Tuning issues!

729 Views 14 Replies 5 Participants Last post by Maverick31, Nov 27, 2005

Maverick31

Discussion Starter · Nov 26, 2005

I just installed my PLX wideband, and I started to retune my car.
I thought I had 450cc injectors, but in order for me to even get it to run 11.5 I had to tune my MAFT to the 650cc base/mid/wot setting. My only concern is that whenever I try to maintan speed, it leans out very bad and stumbles. Also, when letting off the throttle, it leans out very bad and trys to stall. But durring WOT and anything over maintaning speed, it runs great.

Its very strange that this happened... I really thought I had 450's, they are blue tops and everything. The previous owner ever told me they werre 450's.
Also the fuel cut issue I was having seems to have gone away... I guess the car was running way too rich.

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Maverick31

Discussion Starter · #2 · Nov 26, 2005

Ok, I fixed it. I had to richen up the mid setting quite a bit.

These are my MAFT settings:

Base- "7" which is suppose to mean 700cc
Idle- "1" is 5% richer
Mid- "3" is 15% richer
WOT- "B" is 25% leaner

This looks very odd, considering that I was told that I have 450cc injectors.
On this setting at WOT I'm getting between 11.7-12.4 on the wideband.
When I make WOT 20% leaner instead of 25, I run around 11.1-11.6 at WOT. This is all the way through the rpm range.
Any idea's what injectors I have? Is it possible that the previous owner somehow increased the fuel pressure high enough to make it this rich on 450's? I don't have a aftermarket FPR, so I don't know what this guy did to the car.

My boost is set at around 19-20 psi.

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Maverick31

Discussion Starter · #3 · Nov 26, 2005

BTW-
My mods are:
EvoIII 16G turbo(ported, 34mm Wastgate flapper), MHG, 3 inch tig welded turbo-back exhaust, 450cc injectors, Supra TT fuel pump, WAI, Man. boost controller, Evo 3 Exhaust manifold(ported 7cm), M/T ECU, Slow-Boy Racing tubular O2 housing, Fully gutted out, GM 3" MAF, MAFT, 3" Intake Pipe, Magnacore 8.5mm wires, 3rd Gen Revised Lifters, Dejontool Compressor Elbow,Extreme FMIC kit, IPT A/T "Boost Controller". IPT Custom High Stall TQ Converter, PLX M300 Wideband.

nukefission

· #4 · Nov 27, 2005

Back when I had the MAFT I had to set the BASE setting to a much larger injector to get the results I was looking for. I'd say what you're going through is typical.

Maverick31

Discussion Starter · #5 · Nov 27, 2005

You think I have 450cc injectors when I had to lean out that much? It just doesn't make any sense.

Chicago_DSM

· #6 · Nov 27, 2005

well, Im glad you got it tuned, but I would pop the injectors out and observe them...I don't see why someone would lie about the injectors being stock, but if it turns out they are, then it's DEFINITELY time to upgrade...

After injectors, I think getting an AFPR would help you tune also since the supra pumps flow a lot of fuel and whether it is overrunning your stock fpr or not, setting a stock fuel pressure would make tuning much easier...That and a better tuning device

edit: Sorry, I guess I don't mean "stock" injectors...Your auto so stock is not 450's...regardless, it's time to upgrade again

Maverick31

Discussion Starter · #7 · Nov 27, 2005

But why would I be able to take so much fuel out if they are only 450's?
I haven't taken the injectors out yet, but I know they have blue tops... aren't 450's suppose to have blue tops?
Do they make larger injectors that have blue tops?
My 650's will be here tomorrow, and I'm wondering if I should return them or not, I don't want to waste my money, you know?

Maverick31

Discussion Starter · #8 · Nov 27, 2005

Chicago_DSM said:
well, Im glad you got it tuned, but I would pop the injectors out and observe them...I don't see why someone would lie about the injectors being stock, but if it turns out they are, then it's DEFINITELY time to upgrade...

