KJG92

I went thru some of the paperwork that I got with the '92 and found where they did the whole timing belt thing and with that service they put on new caps, rotors and wires. No where did I see plugs. Which was strange to me. I pulled a plug out and it was a NGK iridium plug but it looked like it had some age on it. I was told by a source that you don't need iridium plugs in these cars as they came with copper plugs. I found some Denso plugs that were pretty cheap so I am going to get those.

As for coils, what have you all used? I found some on rock auto but nothing denso or toyota. Is it alright to use a standard motor parts unit? They have Airtex, bosch and delphi as well.

omarg

Iridium plugs basically last forever. Also 90-97 came with platinum plugs from factory. Under hood says replace every 60k, but I think some sources say 90k.

My wife's 00 had 184k miles on the original iridiums. I replaced em about four years ago. I didn't take a side by side picture, but they looked great and were not out of spec. The car drove no better (i.e. perfect ) with new ones. They should come gapped and part numbers by NGK and Denso will end with "11"

Another member "Kansas" said the same thing when he had his replaced on his 00 at 120k or so.

You can use coppers if you like but i hear they're best replaced every 20k miles or so. In the Scion, I put coppers because spark plugs are so accessible. The Lexus gets platinums or iridiums. Set it and for forget it! You seem really comfortable under the hood so do whatever you want. Just make sure you never gap platinums or iridium.

About coils, just get whatever brand your comfortable with. Both failed (about a year apart from each other) on my 94 but neither has failed on my 95.

I used a junkyard one (it was from a 90 so who knows how old it is) and a cheapie ($40) from Autozone because I needed the car fixed that day. That was about 3 years (20k miles) ago.

KJG92

The plugs in the LS400 are pretty easy compared to some but I'll order the platinums and get a couple of the coils. I'm only doing this because I have no record when it was last done and is just one step in trying to solve this issue.

omarg

how are the spark plug wires? are they original? I should test the originals on my 95, but haven't gotten around to it since the car drives like it should.

my 94 came with aftermarket no name spark plug wires. I didn't know how to test them at the time but the car had a miss under mild to moderate throttle. I first replaced the spark plugs with denso plats. Same miss. I put in factory wires (which are very convenient) and that solved the miss.
New factory wires should have these resistances. I got this info from Lexls.com a great DIY resource. Im not sure what the range should be but at least you have a benchmark to go by.

1=4.78
2=4.89
3=14.73
4=14.84
5=16.14
6=16.35
7=10.40
8=10.40

I've worked with NGK wires before, and they seem really high quality and fit perfectly and a fair bit cheaper than oem Yazaki wires.

KJG92

It has some German wires on it. STI technogy I think is the name. I'm having a miss at around 55-60 mph as it shifts into OD. I wonder if that is the issue.

omarg

ha! i should read the whole post more throughly before i reply.

the issue your having does not sound the same as mine.