Ok, So for the last week I have been trying to get my car to run with out stalling. I have a 1987 pontiac firebird formula (305tpi) I replaced the pig tails at first, for the power relay, burn off and fuel pump. I then noticed the platinum wire inside the sensor was broken , so i went and bought a new bosch maf sensor and replaced the relays at the same time. BW R3009 MAF power and BW R671 MAF burn off. still code 34. i checked the ecm just visually to see if i could see anything that looked off and all seems fine.I checked the inline fuse near the battery and it works fine. checked all the vac lines and the pcv valve. i tested the tps .058 and i ohm it out all was fine. i replaced the iac a few months back but i still checked it and its fine. I checked the pigtails on the maf they look brand new. printed out a few wiring diagrams and everything seems to be correct.

My symptoms after i disconnect the battery for 10 mins are it starts right up and check engine light turns on. idles fine most of the times, then when i go to put it in gear it idles horrible. go to put it back in park and the idle barely recovers and maintains a horrible idle.

I am stumped and don't know what else there is to check?
Thank you in advance.

 

??

 

use the trouble tree

 

Thank you, can you please resend again I am unable to open it and it is very small.

 

 

Thank you, its raining here today will check tomorrow

 

There is a known good used maf in the classifieds for $60 in a part out thread. If it turns out to be the maf you are better getting a used bosch than a aftermarket or reman cardone.

 

https://www.thirdgen.org/forums/engi...87-iroc-2.html

 

That was the first thing I bought a bosch mass air flow sensor from pepboys but the code 34 never changed, even with the new and correct relays?
Thanks

 

Code 34- This indicates a faulty maf sensor, depending on your tpi system. MAF: This code is set when the ecm sees the following conditions: airflow less than 2.5 gps, engine speed of 600 rpm or greater and the tps is above 6% angle. The typical problems are usually false air, vacuum leaks, or residue build up on the maf element or behind the throttle plates. Check the wiring and connectors very carefully.

These are the conditions to set a code 34, maf low signal, loss of signal, vacuum leak, bad ecm or maf signal wire to the ecm.

 

Have you checked the fuel pressure? When you shut the car off how fast does the fuel pressure bleed down to zero? I have done a lot of trouble shooting on these cars and have found the main cause of most code 34's to be leaking fuel injector nozzles. Also ohm test the injector coils.

I like to call it a false 34

 

I have a funny feeling it's a bad wire shorting somewhere. I haven't checked the fuel pressure yet, I let a buddy borrow it and he is now in boot camp. I will go get another one today and check. By the way if i had the car professionally scanned would that tell me where my problem is?
Thank you

 

Scanned like at idle GPS reading ? , you can ohm out the signal wire on b12 of the ecm to the maf sark green wire.

 

ok, so fuel pressure was 41 psi after 5 mins it was at 36psi.

Scanned i mean take it somewhere so they can hook it up to a computer to point me in the correct direction. or is code34 all they will be able to see?

I decided to take the iac out and set it to 28mm and reset it following instructions by the book, which i did and nothing changed. so I took it out and grounded a and b terminals and it didnt move so i flicked it and it moved a little, i flicked again and it moved a little more. Weird?

i put in a old iac that seems to work better but after setting the iac it was to high so i went to adjust the idle screw down and nothing changed, i checked the tps and it was all the way down to .034 but idle wasnt dropping?

And I still have code 34?

Thank you

 

Do you run a K&N filter?

 

yes but it's identical to the original design and i don't use oil on it.
I just started it and it seems to run ok but as soon as i go to put it in gear it struggles to maintain for a second then balances out. Then when I go to put it in park the idle goes up then immediately drops down to where it would be in park? still code34?

Thanks

 

Bosch meters are known to have high failure rates, sounds like you are in denial about yours failing. (we all are lol)
Try cleaning the MAF wire with spray cleaner. Even though you don't use oil on it, they come with oil on them.

 

I guess your right, really disappointed because i just bought the mass air flow sensor last friday.

 

Ok, so I exchanged it and my code 34 is now gone. Seems to be about 90% better just need to fix iac.
Thank you for your help.

 

So it did ended up being your Mass AirFlow sensor right?

