My 03 stock block evo is tuned on flex fuel 91/85 running well for over 6 months.


In the past few months I’ve been getting some type of hesitation. I’ve tried a few things from changing coil packs to stock, changing back to stock rom, cams, injectors and all the sort with p0300 popping up on the stock tune.

I went back to my original setup which is listed below and I’ve been getting a misfire that seems to be getting worse. Taking off from a light or stop sign yesterday was terrible with sputtering but once it got moving it wasn’t that bad. Cold and warm start ups misfire as well. All the mods below are what my current tune was completed with. I’ve done a boost leak test with it holding 30psi and bleeding off slowly and checked out good with no bubbles forming around connections during the test.

ive replaced my front o2 sensor with a brand new denso earlier this week as well. I just don’t want to keep throwing parts at it without knowing what else could be wrong or how to diagnose anything else without a cel.

Mods are here:
Speed density
omni 4 bar
ported intake manifold
ported throttle body
stock upper intercooler pipes
vrsf lower pipe
vrsf fmic
hks 272/272
cop kit with toyota oem Denso coils
bpr8eix spark plugs gapped to .024
rc1200cc injectors
how 3 port solenoid
egr blocked plate
walbro 255 not rewired and not modified
fp exhaust manifold
fp54
invidia o2 housing
hks downpipe
ultimate racing hfc
flex fuel kit

 

try a new omni 4 bar. they just break without warning. need a backup anyway

 

even when it logs on Evoscan?

 

Today I’ve checked for spark and have spark. The day started with a cold start and straight misfiring. Lean on the wideband 18-20 afr. Warmed up around 16-17 afr and finally came down to 14.7-15.5. Any throttle input stutters and hesitates. Timing marks on the cam gears match along with crank pulley at tdc. Fuel pressure regulator vacuum nipple is dry and not leaking. I am waiting on a friend for a spare Omni but right now is there anything else that could be it? Walbro 255 whines loud enough where i can hear it standing 5 feet behind it. This pump was in the car when I bought it 8 years ago and has been used with both 91 and e85. Unknown mileage before my ownership.

 

yeah theyre garbage POS's

 

not the map sensor, swapped with a known good one .

 

He's saying Omni map sensors are shut. Get rid of it all together for like an aem one or something along those lines. I have had brand new Omni sensor be junk. Went to aem sensors never had an issue since

 

I totally understand what he’s saying. Right now I’m trying to get my car running.

today cold start after the Map sensor swap was still sputtering. Lean AFR’s and all. I’ve pulled the fuel pump relay and checked for continuity , it does. I checked the ohms. 0.2-0.5 , and the relay clicks with 12v attached.

 

Have you checked for boost leaks? And how old is your wideband sensor? Does it control your car or do you still have oem o2 sensors? I would look at maybe your o2 sensors. If your wideband is really lean it could be on its way out or you have a major leak somewhere. Best way to check that is spray around your intake with starter fluid where everything connects and see if rpm changes. To me I would think its more of a leak somewhere. Cars just don't go lean for no reason. Although I wouldn't count out faulty o2 and or wideband depending on how your car is setup to run.

 

I run the innovate ecb-1 for wideband boost and ethanol. The only portion connected to the ecu is the flex wire. Datalogging is using a data cable for wideband. O2 sensors are both functioning and the front is brand new sensor replaced last week. Boost leak test has been done to 30psi and slow bleed off as normal. No soapy bubbles from any intercooler or intake manifold/ injector seals.

 

Ok so your ecu still runs off factory o2 sensors got it. I would if its not to much of a pita take out the wb sensor and see how it is. Idk how long that has been in the system but they do go bad after a while. I would also log your map sensor. If you have had issues with it and swapped a new one in I would log it and see if could be something else such as wiring or something like that. Could be a ground somewhere going bad and not reading correctly. But majority of problems going lean at any point would be tune changing and thats usually leak somewhere thats being metered by the wideband.

Just thought of this do you run dual maps? If you do you could be in the wrong map. I have done that a million times thought i was in my pump fuel map and I was in the e85 map.

 

im on flex fuel. I removed the wideband last week when I did the front o2 sensor to check it. Recalibrated it as well. It has 3500 ish miles on the sensor. I’m trying to see if my fuel pump relay is bad or going and have ordered a brand new walbro 255 for it as it was whining really loud the other day( hear it even when standing 4-5 feet behind the car). It’s 8 years plus old so figured even if it isn’t that I should replace it.

 

check your tune to see which CEL codes are turned off. turn them on

 

Lol loud 255 is nothing compared to dual 2 525s in the loudness department. If the relay was bad car wouldn't start. Do you have a fuel filter inline somewhere I would check that. And yes if your pump is 8 years old time to refreshen it up.

 

that would annoy me for sure lol. In tank filter only and yea I’m waiting for my new fuel pump to arrive. Relay I checked yesterday and it’s .2-.5 ohms with no power added and when 12v added the ohms change to infinite. Not sure if that’s right.