Truck is getting around 10 mpg on average. when it was newer it would get 14.
The engine was completely rebuilt (by me done right) the only aftermarket part is replacement injectors from 5.0 motorsports, who i called and they assure me the injectors are drop in replacement for the leaky stock injectors.
But the truck was getting bad mileage before the rebuild. has almost 400,000 miles on it. Oh fresh transmission also.
Im attaching my log and config, i think the maf is bad but im not sure.
Timing set is probably worn to heck, get a new ProGear set and dial in cam to 112 degrees on the intake centerline, stock is awful at 119-121 (new!), so a worn chain will be closer to 124 degrees!!! Get a new fuel pressure regulator if you haven't already.
Even with stock leaky injectors I commonly get 13.5-13.9 highway at 75 mph (3.73's and 265 75 16's)
Check out my monster 454 thread. I never thought it would get this long....
My personal best, 15.1 mpg....
Originally Posted by mwg2600
Last edited by n0dih; 11-23-2011 at 03:38 PM.
As rich as it is getting on decel it screaming the fuel pressure reg is leaking. You may never see gas, but take a look at the intake, is it wet on the seams where the upper intake gasket is?
Also, is it hard to start warm/hot and easy to start cold? other signs. These engines are notorious for bad fuel press regs and injectors. At least you got the injectors!
I changed the regulator when i rebuilt the entire engine. Its all new cam and lifters and timing set. checked it was at 118 degrees.
Im going to get a longer log with a wot hit. ill get some carb cleaner and check for vacuum leeks.
Why are the long term trims getting to -10 at idle? I did replace the fuel pump a while back, after that the fuel psi is in spec. (checked while driving with guage under the windshield wiper.
I have seen most L29's tend to be on the rich side, even the L31's.
For a start, change the O2 switch points to 450mV, see if that brings it inline better. And running single bank fuel control helps too.
I want to find what changed and fix that before i start tuning on it, again. years ago when i first started tuning i got the JET DST tuner. Ive since lost the stock file, but ive wondered if i accidentally changed something with the jet software that hpt can not see.
If i get the computer flashed back to stock ( a local shop can do it for $80) would i need to buy another credit? I think its the maf, i saw what you mean in these new logs where it spikes rich on decel. whats with that?
No vacuum leeks, but yes it has some discoloration where the upper intake and lower meet. The engine only has around 6000 miles on it since rebuild.
I was able to look and see that both cats look like new when it was apart. could the STOCK muffler be clogged?
Ive never had any problem that took me this long to diagnose ant its my own truck.
In the first log towards the end i pulled it down into 3 and then 2 off the gas getting off the highway, the o2's go all the way rich...
Last edited by mwg2600; 11-23-2011 at 05:32 PM. Reason: forgot to attach the 2 logs
Is very possible that Jet DST was able to change something that HPT isn't set up to see.
Look in the repository and see if any 2500/3500 454 files are there.
I have a .bin for it, which HPT can read, but I don't know how HPT does the flash. My .bin files are missing certain things that might cause you grief if you flash with HPT. Chris or one of the HPT crew might be able to help advise how HPT does a flash.
If same OS, it should be fine, but a full flash might not be.
N0dih you have to remember the HPT is probably the best software on the market for a newbe. DST has many issues that a newbe would be lost with. It is hands down the best for the guy tuning his vehicle. We all know that you can find more powerful software on the market, but it is more than a newbe needs
Find a stock .bin or stock .hpt file, you can do a compare to your read and see what is different.
You can import those changes to yours or you can just flash it in IF the OSID is the same (do a cal only flash).
Look and check that all segments are the same as yours to be pretty safe.
There is only one tune in the repository for the 454. I have gone through and compared my tune to the repository tune except for a fey tiny differences there the same. As far as hpt can see.
The dst is laid out so that to see all of the settings it takes an hour. hpt found out how to make an user interface, thats not 300 drop down menus.
Send me any stock files you have please! Im tempted to get it reflashed, but i dont know if i will be able to tune it without buying more credits. and im afraid id spend the money and it not make any difference.
I should probably put a wideband bung in it, and put in my lm-1 I haven't been able to get hpt to read the same as the gauge, the voltage offset lesson gave me a headache.
Post your .hpt file so I can make sure I have the right OS for it. I have a bunch of 98-00 454 files.
"stock" tune
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