Rough/erratic idle with engine dieing at times

[junkxj]

Hello all. It's been a while since I have spent much time on the forum (up until a week ago). I spent tons of time on the forum when I had my fj80, and recently bought a 100 series because I have missed my old cruiser since I sold it.

To make this story as short as possible...

Had the 1998 100 series a month. I am second owner and seems to have been extremely well maintained by previous owner. It has 236k on it, factory sticker saying timming belt at 181k. No issues with it till a week ago. Had a very slight miss at Idie. No cel, or any other issues. Pulled a spark plug and it looked a little old. Figured a new set couldn't hurt. Used Bosch platinum. This made the miss slightly worse. After a few days cel came on and had cylinder 3,5,7 miss fire codes. Replaced all those plugs with new ones, cleared the codes. Next day idle was worse, jumping between 300 and 2000. I then pulled codes and got the bad igniter codes for 3 and 7. Replaced those with cheap aftermarket ones and cleared codes. The next day the idle was even worse, and would die after about 4 seconds of a very rough idle. Today pulled the codes again, got cylinder 4 bad ignitor code. Replaced it, cleared codes and no change in how it runs. Cel came back on after driving it this afternoon, pulled codes again and it said bank 1 lean ???

I have read every single thread evenly remotely similar on this forum, and am stumped. above 1000 rpm the truck runs fine. At idles it seems to be running on 4-6 cylinders. I think it might be vacuum related, but have checked every line 4 times. Had my dad check it out today, and after 3 hours he was completely stumped. My dad has been a mechanic his entire life and I have never heard him say that.

Any ideas???

I hate to just throw parts at it, but at this point that's all I know to do.
Maybe fuel filter, MAF, O2 sensors????

Any ideas would be greatly appreciated!

It truly is a sad day when I have to drive my tj because my toyota is broken down.....
Never thought I would say that!

 

[Dwight S]

Coil packs would be my guess but you said you replaced them with cheap ones. I'd try a better quality pack like the Denso, factory coils and see if that helps. Your description of a slight miss is classic coil pack failure.

 

[junkxj]

That's what I have thought also, but it's hard for me to think a fourth has gone bad in a week. it definitely feels like its down more than one cylinder at idles. And the bank 1 lean code I got today?

 

[Dwight S]

I had 5 go bad within about 3 months, so it isn't impossible.... Not sure about the lean code.

 

[junkxj]

I guess it definitely is possible . Feel like I am chasing 2 separate issues at the same time.
Is it possible for driving with a bad coil to cause other coils to fail?

Thank you Dwight S for the suggestion and the info

 

[junkxj]

I have still been chasing this issue. I am still thinking it's vacuum related. Using a small amount of starting fluid I have found that when sprayed down near the injectors it will make the engine rpm jump. Is it common for injector seals or the manifold gasket to leak on these engines? Is there anything under the manifold that could be leaking?

Any ideas or info would be greatly appreciated !!!!!!!

 

[2001LC]

You may have more then one issue here. But first did you wash your engine recently?

 

[junkxj]

I have not. And it has not rained here until today for the last month, so I don't think it could be moisture related.

 

[PADDO]

Do the Bosch plugs you fitted cross reference directly (from a legit OE source) to the OE Denso Iridium SK20R11s? IIRC there weren't a lot of alternates to SK20R11s when I did my plug changeout.

 

[2001LC]

***** Using a small amount of starting fluid I have found that when sprayed down near the injectors it will make the engine rpm jump. Is it common for injector seals or the manifold gasket to leak on these engines? Is there anything under the manifold that could be leaking?

Any ideas or info would be greatly appreciated !!!!!!!

I have not. And it has not rained here until today for the last month, so I don't think it could be moisture related.

Thinking out loud:

I was thinking of injectors' lower seal, which could allow air in. They get old and high pressure wash can blow away dry crumbling rubber. Normally exposed (of lower seal) side goes dry, but business end (inner side) holds the seal ok. Since you noted change "RPM jump" may be worth pulling fuel rail and R&R injectors' seals. Have injectors When to replace fuel injectors tested, cleaned and rebuilt is good idea with mileage you have. On upper seals you'd probable get fuel leak (smell).

