Disabling the SAFC?

[Novablue454]

As most of you know, i've been having severe studdering issues ever since I had an SAFC installed. I've heard that by just unplugging the connector, the car probably wont run at all. Im not too amped about completley removing it, as i just payed $500 in labor to have it installed. So heres my thinking (which is usually wrong).

By unplugging the connector, in essence, your cutting the MAF wire to the ECU so it has no idea how much air its getting. Is this correct? So im thinking that I could just disconnect the MAF signal in and MAF signal out wires, and then reconnect the factory wire to itself so it would basically be untouched. Would this work?

Thanks for having so much patience with me and my stupid noob questions.

 

[JayRolla]

You do have the AFPR installed with that pump right? What is your fuel pressure set at. Also when does it stutter, at low rpm, idle, lo throttle, WOT? Are all you settings zeroed out accross the high and lo settings? Also make sure the SAFC is set to karman and 2 cylinder car so the rpms read right.

Im not too amped about completley removing it, as i just payed $500 in labor to have it installed.

Wow, I cant believe you had it installed for so much. Someone charging that much most likely have no idea what they are doing. Its most likely installed wrong!!!!!! I could have installed mine but I was lazy and payed my mechanic $65 for an hour of work to install it.

 

[twicks69]

darn, beaten to it by Jay@!

More than likely you either have it improperly wired, improperly configured, or something else has been modified or a boost leak.

There are only so many things it can be.

You should check out vfaq.com for electronics install of a S-AFC for a wiring diagram and basic configurations. Otherwise, check out some of the archives on Road Race Engineering's website - look for S-AFC install directions, tuning tips, wiring directions, and configuration setups. Both sites will more than likely show you what you need to know before you start tackling your problem.

Information is key.

As well, it keeps you from getting ripped off in the future for any more work you let a "professional" do on your car. If you know what you are doing, you are going to answer your own questions and have confidence in your mechanic if you understand what needs to be done as well.

That said...

Zero out your AFC; adjust your fuel pressure regulator...return to stock pressure (43psi?) with the boost reference line disconnected, then reconnect it, and reconfigure your SAFC. Then check for boost leaks if is stil studdering/stumbling, then look at other potential items...Spark plugs, spark plug wires, O2 sensor, etc. Things to check first... MAF wiring connection, ECU wiring connections, AFC wiring harness connections into the wiring harness. You should have an ECU socket wiring diagram showing pinouts and which ones to tap into for the use of a SAFC. Then check for proper ground installation on the harness.

After finally fixing all problems....calibrate the SAFC if you didn't do it yet, then disconnect the vehicle battery for 30+ seconds, and let the ECU reset itself.

Only from there you should look at adjusting the SAFC to meet your proper and safe tuning parameters.

 

[GST98BIG16G]

$500 for installing SAFC? tell me who that (******cant use bad words but it makes me mad) was that charged you 500 and ill go with you and get your money back!!!! seriously man , its like 50-80bucks to install it. You need to tune your car (its not another $500 dont worry) Tune it for sure . Drive it slow , dont boost . Keep us posted thanks

 

[Novablue454]

wait. i was wrong on the install cost. it was like 550 for an aeromotive FPR, a hallman MBC, and getting the MBC and SAFC installed.

The fuel pressure is set at 37psi with the vacumn line disconnected at idle.

I wasnt aware it needed to be set at two cylinder. Im pretty sure its at four. I'll go change it now, however im not sure if i'll be able to get it out for a test drive tonight.

Its doing it at everything other then 0-1/4 throttle. On my way home i couldnt get it past 2000rpm when it was floored.

I have one small boost leak at the BISS screw. I dont think this is large enough to be causing this.

The spark plugs were replaced about 50 miles ago with NGK BPR6ES.

The shop that installed it (9 Second Racing) is an almost all DSM shop and pretty reputable.

Ive got a palm m100 from ebay and a cable and software from obdloggers.com coming in the mail. I have no idea when they will arrive though.

and gst98big16g. dont worry, its so bad i cant even get into boost.

 

[Novablue454]

ok. I just got it out for a test drive and setting it to 2 cylinders fixed it...untill i changed the MBC. In the process of troubleshooting this, I had removed the MBC, and just ran a line from the wastegate to the J-pipe. It runs fine like that. But when i put the MBC on, when it hits 10psi it studders out and wont boost past 10. Im at a loss for ideas. Could it possibly be that i have the MBC set for way too much boost and its messing it up? Im not sure where to put it for 15psi.

 

[JayRolla]

Actually If I think about it my car also stumbled off the line when it was cold after the safc install on the first ride home. He said he leaned it out at idle to help it. I thought that was the problem. When I got home I changed the safc to 2 cylinder and never thought that was the problem till you mention it.

Did you do a log. Is it fuel cut? What maf are you running?

 

[spyderturbo007]

As most of you know, i've been having severe studdering issues ever since I had an SAFC installed. I've heard that by just unplugging the connector, the car probably wont run at all.

Last time I helped someone with this, they forgot to cut the MAS wire and just tapped it instead. I would check over the wiring first. Make sure that the correct MAS and ground wire is on the appropriate side of the ECU. It is critical that one of the wires be closer to the ECU than the other.

