RotarySupra

iTrader: (-1)

IVe searched for about 30min and didnt find anything around this area.just like every other 5-speed cars,the my turbovert has alot of power 1st thru 3rd gear,then when i shift to 5th my RPM's drop anywhere from 2k-3k rpm and it takes forever to get to 60mph or 70mph.i was thinking it might be fuel delivery issue.can anyone chime in on this?

Modifications-
S5 T2 engine with street port
cone air filter
VR4 fuel pump
REDOM ecu

Thanks for the help in advance

RotaryRocket88

iTrader: (7)

I think you're just shifting too early. The power band on a stock turbo is about 3-7k.

If not, then you may be overboosting and hitting fuel cut. Loaded up in a tall gear is where it happens most. Got any info on what a REDOM ECU is? Does it have some sort of fuel cut defenser? I've never heard of it.

RotarySupra

iTrader: (-1)

from what i was told from the previous owner its was a redom ecu,and since im berely breaking in the motor,i shift at 4k or below and i hardly boost it.ive done searches on a redom ecu but all the results have to do with a RE ecu and nothing else comes up.to be honest with you,ive never heard of it either.
Any other ideas?

btw-all emissions have been removed as well.

Thanks

RotaryRocket88

iTrader: (7)

Well, off-boost power below 3k isn't great. If you shift into 5th gear and end up at say 2.5k RPM, and try to stay out of boost, it's not going to pull all that hard. Give it a little more throttle and the turbo will spool up quickly.

Was this engine recently rebuilt? If not, why are you giving it a break-in period? If it's not a rebuild, take it over 4k in 3rd or 4th gear at WOT, and it'll feel like a different car.

RotarySupra

iTrader: (-1)

i drove it earlier,and i floored it in 5th and still slow to spool and to take off,it was rebuilt about appx 2 months ago in phoenix.since the fuel pump was relayed,i noticed the postive wire was kind of a small gage,can this be it?is it that the wire isnt pushing enough current to the pump?

thanks

RotarySupra

iTrader: (-1)

anyone else??? help please!!!

RotaryRocket88

iTrader: (7)

What RPM/mph are you talking about when you said you floored it in 5th gear? 5th gear is not for acceleration; it's an overdrive gear. Have you never owned a turbo car before this? You'll have some turbo lag if you mash the throttle at low rpm in a tall gear.

Fuel pump wires don't have to be huge. The stock TII pump only pulls about 7 amps max, and the stock wire size is about 14 or 16 gauge. 14 gauge is rated at 32 amps & 16 gauge is rated at 22 amps. A VR4 pump apparently is like a supra pump and pulls up to 16 amps, so both the wire sizes I listed should be adequate. That being said, I don't really think the fuel pump has anything to do with it.

RotarySupra

iTrader: (-1)

i floored it around 45-50mph at around 2-and 2.5k.ive owned a MK3 Supra Turbo,and TurboCoupe,but its the first turbo 7.since there doesnt seem to be a problem,do you think its the way i drive it?


Thanks for your help so far RotaryRocket

ericgrau

iTrader: (1)

I think power tends to be low between 1.8k and 2.5k. Only below 1.8k does the engine really start to complain and give hardly anything. So if you mean power is hardly anything then that's unusual for above 1.8k but if you mean it's just a little slow (even when floored) but gains power at higher rpms then that may be normal. If you're accelerating really slow you should be able to shift at 2.5k and end up at 1.8k without a problem. OTOH turbo rotaries are supposed to have a better low end than NAs.

Btw, for mpg shift when the shift light says so. For power shift even higher. At mid-high throttle you shift at 3.5k or so; below that point you lose not only power but also gas mileage. It's lose-lose. If you're hardly accelerating at all then you shift at 2.5k.

I mean, you should be at 45-60+mph when you shift to 5th, or I could see why you'd be accelerating rather slowly in 5th. Even 45-50 is kinda low.

AmviciousRav

iTrader: (5)

I think it might be the way you drive, you gotta learn the power band on your turbo car (power doesn't come out of thin air on turbo cars right?)

took me some time to learn how to drive my turbo car right (timing my shifts so I don't feel any power loss unless I wanna hear the turbo spool up a bit or something)

RotaryRocket88

iTrader: (7)

Alright, so 45-50 mph, with a 4.1 rear end, and a 0.762 5th gear, is only 2000-2100 RPM. The engine doesn't have much torque at that level, and it will take it awhile to even spool the turbo up. By 2500 RPM (58 mph), it will start to build boost rapidly & by about 3000 RPM (70 mph) you'll feel the torque increasing rapidly up to about 4000 RPM (93 mph). But at that point, you're speeding excessively .

Like I mentioned before, drop it down to 3rd gear at the same speed, you'll be at ~4000 RPM and it will tear right up to redline. The power band is broad in a stock turbo, but it starts higher than a lot of piston cars. Check out the dyno section, and change the options at the bottom of the page to display old threads. There are many stock turbo dynos that'll show you exactly what I'm talking about. Here's one: https://www.rx7club.com/time-slips-dyno-128/273whp-stock-turbo-814613/. It's blurry, but you can see at 2000 RPM, the engine has very little torque.

Out of curiosity, how many miles have been put on the engine so far? After two months, it may be ready for you to start driving it normally.

RotarySupra

iTrader: (-1)

i saw the dyno post,now i can see.i guess when i finish doing the break in,ill give it a little more juice. theres appx about 800 miles on the motor,its soo tempting.i give a little more than 4k rpm occasionally,is that bad when i havent broke it yet?



Thanks or all the help so far.

jake1191

iTrader: (1)

The whole break in thing has been debated a million different times on this forum. Just search and see. Did the manual say to break it in when it came from the dealer?