And I am not saying that you are wrong. However, you cannot start with a "given" as a premise, and develop a theory, USING that given to prove the "given" to be false. By definition, a "given" HAS to be true and cannot be reversed or negated in the same discussion for which it was defined as a "given". Reread my last post.



Fine, but you cannot use the assumption that the O2 is good, to prove it's bad. If the discussion starts with the O2 being good by definition, then THAT discussion can't prove that it isn't good. Am I not getting through, here?

RACE ON!!!

 

Hi, I just came from Napa & Chevy.
A nice mech. at chevy removed my prom for me & we discused the car for a while.
When I told him it was a cross fire ,he was like "your working then arent ya?"
He knows theyre a nightmare of electricle grimlins.
Anyway he also had MAP questions ,voltage , & ohms, that I couldnt answer.
From the parts guy I found out there is a different prom listed as the correct part #,not the same # on my prom.
They use the same computer remanufacturing place & they are $20 higher.
So I ordered a computer from Napa its in Mephis so will take a couple days to get here.
In the meen time Im gonna try & get those Map readings.

More latter . Thanks all.

 

Let us know how it goes when you get it. And for the record-NO ONE has impressed me more than CFI-EFI when it comes to trouble shooting the problem, plus he has a wealth of knowledge-my hats off to you-even though you're not the most tactful communicator and wait til you read my next post

 

By definition an "assumption" cannot be taken as a "given". You have to porve something is so before you can claim it is a given and I never stated that the O2 being good was a "given"







Yes you can, this method is used every day in the scientific world to prove or disprove a theory when the results are not known. The results from this test is what is then used as a "given" eg. "assumption" Energy = Mass. this is the assumption that Einstine started with when he observed that a bigger log in the fireplace gave more energy to heat his house (read " Einstein the young man"). He then set out to prove it and discovered that E=MCC. Now everyone takes as a given that E=MCC is a "given"

You and I have two distinctly different styles, you just tell people they are wrong, I tend to take the theory put forward by others and argue my point in detail to show why I think they are wrong, I am also qiock to own when I have given bad information, I don't think I have in this instance.
I respect both styles as well as your knowledge.
No offence taken.

At any rate, he has ordered the new ECM so we will soon know if the ECM is the problem.

On another topis, thanks for the tip on posting, with your help it looks like I have mastered it.

 

Ive kept all my reciepts on this car.
I just went thru them to see if I had replaced the MAP, & yes I replaced the MAP in feb. 2002.With a new connector.
But I also noticed Ive put numerous O2 sensors on it.4 or more since 1999.
The car has always run like this.
So I think we can rule out the O2 sensor.

 

On the cover of the old computer it says when installing it.
All sensors & relays have to be ohms tested for not more than 20 ohms each or it voids the warranty.
There are so many sensors & relays I think thats asking a bit much.
How would you guys handle this part of the issue?
Thanks

 

Then please tell me what you meant when you said:I took that to mean for the purposes of those few paragraphs the O2 was, by definition, good. You used the word, "assume". If in that context you weren't making it a "given", what was your point?



If someone makes a misstatement of fact, like, low oil pressure will kill power to the fuel pump, I will say he is wrong. I have not said that you are wrong about the O2 being bad. I am not arguing that it can't be the O2. What I AM saying. is that *I* think some of your reasoning is not without fault.

RACE ON!!!

 

Am I not getting through to you here? My point was that others ( including myself at first) were pointing to the MAP as the culprit here because this could account for the rich mixture inside the cylinders.
I simply took the time to explain why the MAP could not be the sole culprit as, if it were the case that the MAP was causing the rich condition, the O2 sensor would compensate for it IF the O2 sensor was working.
The MAP would be telling the ECM to fatten up the fuel and a properly working O2 would tell the ECM to pull it back out.

And further, if the MAP is reporting to the ECM that there is a WOT condition because of a vacium leak or faulty MAP, the TPS will report that there is no WOT and this conflicting information will cause the ECM to throw a code.

My reasoning is not at fault simply because you misinterpet my correct use of the word "assume" and assumed I ment something else like "given".

Perhaps the new ECM will cure the problem and it is a case of the ECM thought it saw what was not there, or a bad ECM that was incapable of throwing a code.

No need to defend your style, I actually like it, and in the case quoted you were absolutely right.

