code--33
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 6,470
Likes: 2
From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
code--33
I had what I thought was a problem with the vacuum/egr system until I found my code scanner. The car starts/idles/runs great until about 25-30 minutes of driving, then all of a sudden its like somebody throws a switch--- rough running, exhaust smells, idle goes from 5k to 7k up & down. If I shut the car off for about 20 minutes it goes through the same cycle-- starts/idles fine etc. I plugged in the scanner, & got a code 33---MAF sensor or MAP sensor. Which one would be the better bet to be the problem. Of course the MAP sensor is underneath the plenum, so thats going to be a PITA to replace
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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No, not a MAP on 87. Your car is probably being thrown into 'limp home' mode.
Its MAF and/or relays. Inspect the MAF wiring from the sensor to the relays, there are 2 of them behind the battery on the firewall. If the wiring checks, replace both relays, together they shouldnt be more than $25.
See if the code comes back, if it does then its the MAF itself.
Its MAF and/or relays. Inspect the MAF wiring from the sensor to the relays, there are 2 of them behind the battery on the firewall. If the wiring checks, replace both relays, together they shouldnt be more than $25.
See if the code comes back, if it does then its the MAF itself.
Burning Brakes
Joined: Aug 2004
Posts: 1,174
Likes: 125
From: Dunstable MA
St. Jude Donor '05
Kenv, I am writing to you from another corner of Code 33 hell. It's spelled MAF alright. I've replaced the relays and had it scanned and replaced the coolant temp sensor and the O2 sensor and replaced the MAF sensor and the IAC and it goes away for a while after each repair and then ......
"You can check out anytime you want, but you can ne-ver leave!"
Right now I'm riding around with the MAF unplugged. At least it runs.
"You can check out anytime you want, but you can ne-ver leave!"
Right now I'm riding around with the MAF unplugged. At least it runs.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 6,470
Likes: 2
From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
Well, while looking at the plenum, I found a sensor, underneath at the rear right by the vacuum ports. There is no connector going to this thing, & I can`t find any loose wires or connectors. Right now I cannot find my fsm (naturaly 
) anyone know what it is, & could this be causing the trouble. ( let`s see, so far I gotta get two relays & another plenum gasket set. Don`tcha just love having a "hobby"
)
) anyone know what it is, & could this be causing the trouble. ( let`s see, so far I gotta get two relays & another plenum gasket set. Don`tcha just love having a "hobby" )
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
I'll look when I get home...later this evening..don't forget to check the FP relays also.
Rich, I thought your problem was fixed when you installed a new MAF?
If not, it seems like after everything you've done it must be a bad wire or connection.
Rich, I thought your problem was fixed when you installed a new MAF?
If not, it seems like after everything you've done it must be a bad wire or connection.
Pro
Joined: Apr 2006
Posts: 747
Likes: 0
From: Perth Western Australia
The sensor that your talking about is (i may be wrong, just going off description) the air temp sensor. this should have a connection too it, thats only if a second air temp sensor has not installed near the air filter somewhere.
Pro
Joined: Apr 2006
Posts: 747
Likes: 0
From: Perth Western Australia
not sure if it affects the code
try this link i got from another member
http://members.shaw.ca/corvette86/
try this link i got from another member
http://members.shaw.ca/corvette86/
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Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
Originally Posted by Rich Silvestris
Kenv, I am writing to you from another corner of Code 33 hell. It's spelled MAF alright. I've replaced the relays and had it scanned and replaced the coolant temp sensor and the O2 sensor and replaced the MAF sensor and the IAC and it goes away for a while after each repair and then ......
"You can check out anytime you want, but you can ne-ver leave!"
Right now I'm riding around with the MAF unplugged. At least it runs.
"You can check out anytime you want, but you can ne-ver leave!"
Right now I'm riding around with the MAF unplugged. At least it runs.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 6,470
Likes: 2
From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
Update-- I replaced the MAF relays ( AC Delco- made in China- $20.00ea
), that did not cure the problem. Went to AutoZone for a new ( reman) MAF sensor. The wanted $221 + $80.00 core charge. The counter guy answered the phone with " Autozone, cheapest prices guaranteed). I said, " I`ll call you right back ". I called around, & the cheapest place that I could order one was Pep Boys, with a 3-5 day delivery
. I went to the `Zone with the Pep Boys printout, & said " here ya go ". They weren`t happy, but I got it for $165+tax. Now I hope it cures the problem. Oh yeah; the highest price was from my local chevy dealer--- $450 reman---$680 new
), that did not cure the problem. Went to AutoZone for a new ( reman) MAF sensor. The wanted $221 + $80.00 core charge. The counter guy answered the phone with " Autozone, cheapest prices guaranteed). I said, " I`ll call you right back ". I called around, & the cheapest place that I could order one was Pep Boys, with a 3-5 day delivery . I went to the `Zone with the Pep Boys printout, & said " here ya go ". They weren`t happy, but I got it for $165+tax. Now I hope it cures the problem. Oh yeah; the highest price was from my local chevy dealer--- $450 reman---$680 new
Team Owner
Joined: Jan 2003
Posts: 20,324
Likes: 250
From: Summerland B.C. Canada
I hope you went through the flow chart before you threw money at it. 
As for the sensor under plenum, yes it is the MAT sensor and it should have about a 6 inch lead with connectors, that plugs in between the sensor and the main wire harness behind distributor.
As for the sensor under plenum, yes it is the MAT sensor and it should have about a 6 inch lead with connectors, that plugs in between the sensor and the main wire harness behind distributor.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 6,470
Likes: 2
From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
Well ;all the wires looked ok. I`ll let you know if it fixes the problem. FP relay? :o oops!, I missed that one. I hope this works, because if my wife were to find out I spent $165 for a MAF, when it could have been fixed with a $20.00 relay, my *** would be in the dog house, & the dog would be in my house, so if it turns out to be the relay- you bet your butt that I`m going to swear it was the MAF