Could be a vacuum leak or tuning issues.

 

Well remember I said the cars have been properly tuned and have made good power/numbers? And no its not a vacuum leak or a bad MAF or MAP. The issue is more of a stumble, hesitation off idle or crusing and then mashinng the gas. We know what the problem is. We just want to know if any one else is currently experiencing this issue after installing a FAST 102MM intake because we have a fix on the way for this concern. We wanna know cause there are at least 20 other guys that we know that have complained about this.

 

i have that issue but
im running a fast 92
and a 236/240 600+ lift cam
think i need more part throttle and idle tuning.

 

I bet you have a vacuum leak...

Check all the lines that go into the fast...if they check out, have someone look over your tune, if that checks out you should remove the fast and check the intake seals. I have a 230/232 cam with over .600 lift and a fast 102 and my car drives almost like stock.

 

What do you mean almost like stock?

 

Speaking as a technician only, off idle stumbles tend to come back to MAF. It can be a vac leak, but what does that fuck with? MAF. It makes it look wrong.

 

Speaking as a technician only, off idle stumbles tend to come back to MAF. It can be a vac leak, but what does that smurf with? MAF. It makes it look wrong.

yes i would assume it to be a intake leak as well

Well remember I said the cars have been properly tuned and have made good power/numbers?
We wanna know cause there are at least 20 other guys that we know that have complained about this.

just because a car puts down good peak numbers and has a smooth TQ curve and flat AFR, doesnt mean that the car will drive good off the line or part throttle. like steel chicken said, you cant put cake icing on a piece of shit and call it delicious

Define "properly tuned". Just because a shop does it doesn't mean it's right. Hell, plenty of "professional shops" pump out terrible tunes.

I did a LS2 Corvette with a FAST 102, and while it was a bear to dial in correctly, it's possible to do without killing throttle response.

Zero issues with mine! Ran it on the stock engine untuned for a couple weeks and have now put 600 miles on it with the SNL v.X cam and a wrp stage 3 p&p throttle body... haven't experienced any of the issues you described.

yeah, im going to say its probably the tune that is effecting all these peoples driveability. a really good tuner, that puts a lot of effort into the part throttle tuning and doesnt just tune the car on a dyno and/or only for WOT, will have zero issues like you do with driveability.

 

Subscribing, put me #1 on your list, I'm definately interested in your project.

 

Got your PM!!! You definetly will benefit from the VRing! You have all the classic symptoms and the 8 other FAST owners that PMed are also in the same boat. And like we have been saying they didn't know they had an issue until they drove someone elses that has one of the VRings.

 

What is your fix? Removing the intake and putting a stock ported one back on?

 

Hahaha thats funny....lol no its not. The FAST 102 does what it says and is a beautiful functional intake.

 

take a can of brake parts cleaner, and lightly spray it around the manifold where it bolts to the heads. If you have a vac leak or a botched seal, it will suck the brake parts cleaner in at the vac leak and your motor will idle down for a moment. That will quickly elaborate on where your leak is, Then remove the intake, and replace the seal, or ensure that the seal is seating correctly.

Ive had mine on for over 2 months with NO TUNE yet, and have ZERO issues. Drives just like the ls2 manifold did. Runs fat and pops and crackles sometimes, but theres no driveability issues. The only issue ive had is the fucking hvac vacum port is so damn close to the firewall, i cant get a vacum line on it without it kinking. The factory 45 degree vacum elbow was cracked on mine, and all of the parts guys in cincinnati are mouth breathers and cant help me worth a shit find that elbow. Im about to drill and tap the fucker myself and make a new location for it. IMO its pretty dumbass to have that shit all wedged against the firewall and those aluminum hoses on the firewall. Makes it a real **** sucker to work on it back there if you need to replace any of those hoses.

good luck!

 

take a can of brake parts cleaner, and lightly spray it around the manifold where it bolts to the heads. If you have a vac leak or a botched seal, it will suck the brake parts cleaner in at the vac leak and your motor will idle down for a moment. That will quickly elaborate on where your leak is, Then remove the intake, and replace the seal, or ensure that the seal is seating correctly.

