No 17 is correct.See ittlflys post.
I will check your post.
Ive been thinking.I hate to throw more variables in the equation.But I dont know for sure if they left that hose off or it pulled off so easy I couldnt tell.
I was at witts end & took it to a shop 2 weeks ago.
They said my oil was full of gas, so that again proves its getting to much gas.They also said change plugs & O2 ,which I did.
It failed emmissions worse than before I took it to them.I took it back & they wanted to charge me again because I put the parts on. They wanted $200 to put the O2,plugs,& oil change.
Anyway fk them.
Im sure were gonna figure it out soon.
I cant say for sure whether the hose was connected or just came off easy.
So Im all fkd up.

 

Read the post-it MAY solve your headaches. Once you read it-it may sound extremely familiar. RICH AS A PIG !
BTW, it's on page 2 now.

 

this one?
What were your symptoms when ECM went bad?
Read it thanks, yes things are pointing to the puter.
I still want to clean the connections.
Im also interested in checking for grounds.

 

Hi fellas,

My 92 vert with 120,000 miles was running lean because the head gasket was leaking slightly on the drivers side head and coolant/oil was getting into my exhaust. My 02 sensors were getting clogged up with oil and soot causing them to go bad and hence giving me a lean condition. I took my heads off and changed the gaskets; had the heads cleaned and put them back on. After that I changed both 02 sensors and the fuel filter again. Now my vette doesn't hesitate and goes all the way up to 5700 RPM with no stalling or hitting a wall. It's great. I also notice while I was changing my fuel filter that someone had pushed in one of the fuel lines with a jack near the rear tire. I squeezed it with some vice grips and opened that line up some. That may have helped. My plugs had black oil on them too before I changed the head gaskets. If yours has high miles I bet that is your problem too. The oil is coming through that gasket and fouling out your plugs. Hope this helps. Brad

 

Jerris isn't the only one that expressed concern over the scan tool vacuum reading and the vacuum gauge reading being different. Di you still have access to that scan tool? If not, check the voltage output from the MAP with and without the Thermac vacuum hose connected. That could tell you if it was disconnected and if or not it had any effect on the scan tool reading. Make sure the vacuum hose to the MAP doesn't have any cracks or leaks in it. A false MAP reading will trigger a bad A/F mixture. I have seen MAP hoses that had a flap of rubber come loose inside and cause a partial blockage.

RACE ON!!!

 

Thanks CFI-EFI.
You know, that hose looks weathered,kinda flimsy. I will replace it.
What should the MAP output voltage read.
Yes after I fix these couple things Im going back,to see if the O2 is still reading lean all the time & then disconnect the cat & try again, to see if cats clogged.
Thanks all.

 

The point is to see if the MAP output changes with the Thermac connected and disconnected. The MAP output voltages are approximate and listed in your FSM, based on your altitude.

RACE ON!!!

 

Once again I agree 100% with the facts as you state them, however these fact do not explain the present situation if we assume the O2 sensor is good and functioning properly.

If the MAP is giving a bad reading it can cause the ECM to fatten up the fuel curve resulting in a rich mixture within the cylinders.

Now here is the kicker, if the O2 sensor is working properly it should:

1 Send a signal to the scanner that the exhaust casses are running rich. - it is NOT, the scanner clearly shows that the O2 signal is of a LEAN condition in the exhaust gas.

2. If the O2 is working correctly and sending the correct RICH signal to the ECM, because of the MAP, the ECM will compensate by leaning out the fuel curve and putting LESS gas into the cylinder. - We have the opposite situation happening, the O2 is telling the ECM that the exhaust is lean and the ECM is adding more gas in the cylinders which should make a properly functioning O2 sensor report a rich mixture, and in turn the ECM should pull fuel. This is not happening.

Everything I have read in this post points to one of 3 things.

1. The O2 sensor is dead but reading within the parameters although lean.

2. The circuit from the O2 to the ECM is compromising the signal from the O2. Check the pigtail connection.

3. A bad ECM. - I have this as the least likely as the ECM is not throwing any codes, unless it is stuck in a lean condition that is within the parameters set by the factory. If we assume a bad MAP, the ECM is working properly and fattening the fuel curve, if the O2 is good why don't the ECM pull back fuel it added to compensate.

Because of the O2 lean reading, I do not think the MAP is the culprit here. There could be something like a vacium leak at the MAP causing some of the rich mixture within the cylinder, it does not explain why the O2 insist that the exhaust gasses are lean. The lean message to the ECM in itself is a far more likely explanation for the extra fuel in the cylinders when the ECM fattens up the mixture.

