Well ive got a 95 gmc k2500 6.5td 4l80 8800gvw truck. 4in turbo back straight pipe no cat #9 fuel resistor fsd pmd relocator mechanical waste gate marine injectors and running 14psi boost. Ip is rebuilt new lift pump and all new fuel lines. My issues are this. At high rpm above 2400 I get a random misfire that very occasionally just stalls. When it stalls it restarts very hard. Makes plenty of smoke during those cranks and no air in fuel. the other big issue I get is above 82mph I get a check engine light. Right before it comes on it caughs then goes to limp mode. It does it when engine is cold warm or hot no difference. after it happens I cant get any coal out. And for those who want to say a 6.5 wont roll coal dont be fooled. Dyno puts me just under 400hp at the rear wheels so obviously when it runs right it does great. my oil pressure switch is bypassed so not losing power to lp. Anyone have any ideas where to look? The only thing I haven't touched is the noise filter. Btw these issues existed before and after the upgrades.

 

I'd like to see your dyno sheet.

With aftermarket turbo and extensive mods I didn't break 300hp. With all that knowledge you should be able to figure your problem out in short order

 

Not to rain on your parade....

First off you need to find a dyno operator that has a clue...

What kind of dyno was being used?

Dynos lie either by accident or on purpose Do Dynos Lie? - Diesel Power Magazine

Even day to day variances same truck can vary HUGELY

Unless you are modded to level of mods you see in my signature you aren't even seeing 200Hp ACTUAL RWHP.

Only 6.5 I KNOW FOR SURE breaking/making 400Hp rwhp is Bill Heath the world record holder fastest 6.5 2 time Bonneville record setter for the 6.5. his is twin turboed and number of things yours does not have.

My last run before engine change on a custom 4 year build (long story) had me just about 275 or so rwhp and I had then more than what you cite on yours now which isn't much if you are still running your GM turbo.

That is real info from someone with MUCH been there done that 6.5 experience no whizzing match is needed between us why you aren't actually getting the 400 rwhp you saw.

My top recorded speed then by GPS was 121 mph with more to go I came to my senses and pulled back, because for those kinds of speeds you really need to be on a track like Bonneville no other traffic in your way to contend with, and have tires for those speeds and a cage and a lot of safety gear cause crap happens real fast at that speed.

I'm guessing now I should be getting to or slightly better than 300 or so rwhp, but I've pretty much met my need for speed & Hp, my truck pulls my 12K# backhoe on a 6K# trailer for a 18K# load the short 157 miles I might need to move from my home to my camp over hilly terrain and keeping with the traffic, that is good enough for me and all the power I need, maybe if I win 1.4 Billion power-ball tomorrow I'll see just how fast a 6.5 can be made to go .

The 6.5 is a IDI engine and has limits for power unless you do some SERIOUS strengthening. If you want 400 Hp be ready to shell out some serious coinage for upgrades to the 6.5 or find swap to a direct injected engine as your base platform that can make that kind of Hp with a lot less effort.

So back to your issue of +82 mph, and "missing at power" can you post more info and maybe post it with some paragraphs so it is not so hard to read what is going on ?

14psi boost from a GM turbo is actually robbing you of power due to high back-pressure internally in that turbos design.

I don't see mention of an IC listed or WMI for post turbo charge air cooling, so you are hitting high IAT which causes fuel limping, with hi boost comes hi IAT above about 285F and on hot day that can happen quick when you start boosting above 11 psi or so, limping you to max fuel 50mm from the IP.

Since you have a mech WG control I suspect you are also hitting some sort of WG control failure mode; tier 1 defense there is cut boost, it can't since vac control is disabled now, so tier 2 defense is cut fuel, and go limped for max of 50mm fuel until engine is shut off and coding situation has been cleared. BTW high IAT limp fuel does not code, and you have to be connected to a real-time capable scan tool to read the data to see when you have encountered that, it clears on engine shutdown.

I don't see a reprogrammed chip for your PCM so you are fighting GM factory limits and without a chip your IP can't deliver max fuel from the IP and your "Marine" injectors aren't working to full potential, any gains there with current set up would have been same with a set of fresh factory injectors, correcting hi-miles on the removed set; 6.5 injectors on average are good for 100K miles.

Did you do a TDCO learn/offset after swapping to the #9 resistor if not, your PCM does not know you have any change in value from what was removed.

Big myth for resistor swap, bigger #=more power, yes & no; that is a calibration resistor used when setting flow from the IP on a test stand, so that it meets the delivery specs for good delivery from an IP at a fixed load/rpm under a specific load profile your PCM will never request from the IP.

Once installed and if a TDCO learn as been commanded the IP delivery may be marginally more for a limited space of time at first load demand from the APP pushed to the floor.

If you had a factory fresh NEW IP with no wear you might with #9 resistior see a +4mm adder to the first WOT demand request but you lose that when you meet the desired speed as the PCM will then cut back to the program fuel curves/limits and that nulls out the #9 resistors impact. A #9 put on a overhauled or worn IP you might not see +4mm net effect might be less depending on the quality of the overhaul or wear in the IP.

Those calibration resistors are used to make up for wear and tear in an IP overhaul, or in new IPs to "tweak" machining variances that might be putting out more or less fuel required of the test spec, keeping in mind the spec is for meeting not just minimum power but also emission specs./limits when connected to a PCM in vehicle