Timing issue on a 7.3 IDI

[Snowturtle]

Thanks! I messed with it yesterday and, aside from some cussing caused by touching hot parts, it went pretty well. I started out at 6 degrees, bumped it once and ended up at 14 - it's sensitive! Backed it off and found that I was at 10. By then it was almost time for hockey to come on, so I left it there. Truck is running a little smoother and stronger! Still spikes EGT pretty easily, smokes a little less. Should I do it once more and back off a fraction? Or can I move on to the fuel screw now? One issue I have with the timing is that it jumps around a bit - is that normal? Maybe it's just the not-top-of-the-line equipment I am using.

One other question - can I run the truck without the air cleaner in while I check things. I had to remove the air cleaner box to get at that lowest IP mounting bolt. I left the top of the cleaner attached to the turbo, just rotated it up out of the way. I was going to start it then got cold feet and put it all back together again, didn't want to risk sucking something into my new turbo.

Thanks for all the help! I can't believe I have been looking for a shop to do this for years - not that complicated!

 

[DaveBen]

If your engine has a lot of miles on it, the timing will jump around. This is due to the loose timing chain on the cam. Beside replacing the timing gears and chain, there is not a lot you can do about the timing jumping around. It will not harm the engine.

 

[Jesus Freak]

If your engine has a lot of miles on it, the timing will jump around. This is due to the loose timing chain on the cam. Beside replacing the timing gears and chain, there is not a lot you can do about the timing jumping around. It will not harm the engine.

Well.... I'm pulling a Cubey..... there's no timing chain, it's gear on gear. You're fine timing it without an air cleaner unless there's a dust storm. As far as the jumpiness (lm guessing on this one) but I'd say it's a contact issue with a ground or the pezo thing. They say you can do 9.5 at 2000rpm, seems like 10 is pretty good. I'd be tempted to continue to fool with it.

 

[Big Bart]

Thanks! I messed with it yesterday and, aside from some cussing caused by touching hot parts, it went pretty well. I started out at 6 degrees, bumped it once and ended up at 14 - it's sensitive! Backed it off and found that I was at 10. By then it was almost time for hockey to come on, so I left it there. Truck is running a little smoother and stronger! Still spikes EGT pretty easily, smokes a little less. Should I do it once more and back off a fraction? Or can I move on to the fuel screw now? One issue I have with the timing is that it jumps around a bit - is that normal? Maybe it's just the not-top-of-the-line equipment I am using.

One other question - can I run the truck without the air cleaner in while I check things. I had to remove the air cleaner box to get at that lowest IP mounting bolt. I left the top of the cleaner attached to the turbo, just rotated it up out of the way. I was going to start it then got cold feet and put it all back together again, didn't want to risk sucking something into my new turbo.

Thanks for all the help! I can't believe I have been looking for a shop to do this for years - not that complicated!

Snowturtle,

1) You can run with the air cleaner off for testing as long as you are in a clean/safe area. So in a garage or on a cement driveway not next to trees. If something where to fall and get sucked (Leaf, dust, twig, etc.) in that could cause a major issue. Our intakes have a screen top which would keep something large from going down. Not sure if you have to remove for a turbo.
2) At 10 degrees you should be fine to change your fuel now. Just check again after changing your fuel setting a couple more times. If you keep finding your timing is 7-10* you should be good. Not sure why your seeing different results once your pump is tightened down. Maybe your pump advance is a little sticky or your rpm gauge is not too accurate.
3) Timing will effect EGT but not dramatically like fuel ratio or boost can. Once you get the EGT where you feel good try loading the truck or towing Something heavy to see if your EGT’s still are good.

Let us know how it goes.

 

[IDIBRONCO]

Our intakes have a screen top which would keep something large from going down. Not sure if you have to remove for a turbo.

I've seen intakes without those on turbo engines, but I think it's kind of pointless to remove them. Anything that happens to get sucked into and run through the turbo will be chopped up in small enough pieces that the screen won't be able to catch them.

Timing will effect EGT but not dramatically like fuel ratio or boost can.

Timing can affect EGTs pretty dramatically. Fuel/boost ratio will probably affect them more, but poor timing can be pretty dramatic for EGTs.

 

[Jesus Freak]

I've seen intakes without those on turbo engines, but I think it's kind of pointless to remove them. Anything that happens to get sucked into and run through the turbo will be chopped up in small enough pieces that the screen won't be able to catch them.

Wait....are you saying my turbo could be used to make HASH BROWNS! That's fantastic!!!

 

[Snowturtle]

Thanks guys! My EGT's are a little better and power is better with new timing setting. I'll back off the fuel screw and see what happens. I think I'll keep playing it safe and at least put the air cleaner partly back on. I'm working in my driveway, surrounded by trees

 

[IDIBRONCO]

Wait....are you saying my turbo could be used to make HASH BROWNS! That's fantastic!!!

