Typical Head Gasket, now Rough Idle? (1 Viewer)

[mod5csi]

Can I get some thoughts on this? Working through the trouble shooting, but need some ideas.

96 LX450, stock 1FZ, 230,000 miles, 3rd owner

Head gasket replaced due to #6 cylinder allowing coolant into the combustion chamber, but no oil in the coolant. Head and injectors were serviced locally, valve adjustment and head assembly done by me. Started up and only running on 3 cylinders. Spark plug pics attached ordered 6,5,4,3,2,1. No OBD codes.

FSM says "Rough Idle" is Compression or Fuel Delivery.

Pulled the valve cover and triple checked the cam timing. Pics below. Compression is 150-160 psi across the board, tested three times (cold). Fuel Pressure after the filter is ~50 psi, the gauge bounces a little while cranking. Noid light says the ECU is firing all 6 injectors, resistance is good on all 6 injectors. Timing light says all 6 plugs are getting spark. Spark plugs are new NGK G's 7090, wires are ~10,000 mile NGK, resistance is good. New OEM cap and rotor. I replaced the tensioner, but not the chain or guides, those were done 10,000 miles ago along with the oil pan reseal.

During the head gasket I pulled the main engine harness to replace some connectors and wrap the EGR pipe and glove box area. I have not done any of the ECU tests in the FSM, but the injectors are getting pulses and the plugs are getting spark.

Something interesting I noticed, I had fuel mist spray out of the 2, 3 and 6 spark plug tubes during the compression test. Then I remembered I should pull the EFI fuse... But no spray mist from 1, 4 and 5.

Pulled the upper intake manifold to double check vacuum lines (10,000 miles old OEM metric sizes) and injector O-rings, all appear good. Also checked for missing or loose grounds.

So, unless anyone has a better idea... I am going to reassemble, but move injectors around, to see if the injectors are the issue.

 

[chap79]

How many times have you started it and how long have you let it run since the HG replacement? The ECM usually needs a little while and a few cycles of the engine before idle stabilizes.

 

[Mighty690]

My $0.02. You're not getting spark on those 3 plugs. So, why? I've been told by a couple knowledgeable Cruiser mechanics to stick to factory/OEM ignition: plugs, wires, cap and rotor. I don't think your plugs or wires are OEM. (I thought Denso was the OEM wire supplier.)

 

[mod5csi]

How many times have you started it and how long have you let it run since the HG replacement? The ECM usually needs a little while and a few cycles of the engine before idle stabilizes.

It's been started 10-15 times, with about 30 minutes run time total.

My $0.02. You're not getting spark on those 3 plugs. So, why? I've been told by a couple knowledgeable Cruiser mechanics to stick to factory/OEM ignition: plugs, wires, cap and rotor. I don't think your plugs or wires are OEM. (I thought Denso was the OEM wire supplier.)

The plugs are sparking, you can see the black marks on 1, 4, and 5.

 

[TheAmerican]

Fwiw ive seen plugs not firing correctly because of too much antisieze slobbered on them. Try some cleaner plugs

 

[Bardiya]

I personally don't believe injectors are serviceable but I'd start with plugs before getting into more complicated things. They clearly need to be replaced anyway.

 

[Rice]

Does the engine clean up and smooth out above idle or is the rough running up into the RPM band?

 

[mod5csi]

Does the engine clean up and smooth out above idle or is the rough running up into the RPM band?

It does not smooth out, but it will rev.

Fwiw ive seen plugs not firing correctly because of too much antisieze slobbered on them. Try some cleaner plugs

Noted, I will clean them up before reinstall.

 

[yotakrawler]

Maybe try moving an injector and see if the problem follows.

 

[Malleus]

I personally don't believe injectors are serviceable but I'd start with plugs before getting into more complicated things. They clearly need to be replaced anyway.

US injectors are serviceable. Any diesel repair shop can do it.

 

[Equinsu ocha]

Any update on this?