95 3.1L Service Engine Soon

[MobyTruck]

Service Engine Soon light comes on after heavy acceleration and then letting off the gas (ie. climbing a hill and then coasting down the other side) or after driving at highway speeds for a few miles and then slowing down. Aftre the light comes on the car will stutter under acceleration. After the car is turned off and restarted, the problem goes away until the next hill. I took the car to a mechanic and they said the code was EGR malfunfunction...had them replace the EGR valve and the problem still happens. I'm not willing to soak a lot more money into the car due to it's value/age but if it's just a sensor I could replace myself then I would. The car has 82K miles on it and I did a tuneup at 60K (plugs, wires, etc) but have never replaced the O2 sensors. I'm only getting about 21mpg city so I think my mileage is pretty bad too. Any thoughts???

[spytearbite]

Yeah, that stumble sure sounds like a rich condition and you on the lift down the hill is just letting that vapor stick in the pipe is when you give it the gas, your reversion is all extra rich and there you go until the sensor... Now, get this, so you can get our mechanic to refund your money is he took a guess is not how you repair trouble codes.

There are other sensors tied-in and there is your search is why the EGR valve was not it or it would have solved the issue.

With that closed loop telemetry, you have all this wired into one junction box of grounds. These all add up to a closed loop as much as the fuel loop. So, when you have a no-spark condition, it can be tied to the ECM (obviously) to the cam sensor, to the crank sensor is a one time event on some of the components.

One time event is the last good know signal on the key off. The ECM now saved in RAM, the last good signal. Therefore you can start the car. Say the sensor took a crap? Then, you will run that car with that code and once that key is turned off and that sensor cannot reference that certain voltage in 10ths of a volt, then the RAM has an out of voltage value, the ECM sees that as a one time event and you had that event shut your car down is now a boat anchor until you repair the 3 basic variables is it wasn't the EGR, but say what is tied to the EGR is go back to the mech and it is technically a, "come-back"... That car was not fix right the first time.

Someone, not you... Needs to eat that job is get your money back and save that reputation of the shop is name that shop and never go there ever again, they do not care about your drive-abilty issue is 'Berk' yer azz.

[MobyTruck]

Thanks for the info...unfortunately the shop I took it to is no longer in business (big surprise eh?). They disappeared shortly after I took the car there and now I'm stuck with the leftovers. I understand (mostly) what you're talking about but I just don't have a good sense of how all the sensors work in conjunction with each other and how each one affects the next. What would be the next likely thing to check...TPS???

[Jrs3800]

Originally Posted by spytearbite

Yeah, that stumble sure sounds like a rich condition and you on the lift down the hill is just letting that vapor stick in the pipe is when you give it the gas, your reversion is all extra rich and there you go until the sensor... Now, get this, so you can get our mechanic to refund your money is he took a guess is not how you repair trouble codes.

There are other sensors tied-in and there is your search is why the EGR valve was not it or it would have solved the issue.

With that closed loop telemetry, you have all this wired into one junction box of grounds. These all add up to a closed loop as much as the fuel loop. So, when you have a no-spark condition, it can be tied to the ECM (obviously) to the cam sensor, to the crank sensor is a one time event on some of the components.

One time event is the last good know signal on the key off. The ECM now saved in RAM, the last good signal. Therefore you can start the car. Say the sensor took a crap? Then, you will run that car with that code and once that key is turned off and that sensor cannot reference that certain voltage in 10ths of a volt, then the RAM has an out of voltage value, the ECM sees that as a one time event and you had that event shut your car down is now a boat anchor until you repair the 3 basic variables is it wasn't the EGR, but say what is tied to the EGR is go back to the mech and it is technically a, "come-back"... That car was not fix right the first time.

Someone, not you... Needs to eat that job is get your money back and save that reputation of the shop is name that shop and never go there ever again, they do not care about your drive-abilty issue is 'Berk' yer azz.

How can you say this could be a rich condition? It could just as easily be a lean condition... and if the EGR is stuck open its very possible that it could be causing the stumble... Part of the question should be does this car have the Digital EGR or the Linear EGR..

If the Cam sesnor failed in this system the car would still run but it would not run in SFI mode as the PCM would have no clue what true cylinder #1 TDC is... Therfore the timing would be degraded to a set value, and the PCM would not be able run in SFI mode also dropping performance and MPG's..

On this engine wich is the Vin M 3100 V6, the rating for this is 21 City and 29 Hwy.... This car is right on target for City mileage..

The best thing to do is to get a real time scan of the PCM to see what its up to or what problems it may see with the various sensors... If you don't do this you are going to throw your money away trying to fix it..

