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Closed loop


Danteval1
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Im attempting to fix my 1989 Reatta's issue with MPG. Every week, im getting a little bit closer to the resolution. Today, i began reviewing the CRT and went into diagnostic mode. I let the car warm up, went for a drive, and discovered that the Reatta will not enter a closed loop. Right now, i'm averaging 15.5 MPG.  Anyone know the diagnostic procedure for this? Everytime I lookthis up O2 sensor comes up and I want deeper knowledge. . 

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Im only getting B codes. Low AC and missing IPC. My IPC is fried. I ordered a new one from Jim and should be expecting one soon. I'm going to replace the 02 sensor with a Bosch 12014. I dont like my mpg. Its lazy to leave it as is and bad for the environment (well all have to pitch in). Any suggestions on closing the loop will help.

 

Ill update this thread if I resolve the issue. 

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Welcome to the forums.

When you get it running good MPG on CRT should average in 25 MPG range mixed driving. I have gotten over 30 mpg on long highway runs. It takes a couple of tanks for the average to come up from driving. It not an instant MPG system. I am not sure if it uses the in tank fuel level for any of the calculations. My sending unit is bad but MPG averages work the same as before it went bad.

 

I hope you get it sorted soon.

 

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Cam sensor has nothing to do with closed loop and as I mentioned in a previous post, the cam sensor is not necessary at all for running of the engine. The addition of the cam sensor to the 3800 may help engine smoothness at low speed and possibly a small efficiency for emissions but there are lots of non synchronized injected cars running around out there that operate perfectly well. The little brother of the 3800, the 3300 in tons of granny Buick Centuries of the early 90's, all the hundreds of thousand V6 Ford Taurus'es of the similar time period are batch fired injectors.

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5 hours ago, 2seater said:

Cam sensor has nothing to do with closed loop and as I mentioned in a previous post, the cam sensor is not necessary at all for running of the engine. The addition of the cam sensor to the 3800 may help engine smoothness at low speed and possibly a small efficiency for emissions but there are lots of non synchronized injected cars running around out there that operate perfectly well. The little brother of the 3800, the 3300 in tons of granny Buick Centuries of the early 90's, all the hundreds of thousand V6 Ford Taurus'es of the similar time period are batch fired injectors.

My reatta has the cam sensor fault E041 code and I just calculated my mileage as 22.5 mpg. That is mostly city driving.  So I can't immagine the cam sensor is the root cause if he's getting 15mpg.

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My operating temperature is 190 F when I check the loop. I just replaced my O2 sensor with a bosch and I cleaned the IAC. My idle went between 650 to 1100 as it warmed up but it stabilized out at 675 give or take 25 rpm. I imagine it was burning off the remaining carb cleaner. It runs much smoother and idles at about 50 RPM less. Maybe ill just replace the cam sensor and magnet just to see if that helps. Anyone else have any issues on why I cant enter a closed loop? 

 

11 hours ago, Barney Eaton said:

I'm pretty sure if the cam sensor is malfunctioning it will not go into closed loop.

As discussed in another post,  it is a know problem for the plastic retainer for the cam magnet to fail....the magnet falls out and the

sensor does not get triggered.

 

Are the sensors ran on a a type circuit to close the loop? I mean, by definition, a circuit means closed loop, so it makes me wonder if there is a connection, I feel like im reaching with that thought lol. 

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this may be a dumb question, but have you verified that the fuel economy is bad? I mean if you fill the tank reset the trip meter, drive some, refill and calculate based off how many gallons go back in, does that roughly coincide with the mpg reported? Maybe there is a problem with whatever sensor measures the MPG.

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a) if the cam sensor/magnet you will get a code 41.

b) on a cold start there is about a two minute timer before closed loop to give the O2 sensor time to warm up to operating temp (around 600F). Modern cars have heated sensors.

c) Cross counts ED18 will show if O2 sensor is working. Should be low at idle and at least 6 when driving. ED07 will tell you if stuck.

 

I use a laptop to look at several parameters at once.

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