420A 2GNT P0455 P0172 faults

[Red97GS]

97 eclipse original owner. 270,000 miles. Running incredibly rich. Mods are cai and egr delete . These were done years ago and car was running fine.sensors all new and all harness pigtails checked. The only one that is confusing me is the map sensor 5v reference that jumps around between 4.5 and 5.02 volts with just the key turned on. Compression 200 205 205 200

 

[delta448]

Stock MAP sensor? If so, you should check the signal voltage at idle with vacuum being pulled on it. I'm not really familiar with the 420A logic, but I think the factory MAP was never meant to see positive relative pressure. Without the engine running, at atmospheric pressure it makes sense to me that the sensor would report max voltage.

 

[Red97GS]

Thank you for the quick reply. Yes it's a new oem map. But I'm referring to the 5v reference signal through the pigtail. It's changing voltage without the engine running and just the key turned to the on position. I am having a rough idle with fuel trims showing -20 ltft and stft -3 using my scanner .

 

[Red97GS]

Ok so I checked the 5v ref at idle and it was constant 5 .02v. However the signal wire back to the ecu is fluctuating at idle causing fluctuation that seems to correspond to the minor searching the idle is doing between 600 and 900rpm. Been trying to run this down for a year and local mechanics act like just saw a ghost when I pull in. The newer shop scanners won't communicate with my ecu.

 

[delta448]

Does it change when the engine is running? Back probe the connector at idle?

Could the voltage fluctuation be due to power being drawn intermittently from the same source for a separate function? -I would expect a more stable reading with the alternator spinning.

Pull the battery terminal or whatever you do to reset the DTCs and check the O2 sensor voltage at idle. If it's not swinging rapidly between 0.2V and 0.8V, you either have a mechanical problem resulting in a rich mix, or (much more likely) the O2 sensor is dead.

My money's on the O2 sensor.

 

[Red97GS]

Yes I checked the map output with the engine just at idle using a backprobe and for some reason it's not a steady reading. Its almost like the manifold pressure is changing without the trrottle being moved. I will reset the codes and look to see what o2 sensor is doing . It's a fairly new denso unit . I have a screenshot of the map reading at idle on a graph format. If I can figure out how to post it .Thank you

 

[Red97GS]

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this is what the map is reading at idle warm

 

[delta448]

That looks good to me. Intake valves opening can account for the spikes, especially if the scanner refresh is slow. What's the deal with the axis labeling? Is it the scanner or the ECU reporting the values as positive pressure?

In your other thread you mentioned that you smoke tested the intake. Did you do that after the EGR delete? A vacuum leak can definitely cause these symptoms.

And base fuel pressure was measured at 50psi through the service port on the rail?

I also assume that the front O2 sensor has now been verified working properly?

 

[Red97GS]

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here is the front o2 sensor after warm up. And etc reset. At idle. Smoke test done recently. Mods done about 4years ago.this problem was a fine one day and bad the next issue. Fuel checked at the service port. Injectors replaced 2years ago but they are remains from ebay ( yea I learned that lesson by now) . I think that is the scanner format psi up the left and time elapse across the bottom.

 

[Red97GS]

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this is what I'm getting at highway speeds

 

[delta448]

Everything checks out there.

Since they're not original, how sure are you of the flow rate of the injectors?

 

[Red97GS]

I am not sure. However I did listen to them with a stethoscope and they are all at least firing without skips. If injector flow rate is too large this could be why the way is having to max lean the af ratio?I'll order some new ones from a reputable parts house and get them brand new and take them to get them tested before changing them out. Might take a couple weeks to get it done. I'll repost after its done. Thank you

 

[Red97GS]

1. Question concerning fuel injectors. I'm seeing them online listed with 4 holes as an upgrade from the oem 2hole . I don't see any afternarket 2 hole injector. Are 4 hole acceptable? Also could the thep0455 canister gross leak be contributing to the issue? This is a fairly recent code that has pooped up. Thanks. Btw I must have touched a button on the font midstream.

 

[Red97GS]

Did I ask an invalid question in the previous post?

 

[delta448]

Not sure I understand everything you wrote there.
Number of holes in the tip doesn't really matter. Only flow rate. If your car had 190cc/min injectors from the factory and you drop in even 230cc/min, you're looking at 20% more fuel than the ECU expects each time they fire.

The canister code is probably not a factor if it is more recent. That gross leak code gets thrown when the EVAP purge valve opens and the ECU doesn't see any enrichment at the O2 sensor.

I cannot decipher your last sentence in post 13.

 

[Red97GS]

I was referring to the slant on the letters changed midpost. Got brand new injectors and had them flow tested. From what I am reading ,factory flow rate is 230 cc/ min and thats what these tested . I am also getting an egr failure code. Would this cause the ecu to alter anything even though there is no egr?

 

[Red97GS]

Ok had entire intake removed , cleaned , new gaskets and injectors. Found a vacuum leak on a nipple at the vacuum box . At idle in closed loop ltft is now at negative 9. Idle still searching ,but not as often or as rangey. The roughness is less but norideable. Codes 0401 and 0442 . Thanks also now am seeing idle smooth out when cooling fan kicks on?