Ecu issues

[Pete B]

Hi im wondering if any one ccan help, i have a long going and pain in the butt project going on. I have a 1990 lj78 with no power, and a code 12, i changed the pump and the code is gone, still no power though. I got the machine from a local shop which had given up on it, one thing they told me is that while trouble shooting it they shorted out the spill valve, so im wondering if that by doing this they might have damaged the ECU.

Also will the engine run with the ecu unplugged?

Thanks

 

[Postoy]

I can't really help you with this but I have a working ECU if you need it

 

[Pete B]

I can't really help you with this but I have a working ECU if you need it

Is yours for an auto or manual?

 

[GTSSportCoupe]

Hi im wondering if any one ccan help, i have a long going and pain in the butt project going on. I have a 1990 lj78 with no power, and a code 12, i changed the pump and the code is gone, still no power though. I got the machine from a local shop which had given up on it, one thing they told me is that while trouble shooting it they shorted out the spill valve, so im wondering if that by doing this they might have damaged the ECU.

Also will the engine run with the ecu unplugged?

Thanks

I'll try to help you a bit here.

So it starts fine, and idles fine right? Does it smoke?

Can you give more detail about what you mean by no power? Can you get up to any speed at all? Does it move at all?

Have you checked for codes again? If so, what ones have you got?

The spill control valve works like a high speed solenoid. It controls the amount of fuel for every single injection event. This means it is opening and closing every time fuel is injected into any cylinder. It controls how long the fuel is injected for. I'd say if your truck starts, and idles, your spill control valve and ECU are probably not damaged and are working ok. Some people confuse the spill control valve with the fuel shut off valve that is in the same location on mechanical injeciton pumps. They are NOT the same. Putting constant power to a fuel shut off valve is ok. Putting constant power to the spill control valve will burn out the solenoid winding.

If there are no codes, the engine starts fine and idles fine, but just has no power, I think I'd be looking to make sure you are getting boost pressure, and that the boost pressure sensor is connected properly. Do you have a boost gauge? How much boost are you getting? Is it really slow to spool up? There is a vacuum line that goes from the intake manifold to a boost sensor that is mounted on the passenger side of the engine bay on the inside fender. If this vacuum line pops off, you will have NO power, because the computer will not be adding any fuel as the boost comes on. Re connect the vacuum line if this is the case.

Pictures are worth a thousand words. If you can take some pictures of your engine bay and post them up maybe we'll notice if there is a problem. Focus on the injection pump side of the engine.

These electronic diesels are actually really simple. Simpler than a 1990 EFI Toyota Camry. It's just that shops have never seen them or read about them before. They have no clue where to start. So your best bet is to read the material on this site, and learn as much as you can yourself, and do your own work on it.

 

[Postoy]

Hey Pete, Min is an auto. Try what GTSSport has suggested first but if you end up needing one... I got one Ill actually be pulling it out tomorrow

Is yours for an auto or manual?

 

[Pete B]

Ok, I checked for codes, I get 1 flash so that's good, I've checked the timing on both the drive gear and the housing, both good, I have installed a new turbo and boost gauge teed into the outlet from the manifold to the sensor, the moat I get is 6 psi and it revs slowly up to the point were my turbo boost light comes on, nothing much more than that. I do get smoke, white unburnt fuel which I didn't get with my old fuel injection pump. I've removed the egr and cleaned out the manifold. It starts but takes some cranking and like I say it smokes when it does. I've disconnected the muffler just in case it's a blocked muffler, that didn't help. So any ideas, I'm thinking it's timing, which is tweaked by the ECU, hence why I'm thinking that. I've also tried the disconnecting the batteries over night but that made no difference.
Any ideas lol

 

[Pete B]

But now I'm thinking about it, if I have a failed boost sensor that could be messing things up and the ECU is just trying to compensate with over fueling to get more boost, but with to much fuel and not enough air getting in it will smoke.
Is there anyway of testing it?

 

[Nas90tdi]

The slow start and smoking at start up is probably a separate thing. Mine tends to smoke when I crank it as well. 2 cycles on the glow plugs and being more patient helps that.
Are you saying it is smoking when you drive it? Or, just at start up?
Smoke under load could be a number of fairly simple things. Bad fuel filter. Failing injector nozzles. Air getting into the fuel system from a small leak or crack in a line.
Sounds like you checked that the boost port is connected on the manifold. Have you checked that the hose isn't leaking somewhere along it's length on the way to the boost sensor.

