I replaced my hollow cat with a straight pipe as it was droning in the car so much. Droning is gone, but so was the performance. I spent 8 hrs datalogging and making changes. I basically want to know if I made correct changes. This will become easier next month when I finally have enough money for a WBO2 setup. This is the bin I started with http://firebirdandcamaro.net/jason/straight1.bin and this is the datamaster file for that bin http://firebirdandcamaro.net/jason/straight.uni and this is the bin I ended up with 8 hrs later. http://firebirdandcamaro.net/jason/straight8.bin and this is the last datalog I recorded before making the changes to the above bin http://firebirdandcamaro.net/jason/straight7.uni So with all this info, am I making the right changes? I am trying to eliminate knock counts in both PE and VE tables. Before i removed the hollow cat, I had the VE tables nailed down. After it was removed, I had to start over. Didn't expect that honestly, but here I am 8 hrs later and I think I'm doing the right thing. Just thought I would ask the professionals. Edit: I am using TunerCat for my editing. I only edited the upper and lower VE tables, and PE% change vs rpm table. I am trying to nail down the fuel curve before messing with the timing. thanks

Linky Brokey

The only way it seems to work is to 'save target as' then open it separately with tuner cat. Not sure why, but you can view the bin that way.

Grumpy, do you recall David Vizard's exhaust system modifications in his books? Where he would put a box about the size of engine displacement in the exhaust about where the cat would go? Idea was to terminate the exhaust pulses. Would Jaysz28 have accidentally stumbled into this effect?

Just an idea... to explain the loss of performance...

Ernst

Can you do some shorter datalogs?.
They're hard to read as is.
Maybe like just 5-10 secs at a time for cruise, and then one for 5-10 secs at WOT?.

Does it just feel slower, or is it for sure slower?.

Geesh, I dunno, it'd take a box like 4x6x15.
Hmm, now after doing the math it's not that far off.

It looks like he added as much fuel as he took away, just glancing at a file compare.

Exhaust like intakes.
On the intake side, Independent runners are best, and on the exhuast side, the larger the better. The independent runner lets the engine look at atmosphere, and an infinitely large exhaust would have min back pressure, and be very quiet.

I'll head out in the next 30 mins and get some shorter datalogs. Need to try out that last bin anyways lol.

For the most part, the car was just sluggish after I had the cat replaced. Throttle response mainly, but not the type of thottle response that you would benefit from a change in the pump shot. The car would initially react, then kinda trickle off, as the knock counts were detected. I mean at a couple of points in those datalogs, I had 16 degrees of retard. Now the kicker is that in one second, the knock counts would go from 2 to 15. I wonder if I can accomplish that again in 3 to 5 secs lol

I'll reburn the first bin, and do a short datalog of that as well.

Alright, here are the shorter datalogs.

Driving:

http://firebirdandcamaro.net/jason/grumpydriving.uni

and a brief WOT run....... from a roll with a lot of wheel spin in first and a bit of second.

http://firebirdandcamaro.net/jason/grumpywot.uni

On the topic of the exhaust, I was thinking that by gutting the cat, I effectively slowed the exhaust down. Granted the cat was never functioning correctly when I bought the car. After the motor swap, the inside of the cat melted, and just rattled around inside it. Now a cat super heats the exhaust. Hot gases move faster than cool gases. With that in mind, I think I lost scavenging, which affected my air/fuel readings at the O2. With the lazy exhaust gases, it would show it being richer than it actually was.... maybe?

Not sure about this. Just some random thoughts I had while trying to wake up this afternoon.


Next dumb question.... would wheel spin produce knock counts? I'm assuming no, but when the wheels are spinning, there is less load on the motor, putting it in a different KPA range, which could be where my knock counts are coming from..... once the car hooks, I notice no knock counts. Of course there is more load on the motor, and in the higher kpa, there is more fuel. Not sure if I'm thinking along the correct lines or not, hence this post.....

Jason,

I replied to this post in depth last night ... now it's not there. I guess the internet ate it

In short...
1) The lower and upper VE curve have a range of points in common; namely, 1600rpms. MAKE SURE the values for 1600rpms in the lower table matches the 1600rpms in the upper. Yours don't.
2) What I said on #1 also applies to the spark tables. Match them up.
3) 45 and 55kpa at 1600rpms in the lower table appear to be wrong.
4) Your BLMs are all over the place. Definitely try to nail them down to ~ 128.

I had some more things but I can't seem to remember right now.

Tim

Hey Tim,
I'll need to double check, but I thought that I made sure that the upper and lower ve tables were matched up. I even remember pulling up both numeric graphs, and making sure the transition was smooth.

45 and 55 kpa values don't transition to the upper table, so I didn't mess with them. Not really sure

Now the spark tables I have no clue about. I have not touched them at all. This is the same bin you created back during the TGO nationals. This is just what it has progressed to fuel wise. If the spark tables dont' match, its not because of anything I messed with.

The BLM's all over the place.... well I do need to work on it. I thought they were a 100% improvement over what I started with. I used to have it nailed down until the straight pipe went in. I'm seriously starting over here because of this. Maybe its time to run VE Master again.....

Now what I did was look at the graphs, and massaged them so there were no peaks and valleys. It looked pretty choppy in the first bin.

but the question still remains... am I heading in the right direction with the changes I have made? I'll be able to go to the track on the 19th of Dec, I bought a WBO2 that I plan to have installed before then. Just want to make sure I have a grasp of this before getting into the serious tuning that a WBO2 provides.


Thanks for all the responses and for taking the time to look at my bins and datalogs. It is greatly appreciated.

I've seen them rattle around breaking off lots of little bits and pieces get carried back, and start to plug the muffler. If your not running a straight thru muffler, then it well could be partly plugged.

Without the honeycomb in the open section that really messes up the flow thru an empty cat.. There are specific angles of divergence, and convergence for air flow, and the cat doesn't have either right. I'd venture a guess that it's just the lack of backpressure, that drastically effected the self EGR'ing of the engine, and now you just have a whole lot more timing then you really need.

I'll tend to agree with you about having too much timing, but I'm running vortech heads, and no egr.

That was probably crucial info I should have provided.

I am really hesitant about adjusting the spark tables if I can't seem to nail down the fuel tables. Probably just the novice in me, but I keep searching, reading and trying to comprehend the knowledge of this board. Sometimes I swear you guys are speaking in greek.


where did I place that greek to car dictionary????

Yeah, someone should make a DIY PROM Section Dictionary for all us newbs