Apex Missing Full Throttle

[Sibola]

Been tuning my sled with a rb3.MPI Stage 2 10lbs boost, bigger injectors, vortec blowoff valve, headshim, 91 octane, msd fuel pump.

Sled runs fine from1/8 throttle to 3/4. Then you punch it to full throttle it starts to miss and rpm's drop boost drops off. Back off to 3/4 throttle and everything is fine again. A/F readings at 9000 are 10.8-11.2, so I don't think it is a lean miss.

It also does it from a dead stop, punch throttle and it is missing ,farting backfiring, and sputtoring. Talked to Dave, at Hurricane he does think its fuel niether. Checked plugs for resistance they are good(3.8 olhms) set the gap 18000.

Anybody have any ideas sure would appreciate the help.

 

[kinger]

Does it flash any codes? Like TORS?

I would check the throttle position sensor and make sure its reading correctly.

Mine from a dead stop and idling if I punch it has a little hesitation so I have to feather it to get it above 3000 rpms then stab it and its instant.

I am running the GEMS though not the RB3

Good luck keep us updated on the progress

 

[Sibola]

Yes I will keep things posted as I figure crap out. Sure is funny when you read over your own post, and nothing makes sense. Guess thats why I work in the bush, not behind some computer.

 

[hobbes]

Dumb question, but you aren't hitting the rev limiter are you? The stock tach can't keep up with the actual rpms, when you hit the throttle from a dead stop does it build full boost before the backfiring? If so, I'll bet you need more weight in the primary.

 

[uphigh]

Have you tried adding fuel to the bottom and top end?

 

[Sibola]

Yes added fuel to the whole map yesterday. It actually got a little worse, the miss I mean it started sooner. So I think it is way to rich. I say this because I installed my Gems back into it today and it was farting and missing right from the bottom to 8500 rpm wouldn't go any higher. So seeing as I added bigger injectors and a better fuel pump along with BOV, the Gems isn't tuned for all that. BOV open so Gems dumping to much fuel on the bottom, with bigger injectors and better fuel pump its still dumping more fuel than the stock fuel pump and injectores. Another reason I think I got a tiny exhaust leak right where the o2 sensor is welded in. If sucking air right ther would give false reading. Saying it is running lean when in fact it might be rich. Fresh oxygen being sucked in right past the sensor. Another possibilty is I'm getting throttle position code, which effects timing.

 

[wienerwater]

I would seal up the O2 sensor part first, get the AF reading more true and see what happen from there.
Might change a bit with the warm weather we are having now as well, not sure when you rode last.

 

[Wakegod]

. Another possibilty is I'm getting throttle position code, which effects timing.

Have you tried bypassing TORS?

 

[Sibola]

Thanks guys, yes pulling exhaust out today to seal it up. Yes the T.O.R.S is disconnected. Oh I'll figure it out sooner or later . But after hooking the Gems back up it eliminates the possiblity it was the RB3. I'm fairly confident it is just way to rich.

 

[rxrider]

Any boost leak? Where is the boost sensor for the fuel controller mounted? If the sensor sees higher pressure that actually goes into the engine it will add too much fuel, just a thought.

 

[badluck]

Stupid thing but did you check your inner cooler to throttle body and the throttle body to head boots. Again just a thought ! Did it to me before!

 

[Sibola]

Stupid thing but did you check your inner cooler to throttle body and the throttle body to head boots. Again just a thought ! Did it to me before!

Hey thanks, nothing stupid when trying to figure something out every opinion helps. Checked the inner cooler boots but not the throttle bodys one though. So thanks I'll check those.

 

[Sibola]

Any boost leak? Where is the boost sensor for the fuel controller mounted? If the sensor sees higher pressure that actually goes into the engine it will add too much fuel, just a thought.

Thanks rxrider. I have the boost all plumb in together off the throttle body's. So ya what ever the engine see's the boost sensor see's. But thanks again.

 

[jw440/800]

Been tuning my sled with a rb3.MPI Stage 2 10lbs boost, bigger injectors, vortec blowoff valve, headshim, 91 octane, msd fuel pump.

Sled runs fine from1/8 throttle to 3/4. Then you punch it to full throttle it starts to miss and rpm's drop boost drops off. Back off to 3/4 throttle and everything is fine again. A/F readings at 9000 are 10.8-11.2, so I don't think it is a lean miss.

It also does it from a dead stop, punch throttle and it is missing ,farting backfiring, and sputtoring. Talked to Dave, at Hurricane he does think its fuel niether. Checked plugs for resistance they are good(3.8 olhms) set the gap 18000.

Anybody have any ideas sure would appreciate the help.

I had the same problem and it turned out to be the fuel pump. We put an aftermarket one that Ted Jannetty got for me. Good Luck!

 

[TurboKeith]

Too rich will cause similar symptoms. I just did an update on my map and my vmin and vmax numbers were off. It ended up making it way to rich on the top end. It wouldn't run past about 8,000 rpms at full throttle but I did have full boost. After leaning it out, all was good again.