I recently downgraded from my beloved powerstroke due to financial reasons and found myself owning a 6.9 IDI. After hours of research on these things it is apparent that the new rule will be patience while pulling hills,towing,ect. I never could have imagined that a difference of 50 hp would be so painfully slow.

So here's my confusion, and appreciate any insight -

86 f250 6.9 IDI, about 200k miles, changed injectors, return lines, and glow plugs, did the ATF in the filter trick and now she runs like a top. There's minimal smoke, only at full load and high rpm. The truck is slooooow. I bite my tongue when approaching a mountain (live in the WNC mountains) knowing that pulling a 7% grade at anything over 53 mph with an EMPTY truck is a pipe dream. Miserable it's going to be pulling 9000 lbs.

I installed a pyrometer in hopes of turning the fuel up a hair, an autometer gauge. For curiousity sake and a reference point I found a particular hill that I frequently travel and this is what happened:

Note that the probe is placed in the driver side manifold between the 1st and 2nd most rearward cylinders. Idle temp is 250, cruise at 60mph is 700-1000 so I believe it to be accurate.






Is it ok to live with this? Seems potentially catastrophic...

 

Try advancing it a hair and see if that helps(or makes it worse). Timing plays a massive roll in power and EGTs; too advanced and it'll be clattery(lower EGTs usually though), too retarded and the egts will be high and you may get whitish smoke.

Edit: you are definitely not making much power here, which is pretty common for an un-tuned engine. My non-turbo 7.3 IDI truck will go up the steepest hill I found around here at 70(though that's the limit); on the flats it has no trouble holding 70. Empty that is.

If, after tuning, you still need more power? Put a turbo on it. The basic Banks or ATS kits will give you a safe 5-7 PSI, and it makes all the difference in the world. Easy 50-80 HP right there.

 

If you're pinning the needle on a stock setup you're either POURING out black smoke or there's a bad connection somewhere.
Edit: what does the needle read with ignition ON, engine OFF?

Timing is very important with these bad boys. Definitely a good first step. Often when someone sells off an IDI it comes with a worn-out IP and injectors, which also make for slower going. But don't worry too much about them just yet.

 

The pyrometer reads correct for ambient air temp while engine is stone cold. I'm sure the manifold is glowing quite cherry red with these numbers, maybe I should put a camera in there and shoot a video during a steep pull. There is only a slight hint of black smoke during this high temp/load.

Injectors are remans so I'll creep up on the timing and see what happens. Thanks guys, I'm still trying to wrap my head around diesel combustion dynamics as many things seem inverse from spark ignition/gasoline theory

 

That's crazy pants. I ran the **** out of my N/A and opened the exhaust up with a big cold air intake, turned up the pump two flats and never got EGTs like that. I'd be just over 1100* when smoke was easily seen and if it was over 1200* it was too dark outside to see the cloud coming out of my tailpipe.

It does seem like your gauge is reading correctly at least for normal driving.
Assuming those EGTs are correct, you really need to stay below 1150* other than spiking occasionally.
Aluminum melts at 1220*.

 

What kind of exhaust do you got? I put a straight thru hi flow Walker muffler on my IDI, and it reduced EGT's 200-300 deg F.

 

"downgraded from" "found myslef with a 6.9 idi"

hey man your' in the idi club now

they aren't so slow .. at least when tuned up right anyway ..

like the other fellers suggested .. get the timing right .. and check the condition of your injectors ..

open up the exhaust ..

i have NA motor and keep up hills just fine .. often passing other small car motorists along the way .. i can keep it steady 70 or better easy even up a steep grade empty ..

and i'm all stock with the oem muff ..

for me .. making good speed up a hill is about not letting up .. i get light aceleration and then back off a hair and keep the momentum .. if i get stuck behind a car doing 55mph and have to slow down .. then it's hard to regain the speed .. it will do it .. but just very slow acceleration up a hill .. just have speed going in and hold it ..

and yea those temps are insane .. i can't imagine that's accurate .. alum melts at like 1,200 degrees .. so you got a misreading gauge or some tuning to do .. or fixing to do soon ..

congrats the 6.9 is a beastly motor .. you'll grow to appreciate er'

 

Down grade? Ouch! I love my 7.3 and I can't wait to get a 6.9 to play with! Getting hard to find

 

Down grade? You my friend have just upgraded in a big way. Welcome to brave new world in a truck from not so long ago, where a single 12v wire is all that's needed to keep your truck running smooth down the road. And all the diagnostic equipment you need to keep your truck happy is your eyes ears and nose. A basic tool kit will fix most of your truck. And you won't need novellas written by the And if your crafty and thrifty power can be had relatively cheaply.

