1984 C4 Coupe Code 33/34
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Marion Indiana
1984 C4 Coupe Code 33/34
Hello all
I've scoured the forum looking for tips on a code 33/34 for my 84 C4 Coupe. I cant find anything. Has anyone encountered this issue before? Rough idle. Sputtering. When I put it in gear it dies. I've changed out the fuel pump, fuel filter and MAP sensor. Also checked the fuses. Nothing has worked. Any help would be greatly appreciated.
Thanks in advance
I've scoured the forum looking for tips on a code 33/34 for my 84 C4 Coupe. I cant find anything. Has anyone encountered this issue before? Rough idle. Sputtering. When I put it in gear it dies. I've changed out the fuel pump, fuel filter and MAP sensor. Also checked the fuses. Nothing has worked. Any help would be greatly appreciated.
Thanks in advance
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
These error codes don't seem to match up with what I know about '84s:
Engine Trouble Codes:
1984:
code 13 =1 flash followed by 3 flashes =>oxygen sensor
code 14 =1 flash followed by 4 flashes =>coolant sensor
code 15 =1 flash followed by 5 flashes =>coolant sensor
code 21 = 2 flashes followed by 1 flash =>throttle position sensor
code 22 = 2 flashes followed by 2 flashes=> throttle position sensor
code 23 = 2 flashes followed by 3 flashes=> manifold air temp sensor
code 24 = 2 flashes followed by 4 flashes=> vehicle speed sensor
code 25 = 2 flashes followed by 5 flashes=> manifold air temp sensor
code 32 =>egr system
code 33 =>map sensor
code 34 =>maf sensor
code 35 => idle air control
code 41 => cylinder select error
code 42 => electronic spark control
code 43 => electronic spark control
code 44 => lean exhaust
code 45 => rich exhaust
code 51 => PROM
code 52 => fuel calpak
code 53 => system over voltage
code 54 => fuel pump circuit
code 55 => ecm
code 62 => oil temp
Hey Roy, do you have a better list from the FSM?
Engine Trouble Codes:
1984:
code 13 =1 flash followed by 3 flashes =>oxygen sensor
code 14 =1 flash followed by 4 flashes =>coolant sensor
code 15 =1 flash followed by 5 flashes =>coolant sensor
code 21 = 2 flashes followed by 1 flash =>throttle position sensor
code 22 = 2 flashes followed by 2 flashes=> throttle position sensor
code 23 = 2 flashes followed by 3 flashes=> manifold air temp sensor
code 24 = 2 flashes followed by 4 flashes=> vehicle speed sensor
code 25 = 2 flashes followed by 5 flashes=> manifold air temp sensor
code 32 =>egr system
code 33 =>map sensor
code 34 =>maf sensor
code 35 => idle air control
code 41 => cylinder select error
code 42 => electronic spark control
code 43 => electronic spark control
code 44 => lean exhaust
code 45 => rich exhaust
code 51 => PROM
code 52 => fuel calpak
code 53 => system over voltage
code 54 => fuel pump circuit
code 55 => ecm
code 62 => oil temp
Hey Roy, do you have a better list from the FSM?
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Hi Cliff, My info says Code 33 and 34 are both related to the MAP sensor, but Robert has already replaced the MAP sensor. I have no experience with the MAP sensor, so I can't help. Maybe the vacuum line to the sensor?
Pin A: Return to ECM (gnd)
Pin B: MAP sensor output
Pin C: 5 v. reference
My info also says: "Engine misfire or unstable idle may cause this code." Implies problem may by totally different than MAP sensor. Ignition problem? Ignition timing? Vacuum leak?
Robert, have you thoroughly checked for vacuum leaks? Are the bolts around the periphery of your intake manifold top plate tight?
Pin A: Return to ECM (gnd)
Pin B: MAP sensor output
Pin C: 5 v. reference
My info also says: "Engine misfire or unstable idle may cause this code." Implies problem may by totally different than MAP sensor. Ignition problem? Ignition timing? Vacuum leak?
Robert, have you thoroughly checked for vacuum leaks? Are the bolts around the periphery of your intake manifold top plate tight?
Team Owner
Joined: Sep 2003
Posts: 25,382
Likes: 2,736
What is this fellow with an '84 TBI "cross-fire" supposed to do with these later TPI charts.
--------------------------------------------------
OP - HRR mentioned both 33 & 34 are MAP related and that's certainly correct. Did you have MAP codes before you replaced the MAP OR are codes the aftermath of work you've done. It certainly seems that if the codes were there before you started you've possibly many issues. Brand and part # of the MAP you bought?
Is this what you feel a stock "cross-fire" or is there maybe evidence of maybe being "tinkered with". Miles? Was there actually a "diagnosed reason" for fuel pump replacement or you just did it?
Good luck
There's no PM or email in your info. If you'd like to buy a correct FSM to help you with diagnostics and repairs use the email function under my "WVZR-1" user ID. I can sell you both books to help.
