Jump to content
SAU Community

Recommended Posts

Hey all just popping in real quickly again to ask the opinions of the forum. Car is a 95 gts-t with fmic, pod with cai, 3.5" turbo back exhaust split dump, running 12 psi with an ebc, always run 100 ron fuel, plugs gapped at .6 or .7, stock everything else and afc neo. Now I was watching my afr's the other day at full throttle and without a tune on stock ecu the reading I got was never below 11 is that common for a skyline with these few mods? Now I'm thinking the readings are definately off cause while at idle I never get anything below 16 just want to confirm that the wideband is stuffed, when at full throttle I never get anything below 11 and I had the wideband exposed to exhaust fumes and heat for like a week before I got power to it. All help is appreciated and welcomed. Thanks again in advance. Also a friend of mine has a ca18 that he wanted to get 300 - 350 rear wheel hp out of and I was wondering if you guys could help out or point in the right direction car is virtually stock and its an automatic.

Link to comment
https://www.sau.com.au/forums/topic/192302-is-this-heard-of/
Share on other sites

it cant hurt to get your readings checked against a calibrated 5 gas analyser.

Also those WB02 sensors are very sensitive to exhaust leaks.

Unless your exhaust sytem is 100% sealed then your readings are worthless

I think all skylines with stock ecu's do it once you add boost, thats why so many people get s-afc's to get that extra power, mine runs down to 10.5ish on full throttle!! although I haven't run it again after putting in a new 02 sensor. but I wouldn't stress about it mate >_<

Silly question here.. is the AFC actually tuned?

A tune of the AFC would resolve this... being thats what they are used for

Nismoid thats why I am asking the question, not silly at all ,I'm thinking its a bit high for an untuned skyline on stock ecu.With the mods I listed thats a whole lot more breathing room for the engine so I was expecting 10's at least, another mod I forgot to mention is a bosch 040 fuel pump recently installed like 3 months back, also fpr with gauge and stock pressure reads 44 psi at idle without vacuum. At idle also the widebands reads and shows nothing less than 16 and goes all the way to lean as the car warms and in closed loop mode still nothing less than 16 just was wondering if this is common or can I say the wideband is stuffed come on you don't find this a bit strange. Now i can't say my exhaust is perfect but there are no leaks I can visible hear or see.

I think a few people have missed the point. The 02 sensor should be keeping the AFR at ~14.7 in closed loop as Fat is saying. Usually it would be a bit richer at full throttle also.

Most likely either:

1. Stuffed measurement device (AFRs its reading are wrong)

2. Stuffed fuel pump

3. Stuffed Fuel pressure regulator (check fuel pressure at rail at idle)

4. Stuffed O2 sensor (Doesn't explain only 11:1 AFR at full throttle - usually would be richer)

4. Stuffed AFM (less likely)

Edited by benl1981

if you want good ratios, you need a tune.

02 sensor has little to do with it most of the time. thats why some people run it without that feedback. also the ratios depicted may be inacurate depending on where the wideband is installed in the exhaust and the piping size. any leaks (which many cars have) makes it even more "guessy"

11s is not that rich anyway

That's what he's saying - he expected it to be running richer than that. Mine was in the 9-10s when I upped the boost which is usually how they go.

O2 sensor is what sets the AFRs at light load and idle. In fact I can drive around town in closed loop most of the time if I baby it round. The tune has to be close to the mark first but then the 02 sensor will bring it back to 14.7 AFR by playing with the injector duty cycle.

Take it to a dyno and pay $50 to get it checked there both on idle and full throttle, then if its the measurement device you havent wasted your time trying to fix a problem that isnt there.

Edited by benl1981
I think a few people have missed the point. The 02 sensor should be keeping the AFR at ~14.7 in closed loop as Fat is saying. Usually it would be a bit richer at full throttle also.

Most likely either:

1. Stuffed measurement device (AFRs its reading are wrong): Really think so either the wideband O2 is stuffed or there is a leak in the exhaust cause I did all the test on the device to troubleshoot it and everything was spot on

2. Stuffed fuel pump: Brand new bosch 040

3. Stuffed Fuel pressure regulator (check fuel pressure at rail at idle):44psi

4. Stuffed O2 sensor (Doesn't explain only 11:1 AFR at full throttle - usually would be richer): Maybe read that if you have them connected without power to it might stuff it up and i did for like a week thats the wideband tho have a narrowband on the way that I will install ths week

4. Stuffed AFM (less likely): Could be but doubt it

That's what he's saying - he expected it to be running richer than that. Mine was in the 9-10s when I upped the boost which is usually how they go.

O2 sensor is what sets the AFRs at light load and idle. In fact I can drive around town in closed loop most of the time if I baby it round. The tune has to be close to the mark first but then the 02 sensor will bring it back to 14.7 AFR by playing with the injector duty cycle.

Take it to a dyno and pay $50 to get it checked there both on idle and full throttle, then if its the measurement device you havent wasted your time trying to fix a problem that isnt there.

:Wish I could but dynos are rare over here would fix a whole lot of shit but have to wait a month before they bring the dyno back!!! :rolleyes: You all know how it is once you get someting you want it perfect right away just don't have the tools man so I gatta eliminate stuff on my own really think its a leak tho with the seal around the gaskets of the decat pipe might be my mind but think I can hear a little air escaping will get that siliconed also the dump pipe area and move the wideband O2 sensor to just before the deact pipe tis weekend and see if that fixes it.
it cant hurt to get your readings checked against a calibrated 5 gas analyser.

Also those WB02 sensors are very sensitive to exhaust leaks.

Unless your exhaust sytem is 100% sealed then your readings are worthless

Hey Thanks all found the prob as you stated they are very sensitive to exhaust leaks. There is a hole the size of my finger right above the wideband O2 sensor bung half assed welder didn't weld it properly. Gonna get it welded shut on the weekend hopefully this person does a better job and I can finally tune the car properly.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
    • I'm not going to recommend an EBC pad. I don't like them. Just about anything else would suit me better. I've been using Intima pads for a while now.
×
×
  • Create New...