Tuning + Upgrading

[suprastroker88]

I have a 7mgte that I have been slowly upgrading.

SP61gt DBB Turbo
RC 550s
Lexus AFM
3in Exhaust
PWR Radiator

I just recently put in the RCs and lexus afm. It ran great for a about a week and now it seems to run a little sluggish. I dont have a wideband yet so I can't read my A/F Ratios. But one of my friends told me that once i add in more fuel and air, I need to advance my timing a little bit. Can anyone explain this to me please?

 

[radiod]

You want to make sure your timing is at stock as per TSRM (link). I wouldn't adjust fuel at all until you have a wideband in place and can at the very least see what's going on with your AFRs. You will also need something to adjust the fuel with, some sort of SAFC or equivelant.

 

[dubsupra209]

dont get safc they suck for 7ms...i would get my maf gen 2 i have for sale and get rid of that stock afm so you can put it after the turbo..

your going to need

aeromotive fpr
maf gen2
wideband
boost controller
boost gauge

 

[suprastroker88]

I'm sorry if what I said is confusing. I'm not trying to adjust fuel. I'm trying to get my timing correct. I was told that after putting in bigger injectors and having more air flow, I would have to adjust my timing to compensate. Is this correct?

 

[Apollonius]

I would be more concerned about what your A/F ratio is. So no new fuel pressure regulator? Same old fuel pump? And you are not worried at all about where your A/F ratio is?

When I put on Aero FPR/550cc/Walbro/Lex I had a lean miss at idle... Sure part of this was probably due to my BC cams and we also found a kink in the fuel line... After that was squared away fuel pressure would drop on boost... Had to swap out to a diffrent walbro pump and the issue went away.

Point is you don't know whats going on.

 

[mk3_7m]

I believe your friend is basing this suggestion for higher engine speeds and larger throttle openings. Anyway the reason for advancing timing is because you are burning more fuel so complete combustion takes longer.

So by advancing the timing you're making the spark event occur sooner. By doing this you're also making more power. In a stock Ignition timing which is 10 degrees BTDC, you'll notice your timing will advance a few degrees more as the higher you rev as higher piston speeds creates a shorter 'window' for a complete combustion. Thus giving the combustion process more time to occur as the rpm goes up.

So if you do the opposite by retarding too much and make the combustion even happen later your piston would be already on it's way down before the spark takes place reducing the effectiveness of combustion lousy emmisions and less throttle response.

The problem associated with that by advancing timing is your cylinder peak pressure increases so higher combustion temperature therefore increasing the chances of detonation which is bad or even worse pre-ignition (both different things), along with more wear and tear on your rods, pistons and bearings as more load is put into them.


Although I don't see why you need to mess with your timing at this point since this has more to do with a bit of a rich A/F ratio for your "sluggish" problem.

 

[Turbo Habanero]

Well put ^^

 

[suprastroker88]

I believe your friend is basing this suggestion for higher engine speeds and larger throttle openings. Anyway the reason for advancing timing is because you are burning more fuel so complete combustion takes longer.

So by advancing the timing you're making the spark event occur sooner. By doing this you're also making more power. In a stock Ignition timing which is 10 degrees BTDC, you'll notice your timing will advance a few degrees more as the higher you rev as higher piston speeds creates a shorter 'window' for a complete combustion. Thus giving the combustion process more time to occur as the rpm goes up.

So if you do the opposite by retarding too much and make the combustion even happen later your piston would be already on it's way down before the spark takes place reducing the effectiveness of combustion lousy emmisions and less throttle response.

The problem associated with that by advancing timing is your cylinder peak pressure increases so higher combustion temperature therefore increasing the chances of detonation which is bad or even worse pre-ignition (both different things), along with more wear and tear on your rods, pistons and bearings as more load is put into them.


Although I don't see why you need to mess with your timing at this point since this has more to do with a bit of a rich A/F ratio for your "sluggish" problem.

Good info. Thanks. I wasn't too sure. This is my first time doing more than just the basic bolt-on upgrades of exhaust and intake, so I'm trying to figure it all out. And I found out that another issue that is making my car feel sluggish is the fact that my rear differential is going out so it's not locking up on accel, and for some reason when I checked my timing, it was at 5 degrees BTDC. So I set it back at 10.

Another question....... I'm putting in new NGK Iridium IX Spark Plugs since I've had cheap plugs in for awhile. What should I gap them to for best performance? 0.7mm? or standard 0.8mm?

And yes I am working on getting a wideband so I can see what's going on with my Air/Fuel Ratios. Money's tight so I'm doing the best I can right now with what I have

 

[mk3_7m]

Stick with the standard. You might get a bit of cold start issues later on (well that was with the platinums spark plugs I ran back then)

Depending on how much boost you're running and whether you get spark blow out only then should you consider gaping your spark plugs down.

 

[suprastroker88]

I'm running between 15-18psi

 

[thevork]

I got a lot of misfires with the NGK irridiums. Got the copper gapped @ .8 and everything was ok.
While you don't have a wideband, please at least get an AFPR and set your base pressure with the vacuum hose disconnected around 40PSI.
Take out a Volt meter and configure it to read your Vf signal. It's in the diagnose plug. Search these forums on how the Vf works.

After plugging in the voltmeter into your diagnose plug, connect the vacuum hose to your afpr and start the car. Let it warm up and check the Vf signal. It's maximum is 5 (enriching) and minimum is around 1 (leaning out). Lower the fuel pressure until the Vf value is between 2.75 and 3.25. That would make it idle like stock, and be somewhat rich at WOT. Your ecu will then let your car run almost like stock when in closed loop.

But get a wideband and piggyback asap to get a decent tune.

Someone said that s-afc's suck for 7m's? I run one, and 2 of my buddy's do too. I think it's great until you hit 500whp, but when you have that you'll have a whole different setup.

my 2 cents...

 

[Quin]

SAFCs are fine for what they are. Did you jumper the diagnostic connector when you set your timing? Double check it if you didn't. I always ran cheap coppers (Autolite 3923s or NGKs, can't remember the number, 7 range) gapped at .025" and my car liked it.

If you can't afford a wideband right now, I would definitely be pulling and checking those plugs regularly to get a ballpark and how the car is running. Untuned with 550s/Lex should be pretty rich.