2 Spark Plugs Fouling Quickly (1 Viewer)

[Cgbeachbum]

Aloha Mudders!
Im trying to diagnose a spark plug fouling issue that is happening on #1 and #2 cylinders. I first noticed the issue when I was checking the timing on the engine, had some random stumbles and my Induction Light was not giving me consistent light pulses. So I pulled the wire and replaced it with a extra I had lying around. It helped but not fully. I put my light on each plug wire to ensure they were all firing consistently and found that #2 also had a random miss of spark. So pulled both plugs and they were completely fouled, heavy dry carbon soot. I put all new NGK plugs in (BPR4EY), new Denso plug wires, new dizzy cap and rotor. Started it up and she was purring like a kitten, put my light on both plug wires and light pulses were consistent....went for an hour drive, got back and put the light back on and still every so often, the light pulse would miss. Pulled the plugs and both are fouled up again. All the rest of my plugs have good looking light brown, its only 1&2 that seem to foul quickly... How do you run RICH in two cylinders, I'd get a lean conditions if there was a leak or crack but.... If my rings were shot, how am I getting good compression. Anyone have any suggestions on where to look next?

History:
-84 FJ60 2F
-Compression check was done a couple weeks ago and I had an average of 148psi across all cylinders
-Replaced the intake manifold gasket a few months ago... didn't see any cracks... also truck has headers.
-Carb was rebuilt a couple weeks ago, all new gaskets. Still unsure if I got the Lean Drop Method done correctly, as she runs pretty smooth, but when I lay on the gas to merge on the highway, I get a good bit of black smoke from the tailpipe...
-Fixed the Emissions computer, had some solder cracks that wasn't allowing the ICS valve to work correctly.
-Truck is Desmogged, still going through it to get it up to JimC's standards... at least trying too....
-Did a hot valve adjustment about 4 months ago.
-Vacuum is reading 20" at idle, but Its not steady, the needle pulses quickly with in a 1"-3" range in either direction, I read somewhere that it could be an indication of a valve guide gone bad...
-Yes I double checked if my dumb ass put the plug wires in the wrong order.... they are in the right place...

Sorry for the book, just trying get as much info as a can in here that may help... If pics help, let me know, I'll snap some shots.

Thanks in advance, you all are a wealth of knowledge and I appreciate all of it!!!! Oh and that hour drive was also fill with a dip in the ocean... rough life, sorry for those of you stuck in the snow!

 

[Output Shaft]

It could be worn valve stem seals on #1 & 2 letting oil get by.

 

[Cgbeachbum]

It could be worn valve stem seals on #1 & 2 letting oil get by.

True, would a leak down test be the right path to verify this?

 

[NeverGiveUpYota]

My number two was really fouled. I replaced it and marked the date on the wire so I can check how fast it goes. I'm glad to see this post. Thanks for questioning yours.

 

[Output Shaft]

When decelerating, if you have bluish smoke coming out of the tail pipe, that can be a sign of worn valve stem seals. Maybe have someone follow you to see

 

[Cgbeachbum]

never noticed any blue smoke on decel, but i'll check for sure!

 

[Cgbeachbum]

Went for a good drive today and didn't notice any blue smoke on decal, didn't have the chance to have anyone following me, but I was watching religiously in my mirror. Still a bunch of black smoke on acceleration, but I reduced my idle mixture down from 3 1/2 turns to 2 1/2 and it seems a lot happier and less smoke... So just not sure how to verify my problem other than ripping the head off and inspecting the guides. Silly question, say I messed up and didn't time my valves right, would that cause a rich or oil problem in the cylinders?

On a side note, I got my A/C up and running again, converted to R-134, so some progress in the right direction, so nice to have A/C!

 

[Output Shaft]

Although I've never done it, valve stem seals can (maybe) be replaced on a 2F while the head is still installed. Google "valve stem seal replacement". We don't know that that's the issue though, but all the cylinders get about the same amount of fuel, though #1 & #6 normally run slightly leaner than 3 & 4 since they're farther from the carb. On my engine, spark plug #1 & 6 have always been the cleanest.

 

[NeverGiveUpYota]

Although I've never done it, valve stem seals can (maybe) be replaced on a 2F while the head is still installed. Google "valve stem seal replacement". We don't know that that's the issue though, but all the cylinders get about the same amount of fuel, though #1 & #6 normally run slightly leaner than 3 & 4 since they're farther from the carb. On my engine, spark plug #1 & 6 have always been the cleanest.

Ah! Just the answer I was wondering when I read that comment the other day. Thanks OS!

 

[Cgbeachbum]

Thanks OS! I'll do some research... as theres really no activity on this thread, am I the only one to have this problem...???

 

[NeverGiveUpYota]

Thanks OS! I'll do some research... as theres really no activity on this thread, am I the only one to have this problem...???

Doubtful. Like I said #2 was super fouled on mine. And another guy had posted super fouled plugs on the 'what did you do..." section. Regardless, I'm watching!

 

[Cgbeachbum]

Got a little tinkering done yesterday, decided to go through the desmog that the PO did prior using the "How to Desmog" pdf found here to check all the vacuum lines. Something I should have done long ago... . Found a couple issues along the way. One my choke opener was plugged into the Port A of the carburetor, first port to the left if you looking at the front of the carb. That port has been capped and now the choke opener runs to one of the three small ports on the air cleaner. Then I found that port C on the front of the carb, furthest port to the right which is supposed to go to port A of the HAC (I don't have one on the truck.... yet), was routed into HAC Slow Port on the inside base of the carb. That hose was removed and capped at both ports... Also, both of my BVSV's are shot and broken, so my EGR R Port at the base of the carb is routed directly to Port S on driverside VCV. Everything else was routed/plugged correctly and done accordingly to that awesome document that @Borick wrote up with all the good info from JimC.

So heres the ticker... Started up great this morning, drove even better the 30mins to work, took an early coffee break... and pulled both plugs... CLEAN! a bit on the white side of the coloring, so need to do a bit more tuning on the carb, but no fouling.... Of note, I got the A/C working again but there is no VSV (on order) so I had bump the RPMs up to 850 in order to handle the load of the a/c compressor at idle.

Was this my problem the whole time? Could that hose from the HAC Slow Port routed to port C on the carb be the main culprit, messing with the venturi of the carb?

Thoughts?

 

[Cgbeachbum]

Doubtful. Like I said #2 was super fouled on mine. And another guy had posted super fouled plugs on the 'what did you do..." section. Regardless, I'm watching!

Before I found that my plugs were clean, I stopped by Napa and picked up a set of spark plug anti fouler, never used them before, but was going to give them a shot, the set was like $5bucks, read a few reviews where people have used them with success, but mostly they put in on older engines that have serious oil leaks into their cylinders. Not a permanent fix, but just something i was looking into and thought I'd pass it along...

 

[Colorado84]

I'm been searching like crazy, but haven't found anything on this to help the issue I've got on my '84. It's the same as the OP, but only on #2 cylinder. Intermittent spark on the gun. Sometimes it's fine, but mostly it's flash-flash-flash-nothing-nothing-flash-flash...and so on with the timing light hooked up to it. Definitely a miss.

I also cannot, and I mean cannot, get this thing to consistently idle without dying unless I artificially bump it up to 1200+ rpms with the idle adjustment screw.

No intake or exhaust leaks, carb just fully rebuilt by Mark in CA. Tried lean drop method multiple times. Carb came shipped with the idle mixture out at 5 turns, but not sure if Mark 'pre-tunes' his carbs.

Adjusted the valves cold 750 miles ago.

204K miles on the motor. Compression also great at 145psi across the board, vacuum (here at 5,000+ ft) a steady 14" on the gauge (which is correct for my altitude.

Any help appreciated!! Am I potentially looking at worn valve guide seals on cylinder 2? If so, anyone have a writeup for doing it with the head on? I assume I'd put cylinder 2 at the top of its stroke, remove rockers, valve springs on #2, and from there...is it accessible and possible in-situ?

 

[Seth S]

Could be a cap/rotor problem, a bad wire, or a distributor issue as well.

 

[Colorado84]

Could be a cap/rotor problem, a bad wire, or a distributor issue as well.

Seth, thanks for replying!

I've actually also recently installed new (OEM Toyota) cap, rotor, wires, and NGK BPR5EY plugs (by memory on the plug # there might be wrong).

I also checked the advance (main and sub/HAC) on the dizzy last night, and both main and sub- are working as they should. Had the cap off to be sure all was copasetic and it looks good in there - a little white buildup, but nothing notable really. Hit it with fine emery cloth just to rule that out as well.

Just checked the PCV and it's good as well.

All Emissions routed correctly as per the book.

Just pulled the plugs after an ~hour drive and did another compression test too - 140-150 across the board. Plug # two definitely had some black carbon buildup on it; sort of strange actually - one side was nice and tan, the other side had buildup.

Any further ideas?

 

[2mbb]

intermittent electrical issue. To me this is not mechanical (eg. not valve guides). go back and check the electrical bits especially associated with the #2 cylinder--distributor cap, distributor wire and connectors, spark plug (gap or cracked insulator), distributor (signal rotor or shaft run out). That sort of thing.

Also, just to rule it out see if you can borrow a different timing light to reproduce the issue.

 

[Seth S]

I’d measure the resistance across my coil wire and all my plug wires. Just another thing to rule out.

 

[Colorado84]

Good thought so far - do you happen to know what the resistance should be on the plug wires?

Here's a wrinkle to add as well - when I got the Cruiser ~750 miles ago, before I'd done any work at all, and pulled the set of plugs, the #2 looked the same but worse - a small mountain of black deposits on the electrode. After that is when I did new plugs/wires/cap/rotor, etc. This leads me to believe that (across two sets of all this) the same problem is occurring - plug #2 getting carbon or ash buildup.

Would that more likely indicate deposits from worn guide seals or blowby (even though compression is good when tested warm at WOT?

 

[Seth S]

Good thought so far - do you happen to know what the resistance should be on the plug wires?

Here's a wrinkle to add as well - when I got the Cruiser ~750 miles ago, before I'd done any work at all, and pulled the set of plugs, the #2 looked the same but worse - a small mountain of black deposits on the electrode. After that is when I did new plugs/wires/cap/rotor, etc. This leads me to believe that (across two sets of all this) the same problem is occurring - plug #2 getting carbon or ash buildup.

Would that more likely indicate deposits from worn guide seals or blowby (even though compression is good when tested warm at WOT?

you need to do a leak down test to determine if you have a ring or valve problem or possibly something like a cracked head.