Thought I'd post some feedback on this misfiring / rough running problem, which was eventually solved.
After fiddling with the AFM, the problem would improve but kept coming back after a few short trips. I saw that the plugs were carbon fouled which I put down to fiddling with the mixture (too rich) so I cleaned them and set the AFM back to stock and checked its function as per FSM and all good. I reset the timing to stock. I pulled off the throttle body and set up the throttle position sensor perfectly.
As mentioned before, this vehicle sat in the shed for 5-6 years. At some point during the process of getting it back on the road, I changed the plugs. This would have been after the initial process of getting it going, when it ran fine after I'd sorted out the old gummy fuel problem. Being a fool I didn't write down when I changed the plugs in the log book, so I can't remember exactly when I did it. It was probably the same time I changed out the coolant, PS fluid, brake fluid, which I did write down.
I had come across a box of six new NGK plugs still in their packaging with "Surf" written it, along with a fuel filter, oil filter. So in went the plugs, can't do any harm I thought. It would have been after that the symptoms started. But like I say... being a tit I didn't write it down so didn't put 2+2 together with the change of plugs and the onset of the bad running symptoms.
After pulling my few remaining hairs out trying to find the cause of the intermittent missing and rough running, I decided to go right back to basics. I re-tested the HT leads for continuity, re-checked the rotor and dizzy cap, igniter, etc. I pulled each HT lead off the dizzy while running and thought I detected a dead plug, #5. Took it out, swapped with #3, hey presto, its misfiring, nearly dead. But it's new, I said. Hmmm.
Looked up the number on the NGK website, went to get a new plug. Got back, compared to old plug. Different bloody part number!!!!
Turns out the plugs I'd put in were NGK BKR6EYA-11. Plug that I needed was NGK BKR5EYA. Off I went back to the store and got 5 more of the correct number, in they all went.... and you can guess the rest.
The BKR6EYA-11 is a colder running plug for use in 4cyl 16v motors. My old school 3VZ-E didn't like them at all and was not burning cleanly and pre-delivery fouling, the plugs were all carbon fouled again. My symptoms were exactly what was described for too cold a heat range on the NGK website.
Someone somewhere supplied me with 6 of the wrong plugs way back in the late-noughties I'd think. My fault? Maybe. Certainly my fault for not checking them when I put them in the motor. Incorrect lookup in the store by a numpty saleperson? More likely I'd think. I used to buy everything from the trade counter at Repco...
Anyway the truck is going like a Boeing now its got the right plugs, and I've fallen back in love with it all over again. It's been given a birthday big time, new rear coils and shocks, front shocks, steering damper, ball joints, recon'd front brakes, bearings, the works.
To think I nearly binned it. What a foolish decision that would have been!
Last edited by hartster
on Mon, 19 Mar 2018 7:50 +0000, edited 1 time in total.
2013 Hilux KUN26R DC, 2010 Kluger GSU45R, 2006 Prado GRJ120R, 1993 Hilux VZN130R