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1987 305 TPI code 33... ecm help ?

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Old Jun 25, 2009 | 06:17 PM
  #1  
code red's Avatar
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1987 305 TPI code 33... ecm help ?

After doing A LOT of searching on this website... i found a lot of helpful information regarding code 33.... Used MAF cleaner spray...i checked MAF power, Burn-off, and Fuel pump relays- they're good.... on the harness that goes into the MAF sensor A&B- test light on... D (ignition on-engine not running)- zero volts... C (ignition on engine not running)- 1.1 volts so i checked the B12 on the ecm- got 1.1v

Then i cleared the code and checked MAF harness C- 1.1v and the same at B12 (ecm)... Started the car: B12(ecm)- 3.42v..... let the car warm up to operating temp.. got 3.58v at B12(ecm).. reved the motor at 500 increments upto 2500rpm when down to 3.40v.

is there anything else i should check, maybe the TPS ? Or is my ECM on the way out ?

Thanks, Dan
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Old Jun 27, 2009 | 10:55 AM
  #2  
Rolling Thunder's Avatar
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From: CT
Car: 86 T/A, 83 Z/28
Engine: 5.0 TPI, 350 2 X 4 bbl
Transmission: 4 speed auto, 5 speed manual
Axle/Gears: 3.23 posi, 3.73 std
Re: 1987 305 TPI code 33... ecm help ?

Well it sounds like you might have found the problem already. A&B are both grounds (ones an analog ground to the comp and the other is a regular ground). So its strange to me that the test light would be on. How exactly did you test them? Just dissconnect the harness and put your test light from A to chassy ground and then test b to chassy ground? Next thing is at idle the voltage from the MAF sensor should only be around .5 volts and increase when brought up to 2500 rpms. So ide double check thoes grounds and then look at getting a new MAF sensor.
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Old Jun 27, 2009 | 11:35 AM
  #3  
code red's Avatar
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Re: 1987 305 TPI code 33... ecm help ?

well i followed a tree diagram i got from this site... ill see if i can post it... if this is the wrong one let me know...
Attached Files
File Type: pdf
Code 33 diagram.pdf (234.7 KB, 222 views)
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Old Jun 27, 2009 | 01:08 PM
  #4  
Rolling Thunder's Avatar
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From: CT
Car: 86 T/A, 83 Z/28
Engine: 5.0 TPI, 350 2 X 4 bbl
Transmission: 4 speed auto, 5 speed manual
Axle/Gears: 3.23 posi, 3.73 std
Re: 1987 305 TPI code 33... ecm help ?

Ok Well if you followed that flow chart exactly then ide say your down to a bad MAF. What that code is really complaining about is that the output from the MAF is to high given the RPM and the TPS sensor output. That being said i dont think its a problem with anything else simply because the output signal youve measured just simply isnt right. It should be about .5 at idle and go up to about 5 v at WOT. Yours is like 3.5 at idle and roughly stays the same with changes in RPM actually goes slightly down with an increase in RPM. So all and all i think its a MAF problem unfortunetly.
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Old Jul 29, 2009 | 11:31 PM
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gurkgurkgurk's Avatar
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From: SF bay area
Car: 86 Camaro iroc-z28
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.42 Posi
Re: 1987 305 TPI code 33... ecm help ?

Originally Posted by Rolling Thunder
Ok Well if you followed that flow chart exactly then ide say your down to a bad MAF. What that code is really complaining about is that the output from the MAF is to high given the RPM and the TPS sensor output. That being said i dont think its a problem with anything else simply because the output signal youve measured just simply isnt right. It should be about .5 at idle and go up to about 5 v at WOT. Yours is like 3.5 at idle and roughly stays the same with changes in RPM actually goes slightly down with an increase in RPM. So all and all i think its a MAF problem unfortunetly.

does that mean that an improperly adjusted TPS could manifest itself into a MAF code? i too am troubleshooting a code 33 problem
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Old Jul 30, 2009 | 10:01 AM
  #6  
code red's Avatar
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Re: 1987 305 TPI code 33... ecm help ?

i ended up buying a new multimeter.... and followed the tree diagram again... i got proper readings... the MAF was bad... the tps was at the right setting
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Old Jul 30, 2009 | 06:26 PM
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Rolling Thunder's Avatar
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Joined: Mar 2008
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From: CT
Car: 86 T/A, 83 Z/28
Engine: 5.0 TPI, 350 2 X 4 bbl
Transmission: 4 speed auto, 5 speed manual
Axle/Gears: 3.23 posi, 3.73 std
Re: 1987 305 TPI code 33... ecm help ?

Originally Posted by gurkgurkgurk
does that mean that an improperly adjusted TPS could manifest itself into a MAF code? i too am troubleshooting a code 33 problem

It is plausible that a bad TPS could set a code 33 as one of the conditions a code 33 looks to is the TPS sensor. However if that sensor fails it is unlikely that it will fail in such a way that it would not set a TPS code. However it is a condition that can be easily checked for by measuring the output of your TPS sensor.
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Old Jul 31, 2009 | 04:24 PM
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DA BRONX's Avatar
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From: PALM CAOST FL
Car: 1987 GTA
Engine: 305
Transmission: T-5
Axle/Gears: 373
Re: 1987 305 TPI code 33... ecm help ?

i have the same code.I have a mis when the engine is cold then goes away once it warms up around 190?
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