XPiRX

iTrader: (1)

Ive always used 93 Octane in my 94 Z28. Recently, Ive been lowering my octane, low on cash plus gas prices are a bit steep. I have a new job now, so gas shouldn't be an issue in a week or two.
I used 91 for a couple fill ups, didn't notice any problem. Then i tried the regular 87, and every other time (sometimes every 3-4 times) I start the car, it "lags" a bit. Usually when its sitting for long periods, usually over night or after work. It takes about 2 seconds to catch and for the engine to start compared to a quick burst and a roar. I noticed a big power difference between the 87 and 93, thats for sure. I cant do proper donuts, and its hard to burn my tires from a stop, I used to be able to burnout for 3-4 seconds (even with 50% of my tread) when I floored it.

Is it bad that my car lags when starting? It has yet to fail to start, but it kind of worries me. I'm about 60% tank left and I'm probably going to fill it back up tomorrow or Wednesday, should I start to use 93 again?

Edit: It does NOT have a rough idle at all, and still pulls freakin hard as hell Will the car "learn" to use the 87 octane? Its been pampered with 93 for quite a while. Factory says it runs 87 stock, and I only have an SLP Exhaust and K&N Air filter. Nothing high octane demanding.

Revelation Z28

iTrader: (10)

the PCM compensates the lower octane by pulling timing, maybe thats what you experienced is the PCM adjusting.

XPiRX

iTrader: (1)

So the lag when starting is nothing to worry about?

Edit: My friend told me pretty much the same thing last night. Im pretty it is the car adjusting the timings. Just, it doesnt have a quick roar of a start anymore. Doesn't feel like it struggles, just takes longer to get RPM Up.

Formula350

iTrader: (3)

They only 'learn' so far, and I (with my limited knowledge) don't think start up falls under that. I think what the PCM learns only gets applied during closed loop (or whatever loop is when the car is warm, I get them confused heh).

I wouldn't worry about it, though it could be a fuel filter on it's way to being clogged. The lower octane gas is lower quality at some places.

1994Z28Lt1

iTrader: (1)

dont be a cheap ***, put atleast 91 octane in there because the engine was designed for it

yeah i know it will run with 87, but you will pull timing, lose power, have lower fuel economy

Z-RATED94

iTrader: (6)

Use 93 octane like it calls for. On a different note, unless the car requires it, you could have the same proplem with higher than needed octane. Different burn rate.

letsrun97z

iTrader: (7)

i have noticed that too when i bought the car he ran 87 and would always start hard or pre ignite now for that last year i have only used mobile 91 or shell 91 and have had no problems

sweet-94z28

iTrader: (30)

I am actually considering moving my computer's fuel trim back a bit because I have it set for 93 and I have been getting a nasty spark knock when in a heavy overdrive load. I ran 87 once on the stock settings and it ran like crap. I will never do that again. For the past 6 months it has been nothing but 93+ We have a Sonoco here with 94 and it runs awesome on that stuff.

XPiRX

iTrader: (1)

Dont be name calling. Im not trying to be a cheapass, I had no job, and I could barely afford 87, and its my only car. But i have a new job now, and Ill be able to get 93 again. the car hasnt lagged in a few starts either, so maybe it was the PCM just "learning" or some ****.


Also, what about Octane Booster? The guy who owned the car before me said he only used 93 and if he had to use 87, he put a bottle of octane booster that he got from Dollar tree or some ****. What are some good brands to use if I needed, where can I get them, and what are the costs? Ill buy a few bottles "just in case" for the future.

Edit: If I mixed a gas tank with 50% 87-Octane and 50% 93-Octane. Would it mix and make like 90/91 Octane?

infinitebird

iTrader: (11)

Sorry but i've never understood this. The difference between a FULL tank of 87 and 93 is like $3-$4 tops. You can afford the $40-$50 to fill up but not $3 to get the good gas your car was designed for?

Octane booster is a waste of money, does not improve things at all, and for the cost of it, you could just fill up with premium anyway. Again, it makes no sense.

XPiRX

iTrader: (1)

3.15$ x 13 gallons = 40.95$
3.43$ x 13 gallons = 44.59$

Damn...... you're right. *slaps forhead*
I wont be using anything less than 93 from now on(Unless they only have 91 and I'm running on a dry tank).

I seriously thought there was a good 10$ difference. Maybe its because the gas prices have been fluctuating like a bitch around here lately, I didn't take in account for that. I bought 93 one week, it was 50$, then 91 another week (my boss payed for that). And it was 42$. Then I got 87 and it was 40$. Ill do my math next time

Oh and I would of at least gotten 91 If i had the money, but I had 5$, and I asked my dad for some money, but he wouldn't give me any unless I got 87, and I had to show him the receipt :-/ He keeps telling me I don't need the 93, I never listened to him, and obviously I was right.

infinitebird

iTrader: (11)

Well, he's probably just going by what he knows. Most cars do not need it, but we do.

XPiRX

iTrader: (1)

Yea, he knows a bit about cars, he taught me a lot too. But hes never really had a performance engine like us. I told him about my upgrades for May/June, and hes like "Why the **** would you put headers on your car, you don't need them". LOL. He says my car is too fast... yet he had a 71 mustang when he was age, was a rust bucket though lol. Wants me to invest my money more "Wisely". Hahahah, you only live once, why not live it up? 95% of my money goes towards my car, the other 5% is food and bills haha, and Ive cut back on the food to have that extra 15$ a week for my car.

chavez885

iTrader: (12)

Your dad is right, considering you have to ask for gas money, you shouldn't even be THINKING about modding your car.

On that note, use 91+

XPiRX

iTrader: (1)

No, hes been saying that since day1. I ran out of money last week because I spent it all buying parts for my car(I hit a deer ) and I quit my old job the week after I spent all my money. But I got another job, pays better, more hours, and its a lot more fun. I make transmission parts and some engine parts, I operate CNC machines. I could probably make my own tranny....

Revelation Z28

iTrader: (10)

so you mean you're a plastic surgeon?

yea your car is cool for now. when you put 91 back in itll run completely different and normal again

1994Z28Lt1

iTrader: (1)

you were spending money buying parts for your car and you voluntarily quit your job before having another lined up??

Im just guessing but it seems you might be the kind of person that drives around in your car hoping that someone will see you driving it

i think you have your priorities a little out of order

Formula350

iTrader: (3)

My car pops right off on 83 octane no problem. Seriously, it barely cranks before firing.

Dragframe

iTrader: (14)

Yeah... Your gas should have no effect on starting. Just everything else.

XPiRX

iTrader: (1)

I already had a new job lined up. I quit my other job because it was a bunch of bullshit. I don't want to get into details, but my priorities are fine. Its kind of hard to save money with only 20 hours of work each week. And I haven't spent a dime to upgrade my car, thats this summer when I have enough saved.

@ Formula350 and DragFrame - It hasn't started like that in two days now. So im not sure wth is wrong if anything. Maybe I just didn't give my battery enough time to charge fully back up before turning car off, I usually have my subs on pretty loud, they can drain a battery pretty quick. I need a capacitor ...