1996 LX450 Transplant Engine Installed...misfire problem (1 Viewer)

[TheOsprey]

Engine is running rough. Check Engine light is lit and flashing. Code reader gives three codes: P0300, P0303 and P0306.

Codes are "misfire," "misfire cylinder 3" and "misfire cylinder 6."

I replaced spark plugs and wires for cylinder 3 and 6 with no improvement.

I removed distributor cap and cleaned contacts also.

As far as I know I have everything grounded that needs to be grounded.

If there is a ground that might cause this issue do any of you know what it could be?

Once installed everything was plugged in and fluids added engine fired right up but never smoothed out.

Any suggestions?

 

[blkprj80]

Check your injector harness.
Make sure the injector connector plug colors alternate from front to back, i.e., the gray brown gray sequence.
Look at the usual EGR burn area at the top/back of the engine.
Hope you don't have plugged injectors...

 

[TheOsprey]

Check your injector harness.
Make sure the injector connector plug colors alternate from front to back, i.e., the gray brown gray sequence.
Look at the usual EGR burn area at the top/back of the engine.
Hope you don't have plugged injectors...

The guy that sold me the engine took video of it running perfectly in the wrecked donor before he pulled it and sent it to me. I stored it outside in a wooden crate for about six months before I even messed with it. It came complete with wiring harness, intake, accessories, etc. I just plugged everything in. I'm thinking it's injectors unfortunately. I also see a little oil on the exhaust manifold bolts. He did a compression test too and showed me the results. Could the head gasket be bad? I'll keep troubleshooting but at this point I'm thinking it's injectors or a head gasket. I'm thinking about trying a potent fuel system cleaner in the mean time but it runs so rough that the CEL comes on and blinks suggesting catalytic converter damage is possible.

 

[ajax1]

Look at the injectors as suggested

 

[TheOsprey]

Look at the injectors as suggested

I just did. They are in the right order. I did notice however that the #6 injector was cocked to the side. I guess that while installing the engine the plug got caught on the heater hoses on the firewall. It rotated pretty freely but when I started it back up the same misfire was going on. I really, really don't want to mess with injectors but maybe it's my fate...

 

[blkprj80]

Troubleshoot it some more.
Recheck the spark plug sequence. The codes are telling you what is working and what isn't. Use that to your advantage.
Try some BG44K, although I wouldn't expect much by now.
Pull the plugs in the offending cylinders. If they're wet, your injectors are fine and you have no spark.
3 and 6 are right next to each other on the cap. At the bottom. Could be moisture?

 

[ccslider]

Double check the spark plugs wires are not crossed for 3 and 6..

 

[beefjerky]

You can hear if the injectors are firing or not with a stethoscope.... easy enough to see if you are getting spark... I had off and on random misfires for 2 years before I figured out it was the harness behind the glove box...

My guess is some wires got pinched during the swap...

 

[Malleus]

Normally, I'd suggest referring to the FSM to correct the misfire, but if you're satisfied the engine was running well before you installed it, then you already know the answer. You damaged something during the installation. Replacing plugs and wires and cleaning the distributor would have been reasonable under normal circumstances, but you don't have those.

Check the wiring to the affected cylinders. I'd bet you find the problem there.

Why are you worried about the head gasket? (it probably didn't fail while the engine was stored in the crate) Didn't the compression test satisfy you before you bought the engine? That's something you can verify yourself.

You need to develop and follow a deliberate troubleshooting plan; scattershot remedies won't help you solve your problem. Fuel treatment is snake oil.

 

[TheOsprey]

Normally, I'd suggest referring to the FSM to correct the misfire, but if you're satisfied the engine was running well before you installed it, then you already know the answer. You damaged something during the installation. Replacing plugs and wires and cleaning the distributor would have been reasonable under normal circumstances, but you don't have those.

Check the wiring to the affected cylinders. I'd bet you find the problem there.

Why are you worried about the head gasket? (it probably didn't fail while the engine was stored in the crate) Didn't the compression test satisfy you before you bought the engine? That's something you can verify yourself.

