I have been running these type of plugs for almost as long as they have been selling them. But about 2 months after installing a new set, my engine light is on and when I get on the gas it wants to stall out.
When the dealer plugged into my truck to see what was wrong, it came back with a misfire code for cylinder 1. They then noted that I had Bosch plugs and said that my vehicle should only have NKG or Nipandosno.
It cost $97 today for them to tell me that I needed spark plugs.
I'm guessing the real problem is my fuel pump or injectors.
I've already replaced the filter, any input would be appreciated.

Couple q's. When's the last time you changed the plug wires too?
Did the dealer give you the codes, or have you pulled them to see what the ECU was recording? If so, what were they?

Sometimes Bosch's are a little too hot. I used to run platinums for awhile, but have since gone back to NGK's, mostly cuz they're about .70cts cheaper apiece. Plugs and wires are cheap enough; check it out before tearing into the fuel system, if you said you've already changed the filter. Double check your timing and your TPS setup too. <img src="/forums/images/graemlins/kewl.gif" alt="" />

The Toyota mechanics arent lying. Even if Bosch perform well in other vehicles, I have never had a smooth running engine when installed in a toyota. My 87' 4Runner came to me with bosch plugs and when I pulled them they looked like they had been to hell and back. Only 5K on the motor...too bad they didnt assemble it correctly. But anyways, for best performance and fuel economy try NGKs or the NDs from Toyota. Less than $2 per plug for the NGKs and the NDs generally cost me about $3.25 each from the stealership.
~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />

** +4, aint them the ones with 4 prongs over the electrode? Little electrical engineering lesson here...current follows the path of least resistance. Even if there were 16 prongs around the electrode, spark would still only travel to one prong. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Bosch Platinum plugs are very good, except when used in our Toyotas. I never believed it until I put new Bosch plugs in both my Supra and my truck and ran them for about 3,000 miles. Both vehicles started running rough and I could not believe what I saw:



The plug on the left is from the truck and the plug on the right is from the Supra. In both cases, I feared my vehicles were running extremely lean. That's one thing for my naturally aspirated truck, but certain death for the my modified turbo motor.

To make a long story short, I replaced the plugs in both vehicles with OEM Toyota plugs and now have about 6k on each. Both still run well and I pulled the plugs on the Supra on Saturday to make sure they looked okay and they looked GREAT. With twice the mileage they had about 1/3 the build-up compared to the Bosch.

Believe my results or don't. I will never use Bosch plugs in my Toyotas again.

I went through the same ordeal with my 4Runner a while back. I took it to the dealership and they hooked up the computer and told me that it was the Bosch plugs and replacing them with factory Toyota plugs would fix my problem. I followed their suggestion and left the dealership happy with my 4Runner running great, but my back pocket $125.00 lighter. Well, one week later, my 4Runner went back to doing the exact same thing as before the dealership replaced the plugs. I figured there was only one other possibility as to what was causing my problem, so I ran out and picked up a set of plug wires and slapped them on. The 4Runner fired right up and has ran great ever since. This is just my experience, but I hope it helps.

Wow am I glad I saw this. I was gonna put Bosch Platinum 4s in and new plug wires. So looks like ND from the dealer then. How about Disty cap and wires, and particular brand ok or is it another better get it from the beloved dealer?

Thanks

Why the dealer? You can go to any NAPA and get NGK's and ND's at about one third of the markup instead of the huge markup for margin at the dealer's parts counter.

I remember reading somewhere (can't remember exactly where at this moment) that the use of plugs other than ND or NGK in a Toyota engine does more damage than just nasty plugs, stuff like taking out plug wires, bad feedback to the ECU, etc. IIRC, the Toyota ignition system was designed to work specifically with a certain design of plug, wire, etc.

Probably the person who is not posting that knows more about this through pure attrition and testing of parts is Gadget... You are being paged sir.

Mike

I had the same problem when I put the Bosch Platinum spark plugs on my old '89 4Runner long time ago. It never got a better result. I switched back to the ND spark plugs, it got a better performance and smooth idle. It is not worth to have a Bosch spark plug on Toy unless if you know what you are doing with this.

Its just kind of strange that my truck has been running like a champ all this time with the Bosch 4 plugs, and then it craps out on me. But I trust everything I have been reading in the posts above.
The last time I changed my Bosch plugs, I pulled out one and all 4 prongs had broken off into my engine. Whats up with that!?
Its 9:35pm Seattle time, apx 31 degrees, and I'm headed outside to switch back to factory plugs. Will see if this fixes the problem. Even if it doesnt, I'm never installing Bosch again.

Got everything installed, runs better but still rough. I'll drive for a while tomorrow and see if the computer does any fine tuning for me.