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I replaced my O2 sensor a while back and have been having flooding issues and a rich smelling exhuast with explosive backfires on long decel (above 3500 rpm).
I found the wire the O2 sensor connects to leds to nowhere and wasnt getting to the ECU. Trouble I am having now is where does the O2 sensor wire run? I have the wiring diagram but am having trouble seeing where that leads to.
I found 2 wires not Attached to anything in the engine:
1. Runs in front of the intake manifold off the main wiring loom (solid Black - no markings)
2. Connects off the oil pressure sensor loom (Black with yellow stripe and Red markings)
Are either of these right? I put spade connectors on both and haven't seen a noticeable difference connecting to either (or unplugged).
Just came in from the garage to double check; the spade connector in your picture appears to go to a condensor can (capacitor?) that is typically located right behind the vacuum advance on the Distributor. The O2 sensor lead - from what I can see - comes off of the end of the fuel injector harness which runs under the intake manifold.
The O2 sensor is a single lead (unheated, narrow band) sensor that is used by the ECU to do simple fuel map trim only during 5th gear cruise as sensed by the overdrive gear switch on the transmission, which also senses reverse gear selection for back up lights.
That said, your flooding problems may not be rooted in the O2 sensor reading, but in one of the several Water Temp or Intake Air Temp sensors which give reference readings to the ECU so it can decide which fuel map to apply based on engine heat, coolant temp, and outside air temp.
post back with some more symptoms and we'll see if we can narrow it down. At a minimum you should install a fuel pump cut switch on your fuse block to allow you to turn off fuel pump operation for easier deflooding. You can accomplish this by pulling out the Fuel Pump fuse, too.
Here are some things I've done recently which may help with the flooding diagnosis:
- motor was rebuilt 1000 miles ago
- Fuel injectors were rebuilt/flow tested
- new fuel pump/filter
- new coolant temp sensor
- new injector connectors
- timing not set with light, only with what got it to start originally.
- set the idle high (1200) to assist with 1st gear (since it floods, I'd rather not stall it at a light)
- floods on cold starts, I pull the fuse and cranking and usually starts up after one de-flood procedure
- rich smelling exhaust all the time
- backfires on decel about 3500rpm
- idle hunts occasionally (surges up and down by 250 rpm)
- lots of power and pulls strong through whole revrange
Let me know if there is anything else that might help here.
You have a bad injector which isnt sealing properly and spraying all the time, possibly both of them. You mentioned that both injector pigtails were replaced. Were they wired in directly for the replacement connector, i.e., was polarity of the connector observed? This is i portant, as the injector is nothing more than a solenoid that controls a fluid valve. If the polarity is wrong, it will cause the valve to be open when it should be closed and vice versa. Maybe someone can confirm on my understanding of the injector polarity...
Aside from that, I would also check by your Air Flow Meter to be sure someone hasn't shunted the fuel pressure test connector which would allow the fuel pump to run anytime the key was in the run position (vs. Only when air is coming into the engine via the AFM).
My bet is that you have a bad injector or two. I sent 5 to RC Engineering to get 2 that worked and flow balanced properly,...
Observing injector connector polarity is a good idea but injector is a simple magnetic coil and is not bothered by reversed connections so no difference in performance is noted.
Op,i responded to your build/no start threads some time ago strongly suggesting fuel system pressure tests and in particular ability of fuel system to hold pressure on shutdown. Been following your threads and performance issues since,need to rule out fuel system integrity as a cause.
Really should put a timing light on engine and set timing and watch timing light for any unsteady firing patterns.
Mechanically raising idle speed to not stall out,brings its own set of issues as pcm is confused as to throttle position as tps can't track properly,causing among other things improper vacuum advance operation.
You have a bad injector which isnt sealing properly and spraying all the time, possibly both of them. You mentioned that both injector pigtails were replaced. Were they wired in directly for the replacement connector, i.e., was polarity of the connector observed? This is i portant, as the injector is nothing more than a solenoid that controls a fluid valve. If the polarity is wrong, it will cause the valve to be open when it should be closed and vice versa. Maybe someone can confirm on my understanding of the injector polarity...
Aside from that, I would also check by your Air Flow Meter to be sure someone hasn't shunted the fuel pressure test connector which would allow the fuel pump to run anytime the key was in the run position (vs. Only when air is coming into the engine via the AFM).
My bet is that you have a bad injector or two. I sent 5 to RC Engineering to get 2 that worked and flow balanced properly,...
I will see if I can find my flow test results as I assumed they came back ok without checking against spec.
I also have a set of injectors from Autozone which I could throw in to see if that helps. Although I heard those aren't the best either.
Observing injector connector polarity is a good idea but injector is a simple magnetic coil and is not bothered by reversed connections so no difference in performance is noted.
Op,i responded to your build/no start threads some time ago strongly suggesting fuel system pressure tests and in particular ability of fuel system to hold pressure on shutdown. Been following your threads and performance issues since,need to rule out fuel system integrity as a cause.