As GTSSportCoupe said, some really good pictures might reveal the culprit. Sometimes the simplest thing can be the hardest to find after you get too involved in the problem.

 

[GTSSportCoupe]

Ok, I checked for codes, I get 1 flash so that's good, I've checked the timing on both the drive gear and the housing, both good, I have installed a new turbo and boost gauge teed into the outlet from the manifold to the sensor, the moat I get is 6 psi and it revs slowly up to the point were my turbo boost light comes on, nothing much more than that. I do get smoke, white unburnt fuel which I didn't get with my old fuel injection pump. I've removed the egr and cleaned out the manifold. It starts but takes some cranking and like I say it smokes when it does. I've disconnected the muffler just in case it's a blocked muffler, that didn't help. So any ideas, I'm thinking it's timing, which is tweaked by the ECU, hence why I'm thinking that. I've also tried the disconnecting the batteries over night but that made no difference.
Any ideas lol

Make sure that your boost gauge is teed in before the little filter thing that is before the boost sensor (Tee in the boost gauge right at the intake manifold). If it's teed in after the little filter, it could give you the low boost reading, and impact the signal at the boost sensor.

Do you get the smoke just for a minute or so at start up, or all the time? How does it sound when it's running? Does it knock louder than before, or is it quieter than before?

When you removed all the EGR stuff did you also remove the throttle plates in the throttle body? If you removed the VSV that opens/closes the small emissions throttle plate, but did not permanently open that throttle plate, your motor could be getting starved of air on startup. It would cause these issues.

You did not remove the throttle position sensor when you were cleaning stuff did you? This would throw the computer. Another thing that can happen when you remove the intake manifold, is a mix up of the spacers that hold the glow rail. This can cause issues with the glow system. Also, did you make sure the connections to the glow rail and glow plugs were all really clean? There is a lot of current there.

I don't think your boost sensor is failed. They are built pretty tough. And trust me, you don't have too much fuel. But you may not have enough air at start/idle if your throttle plates are both closed.

As said, if you can post pictures of the injection pump side of your engine, it would help. Try to get pictures of the vacuum lines on that side, also the intake manifold, throttle body and injection pump. A video of it cold starting and another of it running warm would be great too.

 

[Pete B]

Ok I did have my boost gauge the wrong side of the filter, changes that and got a little more showing. I do have some pics and vid I'll try and attach them

 

[Pete B]

 

[Pete B]

The vids I have are to big, but I get alot of knock and a load of smoke cold and hot. I tried disconnecting the boost sensor and it made no difference to how it runs. But you did say something that has made me think, like I said earlier a local shop had a look at it and there are not alot of brain cells in the building and I'll put money on them taking the TPS sensor off without re calibrating it. I have removed the 2 butterfly valves from the intake by the way

 

[Nas90tdi]

Could just be the angle. But, in the last picture the seal between the T and the boost line to your gauge looks like it isn't a tight fit. Could you be losing boost signal there?
I haven't dug into setting the TPS on these trucks, but, if they took the TPS off and just tried to put it back in place by eye, it would make the running of the truck horrible. The signal to the computer would always be off in relation to your actual throttle position. And, if set too low, the idle would be smoky and terrible for sure.
Hopefully Nick can chime in on the TPS. I have no doubt he has worked on these little engines far more that me. I am doing my damnedest to catch him though. Actually need to stop working on mine and actually drive it.

 

[GTSSportCoupe]

The vids I have are to big, but I get alot of knock and a load of smoke cold and hot. I tried disconnecting the boost sensor and it made no difference to how it runs. But you did say something that has made me think, like I said earlier a local shop had a look at it and there are not alot of brain cells in the building and I'll put money on them taking the TPS sensor off without re calibrating it. I have removed the 2 butterfly valves from the intake by the way

Is the smoke white and diesel smelling? When I took my injection pump off to reseal it, I ended up putting my timing belt on such that the injection pump was one tooth out. I could have sworn I had it right, but I didn't. What this did in my case is advance the injection pump past the point that the computer could compensate the timing properly. This gave me the same symptoms you are having. The knock was really loud. But one major difference to your symptoms, is the computer threw a timing control valve error, and the check engine light would come on. So this is likely not your problem, as you don't have any error. What I did to get around it for a little while, was I retarded the pump as much as possible (loosened the mounting hardware and pulled it away from the engine). There was enough adjustment there it was fine until I had time to correct the timing belt. Just food for thought I guess.

