ion_four

Basically, here are the symptoms:
1)Car surges or bucks a bit when going into boost at WOT, or when going from no throttle (deceleration) to part throttle.
2)EGT is around 900-1000 when cruising, peaking at 1500 after a hard run though the first three gears.
3) o2 sensor voltage is showing rich at idle and part throttle, but becomes NEGATIVE at high-throttle.
Here's my set-up:
d16z6
T3, intercooled at 7psi
DSM 450's with a MAP trim circuit ala. afc-hack
zfr6j-11 plugs...


I'm thinking that I am running insanely rich, and that I should maybe switch to 7-series plugs...does this seem right? I've pulled the plugs a couple times and they're very black around the base, but not on the electrode or much on the porcelain... could it also be my clutch, since I think it may be going out (stock)...

ion_four

Anyone have any ideas? I'm assuming that surging would be caused by being overly rich, since it pulls hard once it's well into boost...but, could this also be causing the negative voltage on the o2 sensor?

filetofit

Hey you're not still running a turbo no downpipe with the o2 sensor hanging off the turbine outlet are you? Any exhaust leak near your o2 sensor will hopelessly confuse the ECU. A negative o2 sensor voltage is saying you're insanely lean, and that probably means air is leaking into the exhaust stream and confusing the o2 sensor.

filetofit

PS Those are Fahrenheit temperatures right? I guess you would have melted something if they were Celsius. Temperatures seem OK. What voltage are you sending to the ECU on the MAP sensor wire with the key on engine off? With the circuit board in place and 450cc injectors you should be showing the ECU 1.8 volts on the MAP sensor signal wire.

ion_four

No, I have the exhaust fully hooked up from the turbo to the muffler, no leaks that I can tell. I've got approx. 1.7v at key-on and have around .7 at idle. I've tried alot of tweaking and gone between .6 and .8v at idle, to see what happens.

Another weird symptom is that when I'm watching the voltage while cold idling, I've seen it jump up really high (above 3v), but I think it's just something random and weird because the idle was SOOO rough.

Are you sure that negative voltage from the o2 sensor means that it's lean? It makes sense that way, but it goes from about .8-.9volts and then into negative...the o2 sensor is about 1.5 feet away from the turbo outlet now, if that makes a difference. it seems to get a legitimate reading at idle (as the voltage jumps around alot), but goes screwy at WOT...
I'm kinda stumped. I think I may rewire my A/F meter, get some 7-series plugs (colder, just to normalize the temp for tuning) and see what the hell I can figure out. Any clue?

turbod16y8

hey i got the same probalem. Im also running really rich. and my o2 is just dangling from zip ties. my idle is really rough too. i think its beacuse of my o2. Fixing that tomorrow. ill post wat happened.

ion_four

Yeah, but my o2 sensor is properly installed now. It is in the downpipe which is hooked up to the cat. So, it's not the same prob.

filetofit

hmmm, did your o2 sensor get contaminated with oil or water when it was dangling in the turbine outlet? That'll **** it up fo' sho'.

ion_four

beats me man...all I know is that it seems to work fine at idle/part throttle, but flakes out otherwise. I'm REALLY thinkin it's the air-reference that's messed up. I'm going to take it apart, try to burn it out and then reassemble it, repeat a few times, then attempt to use alcohol or water to clean it and then brake cleaner, because if it's fucked, it's fucked and it's worth a try.

filetofit

Also when you say you've seen spikes to 3 volts do you mean the o2 sensor or the MAP sensor? I assume you mean the MAP sensor, and if that's a post circuit adjusted voltage that corresponds to full boost.

I'd take that circuit board off and bench test it with several input voltages. If you send it to me I can do it for you if you want.

filetofit

I'm not sure how compatible most solvents are with o2 sensors. If yours isn't bad then that might be a sure fire way to make it go bad.

I just had a thought. Maybe the MAP sensor voltage spiking could be your IACV valve opening and closing. I wouldn't think it would cause it to spike that high though.

ion_four

I don't believe the MAP can output beyond 5v, for sure and it went above that on my meter, haha. I think the meter is just crap. I'll let ya know what's up after tomorrow or this weekend, depending if I get around to it.

Mr. Vapor

slightly off topic:

whats ideal volts for an 02 at idle, WOT etc.....

ion_four

you'll never get a consistent reading at idle and it doesn't really matter because the computer will always compensate. at WOT it depends on your set-up with FI/N2O I believe you want around .85-.9v to be safe. if you can get it a hair lower (ie. by being tuned on a dyno) then you'll be making max power. otherwise, you'll run lean. remember, it only goes up to 1v, so .9v is pretty goddamned rich.