 

Yeah, I bought one from pepboys but it must have been defective. I returned it and all was better. I didn't realize but the pepboys here guarantees to beat any other auto part stores price if you bring them the price from say autozone.
Thanks

 

Nin87,

Glad to hear everything worked out for u. Now I have to chase a Code 33. Probaly the Mass Air Flow sensor as well. lol

 

This should help with the maf high code
https://www.thirdgen.org/forums/tpi/...ions-here.html

 

I personally know my sensor was bad and all i was getting was code 34. When I unplugged the maf burn off relay i got a code 33 and code 34. I couldn't find the original relays at any part store but did find the identical ones, different brand which i listed the part numbers earlier in this thread. I was able to get those at pepboys as well. Autozone sold me a burnoff relay and said it was the power relay, so don't trust the cashier..lol

 

Nin87

Which brand Mass Air Flow sensor did you buy?

 

Bosch

 

I did see some cheap ones on ebay, thou i am not sure I would trust them?

 

From Pepboys?

 

Yeah of course it was remanufactured, but with the warranty you know you cant go wrong bring in your old one. I think it came to 137.00 with tax here is the link http://bit.ly/1c8N5iT

 

Did you check your relays and pig tails?

 

If you come across a used MAF from an 88-89, it will work fine. After I replaced the TPS sensor and IAC sensor, my car still acted a little odd (idle). I swapped my MAF with one from an '89 350 TPI, and saw a noticeable difference in the behavior.

If you compare the two MAF's, 86-87 and 88-89, they are slightly different in construction, possibly an updated design. A MAF from an '85 would not work at all.

 

I have read this through, I have one question: is it possible for a k&n filter to be the sole cause of a code 36, if the car runs perfect but the ECM sets hard code 36

 

I wouldn't think so, I was getting code 34 and that was a bad maf sensor or power relay. When I unplugged the Burnoff relay, that's when I got the code 36. Did you check that relay? I know if you switch the fuel pump relay with the burn off relay and the fuel pump doesn't prime then its the relay. Did you clean the platinum wire? mine was broke

https://www.thirdgen.org/forums/atta...1&d=1393280398

 

Yea I played with the relays, I had a new ac delco one laying around. I actually performed a test on the relay to make sure it was functioning correctly, all three worked fine. The thing is I didn't touch the maf yet, I, like many have the misconception that it cant possibly be the maf. lol.....until I saw this thread

 

I would check the platinum wire inside and if it looks fine then clean it with maf cleaner. Did you ohm your wires at the pigtails? mine had black goop in every single slot. Also did you ohm your wires from the relays to the maf pig tail? make sure your grounds are good. in my pursuit of finding the problem i some how fixed a ground issue with my stereo...weird. How is your car running?

 

The maf sensor looked pretty good last time I checked it. I didn't see anything burnt out. Now as for the terminals, I was thinking of replacing them (not cut and splice in a pigtail, but rather just replace the terminals. In other cases in this car, there was some separation from age and what not causing intermittent to no connection at all (notably steering wheel control for radio) And the maf ones were a little loose for my liking. So that is one thing I have to pursue. I didn't ohm all the wires, I guess that is another thing I have to add to the list to finish. The car runs beautifully actually. The occasional fake out with stalling (she fakes me out) while at a red light (and difficult at lower temps to start her and keep her running for the first few seconds) , but otherwise, she runs good. I do plan to tear down the engine bay a little, clean it up, etc. I was kinda hoping that by cleaning the maf it would solve my problem, because I did run a K&N filter for a while. Actually it was around the same time that I installed the K&N that I began to experience this problem. After performing the FSM diagnostic tests several times it set another code, 34. And this was after unplugging, replugging everything, so I thought there was a correlation (loose terminal pins). Another thing I do have to add is that I had a performace chip on the prom. Could the chip affect the programming on the prom. I replaced ECM - thinking it was the problem (b/c it would not ground for the burnoff) but not the PROM. Could the PROM cause it not to ground the burnoff- just a thought ...And that's my rant

 

