installed 550s and afc now car won't run right

[CBgst]

my mods are big28, Walbro 255, afpr, 550s, and S-AFC( I think that's all that pertain to this)

Everything ran fine until I put in my injectors and the afc. I put the injectors the other day. I drove it for a day before I put the afc in. It ran fine while just cruising around but it studdered real bad when I got on it. The car wouldn't rev past 4200. I figured it was just running rich and the afc would fix it. Well I installed the afc and I got the same results. I tried the settings on RRE web site but they were no good. So I set to zero so I could drive to work. Well on the way I started playing with it but I couldn't fix the problem. I put it back to zero and now the car studders on and off all the time. I,m going to log it later but what should look for( I just got my logger)? What should my o2 voltage be? How do I tune it? Do I tune for egt or o2 voltage? I can't tune for timing because car won't run right. Please help

 

[2-0turbo]

You are stuttering because you are running too much fuel. Do you understand what you are doing with the SAFC? Do you understand what swapping in larger injectors has done to your car? Do you understand how the SAFC interacts with your car's ECU? You really need to learn before you cost yourself some serious dollars.

Your car came with 450cc injectors. As far as the ECU knows, that is what you have. You have installed 550cc injectors. When the ECU fires the injector for 5 milliseconds, it believes it has injected "X" amount of fuel. You have installed larger injectors and it doesn't know. So, instead of injecting X amount of fuel, your car is getting 1.22X fuel. As a pretty good starting point, set all your points on your SAFC to -22% for low and high throttle. Make sure your fuel pressure is factory spec or set it to whatever you wish and adjust with the SAFC.

I am willing to bet your plugs are pretty fouled by now from running so rich, so you might want to swap in a fresh set.

 

[CBgst]

Yes I do understand what I'm doing with the afc. I understand that larger injectors make it run rich because the ecu doesn't know the injectors are bigger. I understand the the afc hides air from the ecu so it will not put in as much feul. I tried setting it at -20 across the board for the high and low settings. I have researched what i'm doing way before I actually did it. I'm not a newby to the engine and how it works. I am newby to tuning though. I am going to check the plugs. As a matter of fact I already bought new plugs yesterday. Thanks for the reply though.

 

[CBgst]

The feul pressure is set to factory specs also.

 

[CBgst]

I checked the plugs they don't appear to be fouled. They definitly don't look like it was running rich. I went ahead and changed them anyway. Anyone else got any other tips before I go drive it

 

[90tsi]

Make sure your airflow reading is set to KARMEN

 

[CBgst]

The air flow reading is set to Karmen. I just drove it and the new plugs fixed the low end studder but it still studders at about 3700 when the turbo spools. What sort of o2 voltage should I see at wot.

 

[CBgst]

I ran the car again and it still studders like it's running rich it doesn't matter how much I lean it out with the afc it still does the same thing. I.m begining to think it is something else. Also on the last run the CE light came on. It threw a miss fire on cylinder #2. Could a boost leak cause this studdering problem

 

[jambajusfrk]

changed your plug wires lately?
I had the same crap happen to my car....
ended up being the wires...
had aftermarket ones...swapped in the stocks...and no more probs.

if it's a boost leak you should be able to see it in your boost gauge
or hear it.

all the harnessesss that go to the injectors pushed in all the way?

afc setting to 4cyl?

 

[candela]

Yes a massive boost leak could cause this, as could many other things. But I am willing to bet that you hooked up the afc wrong. If youve tried starting with -20 and that still didnt work than I bet Im right. I thought that I hooked up my afc correct, I was possitive, but then I read a diagnostice sheet of common problems and one of them sounds exactly like what you have, which I had at the time. I double checked everything and found my connections werent full proof, and one of them was wrong also. I fixed everything soldered w/ heat shrink and problem solved immediately. Its very common that people mess up installing the afc, so Id check if I were you.

 

[CBgst]

Ok I check for a boost leak and everything is fine. I double checked all the afc connections and they are fine(and connected in the right place). It seems to be running rich but the exhaust gas temps don't reflect this. It runs at about 1300 degrees when cruising at about 3k( with the afc set at zero across the board). When I set it to -20 across the board it still runs the exact same exhaust temps and still studders when I put my foot in it. Should I put the old injectors back in to determin whether or not it's the injectors or something I may have messed up when I put them in. I'm out of ideas here. It seems to be related more to how much throttle I give and not to rpms or boost. If I ease into the throttle it revs higher but once it gets past a certain point it studders. If I just punch it the studder begins almost immediately. Feul pressure is right on so I don't know

 

[candela]

Im still willing to bet you hooked up the afc wrong. As said earlier I had the same problem and went nuts trying to figure it out. I would triple check to make sure you cut the correct wire for the maf, and then triple check that all the others are correct. What did you use as a diagram for the afc install??

 

[BatmanGSX]

http://www.roadraceengineering.com/newafcsetting.htm

Scroll down to "Common Problems". Second one looks like you, Ace. Score one for Candela.

 

[Rob]

Are these afc that hard to hook up? complcated ? or hard to set the setings ? and experence these problems when you hook em up all the time ?

 

[BatmanGSX]

I understand that people have trouble when using the original instruction manual that comes with it. When you use the VFAQ instructions that was actually made by a DSMer, you shouldn't have trouble, it's very straight forward. My friend did mine in about 10 minutes (solder, heatshrink) and it works great, no issues.

But lots of people have had issues in the past with either improper or poor (vampire clips) connections.

I think a lot of newer people don't know about the VFAQs (or other resources) because it hasn't been updated in a long time and isn't talked about by the veteran guys because we know it by heart and don't need to discuss it with eachother.

I can't link to the AFC install pages directly (as per the wishes of Tom Stangle, VFAQ webmaster) but a link to the VFAQs is in my sig. Look under "Electrical". Both 1G and 2G are there.

 

[candela]

Yes they are very easy to install and only takes about 10 minutes if you know which wires to use. Lots of people try to install them with diagrams from different years/models and such and end up splicing or cutting the wrong wires. I installed an afc after I did mine to a friends car and it only took me about 25 minutes for the whole thing. You just need to make sure that the correct wires are being used or you will have problems like this here fella'...

 

[CBgst]

Well I did use the vfaq to install it. I also have already checked RRE site and I checked for all those problems. I'll check the hook ups one more time and take all the connectors off so I solder the wires dirrectly together. Thanks for help guys

 

[CBgst]

Can anyone make any sence of this. I pulled the plugs on my car right. Well when I pulled them it was dark and didn't notice this small little detail. The plugs were white and not black. I can't figure out why the car would be running lean instead of rich. This is all with afc set to zero. Is it possible my feul pump or filter is causing this. Could it be my feul pressure solenoid not raising the pressure properly. How do you test solenoids.