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Car dies when I stop

When I slow down to stop, the car starts vibrating really bad, and dies. It did that for a long time, and then I changed gas stations, and it seemed to quit for the last 3 tank fulls. Now its doing it again.

I did run a check on the computer, and it did say that either the MASS air flow sensor, MAP sensor, or the O2 sensor was bad. Does anyone think that this could be the problem, or just the gas.

How do I find these, and can these be cleaned, or do they need to be replaced?

I only have so many gas stations to try to find decent gas. So far one was working, now its not.

I dont know what to do. Hope someone can help! Thanks in advance!

You need to post the very specific code that you got - format P0123. There are hundreds of codes and many of those can point to issues with those items. The different codes mean different things. Who told you it meant either MAF/MAP or O2?

Here’s a limb I’ll go out on: was it P0171? Don’t guess though. You need to be sure.

I have a car computer code reader from Actron. It is the kind that flashes numbers and you look up the numbers in the book.
That is how I got that info. I was flashing code 34, and code 34 says either the MAF, MAP, or O2 sensor was the problem.

So it must be a '95 or earlier?

And can you copy down exactly what the book says - exact text?

Deleted by Americar

Oh the O2 sensor was auto zones remark about what might be wrong, not the book.

ONE MORE TIME! This doesnt seem to post when I hit sumit for some reason.

I have a 1993 sunbird 4 cylinder engine

CODE 34 reads:
Mass air flow (MAF) sensor- signal voltage or frequency is low during engine cruise.
Manifold absolute pressure (MAP) sensor- signal voltage is low during ignition on.
Pressure sensor circuit signal voltage too hight or low ( carburetor engines).
My car does NOT have a carburetor.

Thanks again for anyone who can help!

A quick Google shows:

GM common codes for OBD1 (for vehicles made before 1995)
34 map sensor signal out of range, low

I also found some Ford OBDI codes for a ford, and 34 means idle valve solenoid, so apparently there was no standard code for all cars.

I also found a page which said in 1994 and 1995 GM used a hyrbrid code, called OBD1.5 which may have different codes. I have not found that yet. PLEASE TELL US WHAT YEAR SUNBIRD IT IS.

Frankly, it sounds like idle speed problems to me, or perhaps because of long-term neglect of this problem, it may have two separate problems, the idle speed problem and the MAP sensor.
Does this car have a tachometer (rpm meter)? If so, when it runs rough tell us the speed on that rpm meter before it dies.


Ok - Note that the text refers to signal - that’s the electrical signal, and the problem can come from a number of different things - but not necessarily a problem with the part itself.

Just to keep it simple and cheap to start with, get some electrical contact cleaner and some carb or throttle body cleaner. Use the electrical cleaner to clean the MAF sensor, its connector pins and wiring harness. Do the same for the connectors for the MAP sensor. Pull the MAP and use some carb cleaner to clean it. Dab some dialectric grease on the connectors for each and reconnect. Look carefully while you do this for obvious signs of issues - frayed or broken wires, heavy connector corrosion, etc. Do that and see what happens. (While you’re doing this make extra sure that your have a nice clean air filter. You didn’t install a K&N or other oiled filter did you?)

The next thing you’d want is a multimeter and the electrical specs for these parts and circuits (repair manuals should have them). So report back after cleaning if it doesn’t change anything.

I’d say that if the parts are cheap just replace them but on a regular basis people replace parts only to find that it doesn’t fix anything - b/c the part wasn’t the problem.

Oops, thanks for car year, we crossed postings while I was Googling for you. First, let us try to eliminate the idle speed on this car when it dies as requested above. This is how one troubleshoots things. Go down the list and either verify or eliminate theories one at a time.

So, if it has an rpm meter, tell me what it says just before it dies.

Then, my next question is where do you get those three separate possibilities for code 34. If it came from Autozone they may not have separate codes for the Sunbird. but, first, idle speed.

Looking through the GM OBDI codes again, there are separate codes for O sensors, so I question the Autozone interpretation, though the word of any of our professional mechanics to the contrary is good enough for me. The Autozone person who checked your car is almost not certainly a mechanic as such. Who knows what he or she read from to give you three distinct interpretations for one code, which seems totally off the wall.

Here is a second URL which specifically lists MAF separately from MAP. This is the same one I posted above on an edit.

I do not have a RPM meter

Okay, if you drive one-footed, which means you use the same foot on throttle and brake, what I am going to suggest next must be done with extreme caution.

If you know under what conditions it dies, find a quiet street or large parking lot so you don’t get your feet tangled up and crash.

When it slows down, and is about to die, put your left foot on the brake, and give it a little throttle, just a tiny bit. You don’t want to burn out the brakes by revving up the motor too high, just a wee bit.

The idle control controls idle by opening a small air intake, under computer control, just enough to maintain the correct idle speed. Not too fast; not too slow.

If the idle valve does not open, or is blocked, when you let off the throttle, the car dies because the air is shut off.

So, what you want to do, to eliminate the idle valve as a problem is give it just a tiny bit of air with the regular throttle and see what happens. If it stops shaking and smooths out, that is not 100% sure it’s the idle valve, but it is a good chance that is the problem.

If that is the problem, first examine it to see if somehow it is blocked by crud.

But, the idle valves do go bad. I have had exactly two cars with FI, a 1989 Caravan, then in 2001 a 2002 Sienna. Both had bad idle valves,the Caravan had two bad ones in a year. I couldn’t find an after market so I had to pay full price for the MoPar part,and it lasted less than a year. By that time, they were available from the parts stores so I got one much cheaper. It was easy to replace. But, those three bad idle controls and how they acted is what made me suspect that on your car.

On the Toyota, it is a major job to replace, so I paid someone else.

