My cam from what I remember is a 234/244 (112 lsa?). Now I know I've seen people with bigger cams than mine running MAF tunes but mine is only mail order tuned as of now. So no real attention has been given to get it running right with a MAF tune. I've sent it off to two mail tuners with the same result.

First I was unable to get a closed loop AFR reading because I bought new headers and need another bung welded. But I did get an AFR reading in open loop just disconnected the original o2 and stuck the wideband o2 in place of it.

Found no vacuum leaks and replaced
MAF, MAP, and TPS.

With MAF connected
During open loop
- the idle is all over the place and dies often with the AFR jumping everywhere from 14.7:1 to as high as 19.5:1
During closed loop
-can't remember if I could get it running long enough to even get it to closed loop

With MAF disconnected and running in Speed Density
During open loop
-idles heck of alot better with AFR reading fairly steady around 13.5:1.
- I can actually drive the car but runs rich.(Probably because both tuners expected me to run MAF tune so didn't do much tuning to the SD side.)
- There is a delay if I punch it. Again maybe cause there wasn't much attention paid to the SD tune side.
During closed loop
-falls flat on its face if I try to press gas pedal.

So it runs way better in open loop speed density mode. So could my cam be at least somewhat to big to where it needs more attention than just a mail order tune to get it running right with the MAF tune. Or is speed density open loop looking like my only option?

I did just purchase a C.A.T.S. tuner with Datamaster. So if there is anything I can check on there I definantly will. Also I do plan on dynotuning it. Just reading alot about tuning and debating if I want to give it a shot of course with alot of help.

Or is there something else you think I should check besides the tune? Thanks for any help.

 

1. do you have a aftermarket TB?
2. have you let the mail tuner try to make adjustments to his tune?
3. is there at least a 3" straight pipe before the maf?
4. is there any work done to the heads?

 

1. Yes, 58mm BBK.
2. Not yet
3. I think I just got my air filter attached directly onto my MAF sensor. Ill check.
4. LE3 heads.

 

Just tune it.

 

yea... MAF will work fine here if you want it. otherwise SD works great!

 

Yeah I know. Just been trying to read everything I can about tuning before I slowly attempt it. As soon as I get the cable I am going to record it on datamaster. Hopefully that'll get me a better idea of what's going wrong with it.

 

You're running a stock TB on that setup?

 

My bad I changed it. I'm using a 58mm throttle body.

 

On my setup I went with a speed density open loop tune. The o2's are non functional and the MAF and knock sensors are deleted. Yes is it cold nature'd but the car runs much better that way. Does it get worse mileage? Yes but it runs a ton better. And it is much easier to change tunes not worrying about o2 readings. It's a bitch setting up the VE tables but I think it is worth the trouble. It all depends on what you want out of the car. Just my opinion!!! And mine is on a 93 octane tune.

 

Sounds like you need to have an experienced tuner take a look at what youve got an get the thing dyno/street tuned. Or do some data logging and post it and im sure someone will take a look at it.

 

Just a side note for yea man. Make sure you have drilled out a hole in your throttle body if you haven't already. Ernest

 

this ^^^ I always ran/run open loop speed density. Minimizes complexity and things to go wrong, unfortunately the car only runs as good as you tune it, no self correcting or learning going on.

 

Very well put

 

No way I would give up the MAF on a mild build like this

 

With SD don't you have to adjust for different weather conditions? Must be one heck of a learning experience.

 

no, it still has a vacuum reference for fuel and spark control.

 

closed loop speed density will vary quite a bit in my experience, at least with a stock LS computer. OLSD might be better, havent tried it.

 

yup what he said^........i tuned my DD cam'd LS2 in Speed Density mode/closed loop and i love it......drives great and idles great

 

not really i tuned my E40 LS2 PCM like that........im in SD mode in closed loop but my long terms are disabled....i left just my short terms enabled.....works great!!

 

Ive been running SD on mine for months and yes it does vary.

Change elevation 1,000+ft or let the temp swing 50 degrees and I notice a big difference in how the car runs and it always corrects the WOT AFR too much in situations like this.