Check engine light on...Code 34 MAP Sensor
Thread Starter
1st Gear
Joined: Apr 2009
Posts: 1
Likes: 0
Check engine light on...Code 34 MAP Sensor
My check engine light has been on for quite awhile now...
the symptoms are:
engine dies when at idle and during decel (intermittent)
runs rough mainly at low speeds
engine code reads 34 MAP sensor
Does anyone just recommend buying a new MAP sensor and resetting the light or is it more then that?!? I read somewhere that the 87's have carbon built up in the throttle body and cleaning it should fix it?
I had my engine light on a few years back and seemed to just keep replacing things until it went off (according to the code...a different one then this time). I don't want to do that again....any advice?!?
Thanks!
Mendy
1987 Corvette Convertible
the symptoms are:
engine dies when at idle and during decel (intermittent)
runs rough mainly at low speeds
engine code reads 34 MAP sensor
Does anyone just recommend buying a new MAP sensor and resetting the light or is it more then that?!? I read somewhere that the 87's have carbon built up in the throttle body and cleaning it should fix it?
I had my engine light on a few years back and seemed to just keep replacing things until it went off (according to the code...a different one then this time). I don't want to do that again....any advice?!?
Thanks!
Mendy
1987 Corvette Convertible
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
My check engine light has been on for quite awhile now...
the symptoms are:
engine dies when at idle and during decel (intermittent)
runs rough mainly at low speeds
engine code reads 34 MAP sensor
Does anyone just recommend buying a new MAP sensor and resetting the light or is it more then that?!? I read somewhere that the 87's have carbon built up in the throttle body and cleaning it should fix it?
I had my engine light on a few years back and seemed to just keep replacing things until it went off (according to the code...a different one then this time). I don't want to do that again....any advice?!?
Thanks!
Mendy
1987 Corvette Convertible
the symptoms are:
engine dies when at idle and during decel (intermittent)
runs rough mainly at low speeds
engine code reads 34 MAP sensor
Does anyone just recommend buying a new MAP sensor and resetting the light or is it more then that?!? I read somewhere that the 87's have carbon built up in the throttle body and cleaning it should fix it?
I had my engine light on a few years back and seemed to just keep replacing things until it went off (according to the code...a different one then this time). I don't want to do that again....any advice?!?
Thanks!
Mendy
1987 Corvette Convertible
The correct procedure is to follow the diagnostic chart for the code in the Factory Service Manual. The flow chart normally has you test the circuit using a Digital Volt Ohm Meter in a systematic way to eliminate each possibility in order, eventually isolating the root cause.
You may get other answers saying " I replaced this or that part and it fixed my code 34." but such responses do not necessarily apply to your car and are little different than the guess work approach that failed you previously, good luck.
Burning Brakes
Joined: Apr 2004
Posts: 762
Likes: 2
From: Huntington ma
Code 34 is MAF airflow low (MAF, NOT MAP - the '87 is not a MAP system). Could be as simple as a vacuum leak, or a low/unsteady idle - not necessarily a problem with the MAF sensor, or relays, itself.
Without running through the proper diagnostic steps you will just be throwing parts at it hoping for the problem to go away - get the Helm manual (the FSM - if you are determined to do this repair stuff yourself) and go about it the right way, save yourself a lot of effort and money.
You are also going to want a Good scan tool at some point - not one of the dime store code readers but an actual Scan tool that will display all of the sensor readings "live".
Without running through the proper diagnostic steps you will just be throwing parts at it hoping for the problem to go away - get the Helm manual (the FSM - if you are determined to do this repair stuff yourself) and go about it the right way, save yourself a lot of effort and money.
You are also going to want a Good scan tool at some point - not one of the dime store code readers but an actual Scan tool that will display all of the sensor readings "live".
4th Gear
Joined: Aug 2012
Posts: 4
Likes: 0
1987 Check engine Code 34
REPLACE the 1987 Mass Airflow Control and Burn Off Relays!!!!
I have had this problem with my 1987 Convertible since the WEEK that I bought it 5 years ago!
Checked all hoses, cleaned throttle body, replaced idle air control, messed around with different PCV valves and more....
My Hanes Manual talked about MAF control and burn off relays under the dash. A couple of weeks ago, after I found the little bastards on the fire wall behind the battery. I replaced them all has been well!
I got the parts on-line from Rock Auto (AC Delco) for $11.00 each. Relay part number 14089936 was the same number as the old ones that nI replaced.
The battery must be removed to install the relays...
After living with this pain in the butt problem I am most pleased to have it behind me.. I would have broken down and sought professional help, but the car's performance never seemed to suffer.
I have had this problem with my 1987 Convertible since the WEEK that I bought it 5 years ago!
Checked all hoses, cleaned throttle body, replaced idle air control, messed around with different PCV valves and more....
My Hanes Manual talked about MAF control and burn off relays under the dash. A couple of weeks ago, after I found the little bastards on the fire wall behind the battery. I replaced them all has been well!
I got the parts on-line from Rock Auto (AC Delco) for $11.00 each. Relay part number 14089936 was the same number as the old ones that nI replaced.
The battery must be removed to install the relays...
After living with this pain in the butt problem I am most pleased to have it behind me.. I would have broken down and sought professional help, but the car's performance never seemed to suffer.
Last edited by Packard Rod; Aug 30, 2012 at 08:46 PM. Reason: Add replacement part number
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Code 34 is MAF airflow low
Could be as simple as a vacuum leak, or a low/unsteady idle - not necessarily a problem with the MAF sensor, or relays, itself.
Without running through the proper diagnostic steps you will just be throwing parts at it hoping for the problem to go away -
Could be as simple as a vacuum leak, or a low/unsteady idle - not necessarily a problem with the MAF sensor, or relays, itself.
Without running through the proper diagnostic steps you will just be throwing parts at it hoping for the problem to go away -
http://www.chevythunder.com/maf_code_33.htm
http://www.chevythunder.com/maf_code_36.htm
