LJ78 Smoking

[VI Cruzer]

Hey guys, sorry if this info is in another post, but I can't locate it.
Had my pump resealed last spring, new rad core, clutch fan. It ran like a champ all summer, no smoke really at all to speak of, bags of power. Lately, as it has started to get cool, now cold, it smokes a little more on startup ( OK Normal I guess) but the real issue, which I had last winter as well, is that I can drive it, all good then shut it down for 5-15 mins, start it up and it white smokes like a demon. Not coolant, the diesel white smoke. Runs a bit rough too, then smoothes out after a bit.
I was starting to look at ECU temp sensors and the like. Any ideas or advice

 

[GTSSportCoupe]

Sometimes the ECU gets confused and doesn't advance the timing and cycle the glow plugs properly when its cold. Mine was starting a bit smokey at the start of the cool weather also. Reset the ECU by disconnecting your battery and turning on your headlights. Leave it that way all night. Reconnect the battery again and see if there is a difference.

You might also consider checking your glow system. You can remove the glow rail and test the resistance of the glow plugs. They should all be very low; I don't remember the exact figure right now, but just a few ohms I think. You can also have someone do the glow while you measure the voltage at the glow rail. Make sure it's 11 volts. When its cold it should stay on for quite a few seconds.

Low compression can also cause issues. Could check your compression.

All that said, I glow mine a couple times in the mornings. Adds up to about 15 sec of glow or so for a perfect clean start (listen for the relay click).

If all that fails, you can advance the base timing a bit which makes starting lots easier. You can replace the timing calibration resistor with a potentiometer and adjust your timing electronically. Works very well. The wires can be accessed behind the glove box at the ECU. Just don't advance to much or it's hard on the big end rod bearings. You can tell when you advance as the motor makes more knock.

 

[GTSSportCoupe]

One last thing, the emissions stuff can cause this problem too if it is starving the engine of air. Mine had that problem when I bought it. The vacuum switching valve that opens the secondary butterfly in the throttle body was not letting air through when it should. I ended up removing all the emissions stuff and removing the throttle plates completely. One of the best things I ever did to the motor.

 

[VI Cruzer]

Yeah I am meaning to do those things! Thanks for the reply! Actually it starts pretty good. # cycles of the glow and it's gold. Like I said, jus a titch of smoke at start, but it starts well. The fact that it smokes just a bit now as opposed to summer is leaning me to look at my coolant sensor for the ecu. Found some cheap ones on amazon, may just try that. I will probably check before I do though. I will probably check the intake air sensor value as well. Not sure what it's supposed to be though, as there is less info out there about it. Do you have a bunch of photos of the couple o mods you mentioned. I put in a can for the pcv, but have not taken off the EGR. How was taking off the hardware at the exhaust manifold?

 

[GTSSportCoupe]

Yeah I am meaning to do those things! Thanks for the reply! Actually it starts pretty good. # cycles of the glow and it's gold. Like I said, jus a titch of smoke at start, but it starts well. The fact that it smokes just a bit now as opposed to summer is leaning me to look at my coolant sensor for the ecu. Found some cheap ones on amazon, may just try that. I will probably check before I do though. I will probably check the intake air sensor value as well. Not sure what it's supposed to be though, as there is less info out there about it. Do you have a bunch of photos of the couple o mods you mentioned. I put in a can for the pcv, but have not taken off the EGR. How was taking off the hardware at the exhaust manifold?

I sort of doubt its the coolant sensor, but no harm in changing it out I suppose. If it is starting that easy it must be just getting starved of air. Check the vacuum connections around the EGR system. Make sure the VSV's etc are all hooked up still. I think you might be able to manually open the secondary throttle plate in the throttle body. You could try this and see if the smoke and rough running stops.

I did not find taking the EGR stuff off that hard. But you do have to fabricate some block off plates. Or you can cut a metal can up and make little block off gaskets that you can sandwich behind the existing EGR pipe connections. If you look through this thread Ideas for improving the 2LTE I think people posted some pictures of the EGR stuff that can be removed.

Here is how mine looked when I removed the emissions stuff (Also, I don't run the catch can in this pic anymore, I just vent the PCV through a hose way back under the truck).:

 

[Jim from Idaho]

I sure wish I could get a picture of all the pieces that come off, in a pile on a shop bench. Then I will know I've got everything done. Plus I need to know what vacuum lines remain, and what they attach to. You had a great schematic of that on this site somewhere a few years ago. Is it still accurate? GTSSportCoupe, you have been a great inspiration to me getting my LJ78 in shape.

[/QUOTE]

 

[GTSSportCoupe]

I sure wish I could get a picture of all the pieces that come off, in a pile on a shop bench. Then I will know I've got everything done. Plus I need to know what vacuum lines remain, and what they attach to. You had a great schematic of that on this site somewhere a few years ago. Is it still accurate? GTSSportCoupe, you have been a great inspiration to me getting my LJ78 in shape.

Hey Jim, I see the picture links are no longer active where they used to be. I'll try to look up the diagram again and post it here.

