Thread: 940 WOT o2 is lean?

m knocking a good 5* on the top of second, im tuning with an afc and scanning with an ls1m. cant get the scans to load on my laptop for some reason either so no scan data. ive been taking a few and im only really knocking in the 9k-10k maf frequencies, so only WOT.

i have:

1.9 modded rockers
S&S headers
ported blower outlet, wall knocked out, lim matched
3.4 pulley
1.5 dhp file, few codes deleted, ~13* timing WOT


my upper o2s start around 970, and im getting no knock there. when it falls off on the top end im around 940s and then i knock about 5*. i thought lean on these cars was approaching the 920 mark? is this solved with more fuel or more mods? just because its cold outside?

kind of want to get it tuned enough so i can run a 3.2.

Originally Posted by Bio248

m knocking a good 5* on the top of second, im tuning with an afc and scanning with an ls1m. cant get the scans to load on my laptop for some reason either so no scan data. ive been taking a few and im only really knocking in the 9k-10k maf frequencies, so only WOT.

i have:

1.9 modded rockers
S&S headers
ported blower outlet, wall knocked out, lim matched
3.4 pulley
1.5 dhp file, few codes deleted, ~13* timing WOT


my upper o2s start around 970, and im getting no knock there. when it falls off on the top end im around 940s and then i knock about 5*. i thought lean on these cars was approaching the 920 mark? is this solved with more fuel or more mods? just because its cold outside?

kind of want to get it tuned enough so i can run a 3.2.

Since the narrrowband is unreliable, it's kind of hard to say what kind of AFR you are running compared to your O2's. When I had the same mods as you I had to run a 3.5 pulley and my O2's were around 955 to 960. Last time the comparision was made on my car that was an AFR of 10.6 (pig rich).

With my XP, headers and a lot of other things, I can only run a 3.25 pulley KR free with an AFR of 11.6 which is ~910 iirc.

are you running intercooled? if so, thats a huge reason why youre able to run so much leaner.

damn that is kinda rich.
I always tried to shoot for .89x-.92x
none intercooled and intercooled

Narrowband suck, I don't even trust them one bit. At one point I had .930-.950 O2's and when I got a wideband, it actually showed low 10's and high 9's in the AFR. I leaned it out into the mid 11's on the wideband and what-do-ya-know......O2's at .930-.940.

Get a wideband if you want to get WOT fueling where it needs to be.

Originally Posted by Toofastgs

damn that is kinda rich.
I always tried to shoot for .89x-.92x
none intercooled and intercooled

How do you know if thats rich or lean w/o WB referencing?

Originally Posted by Bio248

are you running intercooled? if so, thats a huge reason why youre able to run so much leaner.

Mine is not lean at 11.6 AFR (my cars NB -910 to 920) and not I'm not IC'd. The differnece is I have the right pulley installed for my mods so I can run an 11.6 w/o KR. With an IC you can go as lean as 12.0.

im looking to make this car run knock free with a 3.2 and then drive it until the wheels fall off.

today was a decently warm day, took a quick scan and only got 1.8* on the top of second when o2s were around 970s. that sucks and all, but can i be truely correct in thinking that its actually around 970s without a wideband? not really. a wideband is the next thing in my budget for the car, just dont have the money to pick one up yet. im waiting for a few bills to roll in before i make that dive.

i do not want to intercool this car either. i dont want to worry about the extra fluids during winter and id rather just have it like this anyway. if im truely to run this 3.2 at correct fueling, what do you all suggest i do? good ported blower/tb? water injection? i have all the rest of the bolt ons done, headers and rockers.

Originally Posted by Bio248

im looking to make this car run knock free with a 3.2 and then drive it until the wheels fall off.

today was a decently warm day, took a quick scan and only got 1.8* on the top of second when o2s were around 970s. that sucks and all, but can i be truely correct in thinking that its actually around 970s without a wideband? not really. a wideband is the next thing in my budget for the car, just dont have the money to pick one up yet. im waiting for a few bills to roll in before i make that dive.

i do not want to intercool this car either. i dont want to worry about the extra fluids during winter and id rather just have it like this anyway. if im truely to run this 3.2 at correct fueling, what do you all suggest i do? good ported blower/tb? water injection? i have all the rest of the bolt ons done, headers and rockers.

As far as 970 - since it's relative I'm not sure how to answer, other than to say is very likely extremely rich, essentially drowning the knock. Realize that with a more appropriate AFR and a larger pulley you will be faster than running too small of a pulley, running too rich and possibly having your timing reduce by the KR.

What you need to run a 3.2 pulley and not be IC'd? - Cam, so it can bleed off some of the boost from the small pulley.

Don't have pulley evny.

Seems to me the best way to go, is determine what timing you what to run, i.e 17* at 5500 rpm WOT and a goal of say 11.6:1 AFR and get a pulley that can make this happen knock free. IMO thats better than running a small pulley and adjusting the important stuff to less than optimal to match it.

iirc when my car was WB tuned I brought along a 3.0, 3.1, 3.25 and a 3.4 pulley. Although I was hoping for the 3.0, the goals would only allow the 3.25.

I run 840' o2's when my cars actually running good. My buddy runs around 860. Another runs about the same. We all have widebands.

wideband is the next thing im buying for this car when i get $300. i like the AEM setup.