Ive had mine on for over 2 months with NO TUNE yet, and have ZERO issues. Drives just like the ls2 manifold did. Runs fat and pops and crackles sometimes, but theres no driveability issues. The only issue ive had is the smurfing hvac vacum port is so damn close to the firewall, i cant get a vacum line on it without it kinking. The factory 45 degree vacum elbow was cracked on mine, and all of the parts guys in cincinnati are mouth breathers and cant help me worth a shit find that elbow. Im about to drill and tap the smurfer myself and make a new location for it. IMO its pretty dumbass to have that shit all wedged against the firewall and those aluminum hoses on the firewall. Makes it a real **** sucker to work on it back there if you need to replace any of those hoses.

good luck!

Is it tuned yet? Once you get it tuned let me know how it drives and let me know if it hunts for idle occassionaly. Do you have a 90 or 92mm TB?

 

Define "properly tuned". Just because a shop does it doesn't mean it's right. Hell, plenty of "professional shops" pump out terrible tunes.

I did a LS2 Corvette with a FAST 102, and while it was a bear to dial in correctly, it's possible to do without killing throttle response.

 

thats what iim pondering. If its not the tune, and its not a mechanical or electrical fault, the car shouldnt be fucking up. But we have a fix.

 

Where all these cars tuned by the same shop? Where all the manifolds installed by the same person or shop?

 

Some different tuners some different shops.

 

Zero issues with mine! Ran it on the stock engine untuned for a couple weeks and have now put 600 miles on it with the SNL v.X cam and a wrp stage 3 p&p throttle body... haven't experienced any of the issues you described.

 

How is your throttle response? is it crisp and smooth?

 

I like how every shop claims to have the best LS tuner in the country.

Is it possible that some of these owners have put in camshafts that are a teensy-weensy bit on the large side and, as a result of combining with an intake that is designed for mid-to-top-end power, their bottom end is suffering from the simple nature of the beast?

 

Look up Dan Maslic. The only one who tunes the Mosler Supercars. Tunes for a lot of the road racing guys, he wrote a book on Tuning, if you ask around to the sponsors on this site that know of him, they'll tell you he has a solid reputation and is one of the best out there, And you do get what you pay for. At the end of the day it is what it is.

I agree w you that some of these guys might be running too big of cams for the "street" and thats where you run into issues. it is the nature of the beast with a combination like that. But what if you could correct that situation? We have just been being emailed, and called about if we were experiencing this with any of our customers and I have said no. We are just curious if anyone here has had any issues.

 

Ok gentlemen, any of you out there with a FAST 102mm LSXR intake manifold suffering from any driveability issues? Such as off idle throttle response, stumbling/hesitation off idle or when rolling into the throttle, or stepping on it hard? A momentary lag or drop when flooring it? If you have any of these symptoms please chime in and let me know. A few guys we know are having similiar issues. All cars aforementioned have been properly tuned but their owners are reporting issues that they didn't have before. Anyone else having these issues????

Well remember I said the cars have been properly tuned and have made good power/numbers? And no its not a vacuum leak or a bad MAF or MAP. The issue is more of a stumble, hesitation off idle or crusing and then mashinng the gas. We know what the problem is. We just want to know if any one else is currently experiencing this issue after installing a FAST 102MM intake because we have a fix on the way for this concern. We wanna know cause there are at least 20 other guys that we know that have complained about this.

Its more of a dynamic airflow anomaly, not a tune or mechanical issue. That is what we have come to the conclusion with some tests that were being conducted w the FAST 102. We are working on something for this.

The FAST 102 does what it says and is a beautiful functional intake.

opcorn2:
waiting for the cat to be let out of the bag.

 

No issues here

 

I've got a little off idle stumbling, I just accept it as the nature of running a large cam. Don't think it's the intakes fault in my case.

-P

 

Are you running a 427 stroker? That cam is not too big for that motor. Get some tuning lovin.