Really should put a timing light on engine and set timing and watch timing light for any unsteady firing patterns.
Mechanically raising idle speed to not stall out,brings its own set of issues as pcm is confused as to throttle position as tps can't track properly,causing among other things improper vacuum advance operation.
Issues with setting the timing was based on the tick mark wasn't positioned on TDC so I'll need to find that first. I did make sure to match polarity with the new leads on the injectors.
I'll drop the idle down and see if I can keep it idling. Fixing that may help with the other diagnosis.
Does that mixture screw need to be touched? Anyway to know where it should be set if it was changed?
The term shunted in this context means that the green connector by air filter housing has a wire jumpering the 2 terminals in connector. Its purpose is to run the fuel pump for system testing-not to run the car.
Potentiometer(mixture screw) pertains to idle quality,not speed,only and should not be altered unless needed.
O2 sensor readings are not used by ecu til vehicle is warm and in 5th gear(closed loop) at which point sensor input is used in fine tuning of air/fuel mix. Lack of O2 input in operation other than 5th gear is not responsible for hard/no start/flooding cold or hot.
Not necessarily the cause for flooding,but is vacuum hose hooked up to pressure regulator on fuel rail? If not,fuel system pressure is higher,making mixture richer. Its normal function is to keep fuel rail pressure constant and when throttle opened a lot/fully,vacuum on the diaphragm dissipates as manifold vacuum drops and raises fuel pressure to give more injected fuel with increased duty cycle to make maximum power. Have only seen a couple of diaphragms in regulator rupture on a SE. If this happens,system is running at higher pressure/richer all the time AND engine vacuum is pulling raw fuel thru vacuum line into throttle body/intake manifold. This is remote but could be behind the hard start/flooding/stalling at idle. This condition is much more common on piston engine cars.
To test,remove vacuum line from fuel pressure regulator(note if hose/nipple is wet with fuel,if it is pressure regulator is bad),put a vacuum gauge on removed hose and start car observing both vacuum gauge and nipple on regulator line was removed from. There should be no fuel dribbling/spraying from nipple. At idle/throttle closed there should be vacuum of @ 12" or so at removed hose,as you open throttle,vacuum will drop off and return to where it was when throttle is released back to idle. A further test is to use a hand vacuum pump to test diaphragm in regulator,this is done in conjunction with a fuel pressure gauge installed in fuel system and will allow you to observe pressure regulator raising/lowering fuel pressure in response to different amounts of vacuum applied to hand pump.
First off, I am sure the O2 Sensor is correctly hooked up now. I traced the wire to the Injector loom and got that squared away (finally).
Next, as I removed the upper Intake manifold, I noticed one of the nuts was tight, but not as tight as the rest. Could I have had a air leak here? Also the intake gasket was torn, but this may have been from removing the manifold. The gasket looked like it was doing its job (no seeping).
I will be taking the Injectors out later this weekend to see if they were install correctly.
I also confirmed the FPR (Fuel Pressure Regulator) has the vacuum hose connected and no holes/damage.
Anything seem out of place? I am not super mechanically inclined so the concept of flow testing the fuel system is a bit out of my league.
I also attached my injector results. These seem ok as well?
Ok, sounds like an old issue is rearing its head again. The temp sensor on the Dynamic Chamber looks to have broke again. This would make sense why its funning so rich!
Didn’t you guys say check the sensors??? Duh!!! Does this make sense why it would run rich/flood whether warm or cold?
So instead of trying to buy new fuel injectors/regulators, I will try replacing this sensor.
Can you buy this new anywhere? Any luck buying from Napa/Autozone?
Yes, that would explain the ECU thinking the mixtrure should be set rich, and would lead to the engine running rich in nearly all driving conditions. Repairs made in the past include resoldering the leads to the sensor, if you're handy with a soldering iron. Finding these eensors may be more of a challenge these days. Regardless, I would go the route of repairing this, and a few other things I noticed from your pictures;
1. Fuel lines to rail - yours look old and may not be Fuel Injection Hose, which is normally marked prominently on the hose. Regular, low pressure fuel line is unmarked and will lead to over expansion and leaks, spraying fuel under the intake manifold. Replace these now with Fuel Injection hose for peace of mind and convenience.
2. Bolts holding rail to center housing - one of yours is too long (the rusty one). These 2 bolts are different lengths, and the longer one goes through the rail mount where its stepped up. In your picture, one of them is not cinched down fully, leading to uneven pressure on the rail mounts, and likely insufficient pressure to seal that injector on that side.
3. Coolant return & Radiator hoses - RDiator hose looks swollen at the thermostat housing. Proba ly time for new hoses, and easier to do now than wait for a leak or burst hose.
