My car did this at the track, and it was really embarrassing.

I launch my F-max powered Integra GSR at around 4500 rpm's, and I got to about 6k in 1st gear, and the damned thing backfired . . . hard. Anyway, from there, it sputtered its way to about 7k, and I shifted, and went through the rest of the gears relatively trouble free.

I do have the two additional injectors supplied with the F-max kit, and the MF2 is running. My EGT was around 1450 and my A/F meter was spiked on rich.

So, I turned the fuel down via the MF2, and I had more of the backfiring/sputtering problems. I turned it back to the factory settings, then turned the overall gain up by one full turn. It seems to be fine now, but this kind of crap only happens at the track for some reason. I can street race all night without a single occurence, but one I hit the track, it starts to foul up.

i was thinking that something must be happening when VTEC engages, and pushes more air into the chamber, then the secondary butterflies open, and push even more air in, causing a lean condition. However, if this were the case, then why would my A/F meter say that I'm rich, and my J&S knock sensor detect no knock/retard?

Sorry so long winded, but I'm desperate for some suggestions.

EDIT: I ran at the track last week with a modest 14.3 @98.xx timeslip, and last night, due to the craziness of my car's moods, ran a 16.8 - that means that I sat there sputtering for a full 2 seconds.


[Modified by Reverend, 8:25 PM 10/27/2001]

 

were you on slicks at the track? The added load on the engine from the slicks will require more fuel. I would keep MF2 turned up. We had the same problem with my friends car at the track. Accept he would hit third gear and the car would fall on it's face. So we turned the boost down and it was fine. Yet when it's on the street it works fine at higher boost levels, only difference being traction. Also, you might want to get like a skunk 2 manifold or something to get rid of those butterflies. They seem to cause more of a problem then they do help.

 

if he ran a modest 14.3 with an Fmax GSR, then he's gotta be on street tires. Otherwise.....

 

yeah, I was on street tires.

 

my car did the same thing when my inline fuel pump died.....and my a/f still said rich.

 

14.3 w/Fmax?? dude ..I'm running 14.4 on streets with ecu, intake and vtec controller only......

I think you need to retune your fmax...you should be running high 13's at least...

 

Now that I feel that I have to defend my timeslip . . . I have lowered the compression to 9:1 with the use of a thicker head gasket, and I'm only running 7 psi with a more than full interior on what's mostly a show car (full system, a bunch of chrome, etc.). The damned car probably weighs more now than it did when I bought it.

As for this .. .
What do you think I'm doing by posting this!?

 

People, dont attack him because of his time, he obviously is having problems with his car. I think there may be only one real way to solve the problem and that would be on the dyno. The A/F gauge really isnt accurate enough to tune your car by. You cant really check spark plugs because it doesnt happen in the street, so that's not an option.

 

SPuttering and backfiring sounds like way too much fuel. I had the same problem for awhile after I installed my 370's but I got it worked out finally with the VAFC and a little tuning. If you want to more accurately look at your fuel ratio, wire up a multimeter like I did so you can see your actually O2 sensor voltage. It actually helped me tune and then diagnos my failing fuel pump problem. Here is a link to the post were I kinda explained what I did. I spose you are now seeing why there is so much speculation on weather or not togo with the Mf2 setup or not. Well check out the post and even if you don't decide to do the "Shade tree" ghetto rig like me, a good tuning session at the dyno would also get you going in the right direction. good luck http://www.hostboard.com/ubb/Forum40/HTML/008692.html

 

The really big problem with the MF2 that I've found in trying to tune it is that it doesn't measure throttle position at all - just boost. I think it would be a more effective tuning device and fuel solution if it read throttle position as well as boost. Plus, I think it would work a little better if it were tunable in 500 rpm increments, rather than 1000 rpm increments.

Basically, it just took an hour and a half to get the thing tuned well enough before I go and buy a Haltech or Hondata (haven't decided yet). Of course, since its running "well enough" right now, I think I'll spend the money on a clutch and LSD (maybe a flywheel), then do the re-make of the fuel solution later.

 

Ever think about pulling your plugs to check them? Which plug and gap are you runnin.
I bet if the next time it happens, and you shut the motor down and pull them they will be wet. I would think its more of a non-spark or faint spark type of problem. Also how's your timing? Check that too.....

 

Don't laugh, but factory plugs, factory gap. I've been confused about what plugs to get ever since I put on the turbo.

 

That should probably be your problem. Go with the ngk bkr7e gapped at about 32.
This should help your problem out.

 

No one had the bkr7e's, but I did find a set of the bkr6e's.

They're the same heat range as stock - they're not a step colder like the 7's. Do you think I'll have any problems, as long as they're gapped correctly?

Thanks