Long story short I have a 99 SS 6 speed. I added an ls6 intake, tr-220 cam(220/220 551/551 112lsa), qtp race headers and a catted y-pipe this past winter. I got rid of all of the egr and air stuff too.

I had my car tuned by a local tuner. Everything was great except afterwards except I had a cold idle issue. The idle would surge when it was cold. I brought it back to him and then I ended up with a hot idle issue as well as the cold. The idle would drop down to 500 when the car was hot, especially when in stop and go traffic, and more so when the outside temp was hot.

I have been back to the tuner 6 times now. Everytime I go back it seems to work fine when I am there. He also has me drive it around a bit and it seems to work good.

After maybe a 15-20 minutes of driving I end up back where it was before. I still have a hot and cold idle issue.

At his request I bought o/2 simulators. He believes that these are needed so the computer has a reading of some sort. This is contrary to what I have read and been told by others.

I also replaced my idle air control valve.

At this point I don't know what the hell to do. I have wasted a lot of time going back and forth. It seems this should not be that difficult to tune.

Is it possible there is something wrong with a sensor, or something else mechanical that is causing this problem??

The fact that the car seems to work great for 15-20 minutes right after he tunes it seems strange. Is the car re-learning something to cause this idle problem??

Other than the cold start idle the main problem is that the idle dives down fast to 400 rpm or so when coming to a stoplight. The harder I am driving it before that the worse it is.

It also seems worse the hotter the engine is and the hotter the outside temp.

Any help is much appreciated!! I either need to find another tuner or do it myself now. Hopefully there is somthing simple I am missing???

Thanks!!!!

 

I'm not sure how much I trust this guy. He should know having no rear o2's will in no way affect how the motor starts/idles nor would the addition of sims change this as they can be tuned out anyway.

The cam is a mild cam so i'm suprised its giving you that much trouble, a few suggestions would be to have him check the ve table around the area it idles in, is it to rich/lean? Is it cranking over ok? or is the problem only after it starts. Have him lower or even remove the afterstart enrichment values above 60*. If its having a problem cranking over you might need to lower your cranking VE values by .80 to .90%

Also, have you drilled or set your TB set screw? Its possible the iac cannot provide enough air if the tb has been left alone. Hope this helps

 

I thought if tuned right you should not need to drill or adjust the throttle body??

I Did try adjusting the throttle body out one turn before. That did not seem to help.

I guess my main question is: Is my entire problem tuning, or could something else be wrong??

Thanks!!

 

first thoguhts for me is the thigns arent tuned right and when the computer learns some stuff, it messes it up, because it sees numbers it thinks it wrong. i think its all tuning problems

you have to set teh tb set screw then adjsut the effective area, then from a COLD start, which means the car should sit over night and be logged as soon as you start it, log all idle air parameters. sounds like your ve, running airflow, effective area and some small other details are throwing your tune off. if he doesnt do it from a cold start he isnt doign it right. i am having cold start issues which i believe is fueling related, my ve may be off in the start up areas. the hot stuff though all has to do with the airflow, unless he properly addressed all these things then this is what it sounds liek yoru problem is. i have 50 tune for the idle alone, 6 isnt going to cut it IMO if you want it just right, but that is an easier cam to tune i would think

 

Tuning can't always take care of cam idle issues because the iac cannot open far enough thus starving the motor for air. This is normally corrected by drilling or opening the tb. I'm one of the 2% left that does not approve of the tb set screw as some pcms will reset themselves and you'll constantly read 1-4% tps.

 

Got your PM...

Can you post or email a log of your idle and a copy of your tune?

 

No, I don't have a way to do that. I do have an apointment this afternoon with the only other tuner in town. He seems confident he can fix it.

Thanks!

 

well i have afr heads and f13 cam, tps voltage is .61 and says 0% and hot idle shows iac step of 23-25 but i still have starting issues when its cold. so i think my inlet hole is too small with the epoxy filled tb

 

Ask that tuner for the files.

 

Thanks for the input guys. I had my car worked on by the only other tuner in town yesterday afternoon. My problems are now 95% gone. This new guy changed a lot of the programming, drilled and adjusted the throttle body too.

The car feels stronger and idles good!! This is what I needed.

Now wishing I went to the new guy first.

 

I have the MTI X1 Cam and 90/90 set up.My tuner couldnt seem to Correct my Hot and Cold surge.But I did ,Between The IAC and MAF was the Problem mine Idles greaT NOW...

 

fasteddyss: I have the same identical cam ... same car setup. One tuner tried two attempts to get the idle right ... took it to a well-known Performance shop in town and had it re-tuned ... fixed the idle issue and it idles like a brand new stock vehicle ... except for the slight lope, of course.

 

The second tuner got it right. He ended up changing a lot of stuff that the first guy either did not do or screwed up.

Now, for the fisrt time all year, it does not surge when it is cold. It also does not surge or want to die when hot either.

I have learned that there is quite a bit to know about tuning these, and even experienced tuners do not always do it right.

I went back to the first guy 6 times after the initial tune. It never got better, only worse.

The second guy got it 90% right away. I did go back for a tweak. The second time he found some idle crack table or something that had been zeroed out by the first guy.

Now it idles great and actually feels stronger