The more I think about this the more I think he needs a bigger gun to shoot the messenger that is delivering false information, if the pigtail connection is clean.

 

Did my test of disconnecting the vacume & the voltage to the MAP,like I said in the update post, prove anything? Is it good?
I disconnected the vacume at the injector & the engine responded negatively.Doesnt that mean its working?
The O2 sensor is new.
I will double check & clean the O2 connector.
If it was a bad connection would it read lean?
Also the black connectoron the computer looks like it needs cleaning.

 

Not completely accurate. The scanner clearly shows that the ECM thinks that the O2 signal is of a LEAN condition in the exhaust gas. The scanner he mentioned that they are using is not connected directly to the O2 sensor. It reports what the ECM says it thinks it sees coming from the O2 sensor. Obviously one or the other is at fault, or the connection is bad.

Again, the O2 sensor is not necesarily telling the ECM that the exhaust is lean. The scan tool is reporting that the ECM thinks that the O2 signal is of a LEAN condition in the exhaust gas. I do agree that obviously either the O2 sensor or the ECM is at fault, or the connection between them is bad.


A) The FSM says the ECM SHOULD be setting a code if it has turned on the SES light. According to 7thvet, the ECM was actively being scanned when it turned on the SES light but no code was observed by the scan tool. For the ECM that is not factory spec.

B) The scan tool reports the ECM value as being off by a 5psi difference between actual tested MAP vacuum and what the ECM reports. The tested vacuum is accurate and factory spec. but the ECM value does not match. The ECM reading is a known wrong. Why? Is this the fault of the MAP sensor or the ECM? How can a bad O2 sensor play any part in this issue?

C) The O2 sensor if completely dead, grounded, or shorted, will set a code. That is factory spec and as 7thvet and jerris both noted, it has not happened. The O2 sensor is new so we are not unjustified in assuming that it is working correctly. The ECM reports that it sees the O2 sensor sending a contsant LEAN signal when the car is running PIG RICH. Again not factory spec. for a working O2 sensor. Either it is the O2 sensor circuit or the ECM.

Now, what is the ONE single thing all three above issues have in common? Either the ECM is defective or the electrical connectors to the ECM have a problem.

Gee, do you think that might affect the values that the ECM thinks it is seeing from the MAP and O2 sensor? It is the corrosion at the connector affecting the ECM and its readings from the vehicle sensors, or the ECM is defective.

 

I will be cleaning the O2 sensor connection & the computer connections today,I will get back with everyone this evening.
Thanks so much for narrowing this down.I know how much thought it takes as Ive help a few people with wireing issuses before.

 

I think you're on the right track. Funny, the ECM symptoms post responses gets your mind thinking. If the ECM has corroded connections
or in fact has went south, its simply lost it's ability to communicate. You may experience every code in the book, a digi display problem, a hickup in performance-or a car running pig rich without any codes being set. The more I learn here-the less I realize I know. You seem to be on track with your trouble shooting-and that's good I'm
still thinking about your vacumn issue, because I think you should be seeing more like 20#-but I know you'll double check that.Good luck and please let us know.

 

I posted the same problem in "On Board Computer Error Code" I am getting Code # 44 - Left Bank Oxygen Sensor Lean". This started yesterday - I noticed that the engine was running rough, Black soot (sic) at the exhaust tips. I thought well she hasn't been driven for awhile let her warm up - then the SES light came on - as soon as that happend I could hear a change in the engine, it got smoother as though the ECM was compensating for the lean condition. Then the SES light would go out, under acceleration it would seem to be running ok, but then at a stop light it was idleing rough again. SES light would come back on. Got home plugged in the OBD I/II reader and got the Error Code 44.

 

I got to work on it for alittle while this morning.
I cleaned every computer terminal.I found a dremel tool grinder that fit between the pins perfectly.
I didnt use the dremel I just hand turned the bit.
I also cleaned the O2 sensor connection, It looked fine though.
The computer terminals were slight corrosion. When I put magnifying glasses on I didnt see any green corrrosion but I did see sort of a white film on them.
As I said the computer already has been replaced before I owned the car.
Ive had it since 99.
I can see where someone has been scratching away at the terminals before.
Anyway, after cleaning all the above mentioned things.
I start the car & it runs crappy rich like always.
The only difference is now it sets the check engine light as soon as the engine fires.
It never did that before, ever.
So I turn it off check for codes ,none.
Tried it again.
Still no codes.
Im thinking about getting a computer this afternoon.
Do you guys think its time.
Im considering a NAPA one because they willl work with me if theres a problem.
What do you guys think?
Also can I get the prom out without the special tool?
Ya know I might run that computer up to chevy & see if they know if thats the latest updated prom.Because that scan tool said to check for that.
Sorry so long winded.
Thanks again.