 

So whats the fix for these people having this issue? Whats the actual issue?

 

I have had mine on for about two months now and no problems at all drives like it did before the Intake.

 

To Proth... sounds like your reserve torque was totally killed at idle. My LS7 with a 242/254 0.657"/0.648" 113+4 cam can get itself rolling without even touching the gas pedal.



Ditching the MAF isn't always a solution. Retaining both the MAF and SD is the best way to go about things.

 

Out of curiosity, why do you think so? The only advantage ive found the MAF has over SD is low boost applications that the MAF can cover but the stock MAP sensor can not.

 

The MAF will compensate for temperature without using a lookup table. High boost applications aside, MAF tuning is reliable and works well. The MAF also actually directly operates off of airflow, so it is predictable, which means you can fill in areas you haven't gotten data for fairly accurately. My Z06 runs pure MAF, and my engine responds instantly when I touch the gas pedal. Throttle response can't always just be passed off on the MAF, especially when there's people that can debunk it. Ditching the MAF was a fad on F-bodies and C5s simply because the housing was a restriction (meaning not only was it a choke, but the MAF couldn't physically read any more airflow due to the ceiling on the frequency output), but with the cartridge style MAFs now (LS7 style), you can run a 4" housing which has plenty of room to make power.

Why I agree with you on the reversion topic, running in hybrid mode is the best. Now that I have a real VE table (the E38s use equation based VE, and I didn't want to even mess with it before switching to the enhanced OS), I'm going back and dialing in my speed density table so that I can put my car back in hybrid mode. There are situations that the MAF has a hard time collecting data for, and there are situations that speed density has a hard time collecting data for. Working them in tandem gives you the best of both worlds.

A properly done MAF transfer, a properly done SD table, and properly developed timing tables are absolutely key to making an engine respond and drive. The question is... how much time is your tuner willing to dedicate to really do all of it the "proper" way.

 

I always see weird issues with the MAF's though, esp when you are flowing the same amount of air (hz) but in different engine operating conditions (throttle vs rpm).

As far predictable, VE tables are also predictable, to a point. Once you get the feel for how the curve is shaped, and how certain mods effect it, its not that bad.

Good points though, thanks for sharing.

 

Great Info in here... Curious to see what the problem/solution is that Fast has identified.


+1 For Greg Banish... I have and still am reading some of his tuning books.

 

I failed to mention gentlemen, this applies to anyone that has the FAST 102mm LSXR Intake Manifold using a 90mm or 92mm Throttlebody!!! Let me know.

 

So you haven't heard of any problems with people that use the 102mm TB? Would that be your simple fix is to swap over to one of those?

 

No only with the 90 or 92mm TB. If after dropping $900.00 and you don't mind spending another $560.00 for a FAST TB or $600.00 for a Nick Williams TB. then sure it is easier. You tend to lose a little driveability with something that big for the street. You wanna increase airflow without losing driveability. Theres always a compromise.

 

Anticipation, anticipation
Is makin' me late
Is keepin' me waitin'............

 

In due time my friend, someone out there has experienced this and either assumes its normal or doesn't know its there. I can tell you everyone that has this set up does not know its there. Someone out there will chime in.

 

I am running the fast 102 and a 90 tb with no problems to date with throttle responce, I run a 100mm Maf but its on a 427 with a pretty big cam 242/254 653/647... She is a little tempermental at idle from time to time but that is the nature of the beast..

 

Is it a legitimite daily driver or a "street/strip"? Does the car that sees more track time than street? Do you use it to get groceries, go to Target take the wife out to dinner in it?

By the way I love your car. I liked like the photodocumented build!!!

 

What's the point of this again? You have a guy asking a question that he seems to know the answer to, but won't tell anybody yet. Wtf???

 

Just be patient, we are just ironing out issues so we don't violate any forum rules. Testing will be completed shortly and supporting data will be in, as soon as we can announce and launch Johnny (DREVLSX) and myself will post up.