CODE 33 Driving Me Nuts.
Thread Starter
Instructor
Joined: Mar 2010
Posts: 101
Likes: 0
From: Kissimmee Florida
CODE 33 Driving Me Nuts.
Ok this problem is driving me nuts. The Car is an 86 Alumi Head Z51.
1st: I change the MAF, Both Relays, The connector to MAF Burnoff Relay, Cleaned all connections. When this problem comes up I have 5V out the MAF and 12 V to MAF when cranking the engine. The car wil not start when cold but if i touch the gas it will start but it codes to 33. Now if i turn it off and wait 30 to 45 sec and crank it. It starts and no SEL comes on and works all day. Seems to be a morning thing. I also tried setting the TPS to as high as .62V no difference. When it dies acted up I even jumpered the Oil pressure switch. Also all the time i can hear the fuel pump running even when it dont start.
It doesn't do this everyday, just seems to be getting worse.
Iam at my end. Looking at ripping the FEI out. does anyone know of a intake and carb combo to replace this stuff with that will fit under the hood, and do i have repace the Dist ?
1st: I change the MAF, Both Relays, The connector to MAF Burnoff Relay, Cleaned all connections. When this problem comes up I have 5V out the MAF and 12 V to MAF when cranking the engine. The car wil not start when cold but if i touch the gas it will start but it codes to 33. Now if i turn it off and wait 30 to 45 sec and crank it. It starts and no SEL comes on and works all day. Seems to be a morning thing. I also tried setting the TPS to as high as .62V no difference. When it dies acted up I even jumpered the Oil pressure switch. Also all the time i can hear the fuel pump running even when it dont start.
It doesn't do this everyday, just seems to be getting worse.
Iam at my end. Looking at ripping the FEI out. does anyone know of a intake and carb combo to replace this stuff with that will fit under the hood, and do i have repace the Dist ?
Thread Starter
Instructor
Joined: Mar 2010
Posts: 101
Likes: 0
From: Kissimmee Florida
May Have found something
Well this is the wires to the Fuel Pump Relay, The MAF Power Relay looked just like this also. Burnt down for about and inch.
Last edited by dlee425; Jun 22, 2013 at 06:07 PM. Reason: add photo
Racer
Joined: Sep 2010
Posts: 305
Likes: 2
From: Epfenbach BW
Well you seem to have some wiring problems there. I also had to replace the Maf relays on mine but that solved the problem.
The insulation on those wires seems to have shrunken because of heat or burned off for some reason. I would check all the connectors and wiring first to make sure they are all ok.
You may find other similar places on the wiring harness.
Also make sure every ground wire is in place. Missing ground wires also cause some hard to find intermittend problems.
The insulation on those wires seems to have shrunken because of heat or burned off for some reason. I would check all the connectors and wiring first to make sure they are all ok.
You may find other similar places on the wiring harness.
Also make sure every ground wire is in place. Missing ground wires also cause some hard to find intermittend problems.
Racer
Joined: Sep 2010
Posts: 305
Likes: 2
From: Epfenbach BW
I remember I read somewhere, that the insulation material can shrink after 20+ years due to loss of softeners in the plastic material and heat. That causes shorts, often in the vicinity of connectors and places that are prone to excessive heat.
The plastic becomes brittle on those old wires pretty easily.
The plastic becomes brittle on those old wires pretty easily.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
A code means a fault somewhere in a whole circuit ; not just that the major items in that circuit are faulty
You have done the FULL code 33 diagnostics from the FSM; not just replaced parts?
http://www.chevythunder.com/maf_code_33.htm
Wiring insulation problems on the early style relay connectors is well documented on here
You have done the FULL code 33 diagnostics from the FSM; not just replaced parts?
http://www.chevythunder.com/maf_code_33.htm
Last edited by vetteoz; Jun 23, 2013 at 08:06 PM.
Thread Starter
Instructor
Joined: Mar 2010
Posts: 101
Likes: 0
From: Kissimmee Florida
[QUOTE=vetteoz;1584229430]A code means a fault somewhere in a whole circuit ; not just that the major items in that circuit are faulty
You have done the FULL code 33 diagnostics from the FSM; not just replaced parts?
http://www.chevythunder.com/maf_code_33.htm
Wiring insulation problems on the early style relay connectors is well documented on here
Have not been able to get it to do it long enough to do a full diag. Its when it first starts and when i turn the key off and restart the car the SEL dont come on and runs fine the rest of the day.
And somedays it will not do it for 3-4 days.
Tried cleaning connections, repaired the burnt cables, relaced the relays, and maf.
ohm'ed out the wires to the maf. maybe a bad connection in the ecm.
Just grabbing straws.
You have done the FULL code 33 diagnostics from the FSM; not just replaced parts?
http://www.chevythunder.com/maf_code_33.htm
Wiring insulation problems on the early style relay connectors is well documented on here
Have not been able to get it to do it long enough to do a full diag. Its when it first starts and when i turn the key off and restart the car the SEL dont come on and runs fine the rest of the day.
And somedays it will not do it for 3-4 days.
Tried cleaning connections, repaired the burnt cables, relaced the relays, and maf.
ohm'ed out the wires to the maf. maybe a bad connection in the ecm.
Just grabbing straws.
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Instructor
Joined: Nov 2012
Posts: 120
Likes: 6
From: Phoenix AZ
Just went through this with my 88. New ECU, EPROM, power wire on MAF relay and black/white wire on burn off relay and no more 33. Now I have an intermittent 36, which I think is ECU/Burnoff Relay ground related. Got to love the C4!
GOOD LUCK!
GOOD LUCK!
Pro
Joined: Feb 2010
Posts: 677
Likes: 3
From: Metairie LA
When I had MAF codes popping up, I replaced the unit and the relays. Still got the code. Reading through the FSM led me to the TPS. It didn't state to check it in the troubleshooting tree but in the description. The MAF was seeing too much voltage for the indicated throttle position. Changed TPS and all has been well.
Just something else to check. Like Vetteoz indicated (I think) - it may be another part of the whole picture.
Just something else to check. Like Vetteoz indicated (I think) - it may be another part of the whole picture.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
The ECM was seeing numbers out of the expected range
Team Owner
Joined: Jan 2003
Posts: 20,305
Likes: 240
From: Summerland B.C. Canada
Here is some info on 33 from my 86 FSM
http://members.shaw.ca/corvette86/Code%2033.pdf
Thread Starter
Instructor
Joined: Mar 2010
Posts: 101
Likes: 0
From: Kissimmee Florida
I just picked up a USB to RS232 interface (Free as they did not use 232 anymore) and building the 2 transistor interface. The only problem i see is what is the baud rate on an 86.. Some say 160 Pin E and others say 8192 on i think pin M.
I want to see the data stream.. Any ideas ?
I want to see the data stream.. Any ideas ?
Pro
Joined: Feb 2010
Posts: 677
Likes: 3
From: Metairie LA
I pulled all the relay connectors apart and used heat shrink tubing to cover the exposed wires. Then reassembled and used dielectric grease. All good.
I couldn't tell you about the USB to serial interface. I bought the moates cable (and eventually the Ostrich2).
I couldn't tell you about the USB to serial interface. I bought the moates cable (and eventually the Ostrich2).
Thread Starter
Instructor
Joined: Mar 2010
Posts: 101
Likes: 0
From: Kissimmee Florida
Still trying to trace this down. Did find if i turn the key on like iam going to start the car and wait for the fuel pump to stop running then start it I will get the code 33.
I got WinAldl but iam not sure what is normal for the 86 as far as sensor readings.
I got WinAldl but iam not sure what is normal for the 86 as far as sensor readings.