s13/14 ka24de needing 91octane+?

[jvega]

Hello, i have a question.

Why would my car (89 240sx W/ 96 ka24de) need the best gas at the pump?

l notice when i put the cheap gas on this car, it tends to "bog" at WOT higher rpm. The other night it shut off completely when i went to the Mountain.
So higher elevation makes it worse with this cheap gas. ?

The engine is stock besides an air intake and filter, and a cat back.
It is using the stock 96 240sx ecu with the complete 96 engine.

Any input would help. Thanks

[g00se]

I think there is something wrong with your car other than the octane considering it dies.. have you done routine maint?

[n8RPS13]

MAF is probably going bad...or TPS sensor, maybe even your IACV.

[jvega]

I think there is something wrong with your car other than the octane considering it dies.. have you done routine maint?

i gave it an oil change like 3 weeks ago and checked/cleaned the spark plugs.
Remember it only 'bogs' with cheap gas at higher rpm and wot. The only time it died was at a higher elevation, about 3k ft up.

[AsleepAltima]

high octane is the same quality as low octane - it just burns slower.
are you using the correct heat range plugs?

[cdlong]

High altitude also lowers the need for octane, hence why where I live (6000 feet), regular is 85, mid is 87, and premium is 89 or 91 depending on the station. I've been putting regular in my car for years with no problems like yours. There's something else wrong with your car.

[jvega]

high octane is the same quality as low octane - it just burns slower.
are you using the correct heat range plugs?

i know the spark plugs are ngk iridium's, i think they are 7's but not sure. I willl check tomorrow.

[AsleepAltima]

7's are too cold for a stock engine. you should be running 5's. 7's will make the engine sluggish, as you are describing.

[jvega]

7's are too cold for a stock engine. you should be running 5's. 7's will make the engine sluggish, as you are describing.

hey i checked the plugs today and they are 5's. Idk what it could be...

[AsleepAltima]

whats your gap set to?

[jvega]

whats your gap set to?

Alright, sorry i took a couple days, but the gaps are set to .044 on NGK bkr5eix-11 spark plugs.

[AsleepAltima]

that sounds about right - i believe its .044-.047 so youre right there. the problem is, neither octane, plugs or gaps will make it completely shut off. have you tried replacing the fuel pump relay? sometimes, when the relays get old, they dont push the same voltage to the fuel pump as they used to and the pump either stops working or works too slowly for the load the engine is asking for. after a drive, pop the hood and see if any of the relays in the fuse box behind the battery are overly hot.

[jvega]

UPDATE.

It was the fuel pump.. lol..
I changed the fuel pump and it hasn't given me any problems. :rawk: