Bill'sWS6

iTrader: (6)

Can someone please help me out, especially hoping someone from Texas Speed can add their .02 on this.

A little background:

1) I bought my car last August and it had a mild head and cam package (224/228 563/576 on a 112 & 5.3L stage 2.5 heads from Texas Speed) along with a 3,400 stall converter, LS6 intake, stock injectors etc.

2) In September I replaced the LS6 intake and TB with a Fast 92 (ported) intake & 92mm PTM TB from Texas Speed. I also added new SVO Red Top injectors and had the car retuned. Car ran pretty good. 12.2 114mph shifting at 5,500 1-2 and 6,000 2-3. The shifts were set low becasue the car has a nitrous system on it and the tuner accounted for me spraying a 150 shot ( I never used the system).

3) October of last year I found out I had a blown head gasket so I put the car up for the year.

4) A couple of months ago I had the car taken in to get the head gasket repaired. Since everything was coming off I decided to clean the heads up, milled .023 and a new valve job (3 angle and blend) & go bigger on the cam (installed a Texas Speed 233/239 596/605 on a 112). When the heads were reinstalled we discovered pulled threads in the block (one head bold hole). The block was drilled and an insert was installed. Everything went back together fine.

5) Lastly, of to the tuners to get this puppy running right, so I hoped. The tuner does street tuning using HP Tuners. He is a very well known tuner and has a great rep for doing great work. He is the same person who did my tune last September and I was very happy. Over the last week that he has had it I got some emails that the cold start was giving him problems and he was also having problems with driveability issues. He commented on the fact that every time he took the car out and made a change to one thing it would screw something else in the tune up. He couldn't figure out what was causing the problems. So, finally after about a week of working on and off with it he said he got it about is good as he can get it. He is pretty sure there is something wrong with the parts combo or a single part on the car. Below is what he said in an email:

"I dunno what it is for sure, but the intake/throttle body combo is making it difficult for sure. Before it had an issue with IAC port flow control and now with even less vacuum at idle it exasperates it. I pretty much want to turn it loose to him and see what happens and see is something finally breaks showing me the cause."

The intake and TB he is mentioning in his email above is the Fast 92mm and PTM 92mm TB. When he says before, he is talking about when I took it to him last year for the tune with the same intake and TB but the smaller 224/228 563/576 on a 112 cam.

I am hoping someone can give offer some information on this situation. It is over my head. According to his email it sounds like a vacuum issue? I am sure he checked for leaks. Can the less vacuum be caused by the bigger cam?

PLEASE give me some help on this one...... I just dumped a bunch of money into the car and need to figure out what could cause this? I am going to pick the car up this weekend and would like to get things looked at ASAP. I just want to get an idea on what could cause these issues?

By the way, what is IAC port flow control and what does it do?

Would going to a Speed Density tune eliminate this issue?

Thanks in advance for any help you can give me.

Bill

dudeiwin86

iTrader: (1)

yes, a larger cam will cause less vacuum.

maybe you should find a new tuner.

also...
are you sure the heads werent already milled before you got the car?

Irocss85

iTrader: (1)

bill got all the paperwork with the car, and there wasnt any mention of milling the heads from tsp on the reciept. however, that shouldnt have anything to do with it cause more compression would equal a more efficient running eng. that would smooth out some of the big cam stumbles, wouldnt it?
and what "the tuner" is saying is it is not a good, efficient combo thats "hard" for him to tune I guess.

after I got done assembling the engine, it does have a hard time idleing when cold started, but after it warms up a couple min.s holding say, 1000 rpm, it'l idle just fine. and sound very good doin it. it revs very cleanly w/o any hesitation or misfires. if it had a vacuum leak, the IAC (idle air control) valve would be trying to shut to hold the engine at a given rpm. dont remember what the iac counts were idleing, but there were in the normal ballpark.

I should also add that "the tuner" thinks this is a massive cam, and its way too big for bills needs. not his exact words, but that was the jist of what he was saying at first. I say fooey on youey. I know its a pretty common group of parts. and will work great together unless your goal is idle to 5000rpm performance.

did "the tuner" check out the iac valve? I guess its not his place to but Im just curious if he tested the iac valve or looked at the wiring of it?

one more piece of info. I drove this car quite a few miles and those were the only issues with the tune that was in it as far as driveability goes. rough cold starts, and would stall if you let off the throttle too quick after accelerating. aside from the WOT stuff. which ofcourse was not attempted.

youguessit

Lemme guess, it never really runs right... start it up and put it in gear it falls all over itself and wants to die. wait till it warms up and it will want to die when you come to a stop? If this is the case, check the heat range of your plugs... try running a cooler one. If your running a tr5, go to a tr55, go to a tr6. Also pull your valvcovers and silicone your rocker bolts heavily and allow to set before you start. I didnt see what intake but if its a fast silicone the top to the bottom and the map sensor in back very well. Check for exhaust leaks around the header and collector. Small leaks can cause funny symptoms. Check for any kind of vacuum leak at all. Try cuting off vacum to your power brake booster and see if it helps. try deleting the pcv system to see it it helps (better to run this but just to test). Thing that mostly did it for me was running correct plugs, siliconing everything (rocker bolts) and making sure exhaust is perfect. Good luck an keep informed. also get it tuned again if it changes after you do all this...

Irocss85

iTrader: (1)

good point about the map sensor. that thing just kinda floats around in the hole in the intake. not a good/positive seat, and nothing to keep it in either. we'll glue that sucker in soon as I get at the car again.
as for the rockers, I did use thread sealer on all the rocker studs. even though only the intake's were actually into the port on the sidewall.
he's got tr6's due to the nitrous kit. but since he's selling that, we can swap them out for some stock platinum plugs.
bill send me an email let me know if you picked upthe car or what?

Bill'sWS6

iTrader: (6)

I picked the car up and it seems to be having a VERY hard time with cold start. Once warmed up, it seems to idle much better. From time to time the car will still search for the idle, up and down between 1,200rpms and 600 rpms. In addition, it will die sometimes too. The WOT and driving as a whole is pretty nice. I haven't got on it yet that hard but it will set you back in the seat from a 20 mph roll

I am emailing you an idea that I found on this site. Let me know what you think.

Thanks for all your hard work!!!

Bill

Bill'sWS6

iTrader: (6)

Thanks, we will check these out... It is really bad with cold start but is much better once warmed up.

I am going to put it on the dyno and see what it does.

Thanks,

Bill