Re torque intake manifold split & intake to head bolts wroth it. Get those valve cover bolts and clean the PCV while in area worthwhile touch. The PCV hose go bad so inspect them as well.
Split Intake Manifold take a look & Gaskets & Seals Poll

It's difficult to eliminate spark plugs & coils on plugs (COP) when aftermarket used. Typically one would swap suspect COP's with good one's to see if code moves. Did you or can you inspect old spark plugs I.E condition: leaks, coating, color, resistance, gap. When to change spark plugs?
When to replace Ignition coils.

Injector fouling can make cylinders run hot (lean). Heat is enemy of COP's causing failure of old weak ones, which is associated with bad spark plug. O2 may get funky readings and try to compensate exasperating issue.

 

[2001LC]

Bad injector, COP or spark plugs can lead to burnt valves if left unresolved for to long.

Next step would be compression test, then leak down. Any coolant loss, and a coolant system pressure test is in order. Over heating causes head gasket issues. Sign of over heating may included swollen coolant & heater hoses.

 

[Julian Stead]

Because the faults are all related to bank one, cylinders 3,5,7 I think it is worth checking your valve timing, just in case it has jumped a tooth on that Cam. Running lean just means that there is to much oxygen in the exhaust, you would expect this if you have a misfire due to the unburnt fuel mixture(high in oxygen). I would check the valve timing, if that is OK then swap all coils from bank 1 to bank 2. If the fault codes haven't moved then try swapping the upstream oxy sensor across from bank 1 to 2 as well. This shouldn't take to long to do, if problem still persists then carry out compression test. If you can get a exhaust gas check you can check the fuel delivery, as a misfire with high HC means there is fuel, a misfire with low HC means low fuel. You can smell the unburnt fuel most of the time though.

 

[Julian Stead]

Ps. Make sure the correct spark plugs are fitted as paddo mentioned, it might of been a simple COP fault, made worse and more confusing due to incorrect spark plugs being fitted.

 

[2001LC]

Interesting, but no #1 issues reported.

 

[ponytl]

ok unless you have a bad plug it ain't your spark plugs... pretty much the only difference you will see in plugs is in service life... I'm calling/leaning towards it being a fuel issue and not a spark/ignition issue... for $19 you can get a HF inferred point and shoot heat / temp. gun with the engine running after a few minutes, shoot the gun at the exhaust manifold as close as you can to each exhaust port .. do this on all cylinders and record temps... they Should be all close with the adjoining cylinders being a tad warmer... too much fuel will cool the exhaust while a lean cylinder will run hotter... this should prove a fuel issue...

the other things that come to mind are... are you sure you got the correct wires on the correct injectors? and the correct wires on the correct coil packs? I'm not sure you can screw these up but?

I like propane over starting fluid for checking for vac leaks... you can run a small hose (like fuel line ) from a simple plumbing torch and move it around the injectors and manifold, now I would do this WITHOUT the serpentine belt on the engine... you can to this for a few minutes with no issues it will keep the propane where you want it and keep you safe from a spinning fan... I have never seen a vac leak at an injector most leaks there are fuel leaks...

 

[junkxj]

Do the Bosch plugs you fitted cross reference directly (from a legit OE source) to the OE Denso Iridium SK20R11s? IIRC there weren't a lot of alternates to SK20R11s when I did my plug changeout.

The plugs were a match according to the Bosch Web site , but I am starting to think about changing all the plugs again because the problem started when they were changed.

 

[junkxj]

Thinking out loud:

I was thinking of injectors' lower seal, which could allow air in. They get old and high pressure wash can blow away dry crumbling rubber. Normally exposed (of lower seal) side goes dry, but business end (inner side) holds the seal ok. Since you noted change "RPM jump" may be worth pulling fuel rail and R&R injectors' seals. Have injectors When to replace fuel injectors tested, cleaned and rebuilt is good idea with mileage you have. On upper seals you'd probable get fuel leak (smell).

