I just recently purchased an 03 350z 6mt with 70k miles

This is my 3rd 350z, and this one seems to run very sluggish..
The motor sounds fine.. idles perfectly.. no noticeable sounds/shaking at all..

HOWEVER. its SLOWWWW.. very sloww to accelerate.. when im cruising in 2nd gear going 40 and punch it! it is very slow to accelerate.. The rpm's climb slowly and it doesnt have that 'kick' when u got WOT..

If the Previous owner was using regular gas.. did he PERMANENTLY screw up the air/fuel mixture..? Can this be reversed if i started using PRemium fuel only?????

Please advise...

 

Ps. Clutch is NOT slipping. It has a brand new clutch n flywheel

 

maybe you need nos

 

Run your codes. Check intake and exhaust for blockage or old age. Run injector cleaner and super gasoline through it. If it still sucks, you might need a compression test.

 

Don't VQ's pull timing when sensing knock? The lower the octane the more susceptible you are to knock. I was told the car knows the differences...

 

Kinda throws water on the last "myth", doesn't it?

"Using regular gas in a car designed for premium will definitely damage the engine.

"We don't believe that any modern engine that claims to require premium will be damaged by using regular unleaded judiciously. Neither do any of the sources we've checked with — including the American Petroleum Institute, the American Engine Rebuilders Association — even a chemist (who would rather go unnamed) at a major gasoline company."

http://www.cartalk.com/content/featu...ths.html#myth4

I guess it depends on your interpretation of "judiciously". Driving the car gently probably won't hurt a thing and won't aggravate the knock sensor.

 

Refill with premiem gas, change your plugs and reset the ECU. Report back with results.

 

My question is.. if the car has been running on Regular gas for years... Is it too late to change it up with premium? Will using premium change the timing back to what it needs to be?

Also.. what is considered 'normal' compression for a Z? I will run a compression test tomorrow and report back.

 

did you drive it prior to buying it or did you just buy it then drive it? if you drove it before you bought it might have saved you some money.

 

Reset of the ECU will put it into learn mode, if it senses detonation it will retart timing. If not it will operate under stock parameters. The plugs have probably been trashed from running the lower octane gas, change them. The compression, well running regular gas will not effect that at all, the ECU is very advanced and will porotect the motor from damage.

Before my car was tuned i ran 89 on road trips, no problems. Its not really a big deal on an stock to semi stock Z.

 

Great info.
Im gonna do this and report back..

 

"The plugs have probably been trashed from running the lower octane gas, change them."

Why is that? Plugs usually last 100K miles on regular in lots of vehicles using only regular gas. I'd go with putting in premium gas, resetting the ECU, see how it runs, and then take other action as required.

Don't do the compression test until you find out if more work is required. You can do it when you change the plugs, IF you have to change them. If it runs right after the ECU reset, you're good to go.

 

FSM says Standard reading is 185, Minimum is 142, and max variance is 14. This is from the FSM for a 2004 G35, pg EM-90 for reference When I did mine though, I got mostly 190 numbers, I'm at almost 80K with maybe 5-6K with TT

 

what are some symptoms of bad compression in motor

 

how do i reset the ECU?

 

Unplug the battery for 10 minutes, pump the brake pedal a few time wihile the battery is unplugged.


Oh they question about the plugs, detonation hurts the plugs. It beats up the electrode, just like it does to the face of a piston.

 

Regardless of mileage, I always tune a car up when I buy it. You don't know how the previous owner treated it. And I have seen plenty of cars come in the shop with under 100k and a misfire cause the plugs are fried. They don't last forever.

 

^^ This

 

sluggish, slow to acclerate, misfiring, its more apparent on a f/i car

 

If that's what you're worried about you need to have your compression checked. You need a special set of gauges.