ls1builder

ms4
prc ls6 heads
longtubes
loudmouth
clutch
ls6 intake
halltech stinger air intake
TEXAS SPEED MAIL ORDER TUNE


when i finally got the car running it idled GREAT... now it is getting worse and worse and worse idle surge. when coming to a stop it will dive down to 400 rpm then surge up to 1200 3 or 4 times then will find idle... but if i let it sit it will do it on its own over and over again.

please help

mike

brad8266

iTrader: (23)

more tuning. Sonds like the idle air needs tweaking along with throttle follower/cracker. Maybe add timing too.

PREDATOR-Z

N4cer

iTrader: (11)

Yup. That's the only option.

Patrick G

iTrader: (14)

Probably need to limit the amount of Long term idle trimming the pcm can do if you're giving the motor more than the pcm thinks it needs.

GT Griller

iTrader: (8)

Mail order tune is just that man....an educated guess, but every car is different.

brad8266

iTrader: (23)

Yeah if the O2 are reading lean due to valve overlap the PCM will just keep dumpng fuel in trying to correct a false lean condition.

N4cer

iTrader: (11)

Wouldn't the O2's read rich due to overlap? Because you're getting more intake charge blown straight through the cylinder into the exhaust.

Mail order tunes are a joke. I hope you didn't PAY for that.

cowboysfan

due to all variables the pcm does not know what to do, so it could be fighting a lean/rich, rich/lean . trying to find it;s self but then you throw in timming, maf. not sure how this works but, cam can make pcm think it's misfireing too so it's trying to correct that as well. dyno tune is the only way I go.

brad8266

iTrader: (23)

Mine work fine FWIW.

The O2 would read a lean condition and the PCM would keep adding fuel to compensate, thus resulting in a very rich burn in the chamber but would be more lean at the O2 sensors because of the overlap pulling fresh air through after the combustion happens.

regorih383

iTrader: (21)

what kind of power did that set-up put down

bowtierodder

iTrader: (3)

dyno tune time i had the same issuse after my cam install, but after dyno tune

lt1formula2000

iTrader: (10)

I've had the tsp mail tune on my MS4 for almost a year now with absolultey no problem. But yes in your case it seems like it needs some more custom tuning

oh yah I forgot my car did this as the cam pos. sensor started going out. It would set there and idle fine then after an few minutes it would hunt around for a idle then repeat the process after the next few minutes. then got to where it would die when the idle fell. then it just wouldn't run period. Swapped out the cam sensor and no problems since. For some reason the only code the computer showed was for the fuel pump. I guess the fuel pump may be activated off the cam sensor. but it never showed a code for the cam senor itself until it failed completly. also it did this 3-4 weeks after the cam install.

Shinobi'sZ

Back in the old days.....it was so simple to just drill a hole in the tb to help over come some vacuum loss created by using a larger cam shaft. Are all of your fuel trims zero'd out...or close????

dazman

this is mike... cars owner.


i dont know what kind of tuning was done by tsp. but it ran great for a while but now it got progressively worse, i could sit there every day and see how it just got a little bit worse every single time i ed the car. car ran great for the first 200 miles now its acting like a bitch again...

would drilling out the tb help???

who else thinks its the cam position sensor.???

thanx guys!!

mike

bowtierodder

iTrader: (3)

drilling the tb a little bigger might help....but you might still have problems like stalling when the ac is on,or when you turn the wheel all the way to one direction.........as stated above id just get a dyno tune and have it run they way it should

N4cer

iTrader: (11)

It's not a cam position sensor. It's the tune. The MS4 is one big cam. You really should probably be running in open loop mode. That means no O2's messing up your tune.

You should have a tuner look at your mail order tune. I know a guy who got one from a company (NOT SAYING WHO SO DON'T START YOUR WHINING YOU PUSSIES FROM THAT COMPANY) and it was a 95% stock tune... but was going in a 402ci LS2 motor! That's why mail order tunes are a bad idea. They don't know your elevation, environment, weather, or what your specific car likes. Get a real tune. Street tune, or a dyno tune on a variable speed dyno. Not just a WOT tune like some idiots do.

LS1C5Vette

iTrader: (11)

Get a dyno ture and it will drive like a dream (if the tuner is experienced!)

99WS7

iTrader: (13)

hmm, mine is doing the same thing and I got a dyno tune from TSP...Im not all saying anything about TSP, Ive bought a lot from them and had two tunes from them. But I have noticed my car starting to a little worse as time goes on kind of like it did before I got tuned. It just seems like it ran better. My idle does the same thing, it will drop down when Im backing out then stopping to go forward or other times when I go to a stop. It totally stopped doing that when I got tuned about 600 miles ago. I was thinking maybe my plugs were getting messed up or maybe my 02 sensors needed to be cleaned. I have a fast 90 wich I really dont like to much anyway, anyone think it might help to drill a small hole in it??

ls1builder

somthing is not right.... makes no sense whatsoever.... some have the problem without dyno tune, some have it with a dyno tune... wtf? all the emmision sensors in the car are new so wtf other variables could there be messing it up? i really hate to drop 500$ on a dyno tune for 3 hp and MAYBE a fix to my problem. would a dyno tune show more of what is wrong with the car?

mike