near 20 MPG in my diesel truck.

 

I agree that its not going to pull near as well without the 4.10s, but if he's not pulling heavy all the time he's just wasting $5/gal fuel. If the truck spends most of its time driving around unloaded then 3.55 gears are well worth the money. The alternative is a Gear Vendors or US Gear unit which would let you keep the 4.10s for pulling, but get a much lower RPM at highway speed. The downside is that they're around $3000, but at todays fuel prices it can actually pay for itself unlike a few years ago.


It used to take close to 100k for it to pay itself back, now its about half that.

Say you get 14mpg now, and the GV unit gets you up to 18mpg. Assume fuel is $5/gal (current price here).

$5/gal / 14mpg = $.357/mi cost.
$5/gal / 18mpg = $.278/mi cost.
$.357-$.278 = $.079/mi savings.
$3000cost / $.079/mi savings = 37,974 miles to pay for itself which isn't even 3 years of light driving.

Just another thing to consider if you do still need to tow heavy.

 

If you get some 3:55's you might get 21mpg - hehehehehe...

 

yeah, the best way to use a diesel.....I mean, maybe different choice in truck would be well worth the money if that were the case.

Anyway for what it's worth - To the OP:

Powerstroke73 usually knows what he talkin' about - just havin' some fun here!

 

Daily driving a diesel truck seems to be the "cool" thing to do anymore, though I do the same thing. The only reason I can do it is that I'm on the road 6mo a year so my fuel costs are low, plus I need the truck for occasional towing. Though in my defense I was driving it before it was cool to own one.


But if someone really wants to save some money a VW with a TDI diesel is the ticket (yeah I know they're chick cars). 50+mpg and you don't have to replace batteries every few years. If I didn't travel for work there'd be one sitting in my driveway.