 

I know that I will get shot down for saying this, but I changed one for a friend and one on my car and I simply ignored it and plugged in the new one, after swapping the chip, with no adverse effects.
Not necessarily "good" advice but the truth.

Perhaps someone on the forum has a quick method of checking them. If they do it would be information worth me saving to the Tech Tips.

Dont forget to write down the information from the tag on the old one onto the new one.

On another note, the fact that you changed 4 O2 sensors since 1999 does not mean that they did not need changing.
If they temporarely fixed the problem each time this would point to something contiminating the O2 sensor and knocking them out that needs to be fixed like oil or coolant seeping onto the cylinders and contaminating the O2 sensor.

Hope this helps.

 

I get it. You think the O2 is bad, and you give some pretty compelling reasons. I am not arguing that you are wrong. At this point I am just not convinced it is the O2, for sure. It is *I* that am not getting through to YOU about stating a "given" and revoking it mid discussion.




I agree with that statement, but so far it appears that codes being generated aren't being displayed. Like the tree falling in the forest when no one is there, if a code can't be retrieved and read, does it exist?

A point I haven't seen you take into account is one of a lean mixture at the O2, while the mixture in the cylinder is pig rich. The O2 sends the lean info and the ECM pours the juice to it to try to fix it. If the mixture at the O2 remains lean, due to false air, as an example, the ECM doesn't know to change anything.

To be continued in the AM.

RACE ON!!!

 

I agree with you that any O2 sensor could be contaminated immediatly after being installed. So that means that the new O2 sensor could be dead as you state. What I see you dancing around is the fact that 7thvet has reported testing the MAP and vacuum and they are in factory spec, yet the ECM says different. This is a tested component and a KNOWN error by the ECM. Why? Why do you not address this.

IF this is due to an ECM problem it would possibly also explain the reason the ECM is reporting a lean condition signal from the O2 sensor, when we know by observation that the lean condition is not true. Without knowing about the MAP vacuum error I would ordinarily agree with you about the O2 sensor being the more likely cuprit versus the ECM, but when you add in the problem with the MAP vacuum value it causes me to reassess and assign more weight to a probable ECM issue.

7thvet specifically reports using a scan tool which showed two sensor conditions not in agreement with the real world results as tested and observed. Both values from two different sensors, one on the intake side, one on the exhaust side, are reported by the ECM and are in error. Additionally, the ECM reports NO CODES for either sensor. It has set the SES light while being scanned without reporting a code which is another error according to the FSM. Three issues or four issues. When added together they point in the direction of the one central component. ECM or its connection.

If cost was the only basis and he was swapping parts in a desperate attempt to solve the problem without testing I would agree. However, he has had the facility to test, as he has posted in the beginning that he used a scan tool. He has also physically tested the vacuum, found it to be at factory spec., and found that the ECM reports an incorrect value for which it has set no code. 7thvet has done the testing.

You still say it is the O2 sensor that should be replaced. Why do again what he has already done 4 times in the last 5 years with no improvement? Why dance around the obvious known discrepencies reported by the scan tool used by his mechanic friend?

 

totally, I kinda came to that conclusion because of my latest
ordeal-which ALMOST lead me to a conclusion the ECM was the culprit,
in my case it wasn't-but from the post I had posted regarding symptoms it's easy to see you can chase and replace parts you suspect are bad-I mean if the computer points you to the 02 sensor-what kinda test are you going to perform on the 02 sensor? If I was constantly replacing 02s I think I'd be looking for the cause elsewhere, and since the scan and the computer are not in sync-I'm not gonna bet the farm-but it sure looks to-or seems like the likely candidate in 7thvets situation is the ECM has lost its ability to function
properly-whether through corrosion, lose conections or whatever.
Now that he's ordered it-we shall see.

Hey 7thvet, although I might be tempted to ohm the sensors-I doubt
in all honesty I would.I mean give me a break.

 

Thanks again.
I can add that none of the O2 sensors ever helped, not even for a little while.
Same as this last one, no difference.
But thats what code I used to get,44, years ago when I was replaceing them alot.
Thats what all mechs. say right off the bat.Its kinda the first part you get when you resort to throwing money away.
Its just got to be the computer after all the parts Ive tried.
I can ohm some of the easy ones.
The temp sendor the map, the the tps.Its new also.
I think Ive replaced every sendor on this thing.But Ive always been reluctant to go after the computer.
I hope it fixes it.
Thanks again.