Originally Posted by TheRealKoop

I run 840' o2's when my cars actually running good. My buddy runs around 860. Another runs about the same. We all have widebands.

Since you have WB's what is your AFR at 840 and your friends at 860?

Oh sorry, thats about 11.8-12:1 AFR for the both of us. I meant to post that ><

Also- not saying you should run that, just saying NB o2's are next to worthless.

Originally Posted by TheRealKoop

Oh sorry, thats about 11.8-12:1 AFR for the both of us. I meant to post that ><

Also- not saying you should run that, just saying NB o2's are next to worthless.

Ah ok. Yes your example and mine of 910 -920 being 11.6, shows the unreliablility of NB readings.

soon, soon. ill buy one coming up, i just want to get a few more dollars first. i cant just throw $300 around being a poor college student. otherwise the car is set up great for DD manuevers.

took a quick blip scan today on the way back from class this morning. finally logged some IPWs and boy am i surprised. im seeing mostly mid 21.xx and blips of up to 23.xx. so, how close to being static is this, because im pretty sure its damn close. ltft's locked in at -1.6, stft's at 0. o2s around 940-960. knock hits 5.xx* at 111xx maf Hz, top of second. timing at 16* before it started pulling it from knocking. 10.5 psi of boost.

only running a 3.4. should i really be maxing out my injectors? do the IPWs go up if the injectors themselves are bad or dirty?

Bad fuel pressure, a ****ty fuel filter, or crappy/dirty injectors will cause your IPW's to go up (this is assuming you tune, you would have to "add" fuel to get your car to not die)

you really shouldnt max out your injectors on a 3.4, and you are. 20ms at 6krpm is MAXED.

Your ipws are definately on the high side for your mods and you dont want to see over 21, 20 as mentioned above is definately more towards the safe side. Something not mentioned about your high ipws could be that you are just flat out pooring too much fuel to the engine and as Lee mentioned earlier in this thread making a car run overly rich to cover up KR is not the ideal answer and wont make the best power. Once you get a wideband it will tell the story and until then I probably wouldnt mess with it more until you know exactly what your afr is. My L67 cutlass 02s are around 885 when the wideband is in the 11.8 range and i find many cars show low 900s, but I have also tuned cars in the 12.1 range intercooled and its showing 840s. The worst oddball I found was a car with S1X cam and headers and it was 965 02s showing 11.6 afr! I also find that on repeated runs the 02 numbers are never consistant but the wideband will stay on the money. This alone can lead you astray as after you make adjustments the 02 numbers dont follow what you thought they should. You can also get KR from running too rich. Im not sure who did or did not follow my thread last fall on cgp about exhaust restrictions but when I was working on Lee's Impala last october I ran into 3-5 deg of KR at the stop of second no matter what pulley I had on the car. After scratching my head for a few days and getting agrevated that I could not find the reason in the tune or fueling to not cooperate I decided to pull out the front 02 sensor and install a pressure gauge. BAM right off the bat the problem was obvious! In second gear over 4K rpms IIRC my 10 psi gauge was pegged! I thought well maybe the car was too rich in the past prior to my work and the cat was trashed so I removed it and it looked fine. Then I put the gauge in the rear 02 sensor hole and drove it again, same exact thing it pegged my 10 psi gauge. When I came back this time around and let the car sit I jacked about 10 minutes and jacked it up to remove my gauge fitting and wow was I shocked. He had just had the resonator replaced and it was apperently WAY too restrictive. 10 minutes after the car was shut off I got my infrared temp gun and the resonator was over 100 deg HOTTER than the cat was!!!! Bingo problem found. I took the res out and welded in a piece of 2.5" pipe in its place to rule it out and took it out and the pressure dropped way down and the KR was gone. Without testing backpressure in the exhaust I would have never found this and would have been a bit dissappointed in the performance and pulley sizes we were swayed to use, so try to keep in mind ANY possibly problems!

Added.... I forgot to mention that to prove the resonator was at fault I took the catback off the car and drove it again with the gauge on it to make sure the backpressure problem was gone and that it WAS in fact causing the KR problem. Unbolting the catback is easy and you can often just wire up the exhaust to keep it from hanging low and not have to remove it completely.

clogged cat eh? i have a pretty new giant glasspack, so im assuming it wouldnt be that. a clogged cat would not be out of the question either since its been on the car since i bought it.

ill check around on a few things, but im thinking it is just that im pouring too much fuel in as you stated.

there is an SSIC on clubgp with a st2 fmhe for $300 shipped. i want it bad, but i really dont want to go intercooled as its one more thing i have to worry about to take care of on the car.

Im impressed you knock with rockers, headers, and a 3.4. Pouring fuel could definantly be the cause, you can get kr from running too rich as well as too lean.

if i lean it out any, the knock comes back.

im picking up an SSIC and st2 fmhe from clubgp. now i just need to find a pump and either injector spacers or modded rails. i definately dont have enough money for a set of logs. but this probably wont go on for a couple months when its nice outside and i can actually take my time and do it.

also, im pretty sure my tune is completely crappy. im running basically a 1.5 dhp file with a few codes deleted for my egr and random misfires. id love to get a tune going and make sure my PE vs time and all those other tables arent screwed up like they probably are now. i dont have a tuner, thats the problem. im going to have to hook up with a few of the guys from the manitowok area because no one around here really has one. i pay in beer.