Stevey629

I rebuilt my motor with a 2nd stage street port and cryo. Upon installing the motor, bonestock otherwise, the car stuttered terribly and backfired to the point where 4-5 ft flames would shoot out of the exhaust, and it was getting around 2-3 miles to the gallon. Again, bone stock, aside from a fuel pump, drop in K&N filter and a turbo timer. NE how, I determined that there were no vacuum leaks in any of the vacuum lines, after replacing all of them with silicon hoses and zipties to hold them down. I assumed that it was a fuel problem, so I went to the fuel pump first, and put the stock one back in. Not much difference, actually practically the same. So now the injectors. Replacing the secondaries with stock ones that worked, and just spraying carb cleaner in the primaries (didnt have an extra set of primaries on hand) and hoping that this would cure the problem was the next step. It amazingly did, and the sputtering has dramatically decreased, and it actually rev's up. However, it still feels unresponsive, and Im hoping that this is just due to bad spark, or possibly a bad coil pack or something. Is there NE thing else I should look for?

What my real questions are lie in what I can do to the exhaust system. Im also under the impression that my cat's both main and pre are fried, or completely saturated rendering them useless. Is there a way to tell if they've gone bad besides taking them to a sniffer?
Would it be okay to replace the pre-cat with a downpipe, and replace the main cat with a new one? How much does the main cat cost, cuz it looks humongous and mazda dealership pricy. As far as my muffler goes, I need a brand new one. The backfiring and excessive amount of fuel build up has basically made the bottom of my muffler look like a cheese grater, pummeled with holes. Time for a new and upgraded one, only heres the concern: If I am running a drop in filter, street port, down pipe and high flow exhaust (HKS or something), am I pushing the limits of my luck here? Theres that good 'ol rule of three mods, but Im wondering if I can do this if I upgrade the fuel pump. I installed a fuel pump right after my rebuild, and I started to pin blame on that thing because of how rich it was running, so I took it out. Only, I realized later that having a higher flowing fuel pump doesn't do much with the stock fuel pressure regulator, or am I wrong here?

Sorry for the complete rambling, my thoughts are jumbled and Im too tired to orgainze my thoughts. If anyone can make sense of my questions and ideas, that would help a bunch. Oh and a reply would help too

tomsrotary

has it been tuned since the rebuild??
what computer are u running, i'm sure the stock FD computer wouldn't like the streetport, and or, if u have increased boost. are u still running the stock twin turbos???

Stevey629

yes. The cpu is stock, as are the stock twins. I have NO fuel management. This is why I posted this question. Is it even okay to be running my car like this...etc.

Sesshoumaru

iTrader: (1)

The street port would affect the timing of the engine.

check you fuel pressure regulator..........

Stevey629

what should I "CHECK" on it? how to? The fuel pressure regulator isnt going to let any more fuel through than it should, so technically, my aftermarket pump wont do NE thing. is this correct?

Sesshoumaru

iTrader: (1)

if you dont 'have a vac line it will let in more fuel than the computer thinks not less. The FD's also have a solenoid to control it.

pomanferrari

iTrader: (1)

check the green thermosensor connectors for water and fuel. They are identical and located so close that I swapped them by accident and my car spits flames, idled high and generally ran like ****. If you have a PFC with a commander, you can look at the temp of water and fuel to see their values before swapping.

Check the high idle cam facing the firewall near the coolant inlet nipple. It's right above the throttle sensor connector. Try lifting the adjustment screw away to see if it helps idle.

cabaynes

iTrader: (4)

i was under the impression that it is a very BAD idea to try and run a ported motor off the stock ECU... the best thing for you to do would be get a PowerFC or some other type of fuel management and get your car tuned ASAP. I think you are really pushing your luck running a brand new ported motor on stock fuel management.

Also, i would very stongly reccomend you get a DP, high flow cat or MP, and replace your exhaust (get he car tuned with these mods on) also, don't forget to put in brand new spark plugs just before you get tuned!