4. Routing of injector wiring in front of rail - Injector wiring should route around each side of the rail to the injector that it energizes instead of around the top of the rail. This reduces the strain on the injector wiring harness and prevents side pressure on the connectors, which can lead to poor connectivity. The shortest path with the most slack should be used.
Thanks LongDuck! Appreciate you taking time to read and look through my work here. I will definitely address those items you mentioned. I may have tracked down a sensor from a forum member but will see if I can fix the sensor. Since the sensor has been repaired once already I might be our of luck there.
Ok, New Air Temp Sensor installed, new fuel lines installed and made sure all bolts for the injector rail tightened.
First drive, when I first started it up and let it idle down, it settled at 1000rpm. As I went for a drive it was settling at 1500 RPMS. Not sure if it was related to the cruise control cable but I backed that off a bit in case that was binding causing the idle to be high.
Warm restart was good and has worked for me in multiple scenarios so far. Once cold or extended (over 4 hours) breaks, it does seem to flood (Leaking injectors??)
Exhaust seems to not smell nearly as bad but I have the full RB system so does no CAT exhaust smell fairly strong (assuming so)?
Yes, RB exhaust with no cats will make your eyes water in close proximity. You would be able to smell the fuel however, if its running overly rich. I'm still thinking you have a leaky i jector, but no way to tell without pulling them and sending them out again for testing. As mentioned before, I only have 2 in spec out of 6 that I have in my toolbox. Let me think on this some more and post back.
As far as the richness goes, it's much better. I wouldn't dare let it idle in my garage with the door open before. Now it smells but way less painful. Also the exhaust used to burble/poof on short revs but it's much smoother sounding now.
Anyone used on of these before?
http://mazdatrix.com/c-bleed.htm
So I started up the car today and it fired up no problem. Something I did notice is when revving the motor, the idle would settle fine around 1000rpm. When partial throttle was applied and held around 2000rpm, the rpm would float/surge very slightly.
TPS going bad?
Also does the burping sounds from the exhaust mean anything?
Showing signs of running rich. That idle is just fine - 1000rpm and rock solid like that is actually unusual for an -SE. Throttle response is excellent when you rev it, too. Having a slightly rich mixture will allow for good throttle response at the expense of economy because you have plenty of fuel for when the ignition advance kicks in. The burble on deceleration is somewhat normal (*esp. with a rich mixture), as the Air Pump starts to flow clean cool air into the exhaust ports on deceleration and the unburnt fuel will tend to suck that up and cause that burble as the fuel burns off. Also, it's heavily dependent on what exhaust you have on there; burble on decal rarely happens with factory 3-part Cats installed, because there's plenty of backpressure on decel to slow the existing exhaust gases. With a header and presilencer, there's very little backpressure to slow the exit of the clean air and exhaust.
That fuel injection pressure bleed thing is an interesting concept, but meant for 2nd & 3rd gen cars. What you might try doing is when you shut it off - pop the fuel door and remove the fuel cap. This will release the pressure in the tank and should eliminate pressure at the rail apart from where the pump is in the system. Certainly, it should allow for return fuel to flow, and reduce pressure at the injectors. Might give that a shot and see if it changes any of your symptoms. If it does, that may identify that you have a leaky injector (and you only have 2 to be concerned about...).
Was that a backfire at the 1:00min mark? Backfiring is obviously a sign of significantly rich mixture.
I'll try the fuel cap trick. I did smell a strong fuel smell after my drive yesterday. Didn't see any leaks after pulling the throttle body off? No drips or anything on the ground either.
I dunno about you, but it takes me at least 30min to remove the intake manifold to the point that I can get to the fuel rail and injectors and any excess gasoline from injector leaks would have evaporated by then.
Rich mixture (excessive) usually goes back to coolant and intake air temp sensor(s) being bad. Any of these multiple sensors are bad and the ECU thinks it's prudent to be in cold start mode with more fuel added via injector duty cycle. Not much else to be done except find the bad sensor and replace it.
Well...i just sent to warm it up and it sputtered like a misfire. Popped the hood and fuel was pouring on top of the block. How thr heck to i have a fuel leak after driving it into the garage with no issues? Good grief!!!
guess im pulling the intake off again and see what's up!
oh both sensors were replaced (intake and coolant). Is there another sensor im missing?
There are 2 Air Temp Sensors - one at the Air Flow Meter in front of the air door, and another at the base of the Dynamic Effect Intake chamber on the driver's side.
There are 3 Coolant Temp Sensors - one at the back of the Water Pump, one at the bottom of the Radiator, and one at the rear iron (IIRC...).
On your fuel pooling issue, I'll bet you just have a cracked Fuel Injection Hose from either the feed line or the return. This is an easy replacement once you pull the Upper Intake Manifold off. Be sure you're replacing it with FUEL INJECTION HOSE, which will be marked as such. If you use low-pressure hose for carb engines, they will split quickly and cause fuel to spray, sometimes leading to engine bay fires...
03-12-18, 10:38 AM
