i have a 95 a4 z heads/cam car. when i get on it everytime at 5500 the motor breaks up bad. i have no clue what it is. also is my stock fuel pump adequet for my engine. nothing is stock performance wise with the car except the fuel pump and the maf sensor. I have the 230/236 cam, cnc heads, injectors, throttle body, vigilante 3600,etc... Any help will be appreciated. thanks

 

Are you sure you're not just hitting the fuel cutoff rev limiter?

 

i dont think because ive had the car tuned twice, the second time due to the bigger stall. then i went to an even bigger stall and its cutting out before the shift point. beats me

 

Does anyone thine its the stock fuel pump or the optispark?

 

Do you have your file for you tune? Datamaster or other logs? Dyno graph?

Could be fuel, valve float, spark.... tuning. Could be tons of stuff.

 

I have the same exact problem. Mine consistently breaks up at that rpm. I have eliminated lack of fuel (checked w/ pressure gauge). It could be several things. 1)Opti 2)Coil 3)Coil Wire 4)Plug wires touching/cut/grounding out

I have 2 plug wires squished under my alternator, so I am going to make 2 new wires. I am also going to make a new coil wire. If these don't fix it, I'm gonna borrow a coil off another car and pray it's not the opti. I have also eliminated tuning as being the cause of this. I'll post up later if one of these fixes it.

Ryan

 

I'd say opti, fuel pump, tune, have you changed the fuel filter? Maybe even that.

However plugs and wires are not usually associated with stumble at a particular rpm usually they stumble randomly or all the time if there is a problem. But certainly don't rule them out because it is something you'd want to check.

- Z28wannab

 

My stumble cleared up after I made a new coil wire, cleaned the contact on the coil, and fixed my two plug wires which were squished against the alternator. Hope this helps.

Ryan

 

thanks for the advice guys now i have a bunch of starting points.