If you unplug the connector, the car will not run properly if the SAFC was installed correctly. The MAS signal goes through the SAFC before it reaches the ECU. If you unplug the SAFC, the ECU will never receive a signal from the MAS and will throw you in limp mode. You will also get a CEL.

Im not too amped about completley removing it, as i just payed $500 in labor to have it installed. So heres my thinking (which is usually wrong).

Ouch.

By unplugging the connector, in essence, your cutting the MAF wire to the ECU so it has no idea how much air its getting. Is this correct?

Correct. But like I said above, that's dependant on a correct installation.

So im thinking that I could just disconnect the MAF signal in and MAF signal out wires, and then reconnect the factory wire to itself so it would basically be untouched. Would this work?

Hummm......Let me think about this. The TPS and RPM wires are just tapped and unmolested by the SAFC so that won't cause a problem. The ground wires are also just tapped, so I don't see a problem there. In theory, your thinking is correct, but I have never done that before. I would check the wiring first. Here is a nice walkthrough you can use to verify the wiring.

http://my.prostreetonline.com/forums/showthread.php?t=97

This will show you the ECU pinouts:

http://www.vfaq.com/mods/ecu-harness-2G.html

Post back if you aren't sure how to interpret the pinout diagram or have questions about the installation walkthrough.

Thanks for having so much patience with me and my stupid noob questions.

No one knows everything when they start something like this. We all have to start somewhere. It is nice to see you attempting to rationalize your problem before posting your question.

 

[Novablue454]

i havent done a log yet. My software, cable, and palm are in the mail, but im not sure when they are going to arrive. And my one friend with a DSM in the area has DSMlink and no logger.

But now im really confused as to why the MBC would make it studder, but it doesnt at stock, and why it wont boost past stock.

 

[JayRolla]

So if you take the MBC off it boost's fine and no studdering?? If so I would try another mbc to see what happens. Also flip the vaccuum lines around on the mbc, it may be hooked up backwards.

 

[Novablue454]

So if you take the MBC off it boost's fine and no studdering?? If so I would try another mbc to see what happens. Also flip the vaccuum lines around on the mbc, it may be hooked up backwards.

Yes, it runs fine with just a vacumn line running from the wastegate to to the j-pipe. But when I put on the Hallman, it studders out at 10psi. I have the side connected to the wastegate and the bottom to the j-pipe. I tried putting my homemade one on that i was running 15psi with before all of this, and with the screw all the way in it wont boost past 10psi, but it doesnt studder.

 

[Ceddy]

You can bypass the SAFC by unpluging the two wires with bullet connectors(pink and orange on safc side) and plug the ecu wire back together. Leave pink and orange unhooked.

I did this when I went back to running 450s and my car ran better than having safc zeroed out.

 

[Novablue454]

ok, perhaps i'll try that. Those are the MAF wires correct?

 

[Novablue454]

I decided to go do a quick test to see if the SAFC was tapped into the MAF right by unplugging the connector. It immediatley dropped the idle and threw a CEL. So im assuming that the SAFC is installed correctly.

I just remembered something that might be a contributing factor. During this last big storm we got, I clogged the front bumper with snow and overheated the car badly twice. I wasn't paying attention to the guages as I was more focused on getting unstuck. Both of these times when I popped the hood the turbo was glowing red. I am in bad need of a new dipstick as mine pops at anything over 8psi, and at the time i was running 15, so it sprayed out oil and ignited it. It was only on the power steering pump/dipstick area so Im pretty sure that nothing was affected by the actual fires.

I also badly overheated the car once on my way to aurora when the coolant line running from the thermostat housing to the intake manifold decided to split and dumped all my coolant.

Is it possible that these extreme tempatures in the turbo melted the seals or anything like that and its actually a bad turbo causing this?

 

[twicks69]

Well, when you add that "small detail" into the equation, it opens up the potential severity of the problem.

Have you done a compression test or a leak down test????

You just opened up a can of worms that include a blown head gasket, or damaged piston rings.

When you are blowing out the dipstick, that is NOT a good thing -- meaning that you have excessive blow by. Have you even checked your PCV valve to make sure it isn't clogged/or failed?



Have your engine problems started since the overheating incidents?

I would start looking at more than just the SAFC and MAF if I were you.

 

[twicks69]

Have you even taken off the intake pipe to check the turbo compressor side for damage? shaft play? resistance when spun by hand?

Have you taken off the exhaust to see for damage on the turbine side?

 

[Novablue454]

No, I have not done a compression test. The pcv valve is good (as far as I can tell by blowing through it).

Im pretty sure the dipstick is popping becase the seal on it is only 1/2 there. Its turned to plastic and broken in half. Its so bad it wiggles in the hole.

No, I have not checked the turbo.

BUT THE PROBLEM IS FIXED.

I finally gave in and decided to replace the plug wires. I stopped by work this morning and picked up a set of Bosh wires. Now it runs better then when I got it. I decided to get cheap ones first instead of the expensive performance ones just to see if it fixed it, and since if that wasnt the problem then I could return them no problem. So now some performance ones are next on the list.