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Supercharged 06 gt idle problems

5K views 20 replies 5 participants last post by  Lgarretto 
#1 ·
Hey guys. So I have a Paxton Novi kit from brenspeed. The kit is on the car and tuned now, and after several days I finally am getting no codes or engine lights. But the car can’t idle steady at all. It surges from 500-750rpm constantly. Last night I let it idle for 10 or 15 minutes and then went to take it around the block anyway. It died backing out of my driveway and now every time I start it it just dies immediately. Doesn’t even try to catch itself. Still no codes. Do y’all have any suggestions before I take it to someone? I was thinking of cleaning my throttle body just to check. Anything else I may try?
Thanks guys. Anything y’all got would be appreciated
 
#2 ·
Blower surge. Back in the day, most guys wouldn't even bother to try and tune it out of the idle.... It sounded too badass!
Those were the days when a supercharged engine stuck out two feet above the hood. Hearing the whine, and the surge, and watching that three inch belt spinning a beautifully polished blower was glorious.

Who tuned your engine?
If it is a tune that came with the supercharger kit, that is a tune that they give you to be able to start the engine and limp it down to a shop so that the engine can be properly tuned.
 
#3 ·
It’s the Paxton throwback kit from brenspeed. The tune is made for my engine strategy, I pulled it before they made the tune and gave it to them. The car is stock other than the supercharger.
A little surge isn’t an issue, but it won’t even idle on its own. It starts and immediately shuts down without pushing the throttle
 
#4 ·
The ONLY advantage to using Electronic Fuel Injection is that it makes it very easy to tune out the surge on boosted applications, whereas the carburetors of yesteryear presented more of a challenge.

In the absence of any diagnostic trouble codes, I would be suspicious of the tune.
I presume that the engine information was sent to them prior to the installation of the supercharger?
 
#5 ·
Yes. I pulled my engines strategy and sent it to them before they ever made the tune. Then they made the tune to my engines strategy and emailed it to me.
I have triple checked all the piping and vacuum lines, checked and clocked the maf sensor and wires, checked the iat sensor and made sure it was sealed. And double checked all the seating points all over the car. Cleaning the throttle body I suppose could help the idle surge, I think the s197s control the idle with the throttle don’t they? I will do that but I can’t think of anything else to try other than a new tune
 
#7 ·
Ah, no. No data has been sent since the supercharger was installed.
I asked brenspeed about that before I bought the kit. They said that the tune they send you along with the kit should be the only one you need. Supposedly they have been selling the same kit for 12 years. They do make it a point that it will only work if the car is completely stock otherwise of course. But mine is.

Either way, no. They send a handful of things and the tuner, then Paxton sends the actual kit, and while you wait on that you pull your engine strategy with the tuner and send them that code. They then make the tune for that engine strategy and email you the tune. Which is supposed to be the tune you use to run the car.
 
#8 ·
I've heard that before, but I don't know of anyone who actually runs that "canned" tune as the final tune.
Unless you can find something that is obviously wrong, or a code appears, I think that you are probably going to have to seek out a professional tuner to write an appropriate tune for your engine.
 
#9 ·
Well, at this point I’ve tried to get hold of brenspeed for 3 days and can’t get anyone to answer the phone. I am going to take my car to tricky performance here in Oklahoma. They are pretty close anyways. And they have a dyno and can make me a tune that will actually work.
I have to say, I was a bit skeptical of a canned tune. But I figured I’d try it. A dyno tune will be better anyway. I appreciate the help
 
#10 ·
Your experience seems typical of Brenspeed. If you want the top notch customer service you need to spend more money with them.
 
#11 ·
If that is the case and my experience with brenspeed is a typical one then I will never make a purchase from them ever again. If I make a purchase from a company I expect the same customer service as anyone else. Particularly on something that costs 5k. If that is the case then that is ridiculous. Customer service shouldn’t be based on how much you spend.
 
#15 ·
Unfortunately I can’t spend too much time on it. I bought the kit because it was supposed to be reliable and simple. Luckily my wife doesn’t work and I have been driving her car, but I kinda need my car running again. It’s been a month now because brenspeed forgot to send some parts I needed.
I am gunna take my car to someone who can maybe go ahead and just make a new tune for me. I found tricky performance, they are like 15 minutes away from me here in Oklahoma. Y’all know anyone else around okc that can tune a mustang?
 
#18 ·
Good to hear you fixed it! However I would still look into a good remote tuner at least looking at your logs. A log analysis shouldn't be much money and I'd do it for piece of mind especially if its just a canned tune from them.
 
#20 ·
Not sure how much of asses OKC cops can be but just FYI its a federal offense to remove them and you can and will get impounded by a cop having a bad day. If you do delete them I'd recommend dummy cats. What I'm gonna have to do if I delete mine out here.

Also, if you don't yet have a wideband, get a wideband. Then you can at least have some idea if your AF ratio is good. Flying blind without one.
 
#21 ·
Yes. That is true. I haven’t decided on that yet but I’m not too worried. Out here nobody cares. Cars don’t have to pass any sort of emissions. And in the tiny town I live in, it’s normal for people to drive their lawnmowers and tractors to the gas station. And straight pipes are so common they are almost a formality
 
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