Do you get missfiring and really rough running on startup? This coupled with the knocking and smoke could indicate a bad air leak. But unless it's really bad, usually it clears up after running for a bit. I put hose clamps in place of the factory spring clamps on all my fuel hoses, you could give that a try. Also, check that the injector hard lines are torqued properly and not leaking. Check that the fuel filter and water drain thing have intact seals and are tight. Check your primer pump. The factory ones do wear out and let air into your system. Look just under the plunger/button thing on top for diesel. This would indicate a leak. I changed mine out with a no name cheap ebay one and it works great.

Did the shop pull your injectors and mess with them? That could also cause these issues if they screwed them up. If things get desperate, you could send me your injectors and I can test them for you. I built a injector tester here at work. Rebuilt my injectors with new Denso nozzles a while back. Could probably fix your injectors too if the shop did mess them up.

Regarding your throttle position sensor. That idea was just a shot in the dark. Take a very careful look at the screws that mount it to the throttle body. There should be paint on one or both of them. You should be able to tell if the screw was loosened. There is a procedure using a feeler gauge and a multimeter to set it back to factory setting. I don't know the spec off the top of my head, but could find it if you need.

Can you upload your videos to youtube? Nothing in your pictures concerns me at the moment (except what Nas90tdi mentioned), but I'll take a closer look when I get some time. One thing I've done is put zipties on all my boost line connections. I found when I started running 19psi the vacuum line would pop off. Nas90tdi is definitely right though, your one hose at the boost t looks really loose. That could be causing your power problems. However your smoke is something else.

 

[Pete B]

I've had the cover off and checked the timing and it's spot on. The engine does actually run pretty smooth just doesn't accelerate. Everything is dry and tight so I'm not thinking I have a problem with the fuel lines ( I've also tried running it out of a separate container to eliminate the fuel lines back). The smoke is white and defently unburnt diesel. I've uploaded a vid on you tube titled 2lte knock and smoke for your viewing pleasure. I've also cracked all the injectors one at a time and the are all working and there isn't one in particular that gets rid of the smoke.

 

[GTSSportCoupe]

I've had the cover off and checked the timing and it's spot on. The engine does actually run pretty smooth just doesn't accelerate. Everything is dry and tight so I'm not thinking I have a problem with the fuel lines ( I've also tried running it out of a separate container to eliminate the fuel lines back). The smoke is white and defently unburnt diesel. I've uploaded a vid on you tube titled 2lte knock and smoke for your viewing pleasure. I've also cracked all the injectors one at a time and the are all working and there isn't one in particular that gets rid of the smoke.

Thanks for the video. Was your engine cold or warm in that video? How cold was it outside?

When the temps get negative here (which isn't often, LOL), my truck makes exhaust smoke also. I'd say it makes the same amount as that, and it dissipates fairly quickly in the air just the same. Sort of about the same as you'd expect from a gas engine while it's warming up in really cold weather. That is normal in my experience. Once the engine is fully warmed up, it does reduce, but in super cold weather it might continue.

Rough starting should be expected if it's really cold out and you don't have a block heater. Make sure you do at least two 8 second glow cycles (listen for the relay). Even three cycles if it's really cold out.

I'm assuming your engine was not fully warmed up in that video. If that's the case, I think the motor sounds ok. The computer advances the injection timing when the engine is cold, and it'll sound quite knocky. Once it's warmed up, the knock will reduce enough that it almost sounds like a gas engine.

If your engine was fully warmed up (1/3 on the temp gauge), I'd say the idle does not sound right, and it's possible something is a little off in one or two cylinders.

How much have you actually driven it? In that sort of weather it takes a while to totally warm up. In fact, idling in winter weather like you have there, I don't think my motor would ever warm up. I actually have to drive it hard to get some heat. You could block of your radiator to force it to warm up more.

