Fast 90 installed but why is this.....
10-31-2007, 11:50 PM
#1
Fast 90 installed but why is this..... I installed my Fast 90 with a de screened delphi MAFS. I installed everything even added some RTV around the MAP sensor. I will be getting it retuned on Saturday at straightline but I have been driving it a little and I noticed that my rpms seem to stay kinda high when I come to a light sometimes around 1500 rpms then once I stop completely it will come down to 900-1k where it usually is. Do I have a vacuum leak? It doesn't do it all the time.
Then If I put it in neutral and coast to the light, I hear like some sort of air like pump come on from behind the brake pedals. What can that be?
All help will be greatly appreciated.
Then If I put it in neutral and coast to the light, I hear like some sort of air like pump come on from behind the brake pedals. What can that be?
All help will be greatly appreciated.
11-01-2007, 07:05 AM
#2
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Sounds like you either have a vacuum leak or you juts simply need to turn your running airflow down in your tune to compensate for the larger throttle body.
11-01-2007, 07:28 AM
#3
+1 it sounds to me like the larger throttle body is throwing your idle. a 90mm tb is going to let a lot more air thru at the same % throttle as a 78mm tb. i recommend getting it tuned.
the air pump sound could be caused by insufficient vacuum, tho it might not be a leak necessarily. if the engine PCM is still reading incoming air (via your new and untuned MAF and excess 12mm of tb) it will still fuel the motor and give your rpms a kick, like you've been seeing. the excess of incoming air is probably lowering your net vacuum so the brake booster, which is vacuum assisted, has to try harder to apply the same pressure.
the air pump sound could be caused by insufficient vacuum, tho it might not be a leak necessarily. if the engine PCM is still reading incoming air (via your new and untuned MAF and excess 12mm of tb) it will still fuel the motor and give your rpms a kick, like you've been seeing. the excess of incoming air is probably lowering your net vacuum so the brake booster, which is vacuum assisted, has to try harder to apply the same pressure.
11-01-2007, 08:24 AM
#4
The RPM thing is the TB Zeke, classic problem symptom. Then when you come to a stop your PCM automatically adjusts it back down to idle right? I bet.
More air, its just trickin your car, after tuning you will be all good.
More air, its just trickin your car, after tuning you will be all good.
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11-03-2007, 07:46 PM
#14
No throttle body issues!!
I went with a UMI Tb and it is awesome!!
My issue was all in the TUNE!
Mike at StraightLine tuned it up and saw NO vacuum leaks!
He also gave me a BADAZZ tune to the sound of 406HP @ 6251 and 376.6 Ft/Lbs@4730
Up from 393Hp @ 6087 and 366 Ft/Lbs @ 4110
Like I said not bad for a HOTCAM! all with 28 deg of timing and 13.1 AFR across the board!
What do you guys think? Jonas let me know!
I went with a UMI Tb and it is awesome!!
My issue was all in the TUNE!
Mike at StraightLine tuned it up and saw NO vacuum leaks!
He also gave me a BADAZZ tune to the sound of 406HP @ 6251 and 376.6 Ft/Lbs@4730
Up from 393Hp @ 6087 and 366 Ft/Lbs @ 4110
Like I said not bad for a HOTCAM! all with 28 deg of timing and 13.1 AFR across the board!
What do you guys think? Jonas let me know!
11-04-2007, 12:12 AM
#16
No throttle body issues!!
I went with a UMI Tb and it is awesome!!
My issue was all in the TUNE!
Mike at StraightLine tuned it up and saw NO vacuum leaks!
He also gave me a BADAZZ tune to the sound of 406HP @ 6251 and 376.6 Ft/Lbs@4730
Up from 393Hp @ 6087 and 366 Ft/Lbs @ 4110
Like I said not bad for a HOTCAM! all with 28 deg of timing and 13.1 AFR across the board!
What do you guys think? Jonas let me know!
I went with a UMI Tb and it is awesome!!
My issue was all in the TUNE!
Mike at StraightLine tuned it up and saw NO vacuum leaks!
He also gave me a BADAZZ tune to the sound of 406HP @ 6251 and 376.6 Ft/Lbs@4730
Up from 393Hp @ 6087 and 366 Ft/Lbs @ 4110
Like I said not bad for a HOTCAM! all with 28 deg of timing and 13.1 AFR across the board!
What do you guys think? Jonas let me know!
What kind of problem did the tune give you? By badazz tune what did Mike do? Do you think that the 90/90 was worth the 13/10? Did you buy the 90/90 used or new? Also are you still on you stock 28lb injecctors? I must say your car is not bad for a HOTCAM! Your right there with my as far as HP!
11-04-2007, 12:33 AM
#17
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High Idle when stopping Mine did the same thing. Try turning your minium air rate screw out a little. I did that and it went away. Your throttle body plate is open to much at idle. Let me know how that works for you.
for that cam 
