Richening A/F on mildly modded 1G

[87MustangGT]

I just purchased a 92 TSi FWD - list of mods can be seen here: http://newengdsm.org/forums/viewtopic.php?t=13306

Among the mods are a 255lph fuel pump, but no other fuel system mods to my knowledge. I'm running 17 psi...

1) Are the AutoMeter digital A/F gauges any good? I know AM makes good stuff, but one of my buddies (a former DSMer) had nothing but bad to say about their A/F...so I wonder...
2) My A/F never shows more than 2 red bars, indicating that I'm running very lean if it's accurate. It's been a while since I've been in the car scene, and I hate to ask a fairly noob question, but how should I go about richening up the mixture?

Thanks a lot!
Bill

 

[perley03]

I just purchased a 92 TSi FWD - list of mods can be seen here: http://newengdsm.org/forums/viewtopic.php?t=13306

Among the mods are a 255lph fuel pump, but no other fuel system mods to my knowledge. I'm running 17 psi...

1) Are the AutoMeter digital A/F gauges any good? I know AM makes good stuff, but one of my buddies (a former DSMer) had nothing but bad to say about their A/F...so I wonder...
2) My A/F never shows more than 2 red bars, indicating that I'm running very lean if it's accurate. It's been a while since I've been in the car scene, and I hate to ask a fairly noob question, but how should I go about richening up the mixture?

Thanks a lot!
Bill

First off, im not here to bash you. Just trying to get you going down the "right" path.
If you are running a 255 pump, you need some way to regulate the higher flow of fuel by using an adjustable fuel pressure regulator, or AFPR. Second, the a/f guage is basically useless, since its off a narrow-band sensor, which doesn't tell you what your a/f mixture really is, its either lean or rich, there is no imbetween. If your guage is showing 2 bars at idle, that is fine. If its showing 2 bars at WOT(wide open throttle), then it tells me that your 02 sensor is not working properly. (Probally will need to replace it.) My bet is that your car is running very very rich right now, due to not having a way to regulate that fuel, which is basically dumping it into the engine while idling or off boost.
I hope this helps you, and i'd be in the market for a new 02 sensor and buying an AFPR. Good luck, and let us know your outcome.

 

[hewhoisknot]

Yeah, like perley03 said a narrowband is pretty much good for nothing but watching how much gas your using while you drive. If you determined to get an AF guage I suggest you go with a wideband such as AEM.

BUN

 

[87MustangGT]

So once I get an AFPR, how would I go about tuning it? Don't have time to search right now - but should a search get me the appropriate info?

 

[JayRolla]

If you want to go the cheap way get a apexi SAFC2 so you can adjust your injectors. Or you can go with dsmlink which is way better but cost a lot more. I would search about these. Also you would need larger injectors. Also i would guess you are getting a lot of knock at 17psi without any tuning. You need to turn it down to about 12-14psi. I would get a data logger so you can monitor your motor before running that boost. You need to do a lot of researching before you go about modding and tuning.

 

[hewhoisknot]

You might wanna rewire your fuel pump if that hasn't already been done. But to seriously tune you do need a wideband AF display if you are going to attempt it by yourself.

BUN

 

[awdtalontsi1992]

Everybody seems to be giving good advice so far. I definately agree that an AFPR is a must at this point. The 255 is overrunning the stock FPR causing you car to be rich.....which is probably why the car is still running at 17psi. You can do a search and find alot of threads on what the correct pressure is to start. I wouldn't recommend you tune with fuel pressure. I would recommend two routes....

1. Cheapest : Datalogger and Apexi SAFC2
2. More Expensive : DSMLink.......more expensive but will do the job very well and help with future upgrades.

Finally ditch the Autometer A/F gauge. It is a narrowband gauge and a piece of crap. Choose either of the two options and I would highly recommend you get yourself a wideband A/F gauge to tune with. I think Autometer has started to make Wideband A/F gauges. I personally use an AEM UEGO. It can mimic the stock narrowband so you can just replace the stock O2 sensor and not have to weld in a new bung.

 

[dsmsucks]

I would still turn the boost down to around 15psi. Just to be safe!

 

[JayRolla]

I get knock on a stock fuel system at 13psi. So I would get a logger and turn it down to 12psi. There is no reason to hurt your motor just for a few psi thats not tuned anyways so doesnt make that much of an impact.

 

[87MustangGT]

Interesting... I'll def dial back the boost for now until I can get all this straightened out... Thanks!!