Regarding your power issue, I'm going to say you've got a boost leak at that T-connector where your boost line comes off. Try to fit a different sized T, so the larger line from the manifold can't leak. Also, these motors don't make much power at all when they're cold. It gets significantly better once they're warmed up. Although still not much...LOL.

Finally, try to open your waste gate with your hands. Make sure the spring is really tight, and when you close it you hear the wastegate flap (in the turbine housing) close tight. If the waste gate is not closing, it could cause issues too.

You should get a manual boost controller and turn the boost up a bit (maybe 12psi). Will make a good difference in power.

 

[Pete B]

The problem was there before I installed the boost gauge and everything was tight, as for the date gate it is brand new as is the turbo. As for driving it, that's out of the question as it only does 30km/h but I've had it good and hot, I still have the smoke and no power. I have a recirculation heater on there which heats up the engine to nearly running temp before I even turn the key

 

[GTSSportCoupe]

The problem was there before I installed the boost gauge and everything was tight, as for the date gate it is brand new as is the turbo. As for driving it, that's out of the question as it only does 30km/h but I've had it good and hot, I still have the smoke and no power. I have a recirculation heater on there which heats up the engine to nearly running temp before I even turn the key

Was that truck sitting for a long time before you bought it? Have you checked the pick-up in the tank? There is a little filter there. Sometimes diesel can grow algae in the tank if it's left for a long time. It's possible your filter has plugged up and is starving the engine of fuel. I think you can access the pick-up without dropping the tank. There is a panel in the floor above the tank you can remove.

You mentioned you ran it with diesel from a container, but did you actually drive it that way to see if the power changed? Or just look for smoke?

Also, how long has it been since you've changed the fuel filter?

There is also a little screen under the spill control valve. If that gets plugged with debris, it can cause fuel starvation also.

When you change the injection pump, you left the resistor on it that came with it right? (those two colored connectors on the side). They are supposed to stay with the pump, not the vehicle.

I still don't think your engine has a bad ECU or spill valve. You have to remember that the throttle on these is totally electronic ('drive by wire'). When you rev your engine, the only way it is happening is the computer is changing the duty cycle of the spill valve as it sees the throttle position sensor change. If you did want to check your spill valve, you can do so with a multimeter by measuring the resistance. I believe it should be 1.4Ohm. Would be good to check that. You have to make good contact with the multimeter probes to measure such a small resistance.

Just trying to give you all the ideas I can think of. Hard to trouble shoot an engine half way across the continent...Haha.

Here is the little filter under the spill valve:

 

[Pete B]

The pump and the spill valve have been changed, the original pump had a a problem with the engine speed sensor which some one had apart and filled the pump with some sort of sealant. I changed the pump with one off a running engine and the code has gone, but still no speed , I'm thinking the original fault was the pump but people tinkering have messed something else up. I'm going to pull the front cover to recheck the timing marks, unfortunately it's -30 and even though I'm in sask I live on a big hill and the truck hasn't the power to get up the hill lol. I'm going to try and check the tps. There is no paint on the screws and it's right smack in the middle of its adjustment so I think they took it off when they were messing with it

 

[GTSSportCoupe]

The pump and the spill valve have been changed, the original pump had a a problem with the engine speed sensor which some one had apart and filled the pump with some sort of sealant. I changed the pump with one off a running engine and the code has gone, but still no speed , I'm thinking the original fault was the pump but people tinkering have messed something else up. I'm going to pull the front cover to recheck the timing marks, unfortunately it's -30 and even though I'm in sask I live on a big hill and the truck hasn't the power to get up the hill lol. I'm going to try and check the tps. There is no paint on the screws and it's right smack in the middle of its adjustment so I think they took it off when they were messing with it

Based on your video I think your timing is just fine. Unless your cam timing is out. That would kill power and not throw any engine codes... Pretty unlikely though. Mine knocked way louder and made way more smoke and threw codes when the injection pump was out one tooth. Yours is not nearly as bad as mine was like that.

Here are the specs for the 2LTE TPS I believe. If yours is out from that, then it needs to be set with a feeler gauge. I'll try to find those specs for you too...