Ive got 50 lb injectors,TE-44 turbo and Eric Marshall street chip. I can not get the o2 millivolts over about 525-550 even at only 12-13 lbs boost. Ive got fuel pressure up to 48, maybe only 1-2.0 kr on 93 octane. I added fuel with the chip, left timing alone and o2 sensor is new Denso. Started raining and haven't driven since making these changes. Any ideas if o2 millivolts don't reach around 750???
Cant get o2 readings correct
- Thread starter 2QWIK4U
- Start date
O2 sensor change made no difference. Don't have car with me and will be a few days before I can drive it again. Pretty sure TPS is .42 and IAC not exactly sure the number but its within spec by the sheet with the chip and idles fine. Im thinking it was around 20-25
In that case, what happened right before the o2 sensor started reading low?
Do you have any exhaust or vacuum leaks that you know of?
How old are the spark plugs?
Spark plugs are new NGK UR5's gapped at .32, I installed new o2,injectors and chip at same time. I can not find a vacuum leak anywhere and car runs so smooth I don't think it has one. Ive checked all lines,intake,throttle body and vacuum block gaskets with carb cleaner. If exhaust has a leak its post turbo at mufflers. (ATR mufflers have some pinholes in bottom)
Was this the reason you changed these parts or was it just an upgrade you had already planned?
So the engine was running good and the o2's were reading normal and then all of a sudden started reading low. Is that correct? Then you changed the spark plugs and increased the fuel pressure at idle. Sorry for all the questions just trying to get a clear understanding of what happened prior to the o2 readings being low.
Last edited:
- Joined
- May 28, 2001
TPS at WOT is?
MAF reads ? at WOT?
Fp rises 1:1 w/ boost?
MAF reads ? at WOT?
Fp rises 1:1 w/ boost?
I swapped out a tired old set of red stripes for the 50's. Best I can remember the millivolts were closer with the red stripes but kr was crazy high. Upgraded to the 50's, got Turbo Tweak chip,changed spark plugs,Denso o2 sensor. KR is fixed but now millivolts are low. Ill get MAF,TPS and fuel pressure numbers this weekend, hopefully if I have time to drive it. Im wondering about the fuel pump because its old. Thanks for the input.
My culprit is fuel pump.I had fp set at 48. I watched gauge and it flutters bad at 50 psi then is steady, but the most fp is 53-55 if I'm at 10 lbs of boost or 15 lbs. I've had another problem of highest boost level was 12 lbs but wasn't to concerned until I got fuel pressure checked. I found the connection to MAP sensor was rotted and leaking and the intercooler to turbo hose had slid off. Boost is now as high as I want it. At wot MAF IS 255, TPS 4.44, no kr with millivolts 490-535.
I noticed battery voltage was 12.9 at wot and would like to know if that's to low?
Who's got the best deal on the intercooler hose for Duttweiler neck and the hd clamps?
Thanks for all the replies and help so far.
I noticed battery voltage was 12.9 at wot and would like to know if that's to low?
Who's got the best deal on the intercooler hose for Duttweiler neck and the hd clamps?
Thanks for all the replies and help so far.
- Joined
- May 28, 2001
I'd look at the knock sensor.. At this MV, and no knock???
try Cottons for the hose, and clamps.
Batt volts at the Scanmaster? If so, likely reading low.
mikestertwo
Well-Known Member
- Joined
- Sep 13, 2006
I find it hard to believe the O2's are that low with no knock or backfire in the intake. What are you using to read the O2's? Did you move your grounds for some reason? Did you check the grounds on the back of the head to make sure they are all connected and tight? Are these readings at WOT?
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