Last edited by WVZR-1; Jun 9, 2016 at 07:21 AM.
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Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
What is this fellow with an '84 TBI "cross-fire" supposed to do with these later TPI charts.--------------------------------------------------OP - HRR mentioned both 33 & 34 are MAP related and that's certainly correct. Did you have MAP codes before you replaced the MAP OR are codes the aftermath of work you've done. It certainly seems that if the codes were there before you started you've possibly many issues. Brand and part # of the MAP you bought?Is this what you feel a stock "cross-fire" or is there maybe evidence of maybe being "tinkered with". Miles? Was there actually a "diagnosed reason" for fuel pump replacement or you just did it?Good luckThere's no PM or email in your info. If you'd like to buy a correct FSM to help you with diagnostics and repairs use the email function under my "WVZR-1" user ID. I can sell you both books to help.
Sorry I just googled it and did not notice. Did not mean to cut into your internet business.
Sorry I just googled it and did not notice. Did not mean to cut into your internet business.
Burning Brakes
Joined: Apr 2016
Posts: 781
Likes: 73
Interesting issue.
Looking at my 1984 FSM, a code 34 and a code 33 point to a failed MAP sensor or a plugged or failed vacuum line.
The rough idling would also seem to point to a vacuum leak.
The FSM also indicates that a 33 can be set due to an unstable idle and the idle issue should be resolved before assuming there is a map issue.
The code 33/34 together seem to point to a MAP issue.
Looking at my 1984 FSM, a code 34 and a code 33 point to a failed MAP sensor or a plugged or failed vacuum line.
The rough idling would also seem to point to a vacuum leak.
The FSM also indicates that a 33 can be set due to an unstable idle and the idle issue should be resolved before assuming there is a map issue.
The code 33/34 together seem to point to a MAP issue.
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Marion Indiana
Hi Cliff, My info says Code 33 and 34 are both related to the MAP sensor, but Robert has already replaced the MAP sensor. I have no experience with the MAP sensor, so I can't help. Maybe the vacuum line to the sensor?
Pin A: Return to ECM (gnd)
Pin B: MAP sensor output
Pin C: 5 v. reference
My info also says: "Engine misfire or unstable idle may cause this code." Implies problem may by totally different than MAP sensor. Ignition problem? Ignition timing? Vacuum leak?
Robert, have you thoroughly checked for vacuum leaks? Are the bolts around the periphery of your intake manifold top plate tight?
Pin A: Return to ECM (gnd)
Pin B: MAP sensor output
Pin C: 5 v. reference
My info also says: "Engine misfire or unstable idle may cause this code." Implies problem may by totally different than MAP sensor. Ignition problem? Ignition timing? Vacuum leak?
Robert, have you thoroughly checked for vacuum leaks? Are the bolts around the periphery of your intake manifold top plate tight?
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Marion Indiana
Interesting issue.
Looking at my 1984 FSM, a code 34 and a code 33 point to a failed MAP sensor or a plugged or failed vacuum line.
The rough idling would also seem to point to a vacuum leak.
The FSM also indicates that a 33 can be set due to an unstable idle and the idle issue should be resolved before assuming there is a map issue.
The code 33/34 together seem to point to a MAP issue.
Looking at my 1984 FSM, a code 34 and a code 33 point to a failed MAP sensor or a plugged or failed vacuum line.
The rough idling would also seem to point to a vacuum leak.
The FSM also indicates that a 33 can be set due to an unstable idle and the idle issue should be resolved before assuming there is a map issue.
The code 33/34 together seem to point to a MAP issue.
Thanks for the info.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Thread Starter
7th Gear
Joined: Jun 2016
Posts: 7
Likes: 0
From: Marion Indiana
Hi Cliff, My info says Code 33 and 34 are both related to the MAP sensor, but Robert has already replaced the MAP sensor. I have no experience with the MAP sensor, so I can't help. Maybe the vacuum line to the sensor?
Pin A: Return to ECM (gnd)
Pin B: MAP sensor output
Pin C: 5 v. reference
My info also says: "Engine misfire or unstable idle may cause this code." Implies problem may by totally different than MAP sensor. Ignition problem? Ignition timing? Vacuum leak?
Robert, have you thoroughly checked for vacuum leaks? Are the bolts around the periphery of your intake manifold top plate tight?
Pin A: Return to ECM (gnd)
Pin B: MAP sensor output
Pin C: 5 v. reference
My info also says: "Engine misfire or unstable idle may cause this code." Implies problem may by totally different than MAP sensor. Ignition problem? Ignition timing? Vacuum leak?
Robert, have you thoroughly checked for vacuum leaks? Are the bolts around the periphery of your intake manifold top plate tight?
Burning Brakes
Joined: Apr 2016
Posts: 781
Likes: 73
I changed out all hoses. There were some smaller hoses connecting the MAP sensor and I changed those out. The car fired right up. A little sluggish still from stop to go. Drove it around all day today with the top off. Felt good to be back on the road. Thanks for all your help.