Chriz88DX

iTrader: (1)

first off i was thinking my engine blew a few months back with 210k on the dash. it ran really lumpy and at a low ide almost like on one rotor. weird thing about it is that the aem ugeo wideband read maxed lean or 18.0 afr which thinking about it now should of been max rich due to the lost of compression.

so i got a good deal on a rebuild and half bridge port so i did it and put the motor in and tried to start it and it surges pretty bad like in the video and still reads lean so does my narrow band o2 sensor.

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so i got some 550cc and 720cc injectors and maxed out the fuel on the rtek and still reading lean there are not any codes and all sensors are reading good

now i have been reading up on it here and have noticed a few other poeple with similar problems and some have fixed it by replaing the leading coil but i can't understand how a bad leading coil can make the car run lean. also if i manually pull the vdi open the car dies

so what do you guys think

mods
Rtek 2.0
720cc secondaries
550cc primaries rebuilt
corksport header
greddy cat back form a FD
s5 intake
bridge ported engine
rats nest removed
corksport ss oil cooler lines
solid motor mounts
ceneter force clutch
Aem ugeo wide band
walbro 255 fuel pump

SirCygnus

iTrader: (1)

bump up the idle. also, your intake manifold is not designed to handle a bridge port.

cptpain

iTrader: (1)

if youre reading lean conditions..... and you've maxed out your injectors.... which is bad, cause now you've got fuel dilution, i would like to think both your sensors crapped out.

if that doesnt make things any better i would next try looking over the entire fuel system front to back and back to front.

durtled

yeah after a bridge port af anykind the cars idle higher ur gonna want a high idle its trying to be low idle still but it can't. def get some bigger injectors and then u should be fine im no expert but it seems to be the problem u sure it was timed correctly after it was rebuild?

j9fd3s

iTrader: (3)

if this is just at idle ignore the o2 sensor and tune it so it runs the best. bp and PP misfire @idle, misfires = lots of oxygen in the exhaust = lean o2 reading.

its actually one of the conditions where the o2 sensor doesnt work. you can use it for part and full throttle still, you'll see it start to read right when you let the clutch out and give it some rpms

Chriz88DX

iTrader: (1)

well i did have the main throttle body bore open more in the video and it stll does this ilde surge funny id it did this before rebuild so a misfire can look lean i will to to get the video up of the car befor ei did the reuild it was doing the same thing but a little lower

so if this is right i will replace the leading and trailing coils form a working car and see what happens

driving the car it sputters and bucks untill 3k thing it pulls but since is a new motor i have not taken it higher

so i am guessing this is a misfire becuase the fuel system is working fine even if i turn the fuel all the way up to max it does the same you just smell gas

but can any one tell me how a misfire can make the o2 and wide band read lean tho?

jjcobm

iTrader: (18)

I may be wrong on this but this is the best I can do:

A wideband only measures the completeness of a combustion (lambda). It does this by taking a sample of the exhaust gas and measuring the amount of oxygen that must be added or subtracted from the exhaust to make the gas sample it took, stoichiometric (perfect combustion). To do this though, the air/fuel mixture it is measuring needs to be already oxidized (burned) to a certain extent or the process will "time out" since the sensor takes so many samples of the exhaust gas at given intervals.

Therefore, if you have HUGE amounts of fuel in the exhaust, the wideband will try to take that fuel and turn it into a perfect combustion. Since you have way too much fuel, the process takes too long and "times out" and the sensor begins to pick up a new sample and tries to turn it into a stoichiometric combustion.

Hope I didn't butcher that.

Hybrid G

iTrader: (4)

Calibrate your wideband............................ thats all u need to do vist the aem website to learn how

Chriz88DX

iTrader: (1)

it's the aem wide band auto calbrating

Aaron Cake

iTrader: (1)

Don't tune idle using the wideband. You may never receive a correct reading on the bridgeport due to the misfires. The RTek may not allow you enough duty cycle at low RPMs to run that engine properly. A bridgeport will require about double the fuel as a stock port to idle.

Now, you are going to have some problems either way. The S5 intake is perhaps the worst one to use. It will run, but you are leaving a lot of power on the table.

j9fd3s

iTrader: (3)

sorta. if you just hang the O2 sensor out in the air it'll read 20:1, as i guess normal air has an oxygen content of about 20:1.

normal combustion uses some of this oxygen. if the chamber misfires, like a PP or bridgeport does at idle, then it won't use any oxygen, because there is no combustion, and since that is what the OXYGEN sensor measures, it will read lean.

my PP idles around 40:1 on the wideband. if you believe that a rotary would run that lean, i would be happy to sell you a bridge (port)....

there are 5 gas analyzers, or smog machines, that look at hydrocarbons, CO, Co2, NOx, and um oh yeah i think o2, which actually would give you a reading on a PP or bridge at idle.

the WB seems to work fine once the throttle is open...

and its phenomena i wouldn't have thought of until i put the sensor on my own car...

Chriz88DX

iTrader: (1)

Face plam:

so should i

A get a adapter plate and run a re uper intake
Or
B run the s4 manifold i have

and do you mean power flow wise as in i will out flow the intake or have drivablity problems.

Chriz88DX

iTrader: (1)

car ildes now problem was the leading coil and neutral safety switch

idle is between 1600 and 1800 at 17 degrees advance on the leading with 0 split

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Aaron Cake

iTrader: (1)

You have few intake choices.

The TII intake would be the cheapest way to make this work, but less then ideal.

You could also block off the VDI (set it to the high RPM position) and gut the plenum on your S5 intake. Again, pretty crappy.

Going down to an S4 upper intake with the plenum gutted will also be an option.

But really, what you need is a nice set of ITBs with a side draft Weber style manifold...And a standalone to run it.

SirCygnus

iTrader: (1)

or just be cheap and go carb.

one way to richen it up is to crack open that airflow meter, and turn that COG wheel so that it increases the spring tension. this delivers more fuel.

or, upgrade to 550cc injectors all around. but still, at this point all your doing is guessing.

Chriz88DX

iTrader: (1)

why 550s all around?

Chriz88DX

iTrader: (1)

the turbo manifold is less than ideal why. i am guesing sucky bottom end

Aaron Cake

iTrader: (1)

Your bottom end is going to suck no matter what with an NA 6 port bridge engine.

The TII manifold is a choice only because the plenum is straightforward and Mazda didn't put the tuning into it they did on the NA manifold. So it is a compromise between a manifold that doesn't match the engine at all, and one that matches just a little bit better.

joeylyrech

iTrader: (11)

Drop the idle down to 1500 rpms and put around 15 degrees of split and you will see the motor idle way better,vacuum will improve also.My 4 port bridgeport idle was ugly as hell until i advanced my timing at idle to 25 degrees and 15 of split.After the change in timing some fuel was removed at idle and some fuel was added at startup and now i get a hard on every time that start the car,steady louds brap,brap,brap.

Chriz88DX

iTrader: (1)

cool man i will try that but is that much advance safe on brand new rebuild?

Chriz88DX

iTrader: (1)

ok i think i will try this first but for records sake after break in i will run the s5 on the dyno then try the turbo manifold the s5 turbo manifold is better right or would you recommend the s4

thanks alot for you input you info is very much appreciated