On this engine a Miss could be anything from an injector, to a plug, to a plug wire, to a coil, to the ICM......... Or even a failing intake gasket...

And if the SES has been on more than once you could have some history codes... I'd pull the codes just to see what you have... Just because you replaced a part, that doesn't always make the part good...

[spytearbite]

Originally Posted by Jrs3800

How can you say this could be a rich condition? It could just as easily be a lean condition... and if the EGR is stuck open its very possible that it could be causing the stumble...

You need to look up the word, "digital" so you understand what a single signal is. Cars run under analog. Codes run under digital or electronic is depends on the lawyerage speak.
That is why I use either, fail-safe or backup meaning the same thing between factories using the same generic sensors for fuel injection.

So, when you run analog, you have that proportional throttle climb all lean and mean. But when a sensor fails, it codes to the digital signal and that runs under the 1Atmo or 14.7 atmospheres meaning the same value.

Open a shop manual and read the analog values. The lower the values, the richer in proportion. So if you WOT the throttle, you WATT the fatter fuel as the rise in rpm swing that proportion of voltage lowers and the fuel increases.

Now, since the code is set and usually fuel codes sorta run in the Pa, Pv, etc., as in the 1Atmo match read. Since the code safe-signals to a richer code, the telemetry or the engineers do not know when the code fails so say you are at WOT (wide open throttle), the sensor fails, are you going to tell me the car goes lean and stumbles or do you open the shop manual, read how 14.7 is a fuel trim in the 1Atmo or say 17:1 is cruise at low rpm, and now you accelerate and the engine goes lean is what you are saying?

If you WOT the throttle, what is the read at the WATT signal. Is it open loop or closed loop?

Moby? What the answer if he answers back at all is you better know this cold, Jrs. Sounds like you are stepping on the basics and yer feets are not smelling too sweet is did you work on, Moby's car?

[Jrs3800]

Originally Posted by spytearbite

You need to look up the word, "digital" so you understand what a single signal is. Cars run under analog. Codes run under digital or electronic is depends on the lawyerage speak.
That is why I use either, fail-safe or backup meaning the same thing between factories using the same generic sensors for fuel injection.

So, when you run analog, you have that proportional throttle climb all lean and mean. But when a sensor fails, it codes to the digital signal and that runs under the 1Atmo or 14.7 atmospheres meaning the same value.

Open a shop manual and read the analog values. The lower the values, the richer in proportion. So if you WOT the throttle, you WATT the fatter fuel as the rise in rpm swing that proportion of voltage lowers and the fuel increases.

Now, since the code is set and usually fuel codes sorta run in the Pa, Pv, etc., as in the 1Atmo match read. Since the code safe-signals to a richer code, the telemetry or the engineers do not know when the code fails so say you are at WOT (wide open throttle), the sensor fails, are you going to tell me the car goes lean and stumbles or do you open the shop manual, read how 14.7 is a fuel trim in the 1Atmo or say 17:1 is cruise at low rpm, and now you accelerate and the engine goes lean is what you are saying?

If you WOT the throttle, what is the read at the WATT signal. Is it open loop or closed loop?

Moby? What the answer if he answers back at all is you better know this cold, Jrs. Sounds like you are stepping on the basics and yer feets are not smelling too sweet is did you work on, Moby's car?

How about you explain that in English as I am not a Programmer...

And when I say Digital I mean a Digital EGR... This is the Shop Manual name for the EGR used on many 3.1 Vin T and 3.1 Vin M engines... But I am not 100% sure of the year change over when GM went to the Linear design...

If the EGR is open to any degree and the PCM is not calling on the EGR to be open, the MAF will not measure the added incoming flow and the PCM will not be able to calculate for this.... This alone can create a stumble...

I would still prefer that he had the car scanned for codes..

And I guess I am a total idiot as I do not speak PCM Language....

[BNaylor]

spytearbite,

...................

How about following proper forum etiquette and post in a language with less tech diatribe or gibberish so we all can understand. Try to keep it simple and understandable by the lay person to the best of your ability.

And please no personal attacks or insults upon members.

[spytearbite]

Originally Posted by Jrs3800

And I guess I am a total idiot as I do not speak PCM Language....

Well no, you are not. Maybe you never played with backup signals? Too rich? If the car defaults to a code, it is still drive-able, but more; it is in limp-mode is how you say it is running rich being who knows what temp it is. I have the water sensor not connected, so the ECM already knows what to do in the digital, not analog.

Now, they (GM) may send out all that tech speak, but we are more or less running two signals the fuel injectors can work with. One is the analog with no dash code. The other falls into the, "limp-mode" and this is a rich fat signal.