 

With this added information, I too need to back off the O2 sensor.
As you have replaced all of the related sensors the lean report on the scanner has to be the ECM or the O2 circuit. Throw in the MAP signal difference and it sure looks like the problem is the computer.

However he eliminated the false air in his first post.

Based on the above fact that the new O2 sensors did NOT make a temporary difference in the past I agree with CFI-EFI, Rick, Mike and everyone else who said that the likely culprit is the ECM. I WAS WRONG.

I am so sorry I shot the O2 sensor, I hope I have not buried him yet and that his family is not taking this the wrong way.

 

Jerris, no need to appologize, in your defense the 02 sensor certainly would be the likely candidate, and without knowing his history of replacing so many in such a relatively short period of time (although I have a low opinion of the quality of 02 sensors available) it would have been where I ended up-but given the conflicting tests it seems (and this isn't proven yet either) that the ECM now certainly stands out as having a communication problem.

 

But I said, "due to false air, as an example, the ECM doesn't know to change anything." I didn't take the time to figure out what other inputs might keep the ECM seeing lean, when it wasn't. Maybe there are none, but I hate to close my eyes to that possibility, yet.



You only agree with me, if you still have an open mind. I never was convinced, thoroughly, of the cause. Personally, I think the, "I WAS WRONG" card is premature. While it may be true, the jury is still out.

RACE ON!!!

 

If you are in doubt and have the time, I'd ohm out the MAP sensor and TPS at the least. The coolant temp sensor is going to be more than 20 ohms right off the bat, its ohm reading is dependant on temp, also the same for the MAT sensor. Relays? Yeah right, too many of them to fool with.

 

rick has nailed it. We have nothing that absolutely proves it is the ECM, but all indicators appear to point in its direction. It is particularly important to keep in mind that the ECM itself might actually be good, with the real culprit being the connections to the ECM. A perfectly good ECM cannot tell it is being mislead if the connection from the O2 or MAP sensors are corroded enough to affect the incoming voltage levels, but not enough to throw them off enough to set a code. I think two important tests are to check for resistance from the ECM O2 connector terminal to the O2 Sensor wire. The same is true especially in the case of the MAP sensor because unlike the O2 sensor where we know it is rich but have no known specific value for the mixture, we KNOW the physical vacuum value and we KNOW it is at factory spec. Just like algebra you use the knowns to eliminate the unknowns.

7thvet has mentioned that there was noticable corrosion and appearent user activity at the ECM connector. If the connectors are in bad shape it is unlikely but still possible that the data to the scan tool from the ECM was not accurate. Based upon the fact that 7thvet has had use of a scan tool and the ECM did not report a code, yet was able to set the SES light, I lean toward the idea that swapping in a known good ECM is cost positive. Testing the connection to the MAP and O2 sensors does not rule out wiring issues in all of the connections to the ECM, but it would definately point a bigger finger at a bad ECM if they are completely good. If those two tests show no problem in the wiring to the two sensors, I feel that a new ECM was money well spent.

 

Jerris, I hope that I have not come across as rude, for I truely feel that you arguments for the culprit being the O2 sensor were reasonable and logical. As I have stated in previous posts, given no other info I would have agreed with you wholeheartedly, so I feel that you have provided excellent feedback and made me really evaluate my position at every step. As you say, it is a lot cheaper to replace an O2 senor than an ECM.

What also has not been addressed is the possiblity that the mem-cal is faulty. Wen we say ECM I think most assume the ECM and mem-call (prom) chip are one component, but they are not. Here is recent new information that bothers me:
This is not necessarily bad, but it certainly isn't good in my book. If the wrong prom or a shorted/defective prom is used in a good ECM it will not solve the problem and 7thvet will have bought a new ECM for nought. The correct prom is CRITICAL.

ECMs are generic to a model year or several model years, but proms are programmed specifcly to model year and transmission type. An 88 auto prom will not be correct in an 88 manual tranny car, whereas the ECMs are the same.

7thvet, The correct properly installed PROM must be used!

 

A reconditioned ECC is $70, from Napa. $100 from chevy.
The prom from chevy is $60.Napa couldnt get that perticular one.
A O2 sensor from chevy is $60, & $35 from Napa.
I want to try my prom in the Napa.
I dont want to wait for chevy to get that prom.
Money isnt that tight , but I know you guys dont want me to spend it.Thats why I didnt opt for next day air.
Thanks for your concern.
Thanks everyone.
We'll all know tommorrow at about 5pm.