in the mix of completing my full tune up on the 400 and trying to figure out this random misfire when accelerating as many ppl are having this issue based on the countless threads i have read with no resolution to the problem.....so after timing belt, distributor caps and rotor buttons,driver side coil, cleaned maf. wires with new spark plugs and trying 12v mod problem was still there...so i spent my day going through sensors, wires, vacuum lines etc, i noticed a maintenance sticker inside the hood that says PLATINUM plugs to be used which is not what i bought when i replaced them and it still cost me $4 bucks a plug...so made a phone call got a deal on some bosch platinum's $20 bucks for all 8, gapped them to .44 dropped them in an wow this car is finally driving so nice accelerates with no issues idles nice and has all its power back in all ranges of the rpm......so to my 400 drivers who may still be having hesitation issues when driving platinum plugs gapped to factory specs .44 makes a night and day difference.....

 

Do yourself a favor. NEVER RUN BOSCH plugs in Japanese cars. Your engine will love you for it. NGK OR DENSO ONLY !!!!!! SORRY just gotta hate on Bosch plugs. Never seen the reason behind them. Factory specs call for NGK / Denso usually.

BUT Yeah spark plug gap is very important.

 

I'm about to buy some NGK's (most likely) for my '99 SC4. What are they supposed to be gapped to? Same thing as non-vvti?

 

I was losing a lot of HP as well in my 95 SC 400. After replacing only 4 spark plugs I got a lot of it back. I bought them from Lexus for $10 each, probably paid a little extra but knowing that they are Toyota plugs is worth it.

 

.44 is factory spec gap

 

Jeez! Get the other four somewhere else because Toyota doesn't make spark plugs and you can get the same plugs for way cheaper. As for Bosch, I would have rather seen those when I pulled the spark plugs out of my SC for replacement than the Champions that the previous owner installed.

 

anyone have a DIY spark plug change.. i cant reach cylinder #3 and 4 .. gonna try to do a full tune up before putting my car up forsale.. oh a DIY for a sc300! .. not 400

 

take off your throttle body.... imo thats the worse place for a intake manifold ever! haha

 

anyone know how many bolts are on the throttle body? .. and yes.. that is the worst place ever!

 

Seriously??

7-1/2 years and 1000 posts!

 

Edit for you

 

This is interesting. I just did the full tuneup and I installed NGK laser iridiums. Haveing the hesitation issue in lower RPM's. I have a TPS sensor on the way and this is after I have had everything else apart. IAC valve. EGR valve. Replaced ECT sensor. Have removed and carefully cleaned my MAF a couple times. Would suck if it is something as simple as plugs. Oh well wont hurt to have a new TPS sensor.

 

+100000 lol

 

Make sure if you are gapping platinum plugs - which you usually don't have to - that you do it right. Don't wedge stuff between the center electrode and the ground electrode.

 

This is absolutely mandatory for gapping Iridium plugs


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