Knock with Super gas

jedireez · Postby **jedireez** » March 11th, 2011, 7:49 pm

Hey folks, I'm starting this thread in order to determine if anyone else is experiencing the same problems with the Super gas from NP. I have a 323 BJ and an AE100 L touring wagon and what I've notice is over the last year or so both have started to experience knock when it get's really hot like in traffic. I've been using Super for the last 10 years in the BJ with no issues and I recently got the wagon last year and it also has the same knock. I've switched to Premium and the knock is gone! Because of the cost I've started to fill up with Premium then the next fill up I'll use Super. If a great many people are experiencing this then something might have changed in the Super formula. If not then I'll have to get both Knock sensors checked or changed but coincidence like that is rare.

PS. Sorry for the long read...

Big Z · Postby **Big Z** » March 11th, 2011, 9:20 pm

Have you done proper servicing of the cars?
Carbon buildup on the valves and inside the combustion chamber cause issues like what you are experiencing.
Carbon buildup (for lack of a better word) in the intake manifold also reduces performance.

jedireez · Postby **jedireez** » March 12th, 2011, 7:58 am

Apart from the usual maintenance of injectors, throttle body and oil/coolant changes I haven't had any other reason to go into the engine. Is there any simple way of checking for this apart from actually taking the head off?

thegtiman · Postby **thegtiman** » March 12th, 2011, 3:34 pm

"Super" gasoline (RON 92) in Trinidad is more prone to combustion knock than "Premium" (RON 95)
Heat introduced into the air charge and carbon build up over time would only help to increase the likely hood of knock.
Mind you both if those vehicles you have were calibrated for JDM 100 RON fuel with minimum use of RON 95. Servicing aside it does not take much to tip them into knocking conditions with crap fuel.

Postby **~VēġÃ³~** » March 13th, 2011, 9:37 am

could he try an octane boost fuel additive? does it work and if so would it be cheaper to use that with his super fuel rather than using premium?

EVA Unit-01 · Postby **EVA Unit-01** » March 13th, 2011, 10:11 am

^^^not really... octane boosters raise RON by a few points, where a point = 0.1 RON

so instead of spending $50 to get a 1 RON increase, put the premium instead...

thegtiman · Postby **thegtiman** » March 14th, 2011, 5:46 am

^^^ Very good point...

Postby **~VēġÃ³~** » March 14th, 2011, 10:09 am

thanks for that clarification EVA Unit-01!!!! :cool:

jedireez · Postby **jedireez** » May 11th, 2011, 8:43 pm

Hey folks, It's been a while but I had to share this with you all. strange thing happened last week with the 323. one of the ignition coils started acting up. When it got hot and the engine was under extra load like the AC it would stop firing. Had to drive over the pricesmart flyover on two cylinders and let it cool off. Anyways I ended up changing both coils last weekend and all this week I've been driving it in traffic with Super gas and the knock isn't there anymore. No joke it's completely gone! I'm sure because I didn't fill up with Premium for a month now and get this, it's driving with more power now then with the old coils. I got the new coils at M&N if anyone is interested. I still need to check out the corolla but at least this one is solved.