It seems like a few people on here have had problems with hesitating problems when the engines cold after putting headers on. A friend of mine at work said when he went from full stock to full aftermarket on his bikes that he developed problems too. If this is in fact a factor is it a matter of just adjusting the ECM? thanks

 

you know it's funny, just yesterday I made a post mentioning that I'd never heard anyone complain after installing headers...

there's a handful of possibilities here. one of which could easily be that your new huge headers are now causing your wires to arc onto them, and they need to be moved and/or replaced.

and easy second option is that your engine could've been running lean or even at the usual fuel rating, and may need to richen up a bit. you could go the various routes of richening the fuel mixture(prom tune, vafpr), or wait a tank of gas or so and let the ecm richen the mixture on it's own(far less accurate or efficient, but it could do the trick).

a third possibility is that if you ONLY changed the headers, not the y-pipe, you could be causing a sort of initial backpressure hiccup when starting the car, while the exhaust flow is sort of "adjusting" itself to the rather large reduction of flow from your collectors to your stock y-pipe(specificially on the drivers side exhaust, as it does a top T drop kind of thing...look at the exhaust, you'll see what i mean). if you haven't changed the y-pipe yet, this would be my first guess.

you may want to check your timing too, maybe advance it 2 degrees or so, that may be the issue. considering your mods, it's a possibility.

 

I just finished installing my headers the other day and i didnt realize i cracked 4 spark plugs trying to get the ****ers in.. But what had me clueless for a while was the fact it ran fine until the motor warmed up.. At first i thought it was the new wires i bought because i made up the plugs myself which was new to me.. But i havent had any problems with it running.. im going to the strip this weekend to see if my new tune and headers made any diff..

 

Your noticing that the fuel tables no longer line up with what the engine really needs. The ECM doesn't use the O2 sensor or self learn routine untill it's warmed up. So you are relying on the stock fuel tables untill the O2 lights off....hence your stumble.

The ECM also turns off self learning when you go WOT, as you can imagine having the fuel tables correct is rather important.

I've seen headers screw up the fuel tables by as much as 10% which is right near the limit of what the ECM can compensate for.

 

very interesting.. i did replace the y-pipe, its 3" from the cat-back. Whats Vafpr?
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Hmm. thats interesting as well. I guess I over estimated the ECM's ability to adapt. Gonna have to see how much a chip might cost me.

 

you may want to look into diy prom tuning it is your best bet mail order chips will never be perfect for your setup

 

vafpr is variable fuel pressure regulator, it's a relatively cheap and simple change from the stock regulator, and you can richen your fuel mixture a bit.

it's not nearly as efficient as prom tuning, but it would fix the problem, assuming fuel is the issue.

 

I second this. At one point my car had a full exhaust (headers into 3" cat and cat-back), open element, Edelbrock TBI intake and TBI spacer and it ran like poo. Wasn't much faster than stock. At the time I didn't realize how far off my tune was at that point with just those mods.

 

Mine doesn't feel much fast either. Im currently getting a laptop so I can log some data with WinALDL. Thanks guys

 

The first time you tune and make simple improvments you will be hooked. When you hone your skills and knock time off your ET you will be set for serious mods.

 

I'm excited to hear that, I gotta get out of the 16's lol

 

i though i was the only one.... but i didnt even put the 2 together, i was wondering if the headers were to blame


my prob is an intial hestitaion if i hit the gass while the idle is below 750 it misses 2 cylinders then pulls like hell the only way i've ever gotten it to go away was to put like 10 degrees base timing, which is way too much timing and slows the car down but did help with the hesitation. my car also pops like a **** when you let of the gass or down shift, unless i have about 4-6 degrees of base timing which seeems to work well with my mods and stage 2 chip, i just have to run 91 octane to keep everyone happy