Check Engine Light
 

My 1991 Camaro RS 3.1L V6 has a check engine light problem, and it's legitimate. And the elusive problem is getting worse. Here are the symptoms:

1. Bad gas mileage -- Has gone from 21 MPG to 15 MPG.

2. Lags at highway speeds -- I have to keep the accelerator mashed to the floor to keep it at 70 MPH. Certainly, this is where my gas mileage is suffering.

Back in November is when this problem began. I headed it off at the pass by getting new spark plugs. I mean, that's what this sounds like, doesn't it? Well, I changed the spark plugs.

About a month ago, this problem returned. Surely one can't blow through spark plugs that quickly? What a racket the auto parts suppliers and mechanics are running if you can.

For more information on this car, such as its tumultuous history with fuel injectors, please refer to this thread:

https://camaroforums.com/forum/v6-te...lse-new-61827/

flash for trouble codes and let us know what comes up. http://shbox.com/1/dlc2.jpg yours would be the same as a 93

Thanks. You're as helpful as a Chilton's. Mmh.

How the heck is that supposed to help me? See, this is what I hate about repairing cars and the whole car repair industry in general. WHERE THE FRICK DO I FIND THAT DIAGRAM YOU LINKED?

And how do I "flash" for trouble codes? Lift my shirt up at passing traffic? What does that mean?

That's the best you could come up with? "Flash for trouble codes"? You can't give me a direction like, "It might be the fuel anti-matter containment pod"?

Look. I don't drive this car for fun on the weekends and have a boat and a motorcycle on the side. THIS IS MY TRANSPORTATION; THIS IS MY LIVELIHOOD. I'm here out of desperation because I don't want to throw money or time at the problem because it's something I don't have.

So I'll ask again: given the symptoms listed in the first post, what does this sound like to you?

What the bloody hell was all that about? Your check engine light is trying to tell you what is wrong, but you have to flash the codes to find out. Without knowing, you'll just be throwing money and parts at the car till you get lucky, as any one given symptom could be from a choice of multiple different causes.
Here's the procedure: https://camaroforums.com/forum/3rd-g...d-codes-20385/
Here's what the numbers mean: http://www.troublecodes.net/GM/90-91_31V_mfi.shtml

just got home from work, fishing was not good today. if you click the red part of my post http://shbox.com/1/dlc2.jpg you will be taken to a post in a site that will give you directions on how to flash for trouble codes. the same goes for 69's post the parts in red (or different color not sure how your computer will show) are links to other posts or threads at another location, put your curser on the red and click. its called flashing because when you read the codes it is done by counting the number of times the ses (service engine soon) light flashes during the process. this process has been explained so many times that sites have posts that cover it pretty good. instead of posting the pocess over and over we can link you to the proper way to do things and not have to repeat ourselves to the point of burnout.

The symptoms I have listed should be enough elements to figure it out without needing to read the check engine codes. That's my grievance.

But what you have posted has been the most helpful thing I've read on the subject.

Before I go, here's my next question: how do I distinguish, say, a Code 66 from a Code 15? Where's the Rosetta Stone for that?

That's Chilton's-like garbage. It's not helpful whatsoever. It's more a rant against that link than you. What Camaro 69 posted with the pictures of where you can find the box and what it looks like is substantially more helpful.

Like I said, I'm not ragging on you so much as the link you posted. I'll gladly share with you what I have found. Although I think your time would best be spent working on my car for me than fishing. ;)

All right, I went out and read the codes using a paper clip. But, before we begin, let's recap with the symptoms, because I think those are far more telling than what the codes say:

1. Bad gas mileage -- Has gone from 21 MPG to 15 MPG.

2. Lags at highway speeds -- I have to keep the accelerator mashed to the floor to keep it at 70 MPH. Certainly, this is where my gas mileage is suffering.

3. 210 degrees triggers it all -- It's something else I noticed. If the car approaches 210 degrees, the first two symptoms and the check engine light will come on.

Don't forget -- Back in November is when this problem began. I headed it off at the pass by getting new spark plugs. I mean, that's what this sounds like, doesn't it? Well, I changed the spark plugs.


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So I checked the codes using a paper clip. It flashes Code 12 three times, and this is how it did it:

Flash. Short pause. Flash. Flash. Long pause.

Flash. Short pause. Flash. Flash. Long pause.

Flash. Short Pause. Flash. Flash. Long pause.



Then, it flashed me a Code 33:

Flash. Flash. Flash. Short Pause. Flash Flash Flash.

It did this about three more times, so I shut the car off because I figured I had my code. Anyway, here's what a Code 33 is, according to this link:

"MAP sensor voltage was too high for 4.8 seconds when throttle angle was less than 2%."

What the eff? That's causing all of THAT up there?

Anyway, how is the MAP sensor voltage causing that? And how does one fix the problem?

it flashes all codes three times. there may be more codes so better flash again. should flash a 12 again when all codes have been flashed.

chiltons is the simplest repair manual there is. if you liked that your gona love this

Attachment 21174

Attachment 21175

To answer your question, yes the MAP sensor could be causing the problems you're having. But do check as suggested to make sure you don't have any other codes present. To answer your next question, the MAP sensor is a little black rectangular-ish looking piece. It's mounted on a bracket at the top edge of the firewall, either drivers side or closer to center, and has an electrical plug and vacuum hose connected to it. Make sure those connections are in good clean, and uncracked condition.

