car : Evo 9 GSR

Mod : full bolt on , stock turbo, stock block, kelford 272 , srping and stud upgraded , full tubular manifold, open dump , Spoolin up COP, tune on 91 octane with a good local tuner .

Problem :

Well this is killing me . i'll do my best to explain it . Got my brand new Zeitronix Zt-2 kit about 3 months ago . Everything worked perfect for two months . Couple weeks ago, i went on a road trip , and on my way back to home , something weird happened . The AFR on the gauge always move a little even when cruising as you know . I was cruising at 65mph with constant pressure on the gaz pedal . Suddently, the car started running weird , like little hiccup , I checked on the ZT gauge and the AFR were stucked at 14.6 . after a couple of seconds , i pull off completely my foot of the accelerator and the reading was still stuck at 14.6 when normally it drop at 21.0 .

I did not care at all at the moment because it just last like 10 seconds and it never happened again for like two complete weeks .
But it happened again last week two time , and now today was the worst of all .

Same situation, but the AFR stucked again at 14.6 for like 1 minute and the car was running like a pig . When trying to give more gaz, the car hesitate a lot because the ECU probably run on a safe mode and adds lots of fuel .

I also use my wideband sensor as a narrowband simulator , because my OEM front o2 sensor is broken .

Problems keep occuring randomly and car runs like a pig . I was doing some test yesterday and my laptop was ready to log . There is obviously somethings wrong . What the gauge reads does not match at all with what Evoscan reads , which is the one to trust as it reads directly from the ECU .
The formula that I use in evosan to show AFR values is the same I use since 3 years , the same that I found here which is 0.0392156863*x+9.6

That said , while on idle , gauge read between 14.4 and 14.9 and it reads 13.5 - 13.9 on evoscan . When cruising and lift off the foot completely from the gaz , gauge read 21.0 and evoscan read 17.4 . I could continue like this on and on .

A talked to my tuner and he don't know what is going on .

Zeitronix keeps telling me that my sensor is just fine and that i should change the formula to match AFR ( b1tch , please ...)

Now, could my sensor already broken or damage ?? Not supposed to happen after roughly 3 months of use, and considering that my car is not my daily drive .

Any advise ?

Thanks a lot !

 

Oh , and as a complement .

Since i own the car , whenever i drive by a stop or red light and that I start decelerating while holding the clutch the idle bounce like crazy . It goes from 1000rpm to 1800rpm on and on until i completely stop the car from moving .

I've search and found that thread : https://www.evolutionm.net/forums/ev...cing-idle.html . Some people say that changing the ISC valve could solve the problem .

I started by removing the throttle body last week and cleaned everything including the ISV valve. I took the occasion to replace the seals with mil spec one . I putted back on the TB and problem was still there . Next step is to replace the ISC with the one linked on the bouncing thread.

Could all this be related ???

 

I apologize for not reading ALL of your pose, but I can tell you from experience with ZT-2, if you are reading a constant 14.6 no matter what, then the wideband ECU is not detecting an 02 sensor... like it is unplugged.

If everything is plugged in (I had this happen before) the sensor is bad.
I've been running 2 ZT units for a long time now... gosh its been like 8+yrs lol

 

I'll try to get a new one under warranty, but they really don't give a **** of me ...

 

I would suspect a faulty sensor as well. My aem unit reads 14.8 solid with no sensor connected.

 

Update :

Got 2 SES codes yesterday .

P0172 : system too rich (bank 1)
p0134: oxygen sensor circuit no activity detected (bank1 sensor 1)

 

You can test the WB sensor by putting soaking a rag with brake cleaner and put it around the sensor. It should read rich. Then remove the rag and within a few seconds it should be full lean.

Also, I would run OL if not wanting to use a narrow band O2 for CL. Or get a new o2 sensor.

Here's a vid of how to do test the wideband:

 

Update :

I finally bought a new sensor last year and it did not happened again .