So, ask yourself if you can stumble on lean gas is no gas in makes it lean on your face lean, (the front end dives you add throttle). But this is not the case; since you need to recognize the 14.7 preset. The fuel cut goes rich say from analog 17:1 normal top gear, cruise the rest of the car's life in the lean analog.

There are 3 wire variables that fail: 1. Not connected connectors. 2. Wire out of connector hanging in the air. 3. Wire short to ground but not blowing fuses but short to ground as a resistor with a different electrical signal the ECM does not recognize.

Once you drop a signal, then the ECM codes to say, your generic preset in the digital it now reads a map in the (I will use the water temp peset), is the computer now reads: Tw = minus 30 degrees/Cen to plus/minus 120 degrees/Centigrade.

Now, go look up conversions from the generic 1Atmo are his buddies, Pv/Ta/Tw/Pa for all your water/air/pressure/temp sensors (not is said plasced in any order as in, respectively) for any sort of failure. Then the ECM is going to default to the 1Atmo (your code on the dash = A Pv. or a Ta, etc.); and you can ride your azz from NY to Cali in a default mode that will get you home or across the highway in a certain limp rich/ever so slight stumble mode.

Now, show me where you are reaching out for a lean stumble and I have shown you in the shop manual what to look for to exploit the analog and still keep running.

OK, you did not come back as I asked for your lean stumble is no gas to stumble with. So, have we established a rich stumble, or you gonna tell me we have no gas to save you going over 100mph of road rage and your sensor drops out...... Did you lean a piston, pull over the the side and you now rest your case?

Tell me I am a whack looking in the factory service manual and school your azz is school me? You better think again...


You are receiving very low tech to the high tech is please do not tell me how to work book theory is go and quote the book as per y0ur understanding. You will receive some basic steps is let the tech ride on my end is give me that 16th trophy password = Do not tell me how to teach what I know cold.

You show up at a race track, I will have a nasty tuned machine is just well tuned is all I bring to the table. Either you follow my abstract to the letter, or you read the shop manual and we will be on the same page is let it rude the ride is how you are treated is your ego is going to be on equal ground you start in on me.

I will never play it your way is why we are all in the confused state is this is very complex stuff and I will not bring myself down to your level is step up to my level and deal with how you are going to be trained to deal with tech and not with me is do not break concentration and get me involved with your personal table manors.

Either you act all grown up and leave the insults out or mirror it back at chew. I am all professional and now either skip over my text it is not for you but for the questioner asking for some diagnostics. It runs in the absolute and you start guessing is fine. You better walk your guess is if I come back and walk all over your lean condition.... Is that my fault I have to correct you is you think you are correcting me.

It is no wonder the car/bike/boat/plane industry is losing planes right off the runway. Now you have a new EGR with no shop to correct is I guess they lost their password to the garage is someone here stuck out in the cold with no help is pull my password

You will never change the physics is how do you expect to change me to your thinking. You see my point yet?

[BNaylor]

spytearbite,

Obviously you have a reading or comprehension issue. Just what part of the warning issued to you do you not understand? It you continue to post what appears to be irrelevant garbage and/or continue to attack or insult other members then I will have to take measures to bring you into compliance. This is your last warning.

Originally Posted by BNaylor

spytearbite,

...................

How about following proper forum etiquette and post in a language with less tech diatribe or gibberish so we all can understand. Try to keep it simple and understandable by the lay person to the best of your ability.

And please no personal attacks or insults upon members.

[HotZ28]

Spytearbite, I am not trying to be sarcastic here but, who are you; Cheech, or Chong? (90120)

I have not seen anything in your previous post where you offer a definitive approach to solving the OP’s problem. Until you come up with a solution, don’t waste any more of our time and bandwidth with your meaningless philosophy of how the PCM and sensors communicate! If it is possible for you; try to offer at least one simple solution to the OP that is understandable! In addition, do not ignore the previous warnings of Moderators, or you’re posting rights and membership will be terminated!

BTW, if you don’t mind coming down to earth long enough to post a pic of that “1962 Citation” (the one you say you own, in your profile), I would love to see it. I did own a 1981 X-11 Citation, so I am familiar with how they looked in the 80’s, but I have never seen a 1962! The Citation was released in April 1979 as an early 1980 model and continued production until 1985, at which time production ceased, due to declining sales.

[HotZ28]

Well, I guess I will not get to see a pic of the mysterious "1962 Chevrolet Citation" since this dude was banned from participation on AF! If you ever come back, be sure to post it!