Cam that will not smell of fuel
Cam that will not smell of fuel Currently have a medium sized cam with 4.5* of overlap and even after tuning (and with cats) the smell of fuel while drive is getting annoying. I personally *could* deal with it, but I want to take my young son and wife along for rides without them breathing in this stuff and their clothes reaking of fuel aftewards.
What sort of overlap do I need to shoot for to just about kill any trace of smell while driving?
Edited for valve events:
What sort of overlap do I need to shoot for to just about kill any trace of smell while driving?
Edited for valve events:
Last edited by redtan; Sep 10, 2014 at 09:05 PM.
That's a great informative post, and reiterates the idea that if you close the exhaust valve sooner than before (thus reducing overlap given everything else remains the same) you will reduce the smell and could potentially eliminate it.
What I'm trying to figure out is how much sooner do I have to close it in order to eliminate the smell? I updated the first post with the current valve events I have.
What I'm trying to figure out is how much sooner do I have to close it in order to eliminate the smell? I updated the first post with the current valve events I have.
The cats are a few years old at least, maybe 3-4 years.
I did play with EOIT and have it advanced quite a bit more than 20* (at idle at least). Is going too advanced going to make it worse?
Also, have played with timing and right now it idles in the low-mid 20s. Why do you say no more than 20* of timing?
O2s are new and switching properly, although STFTs are in the -8 to -12 range. AFRs however are very stable in the mid 14s all the time.
I did play with EOIT and have it advanced quite a bit more than 20* (at idle at least). Is going too advanced going to make it worse?
Also, have played with timing and right now it idles in the low-mid 20s. Why do you say no more than 20* of timing?
O2s are new and switching properly, although STFTs are in the -8 to -12 range. AFRs however are very stable in the mid 14s all the time.
224/228 114+1 is what I'd do. You may need to play with your tune a bit as well. I would think the 227/230 with cats wouldn't be terrible. Hell, I don't even smell fuel with my 234/242 111 with no cats.
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On The Tree
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Diff platform but i was having the same issue in my cammed 2000 gtp. Any time you would touch the throttle or coast off the hwy the car would reak of exhaust and fuel. I just figured it was the cheap headers i had on the car leaking. Well fixed the big leaks as best i could with the same smell. Only thing i could think if was that some how it was coming in thru the back of the car(seal for trunk or somthing like that) so i started to do some digging and turns out my trunk seal wasnt making full contact to the trunk anymore from old age. Messed around with it to get it to seal and its compleatly gone!!
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The cats are a few years old at least, maybe 3-4 years.
I did play with EOIT and have it advanced quite a bit more than 20* (at idle at least). Is going too advanced going to make it worse?
Also, have played with timing and right now it idles in the low-mid 20s. Why do you say no more than 20* of timing?
O2s are new and switching properly, although STFTs are in the -8 to -12 range. AFRs however are very stable in the mid 14s all the time.
I did play with EOIT and have it advanced quite a bit more than 20* (at idle at least). Is going too advanced going to make it worse?
Also, have played with timing and right now it idles in the low-mid 20s. Why do you say no more than 20* of timing?
O2s are new and switching properly, although STFTs are in the -8 to -12 range. AFRs however are very stable in the mid 14s all the time.
Increasing the idle spark timing raises the combustion temps thus increasing Nox. With your cam, I would use 16-18* idle spark timing.
Russ Kemp
You need to retard (delay) the EOIT not advance it.
So is there a downside to too much delay (I have it at 60* idle and tapers off by RPM)?
Also I thought that lower timing values meant hotter exhaust. It's when you have like single digit timing that you start seeing headers glow no?
I will try to lower the timing a bit, but I remember when I had it down to like 13* the car chopped hella hard and it really stunk. Increasing the timing seemed to have helped, but maybe I went too far.
Last edited by redtan; Sep 11, 2014 at 09:33 AM.
Are those STFT's a little to large?
And like I said, AFRs monitored by the wideband are dead steady in the mid 14s so not too worried that it's running lean or rich.
What do you usually have the timing and/or EIOT set at for those cam swaps that you said didn't smell?
I mean delay it sorry.
So is there a downside to too much delay (I have it at 60* idle and tapers off by RPM)?
Also I thought that lower timing values meant hotter exhaust. It's when you have like single digit timing that you start seeing headers glow no?
I will try to lower the timing a bit, but I remember when I had it down to like 13* the car chopped hella hard and it really stunk. Increasing the timing seemed to have helped, but maybe I went too far.
So is there a downside to too much delay (I have it at 60* idle and tapers off by RPM)?
Also I thought that lower timing values meant hotter exhaust. It's when you have like single digit timing that you start seeing headers glow no?
I will try to lower the timing a bit, but I remember when I had it down to like 13* the car chopped hella hard and it really stunk. Increasing the timing seemed to have helped, but maybe I went too far.
My high flow cats are 5 years old and I need to replace them soon as the exhaust is starting to smell. Probably due to the piston/block damage that filled the cats with antifreeze.
Lower timing does increase the exhaust temp, but lowers the combustion temps thus lowering NOx. NOx is what makes your eyes water and gives off the nasty stink.
What is your idle speed? As too low can increase the exhaust odor due to the inefficiency of the combustion at low RPM. I would set the idle at 900-950 RPM.
Russ Kemp
What is your idle speed? As too low can increase the exhaust odor due to the inefficiency of the combustion at low RPM. I would set the idle at 900-950 RPM.
650 was alittle rough, 700 is pretty smooth so far.
It's an 06 LS2 GTO auto 4 speed.
What makes it too low? It idles pretty smoothly at those RPMs so I always thought that the lowest value that it can hold idle is best.
What makes it too low? It idles pretty smoothly at those RPMs so I always thought that the lowest value that it can hold idle is best.
And reduce the Normal EOIT Target Adder vs ECT by 20* (all temp cells) and leave the other Injection Timing tables stock.
And set the idle spark timing to 16*, after doing all this if the exhaust still stinks, replace the cats. Kooks has the green cats that might be better as they are 49 state legal.
Russ Kemp
