Right, but losing a temp sensor is a major enough error for the ECU to throw it into "limp" mode. Obviously the MAS swap you guys were talking about is an alternative to this method. But this is a rather easy quick way to go about it, and not that hard to remedy should it not work. I wouldn't do it unless you'd really know what you are doing and have the right equipment to monitor your engine. I'd recommend having a wideband, a good AFC, and something like AutoTap wouldn't be bad either (logging/viewing software for ECU codes etc. )

 

has anyone tried this out yet?

im sure all the s-afc guys would love to get there expensive little screens to work as i plan on turbo....i'd like to know if an s-afc would work if i just cut the temp sensor...

 

As for wideband, those are very expensive. Also, has anyone read some negative stuff about wideband too? I have, and it has cast some doubts in my mind. I like to read all the +/-'s.

 

there were two things that happened before. one was when i had made my AF gauge incorrectly and used a low resistance resistor. the car idled fine but the revs would oscilate once i started cruising. CEL came on afterwards. i unhooked my gauge and i was fine. the second instance was when i started the car with the MAS not hooked up. this had the car idle at 3000 regardless. i didn't drive it but it would seem that it works fine to an extent if anyone remembers stew's "god cai". so having the car run rich would just be as easy as removing the MAS. if someone out there has a AF gauge hooked up, take a quick stroll around the block without a MAS on. that way if the car runs real lean, stop the car and put it back on. if it doesn't, we've made a much easier breakthrough.

i've never heard of negative feedback from a wideband besides it's price. i guess i'll take a look on other boards.

 

same here, never heard anything negative about wideband other than costing too much.

I've heard of people using wideband meters with stock O2 sensor and running into problems.. which I would very much EXPECT to be the case with that combo. The sensor type has been around for ages, so there shouldn't be any kind of reliability or inaccuracy issue... especially not for how much it costs

I may get a wideband by mid to end of summer if I get my suspension finished and racing isn't costing me too much money going every weekend. If I do I'll definitely take one for the team and start randomly (safely though) removing sensors and measuring the AFR at rpms etc to give us an idea of what seems most effective.

 

FYI for Rhyz- My car is in cobbled together mode untill spring but before it put it away it was set up like this: AFC is zero'd out and the MAS screw is backed out and I adjusted the FPR untill the car wasn't dead lean any more. It is a little rich at idle but functions pretty normal though out the rest of the range.

 

You have to search the net for negatives on the wideband. I was looking for something about digital wideband, and I accidently stumbled across 3 different people with negative experiences. Of course, I didn't read or take it to heart 100% of all their claims, because I wasn't exactly looking for those things.


Interesting articles . . . not the negatives.
http://www.mrcontrols.com/installs/t...e/techedge.htm

http://www.diy-wb.com/

 

it makes sense if it has the ecu go into a 'limp' mode and just dumps godly amounts of fuel in there....than since the ecu only sees negative numbers from the s-afc...or maybe it'd see positive now cuz its like that i dunno...anyways if it has a lot of fuel...u can just cut it down until u reach that 12.5:1 ratio

i'd love to try it...but i dont have an s-afc or upgraded fuel anything or a turbo...yet

 

so i made my cel light come on and tried to change settings with my afc and nothing happened, but then i unhooked my stock o2 sensor, which makes the cel light come on again, but now my fuel ratio is really rich like 12.1 or around there then i try to change settings on the afc and i could richen or lean the mixture as much as i wanted i could make it a 14.7 or 11.0 or whatever. but under boost i still went lean to the high 14's which probably tells me it is something with my car ie bad fuel pump, not the computer

 

Glad to hear that the limp trick works Now hopefully you can get the fuel you need into the system to get away from 14 and get it tuned in.

From what I've read/heard I'd have to lean toward your injectors being the issue. I'd try switching those out first (as they almost always can use a serious upgrade for doing good boost) and then if you still hit lean up top try to go with a larger fuel pump. If you are STILL lean at that point then I'll have to defer to the other guys on here.. but I would move toward running an fpr or something to get a much higher pressure moving through there to keep up.

The new car I'm getting in about a week and a half runs 8, yes 8 550 cc injectors. Tuned to run around 13 afr most of the time and pushes about 247 hp... on race gas the fuel system can keep up to the point of putting down 300whp.

You can actually run a rather aggressive tuning map and so forth if you push your afr's to 12.6. I know it sounds rich but it's the peak power output for gasoline combustion. Set it up so that at anything above 50% throttle you run close to 12.6 and tune closer to 13 or 13.2 when cruising and so forth.

Good luck though! And glad that the AFC is making some effects for you!

Later

Steve

 

sweet, so uh.... s-afc, upgraded fuel pump, larger/bored injectors, rising rate fpr....and im good to go on fuel? or should i get a wideband o2? remember...onyl wanna boost 5-6psi...

you all are true pioneers...taking new cars and doing this type of stuff to them...i love u guys

EDIT: Goku...ur car is SICK! i want all those guages to! looks awesome, love how you mounted the s-afc and avc in the ceiling like that...mad excellent mad excellent

 

thanks for the compliments drive02lancer. just want to put in here that i replaced my fuel pump with the 255lph instead of the 190lph and it runs perfect air fuel ratios (12.3-12.5) with 7-8 psi and thats with out having any cel light on and all s-afc settings at 0%

 

oh, so i guess a 190lph pump isn't good enough to run 7-8 psi. where did you get the pump from? is it a walbro 190?

 

OK... I read the first post and immediatly posted...

DON'T DO THIS...
This is quite possibly the WORST idea I have ever heard regarding tuning. First off...any good fuel computer can add/subtract fuel. Second off...read AEM EFI Basics and some other literature on EFI systems before you post. Your car will run like **** and you won't be able to tune correctly.

 

It's not the fuel computer that's the issue, it's the stock ECU.

From a purely theoretical point of view though it's actually quite clever and should work fine. There may be better ways to put it into limp mode though like the same way a header willl trigger the CEL by returning the same voltages. The cutting of the AIT wire though is guaranteed to work immedately, and is easily reversible.

I don't really see where you're coming from with the whole bad idea thing. The only danger I could forsee is a severe weather change could effect AFR.

Goku, you're probably still lean under boost because you're using the stock injectors. 80% IDC at 6psi = strain.