 

It sounds like an intermittant code like in the wiring somewhere. As for the computer that's your call. If you have narrowed everything down and all points to it then do it. The are really not that much less than $100. If you do and it turns out to be the problem, let us know.

 

Irish-yours sounds like a bad 02 sensor, but you need to check fuel pressure. 7thvet, I too am thinking MY problem might be ECM, I've got one more thing to check temp sensor, then I'm going the ECM route-through NAPPA. Although they say you need the prom tool, at that point I will look at it-but if-when I get a new ECM, I'm gonna ask NAPPA
if they can R&R the prom. TWO things though-I thought I read something about getting rid of a static charge, and make sure you pay attention to how the prom goes in.Let us know.

 

First, please, don't anyone think I am saying the problem is this and that it can't be that. I am simply discussing the possibilities.

If for the sake of discussion we accept the above, you end up switching horses in midstream (paragraphs 1 & 2.). You start out based on on the premise that the O2 is good, "if we assume the O2 sensor is good and functioning properly", and that the rich mixture problem is caused by the MAP, but in the numbered paragraphs you shift the blame to, the for the sake of discussion, the assumed good O2.

You should decide which side of the point you care to discuss and not switch sides without announcing it. You cannot use an assumed position to disprove itself.




I agree with most of these three points. At the end of #3. the reading from the O2 may not be the only criteria the ECM uses to establish the A/F mixture. The MAP reading MAY be the intervening factor.




While I agree this is likely, we have to determine WHY the O2 is reading (and reporting) lean.




Innocent until proved guilty. Not until it is proved the information is false. Then, as Jerris says, "he needs a bigger gun to shoot the messenger that is delivering false information".

Here's some food for thought. The scanner didn't show any O2 activity, right? Is this S.O.B. even running in closed loop? Maybe the ECT sensor is telling the ECM the engine is dead cold, and the ECM is sending a rich, choke-like mixture. Until the temps come up the ECM doesn't "see" the O2, and the scanner is reading what the ECM "sees".

RACE ON!!!

 

It goes into closed loop shortly after take off.
About 1/2 mile, I can feel it happen, the car has a momentary pause.
Also when we had it on the scanner ,while idleing, it thru the code & the engine rpm changed.
So its changing loops.

 

Now that the check engine light is comming on right after startup. It may not be going into closed loop.
I havent taken it for a ride to find out.

 

For clarity let me say one thing I THINK THE O2 SENSOR IS ALREADY DEAD and shooting it will be painless. That is the horse I rode in on and I am still on it.

I only explored the hypothesis that we assume the O2 is good because others have replied that they thought it was Ok and the problem is elsewhere.

If you read my arguments, the assumptions are put forward to DISPROVE that the O2 is good and functioning properly and that the circuit is good, NOT to PROVE it.

Yes I do assume that the engine is running at operating temperature and that it is in closed loop as he had a mechanic connect a scanner to it ( I could be wrong ) and that the the O2 sensor signal voltage is close to, but not below 200 mV as a reason for the ECM to read lean and NOT throw any codes.

As I have stated before, the MAP sensor could be responsible for the rich mixture in the cylinders, although it requires a properly functioning ECM to fatten up the fuel to the WOT settings, due to a low vacium reading, however so could a bad O2 sensor and if the O2 sensor was functioning properly, the ECM would record this rich mixture, compensate for it and throw a code. The only way the ECM knows that there is a rich mixture is if the O2 sensor tells it.
I think the ECM is telling the scanner what it sees, not what it thinks it sees.

I have no idea why others are dancing around these symptoms that point to the O2 as if they are on Dancing With The Stars.
It is almost as if no one ever found an O2 sensor that has gone bad or a new one that has gotten contaminated shortly after installation.

I am saying that if it was my cas and I had narrowed it down to the ECM or the O2 sensor and I did not have the facility to check either, I would buy the new O2 ( after I made sure the circuit was good) before I bought a new ECM, simply on a cost basis.