You mentioned in your very first post the biggest problem with the powerstroke. It's a financial nightmare. I have an 89' idi that I've dropped less than $1000 into in the 15 years I've owned it, which starts every time I turn the key(it is my Sunday funday truck, so low low miles). And I have a 2002 powerstroke that I've put nearly$5000 into in the 9 months I've owned it. Preceding the 2002 I had a 2004 6.0h-no that had been ridden so hard by the PO, that it would have been cheaper to buy a complete engine from Ford than fix all its individual problems, to the tune of about 14,000. Bottom line, they are just too expensive to maintain.

At the end of the day when you get your self out of whatever financial burden the powerstroke continued to. By a nice little injection pump from R and D slap a turbo on it, junk yard or new. And you could have more power than a stock chipped powerstroke a cooler looking truck, and you can take the crank position sensor, out of the glove box and stop watching ipr and icp values while you're driving and keep your eyes on the road. (assuming you were driving a 7.3) And when the truck randomly dies while driving, it'll mean you that for whatever reason fuel isn't making it to the injectors. And you won't need a computer and a guru to help you track it down.

Simple is beautiful, not to mention less expensive.

In case you're wondering why my daily driver is a powerstroke, after writing an idi love letter; I'll give you two reasons. One, road salt, can't bear the thought of my baby getting any more rust. And that's like practically 10 months a year here on the barren tundra. Two safety, the newer truck has head restraints, air bags, and a chance to walk away from an accident. With range rovers blasting all around my area, with 16 year olds behind the wheel i just can't bring my self to drive the old girl except on the weekends when the 16 year olds are killing people on the water instead of the roads.

Give it time you might just learn to love it too.

 

Got me choked up ^^

 

Thanks for all of the replies guys, it is greatly appreciated. It almost sounds as if my lamenting stepped on some toes, didn't mean to. As it stands now I've got more in it than it would ever sell for so anything additional will be a loss - unless I keep it for a long time. And yes, I'm trying to give it a chance, a chance to learn to love it. The good thing here is there isn't a speck of rust on the body or chassis and it's a fairly clean body.


I bought the Ferret timing light converter, a slick unit, and it works well. The timing was at 2* BTC, now it is at 9*. Wow, what a difference! It pulled the same hill 11 mph faster, runs 20 degrees cooler and actually accelerates with more throttle.

The EGT's are now running 1320*, major improvement over the 1600+ temps before the timing correction. Everything including the exhaust is stock. I'm still wondering why those numbers are so high...?

Of what benefit is there to buying an R&D IP over my old unit now? Not sure if I can justify dumping another $750 in it for a minute improvement. Could I not turn the fuel up a hair to compensate for the pump's old age? The injectors are new, I see now it is recommended to change the IP at the same time for some reason.


There's a plentiful knowledge base in the archives here, my thanks to those who contributed. Links to any other past threads/articles on the subject are appreciated.

On a side note - for $550 I drove an 84 IDI home last week for parts. Seems fairly healthy too. I admit, you couldn't buy a spare powerstroke engine,trans,xfer case for that price.

 

Very possible someone turned the pump up. A plugged up muffler, clogged air filter could really make it suffer too. Get some 2.5" or better on there with a good diesel muffler. Make sure the cold air intake tube is hooked up. If nothing else, could turn down the pump a smidge. Or you could always add a turbo. Aluminum melts at 1220* but these have piston coolers for a reason. So long as you werent running that hot for minutes at a time, its likely the 1600* didnt wreck anything too bad.

Got a link to where you bought the meter? I really need to buy one

 

I believe this is it - Ferret Instruments V765-02 Fuel Injection Tester - Fuel System Tools



I've read a lot on here about the threat of high egt's. Where the status quo seems to be misled is that egt's are not a direct indicator of combustion temperature, only a representation, therefore it is safe to assume for all other variables being the same it is a good "guide" to go by. In this case it is obvious that much of the combustion was taking place on the exhaust stroke and in the manifold, which isn't a threat to the aluminum piston, but rather everything downstream - valves and exhaust manifold. And as it would be obvious, the flow rate of those hot gasses plays a big role in the sustained abuse - i.e. more heat transfer into the components with a turbo vs NA.

In the end an egt number isn't always an egt number - while taking into account other variables - cfm, dynamic compression, lead timing, ect.

I'm replacing the muffler with a 40"x2.5" glass pack this weekend and then see what the numbers look like.

 

You didn't step on my toes, apparently I just needed a reason to step up on my soap box. And you are correct, as long as your current pump is good, an R and D probably won't be of much benefit unless you add a turbo. Then the fun will begin! FWIW, I don't have a turbo or big pump on my idi either. Every time I save up the funds to do it, my powerstroke slaps me in the face with another grand on maintenance. I think the rumor that powerstroke will go for ever and never ask for anything, is just people confusing the the pre '95 7.3's and the post '95s. I'm not saying powerstroke trucks suck, they really are pretty great, just more expensive. Dollar per mile the idi is probably the best deal on the road!

 

Put on some straight through exhaust on that bad boy. But your EGT's are still crazy high even for stock exhaust.