You need to develop and follow a deliberate troubleshooting plan; scattershot remedies won't help you solve your problem. Fuel treatment is snake oil.

Well, there is oil leaking from the exhaust manifold studs.

Also, I wasn't present during extraction or shipping of the engine I received.

Rather than try to reinvent the wheel I am consulting IH8Mud forum users for any help they can offer.

The wiring for #3 injector is heavily protected by the intake manifold.

It's highly unlikely it has been damaged during installation.

 

[TheOsprey]

Double check the spark plugs wires are not crossed for 3 and 6..

I have. The wires are labeled as are the ports on the distributor. They're in the right spot.

 

[TheOsprey]

You can hear if the injectors are firing or not with a stethoscope.... easy enough to see if you are getting spark... I had off and on random misfires for 2 years before I figured out it was the harness behind the glove box...

My guess is some wires got pinched during the swap...

Ok. How did you fix that? I'll double check to make sure everything's plugged in right.

 

[TheOsprey]

Troubleshoot it some more.
Recheck the spark plug sequence. The codes are telling you what is working and what isn't. Use that to your advantage.
Try some BG44K, although I wouldn't expect much by now.
Pull the plugs in the offending cylinders. If they're wet, your injectors are fine and you have no spark.
3 and 6 are right next to each other on the cap. At the bottom. Could be moisture?

They're wet and black. I took off the distributor cap and there was no moisture. I sanded the contacts but they're weren't bad.

 

[TheOsprey]

I have another question for you. I won this thing on Ebay last year and the battery it came with is inadequate. I've known that for a while but I still am using it after the transplant. Apparently, the replacement engine has higher compression because even when fully charged this battery won't start it. I have to jump it with my car. Could this play any part in the misfire issue?

 

[Malleus]

No, this isn't part of your misfire problem.

I wouldn't automatically suspect the battery is fully charged without checking the voltage with a meter, both with the engine off and running. Off it should be above 12.5V; running it should be above 14V. Even if the battery's good, the starter may not be as good as your previous one. You need to bench test it to verify that the solenoid and Bendix are good.

I wasn't trying to be snippy. Take the observations or leave them.

 

[Malleus]

They're wet and black. I took off the distributor cap and there was no moisture. I sanded the contacts but they're weren't bad.

Wet and black plugs mean you have an oil leak. Either the valve seals or the plug boot seals (probable).

They should be dry with a slight gray powder coating.

 

[Malleus]

At this point, if you're certain you haven't damage the harness during installation, you have little choice but to pull out the FSM and go through the misfire fault tree until you locate the problem.

 

[inkpot]

If harness stayed on new engine during removal from donor rig, transportation to you, and your installation, it may of been damaged in the typical EGR area. Harness is over 20 years old, and even though it ran OK on donor rig, it may of been damaged at that point, but not critical damage until all of this moving around happened. Try moving harness around by EGR while engine is running. If it affects the miss-fire then it is a damaged harness. I just watched Tools perform this test on Friday, and the results were obvious!! You could just replace it with your original one, if it is NOT damaged.

 

[TheOsprey]

At the moment I'm leaning toward leaking valve cover/spark plug tube gaskets. Both plugs were black. In the process of installing the transplant engine I noticed the valve cover gasket was leaking a bit so I took off the VC. I noticed the gasket was rather hard and dry. It is possible that doing this caused the rings around the spark plug tubes to start to leak. I ordered a new valve cover gasket kit and the right battery. This weekend I get the new gaskets and battery installed then go from there.

 

[TheOsprey]

No, this isn't part of your misfire problem.

I wouldn't automatically suspect the battery is fully charged without checking the voltage with a meter, both with the engine off and running. Off it should be above 12.5V; running it should be above 14V. Even if the battery's good, the starter may not be as good as your previous one. You need to bench test it to verify that the solenoid and Bendix are good.

I wasn't trying to be snippy. Take the observations or leave them.

The battery is too small for this application. I've put it on a charger and it shows to be fully charged. Even if it is, it's underpowered by a significant margin.

The starter is the same from the old engine.

The starter works just fine when I have jumper cables on the battery.