They only had the car for a month before selling it to me. I don't think he had a clue about this car. The odometer says 119,000 miles, but the motor has a metal HG (which the owner knew nothing about), and she runs flawlessly... doesn't even burn oil. I just don't get how 450's would cause the car to run that rich, I have a M/T ECU in the car, so the maps should be programed to 450's.

V8killerTSi

· #9 · Nov 27, 2005

I'd say you're not really leaning...it's just that the maft isn't calibrated exactly like the 1g mas so you have to modify it's output...

Maverick31

Discussion Starter · #10 · Nov 27, 2005

What???
I have a 3" GM MAS, not a 1G mas. And wouldn't you think that I would be overrunning my injectors at 21 psi?
At 21 psi and my current settings I am running a nice 11.4-11.8 all the through the RPM band.

Chicago_DSM

· #11 · Nov 27, 2005

You need a logger...Once you can log your runs, check the inj duty cycle and really find out how much juice you have left in those injectors

btw: A supra pump would definitely raise the fuel pressure a lot more than the stock rating, so this is possibly why your injectors have a little more life in them...Get a logger

16g-95GSX

· #12 · Nov 27, 2005

The problem isnt that you dont have 450's, it is that you use a MAFT. Again, the MAFT SUCKS, you are just seeing how inaccurate it's air metering is without an external source calibrating it. Your injectors I'm sure are 450's, the MAFT just likes to meter at random. Depending on what airflow map you are on the ECU likes to try to give a 9.5:1 AF ratio, or thereabouts, so taking out that much fuel isn't entirely out of the question, since you have raised your AF to 11.8:1 or so. I would just trust in the wideband and the knock sensor to be honest, and say goodbye to reading any airflow readings through a datalogger as they will be skewed.

650's are exactly what I would use for a Evo 16g turbo, and the Supra fuel pump is far overkill for a turbo like that, so you should be good for fueling after the 650's arrive. Go ahead and let them arrive, and when you go to swap them in take a good look at your injectors and look for any part numbers you can on them. They likely are just 450's, however seeing the mods that the previous owner installed, there always is the chance that you do in fact have 650's. If you let the 650's arrive at your door, and you find out that you already have upgraded injectors, you can always sell off the new injectors for damn near what you paid without much issue.

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16g-95GSX

· #13 · Nov 27, 2005

Chicago_DSM said:
You need a logger...Once you can log your runs, check the inj duty cycle and really find out how much juice you have left in those injectors

btw: A supra pump would definitely raise the fuel pressure a lot more than the stock rating, so this is possibly why your injectors have a little more life in them...Get a logger

If he is running 21psi, the fuel pressure regulator should be able to take over once again once he goes WOT and hits max boost, so I doubt thats the issue. It likely is causing alot of overrun during cruise and idle conditions though, I do agree.

One thing Id like to note, if you ever buy a car that has been modified, no matter what the previous owner said, double check every single mod you have on the car to ensure yourself that you really have what you think you do. I actually thought I had a Walbro 255lph on my car, and wound up running 21psi on pump gas through my 16g turbo, and then later upgraded to my FP Green only to realize my fueling wasnt able to keep up any longer. Checked them pump, and sure enough it was a stocker. Turns out the 2g fuel pump when rewired almost perfectly matches the flow characteristics of a small 16g turbo, so I got lucky, but if I had kept going with the FP Green without checking it, I likely would have caused damage.

Maverick31

Discussion Starter · #14 · Nov 27, 2005

Man, I don't want to shell out more money on a SAFC2... but if I do have 450's on there I don't see how I can take enough fuel out for the 650's.
Damn, this sucks!
The car runs perfect right now, and I'm having zero problems when cruising. Although I had to add some fuel to mid in order to get my car not to run lean while maintaning speed. The way I have it now, while maintaning speed, or lightly accellerating I am still pretty lean (14-15's), but I don't feel any negitive effects.

Maverick31

Discussion Starter · #15 · Nov 27, 2005 (Edited)

BTW-
Thanks for the great responses!
This is a learning experiance for me, and you guys are helping me out a lot.

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