OMG I hope i didn't mess up my computer and out $184.76 - Third Generation F-Body Message Boards

85ta4bm · 05-31-2009, 09:59 PM

last week i did the paperclip trick to check and see if i still had a code 33, well i did so i said fudge it and gave up and went to the parts store and ordered a new maf sensor. Today i hooked up the new sensor and started the car (Ran like crap) than i noticed the check engine light flashing, shut her off and quess what, i still had the paperclip in. Would that mess up any thing like short out my computer? I really hope not.
I checked the codes again (took the paperclip out this time lol) still got a code 33 + 42. Looked it up EST module I think, just just went out and i forgot to plug in my est wire from timing it. K cool at least I'm not out $184.76 for the new maf sensor. I take it off and the 5-pin connectors are a little scratched from the connector. Anyway to get those off? I can provide pics if needed.

madmax · 05-31-2009, 10:41 PM

Code 33? Still have the 85 electronics? Might be time to swap to a newer ECM.

wanta427 · 05-31-2009, 10:56 PM

I think running with the paper clip is how you can tell if the computer goes from open loop to closed loop (it's faster 1 way but can't remember which )

85ta4bm · 06-01-2009, 12:27 AM

Ya i still got the 85 electronics, I've been really thinking of upgrading to a 86-89 ecm, just don't think i'm up to that right now, maybe with some more reading and learning to repin on some things i don't care about and most importantly some free time from three part-time jobs.

85ta4bm · 06-01-2009, 12:36 AM

I know the other solutions to the code 33 problem. 1. Shotgun lots of more parts, 2. buy a eprom burner, software and learn how to burn chips(change my gms/sec to 255 I think) and tune, 3. 1. find somebody to burn a chip for me.

1. tired of wasting money on this thing.
2. Don't have the time right now for that.
3. I've tried, but no luck from somebody around here.

madmax · 06-01-2009, 01:15 AM

Generally, the MAF is not the issue. I dont think you hurt anything leaving the paperclip in either.

With your code, chip burning is going to be more problematic because most have not messed with that code... and worse yet its likely not your issue. The 85 are notorious for setting a code 33 when the MAF module goes out (and those are known to do that) and once that happens unless you have a free replacement module that works laying around its time to trashcan the whole deal.

At this point, I'd see exactly what circumstance sets the code and go from there. If its on startup thats not good. There is a flowchart around here for what criteria are required to set the code 33 and that is where you should start to see what might be the root of the problem. Its possible that with a 350 (is that what you have?) that you may be exceeding the airflow the ECM is expecting and throwing the code, but without knowing exactly what circumstances it is set, I dont know. Try clearing the codes, and then see what happens on your next start.

Quote:

from vader
You really don't need anything more than a good volt/ohm meter to diagnose the system. With the igintion ON and engine not running, make sure the correct voltage and grounds are present at the MAF terminals.

Test the MAF Signal Voltages

1. The MAF signal circuit (Terminal C) should be less than 0.3V with the ignition on and engine not running.
2. Disconnect the MAF electrical connector and test the voltage again. There should be a 5VDC reference voltage from the ECM.
3. Verify that the TPS voltage is between 0.47 and 0.61VDC.
4. Test for voltage in the MAF burn off circuit (Terminal D at the MAF) while the ignition is on, engine off or running. Any voltage present can cause the MAF signal at the ECM to be too high.

Diagnosis

A code 33 is set when the ECM has detected an intake air flow above 45 grams per second (about 2.2 volts) for one second when the engine is first started or at ant time when the TPS is less than 1/4 throttle and RPM is less than 2,000.

If you discover problems in the voltage or grounding checks, re-seat the connectors at the ECM and check all the circuit grounds. Make sure the connector at the MAF itself is intact.

If there is a problem with the 5VDC reference voltage from the ECM, re-seat the ECM connectors and/or test for the correct voltage directly at the ECM terminal B12. If there is not 5VDC source (± 0.6V) present, the ECM itself may have a problem.

With the ECM connectors clean and connected, if the reference voltage is significantly higher than 5VDC, there may be a problem with the other wiring shorting to that circuit on the vehicle.

If you are able to read voltage at the MAF burnoff circuit, remove the MAF burnoff relay and retest. You can even run the car in this mode, but will eventually set a "36" code for the burnoff failure.

If all voltages are correct, and all grounds and connections are intact, the MAF itself may have problems. A MAF failure causing a "33" is uncommon, but I suppose it is possible. It is generally more common to find circuit problems or a TPS adjusted too low.

Connecting a 12VDC power source to the fuel pump test terminal ("G" terminal of ALDL) will provide power to the MAF sensor, and the MAF signal circuit should create a low voltage (less than 250 mV) signal to the ECM. Monitoring the MAF signal voltage in this mode and wiggling the circuit connectors and wiring may allow you to detect any intermittent problems. Similarly, an erratic MAF signal with the engine running may indicate wiring or connector problems.