If it isn’t the idle valve, and I sure can’t say a MAP sensor can’t cause it to die at idle, then you need to decide whether to clean it as described by another person, or to install a new one. I suspect this decision will be based on your financial state in this troubled economy. (You need not apologize to anyone here if that is the case. We understand. A lot of good people are in that boat, and others have been at other times in their lives.) Naturally, if you can clean it and get good service, why not? But, maybe it is bad instead of dirty.

If you log into Autozone’s page, you will have to register to do so, you can input your car, and in most cases there is a repair manual. I know it’s free because I have used it and paid nothing. Those manuals may tell you how to install both idle valves and MAP.

If not, you may need to borrow a manual from a good library if you have one nearby, or buy one. I think Haynes tends to be around $20, but that may have been some time ago.

Of course, if you wish, replace or clean the MAP first, because in any case it seems to be bad, whereas the odds the idle valve is bad are less than 100%. If you clean or replace the MAP and it still dies, then you can work on the idle valve. but, if you put in a new idle valve and it still dies, I have just caused you to waste time and money.

We hope to work on that stuff tomorrow, (monday).

I do notice that when I am getting ready to stop, that is when it starts getting rough and dies. I am a 2 foot driver, and I usually have my foot on the brake and I am giving it gas to keep it from dying, a lot of gas! Only about half of the time does it work, it usually dies anyway.

Yes we are on a very tight budget. My husband and I are both disabled. He spent 26 years rebuilding tractor and 18 wheeler truck cluthes. He has brain damage from year of being around the cleaning solvent, and possibly damage from the asbestos they use to grind into. I am disabled, but have not worked enough in my lifetime to recieve disability. 36 years of type 1 diabetes, and I have no health care, so his disability check goes quickly! Sorry to bore you all, but we try our best to do things as cheaply as we can, if we can. If not then I will do what it takes to get the job done. I just would rather fix it myself if I can, as apposed to taking it to a garage.

I do have an auto repair book for my car, but its so old and USED its hard to find everything we need in it to help work on the car.

Hopefully we can find the idle valve and see what could be going on with it. I couldnt find it in the Haynes book.

I will let you know how its going tomorrow. I am in Oklahoma and have no clue how cold its going to be tomorrow, so I dont know if we will get much done.

Can anyone tell me how long after we do clean those parts, we have to wait until its dry?

Thanks again to all of you who are trying to help!

Someone told us to run the engine, and with each part unhook it. If the car dies then the part is good, and if it keeps running, then the part is bad. Well we unhooked the MASS, MAP, and throttle position sensor, and the car did nothing. Which tells me they are all bad? I dont think it worked.

We did clean the parts, and put them back. I will drive it tonight, and see how its running, and let you know what happened.


Well the car did pretty good last night after we cleaned all the stuff on the list.

The biggest thing is wait and see. It has done this before, as far as gotten better, and then gotten worse again.

I did notice that the air filter had came apart. We replaced that also. It was only about 3 months old, but the rubber had came apart from the filter, and there was a pretty big gap there.

I will let everyone know how its running!

Thanks again so much! Julie

Well 2 days and still running pretty good. But this has happened before. It would quit doing it and then start again.
We might have solved the problem, only time will tell.
Thanks again for all the advise! I will repost and let you know how the car is doing!

Well it ran fine until yesterday. We filled up the gas tank, and it started again. As soon as we stopped, it died. I only did it for the first 3 stops we made. We let it rest awhile, and it didnt do it again.
Any suggesions?
Please let me know if anyone has any ideas!
Thank you all again so much!

Your 1993 Pontiac Sunbird, 4 cylinder, may not be cured, you say. It still stalls, sometimes.
Before, you got the DTC Code 34 = MAP sensor circuit error (signal low, which indicates the manifold vacuum is high). Have you extracted the trouble code, again?
This is the test procedure for the MAP sensor. For the scan tool, you could substitute an electrical multimeter (aka voltmeter).
There should be electrical resistance checks in your repair manual. You can get voltage readings if you use straight pins to backprobe each wire. The pin is slid along the wire and makes contact with the wire terminal. The multimeter test lead is touched to each pin (in turn), while the engine is idling, and the voltages are checked on the three wires of the MAP sensor (one at a time). The voltage checks are made with the engine at idle, and above idle.
The signal return, from the MAP sensor, is too low, according to the DTC code 34. This could reflect a true high vacuum (but, I don’t think THAT high), which occurs at idle; or, it could be a MAP sensor / circuitry fault. So, test the voltages and resistances. Disconnect the electrical connector from the MAP sensor, and make sure that it firmly reconnects.
Check the vacuum tube from the MAP sensor—it could be split or deteriorated. Replace if questionable (available at auto parts stores).
Use the throttle body cleaner, again. Be sure to clean the air passages to the idle air control valve (iacv), throttle body bore and throttle plate with the Throttle Body Cleaner.

Well the car died just after filling up, as I last posted. Then it did NOT do it again, until just about 30 mins ago.
I tried to get Autozone to use one of those meters on the parts, and they said they dont do that anymore.
The computer reader I have, just blinks the light on the dashboard, and you look up the code in a book. I dont have a fancy one.
We tried running the computer meter again, and its showing that nothing is wrong! Back to square one.
The first time around it showed this:
CODE 34 reads:
Mass air flow (MAF) sensor- signal voltage or frequency is low during engine cruise.
Manifold absolute pressure (MAP) sensor- signal voltage is low during ignition on.
Pressure sensor circuit signal voltage too hight or low ( carburetor engines).
My car does NOT have a carburetor.
We did clean the parts as suggested above with cleaner, and checked the wires to each one.
I am just at a loss here, because if the computer meter isnt saying anything is wrong, then I dont know where to start.
Being that its only doing this once and awhile, I dont know what to think!
Thanks for any suggestions!