That is confusing and cryptic compared to the information I got here at Camaro Forums. Chilton's is one of the sacred texts of Satanism as far as I'm concerned.

Is this the MAP sensor? And is this what I need to replace?

https://camaroforums.com/forum/v6-te...mponent-61812/

Yes that's the map sensor, but did you check for other codes?, with a thirdgen your going to become very familiar with flashing codes and what they mean.

It also sounds like you need to read, re read and read again a repair manual, if the chiltons looks cryptic to you then you are just looking for easy answers without having to trouble shoot the car yourself

Believe me, we all started at that point, I got my 89 at 17 years old and pretty much repaired everything using a chiltons, yes I got frustrated and yes I felt like screaming my head off but I learned alot from my car, especially diagnostics

Did that map sensor come undone at all? I saw in the link you put up that the clip is broken and another member already suggested a zip tie, if the connection is loose your gonna have problems


Post any other codes you have

No, because I'm confident it's the MAP sensor. If not, then I'll have a new MAP sensor.

Chilton's suck and wasn't there for me when I had to fix the greatest problem the Imperial Interceptor has ever had. You notice how they lump the entire Third Generation into one convenient book? Nevermind that there's vast differences between certain years. For instance, if you read a Chilton's, you'll be duped into thinking your '91 RS 3.1L V6 is sputtering and dying due to the "fuel pump" or "fuel filter" or some other peripheral issue that only a cursory book like Chilton's would tell you to fix. Nevermind it's the faulty injectors that have to ohm out between 12.2 and 12.5 or else the car will sputter and die. A Chilton's won't tell you that.

You know how I learned it was the injectors? From reading the internet, from reading the posts and opinions of Camaro experts like yourself. I then ran a content analysis of all of the posts wherein the problem was fixed and noticed a pattern: once the injectors were replaced, the problem was fixed.

Don't tell me I'm here for "easy answers." I'm here because Chilton's is a superficial tome that provides no interaction with experts. I'm college educated. That doesn't mean I'm smarter than anyone; it just means I know how to use methodology and a system to fix things rather than relying on some nebulous Q Document that sets in front of the counter at O'Reilly's.

So? I'm sorry you had to suffer that, but I'm sure if you had the innerwebs back in 1989, you wouldn't have bought a Chilton's.

No, the MAP sensor hasn't come undone. If it did, would my car be able to even run? I'm not sure. But, yeah, that clip is broken. I'll report more when my dad and I get after it some time in the indeterminate future.

Maybe you should take advice these guys are giving you. I've learned a lot from the forums but you need to break out a manual every once in a while. If you dont like chiltons then order a factory manual. Dont get frustrated with it. Diagnosing a car is more difficult than pulling a code and changing a part sometimes. There is a method to diagnosing problems but you're ignoring it. Flash your codes until you are sure you have them all, because there may be another issue that could be causing your problem or a code that can help point you in the right direction.

so you have not had the junk yard injectors cleaned and flow tested? have you tested the fuel pressure,,, if so what is it? so far you have thrown alot of parts at this car over a year and a half with no luck.

Uh, hello? The car is running after the injector crisis, so I've had more than luck. I've beaten a flaw in the system that has stumped mechanics and technicians. You want to compare that success to the other posts around the internet of '91 Camaro RS 3.1L V6's that aren't running due to the same problem that gets consistently misdiagnosed? "No luck" -- yeah, right.

I put nearly 6,000 miles on the car post injector replacement. And you want to act like it's still that. Geeze.

Haven't you read the thread? They're the ones who showed me how to even read the codes.

And I'm going by process of elimination because I'm confident the problem lies with the MAP sensor. I'd rather put all my chips into fixing a $50 part first that's going to need to be fixed anyway.

I understand that and i understand why you would want to replace it but you came off really bad in some of the post in this thread. i dont think you meant to really, just saying. Maybe i just took it wrong? Anyway good luck with the car.

Example: Can you see where I'm coming from?

Not to mention that last post you posted talking to craby....

I was giving you a chance at proving you were just frustrated, but In actuality your acting like a complete **** head,

I've read and understood my chiltons under all models, they give you full specifications on which engine needs what to be fixed, no its not as complete as a shop manual, but If you understand the troubleshooting tables it's a pretty helpful book

I got my RS in 07' and yes I used a chiltons and the "Interwebs" mainly TGO to solve my problems

The reason I ask for more codes is because you could have an underlying code ie ECM failure that would surpass a map sensor code

You need to take a step back and accept the help you are looking for, if you weren't looking for easy answers your head would be in that chiltons and not on here, that's what sharing this information is about, easy answers, but you still need to understand how and why your car is doing what it is, not just throw the part on and hope its fixed

this thread has not gone to waste , as my gen 3 has the very same fault , so i have pinned out the eobd plug and come up with codes 33 and 34 both relating to map sensor . i have checked all vac pipes and they seem fine so i think i will try a map sensor ! i also have a chilterns manual but its for a chevy day van but the engine is the same as far as i can tell , its been most helpful apart from components being in different places . so hopefully between chiltern and this thread i may have fixed my gen3 so thanks caveman305 most helpful !..

No problem, it sounds like you have diagnosed your problem pretty well, I'd you have any questions just ask, if I don't know the answer I'm sure someone here will