I'm glad my posts have been helpful for you. I'm just learning as I go; it's not the gospel or anything...lol. I do like my truck a lot though, and want other people to enjoy their LJ's too.

 

[Jim from Idaho]

I was wondering if that LJ78 on sale on Craigslist in BC with the same paint job was yours.

 

[GTSSportCoupe]

I was wondering if that LJ78 on sale on Craigslist in BC with the same paint job was yours.

Nope, not mine. Looks like a clean truck though. People are asking a lot of $$ for these things these days too. Not too long ago they were half the price.

 

[VI Cruzer]

Thanks for the advice. It does smoke on a restart every time, just sometimes, and only since it has gotten colder. Like I said, I can shut it off for 5 mins and then when I start it back up, sometimes I get a cloud of smoke and running a little rough. Why would it do that when the motor is fully warmed up, and only sometimes? Could it be a bit of air entering the fuel system round the pump?

 

[GTSSportCoupe]

Thanks for the advice. It does smoke on a restart every time, just sometimes, and only since it has gotten colder. Like I said, I can shut it off for 5 mins and then when I start it back up, sometimes I get a cloud of smoke and running a little rough. Why would it do that when the motor is fully warmed up, and only sometimes? Could it be a bit of air entering the fuel system round the pump?

It's certainly possible. Although an air in fuel problem would not just happen when it's cold out. It would have happened in summer too. Regardless, look around for diesel leaks. Where diesel gets out, air gets in. Look at the hard line connections at the back of your pump. Look around your fuel filter. Look around your injectors.

I still think your emissions is not working right and is starving the motor of air sometimes. Exact same thing was happening to mine when I bought it. Turned out the belt to the vacuum pump and A/C was loose, so there was little or no vacuum. The emissions thing needs vacuum to work, so was not working right. It is supposed to open a little butterfly at idle and startup.

 

[VI Cruzer]

OK just so you all can see the smoke, I took a short video and posted it to my Youtube. Here is the link:

Now when I shut it down, it was running beautiful with just a hint of smoke all the time ( that I could live with ). I put on a 5 minute timer then filmed the restart. It was doing it last winter also, but after I had the work done it was hot and it did not do this in the summer! Arghh! If you guys donÈt mind having a look, and commenting. Now I am aware that there is a high probability that I have some kind of crack in the head, as I push water into my overflow, but it wonèt take it back in, and I have seen bubbles when it is very hot. I have overheated it a few times but have caught it before anything crazy happens, so I am sure I am in line for a head replacement. I wanted to do a bunch of the "GTS" mods first, so I don't have a repeat. Just wondering if the head crack could cause this, but then why only when it is cold?

 

[GTSSportCoupe]

Come by my place if you are ever in Victoria, and I'll help you sort it out.

 

[VI Cruzer]

I am sorely tempted to make a special trip! Maybe in the new year!
I will continue on with check that all my fuel lines are tight

 

[VI Cruzer]

Just an update. I got to thinking that it may be a bit of coolant getting pulled back in somewhere and getting burned. So I got myself one of those Lev-R-vent radiator caps. Right after I shut down every time I flip the lever and vent it into the tank. Now it does not do the smoke show, and will even pull the fluid back into the system. Got some work ahead of me for the summer!

 

[Bryan Mac]

One last thing, the emissions stuff can cause this problem too if it is starving the engine of air. Mine had that problem when I bought it. The vacuum switching valve that opens the secondary butterfly in the throttle body was not letting air through when it should. I ended up removing all the emissions stuff and removing the throttle plates completely. One of the best things I ever did to the motor.

regarding the throttle plates, I removed the small one, is it ok to remove the bigger one too ? as I'm experiencing huge amount of thick black smoke just when I drive off & when I rev up from idle,really is huge amount of black/black smoke...will post video of it tomorrow evening.. any clue to what it might be,any advice would be great.

 

[JimmyPrado]

Thanks to Nick and a few others, I just did this last week. Yes, is your answer. Note, while the little plate unscrews easily the big plate
(in my case) striped the screw heads because the screw was more like a rivet. So, had them drilled out. See the thread in my sig but here's a pic of what you want.

 

[77cruiser77]

I read you did your IP but what about injectors? Mine puffs white on cold start and it's due to that

 

[Bryan Mac]

Cheers Jimmy for the pic, now I fully understand what needs to be removed will get stuck in again during the week & hopefully get one step closer to releasing the inner beast from the 2lte

If I cant get to the bottom of this thick black smoke, I might just get the measuring tape out and see if this 4.2 FTE Beauty will fit.

 

[GTSSportCoupe]

regarding the throttle plates, I removed the small one, is it ok to remove the bigger one too ? as I'm experiencing huge amount of thick black smoke just when I drive off & when I rev up from idle,really is huge amount of black/black smoke...will post video of it tomorrow evening.. any clue to what it might be,any advice would be great.

Do you have the mechanical injection 2LT or the electronic injection 2LTE? Anyhow, sounds like your fuel is turned up dangerously high. The throttle plate removal is a great thing, but not the answer to your smoke problem. Give us more info and I'll help with some ideas.