I'll bet the pieces would be much smaller than hash browns.

 

[Big Bart]

I've seen intakes without those on turbo engines, but I think it's kind of pointless to remove them. Anything that happens to get sucked into and run through the turbo will be chopped up in small enough pieces that the screen won't be able to catch them.

Timing can affect EGTs pretty dramatically. Fuel/boost ratio will probably affect them more, but poor timing can be pretty dramatic for EGTs.

But the screen would stop a broken turbo fan blade or sizable nut or bolt from going down.

Yes if the timing is way off it will cause high egts, he mentioned above he is at 10*. My point was at 10* Vs 8.5* there would not be a big EGT heat issue. His issue is likely over fueling, over boosting, or bad pyro meter.

 

[Snowturtle]

But the screen would stop a broken turbo fan blade or sizable nut or bolt from going down.

Yes if the timing is way off it will cause high egts, he mentioned above he is at 10*. My point was at 10* Vs 8.5* there would not be a big EGT heat issue. His issue is likely over fueling, over boosting, or bad pyro meter.

My timing was a few degrees retarded and is now a degree or 2 advanced but seems to run better. I just finished backing off the fuel screw one flat of an allen wrench and will see how it does. My turbo is brand new, pyrometer about a year old, so hopefully they are good. Thanks for all of the help!

 

[IDIBRONCO]

But the screen would stop a broken turbo fan blade or sizable nut or bolt from going down.

Those don't get sucked into and run through the turbo. They're part of the turbo. If a blade from the turbo is broken off and then tossed out onto the intake screen, there's probably been enough metal pieces that did pass through that screen that it's now time for an engine rebuild. A nut or bolt may pass through the turbo, but it would be catastrophic to the turbo so you'd be looking at an engine rebuild once again.

 

[Snowturtle]

Big difference! Backing off the fuel stopped the black smoke and helped with the EGT's. They still climb high enough that I have to back off when I really put my foot in it though. Is that just something I have to live with or do I keep tuning? In a gas engine, I would keep leaning it until is starts to run worse, then turn it back up just a little bit. Do we do anything similar with a diesel? I will go up the road to the mountain pass today to see how it does. Before, the motor had plenty more to offer but I had to back off due to high EGT. I would love to be able to fly up the pass!
Thanks for all the help so far, the progress is very gratifying!

 

[Big Bart]

Big difference! Backing off the fuel stopped the black smoke and helped with the EGT's. They still climb high enough that I have to back off when I really put my foot in it though. Is that just something I have to live with or do I keep tuning? In a gas engine, I would keep leaning it until is starts to run worse, then turn it back up just a little bit. Do we do anything similar with a diesel? I will go up the road to the mountain pass today to see how it does. Before, the motor had plenty more to offer but I had to back off due to high EGT. I would love to be able to fly up the pass!
Thanks for all the help so far, the progress is very gratifying!

Some thoughts -
1) High EGT’s +1,200 * can start melting pistons, so this is a balance of power and heat.
2) Diesel is very pricey so do you want 14mpg or say 11mpg.
3) Do you let your wife or others drive your truck? Don’t assume they will know when to let up For high EGT’. So make it hard for them.
4) You probably don’t want to roll coal. (Problem solved.)

So if it was me I would make it so I have to get 3/4 or more into the gas pedal and towing up a grade before I needed to worry about EGT‘s. That way I am getting good mpg and not worried about EGT’s except on steeper grades. If I loan the truck to my son and he is not towing EGT’s are not an issue.

Also watch your boost and make sure it’s where you want it.

To answer your question you are not going to make it run poorly like a lean idle or too small of a jet in a carb, but limiting how much power the truck has by turning down the fuel. On a carb you are trying to get the fuel mixtures between too rich and too lean to maximize performance. In your situation you are looking for a balance between slow on a grade and low egts’s and fast with lots of black smoke and high EGT’s. So pick the balance right for you.

Others can chime in where they like to have things.

 

[IDIBRONCO]

You're at a higher elevation than most of us are. You also have the opportunity to go much higher fairly often. I think that it's going to be a choice between having to watch the pyro or having the power to get up the passes at the speeds you'd like to. If you back the fuel off too far, you won't have the power that you want to have and you may still have to watch the pyro.

 

[Snowturtle]

Thanks. I think I'll back off a little more and keep EGT's out of the equation a little more. I'm more concerned about keeping the motor safe than how fast I can get up the pass. I kind of think that once the EGT is lower I won't have to back off the throttle as much and will probably pick up speed, even at lower fuel setting and lower power. We'll see. Thanks for all of the advice.