Re torque intake manifold split & intake to head bolts wroth it. Get those valve cover bolts and clean the PCV while in area worthwhile touch. The PCV hose go bad so inspect them as well.
Split Intake Manifold take a look & Gaskets & Seals Poll

It's difficult to eliminate spark plugs & coils on plugs (COP) when aftermarket used. Typically one would swap suspect COP's with good one's to see if code moves. Did you or can you inspect old spark plugs I.E condition: leaks, coating, color, resistance, gap. When to change spark plugs?
When to replace Ignition coils.

Injector fouling can make cylinders run hot (lean). Heat is enemy of COP's causing failure of old weak ones, which is associated with bad spark plug. O2 may get funky readings and try to compensate exasperating issue.

You brought up several good points I haven't thought of...

I checked all the manifold bolts, and all were tight.
The injector seals are a suspect area, but it's hard for me to think that several went bad at once. Spraying the starting fluid on both sides of the engine caused the same rpm jump.
I have checked the exhaust manifolds with a heat gun, and all are within a few degrees of each other , which I didn't expect.
The strange thing with this issue is I have swapped the ignitorsame around several times, and sometimes the fault code follows them and sometimes it doesn't. I did try swapping a new oe one with the aftermarket replacements tonight and it made no difference.
I do think the O2 sensor may be playing a part in the rpm jump, but have yet to get a code for it.

 

[junkxj]

Bad injector, COP or spark plugs can lead to burnt valves if left unresolved for to long.

Next step would be compression test, then leak down. Any coolant loss, and a coolant system pressure test is in order. Over heating causes head gasket issues. Sign of over heating may included swollen coolant & heater hoses.

I have only ran the engine long enough at one time for the ecu to throw codes, never has it ran hot. A compression test is a good idea.

 

[junkxj]

Because the faults are all related to bank one, cylinders 3,5,7 I think it is worth checking your valve timing, just in case it has jumped a tooth on that Cam. Running lean just means that there is to much oxygen in the exhaust, you would expect this if you have a misfire due to the unburnt fuel mixture(high in oxygen). I would check the valve timing, if that is OK then swap all coils from bank 1 to bank 2. If the fault codes haven't moved then try swapping the upstream oxy sensor across from bank 1 to 2 as well. This shouldn't take to long to do, if problem still persists then carry out compression test. If you can get a exhaust gas check you can check the fuel delivery, as a misfire with high HC means there is fuel, a misfire with low HC means low fuel. You can smell the unburnt fuel most of the time though.

I plan on swapping the coils to the opposite bank tomorrow , but have tried individual ones on both sides . I didn't think of shaping the O2 sensors, very good Idea!
The exhaust does have a strong smell of running rich

 

[junkxj]

ok unless you have a bad plug it ain't your spark plugs... pretty much the only difference you will see in plugs is in service life... I'm calling/leaning towards it being a fuel issue and not a spark/ignition issue... for $19 you can get a HF inferred point and shoot heat / temp. gun with the engine running after a few minutes, shoot the gun at the exhaust manifold as close as you can to each exhaust port .. do this on all cylinders and record temps... they Should be all close with the adjoining cylinders being a tad warmer... too much fuel will cool the exhaust while a lean cylinder will run hotter... this should prove a fuel issue...

the other things that come to mind are... are you sure you got the correct wires on the correct injectors? and the correct wires on the correct coil packs? I'm not sure you can screw these up but?

I like propane over starting fluid for checking for vac leaks... you can run a small hose (like fuel line ) from a simple plumbing torch and move it around the injectors and manifold, now I would do this WITHOUT the serpentine belt on the engine... you can to this for a few minutes with no issues it will keep the propane where you want it and keep you safe from a spinning fan... I have never seen a vac leak at an injector most leaks there are fuel leaks...

As far as I can tell the coils can only hook up to the correct harness, not enough slack to reach the adjoining ones. I haven't (yet) had the injectors out. The idea to disable the fan is a very good idea, it would make pinpointing the leak much easier! I feel dumb I didn't think of that.