I would definitely ohm your wires from the relays to the maf pig tail. I noticed some of my pigtails at the relays looked almost frayed, almost to the point like they could be touching or morning dew could have caused a short. I had cleaned my maf about 2 months before it broke out of the blue. Did you clean your IAC? I once had a problem that a wire on my iac was touching the alternator causing some very strange problems like stalling at lights and hard start, I heard the IAC can cause code 34, same with a vac leak or tps. Which im sure you know are very easy and fast to check. Also before my car went in to straight limp home mode, I noticed my car was getting very hard to start and idle extremely rough when cold. I have always had a K&N filter with oil, but i purchased a non oil filter now to be safe. I know that oil on the wire can cause havoc being as though it doesn't evaporate and dirt sticks to it. you didn't switch the burnoff with the power relay, or did you? I am no good with proms though im sure they have a thread about that here at thirdgen. If i had to assume, I wouldn't think the prom itself would cause a bad ground. I'm leaning more towards relays and wires.

 

could this also cause our cars to be hard to start and idle rough when cold I have an 98 2.8 v6 that will turn over and run rough for a few seconds and will stall out until I get a little heat in it.

 

My iac is clean last I checked, the vac is another thing I will have to check on. I did not know it could set off code 34, must've missed that. I replaced most of the hoses, but the bigger ones I couldn't find yet. My car was hard to start. Actually I blew the oil pressure sensor by overcranking and replacing it fixed it. But when it's like 20 or 30 degrees outside, if the engine is cold, she will start and as soon as every cylinder fires at least once she will shut off. The next start right after is perfect. As for the relays I switched them both around (both that were interchangeable) and tried the spare, but I will try that again and verify all relays are good. I gotta keep searching about the prom. I put the chip in around the same time I put in the k&n and I have removed both since. When I clean the maf I will know for sure. As for the wires, I did see one that was frayed but that was for the fuel pump relay and I have to fix that again when I pull her out in a couple of weeks or so (after the snow leaves).

 

lma47940: Personally if I thought my iac was causing my hard start I would try and start the car with my foot slightly on the gas and see if it starts and doesn't stall, if that works I would take the IAC out and see if it has a bunch of carbon on it. try cleaning it with a mild cleaner maybe maf cleaner and a drop of oil and see. I tried to take the pintle out a long time ago and broke the white plastic inside so I wouldn't try taking it out..lol. Though I also had a wire from the iac ground out on the alternator and the pintle wouldn't move causing a very hard start. I believe the coolant temp sensor works with the ecm at low temp, I don't think it would cause stalling. Do you know if its running rich or lean?

alex722607: Code 34 from my understanding could be set from tps being set wrong, air leaking in from somewhere above the mass air flow sensor itself, air leaking in from injectors, bad relay, bad ground, or bad sensor. Its ridiculous the amount of things that can cause a code 34. It drove me crazy trying to find my problem. also you said you replaced your oil pressure sensor, I read somewhere that people were having problems with a wire grounding that goes to the oil pressure sensor and it was causing a code 34. Also just to be clear your changing the fuel pump relay and burnoff relay. I know the maf sensor power relay is different I have a part number for the power relay which pepboys carries, "borg warner r3009" -advance auto,auto zone,pepboys all will sell you the burnoff and say its the power relay. but make sure you get r3009 if you need a new power relay

 

I just realized something. My car is vin f, but my dad put in a 350 in the 90's. At first he didn't even change the injectors from 305 to 350, till one day it stalled and scared the crap outa me and then we swapped them. But one thing I know for sure, he never got the 350 prom. Would running a stock 305 prom on a 350 engine be a cause of code 36. I know code 34 is listed as one of the possible false codes. (don't know if it's post gm-upgrade or not- the older ones I am led to believe gave false codes)

 

she smells rich. iac?

 

With foot on gas it will start easier but still stalls out. Once i get her to stay running she has a very rough idle (1500-475 rpm) and bogs down or stalls if you hit the gas

 

alex722607 Do you personally have a custom prom for the 350 you have now? at the moment are you running a prom for a 305?

 

lma47940 Have you played with your tps? you said it will start easier with your foot on the gas, does it die with your foot still on the gas or do you take it off and then it dies? What is your voltage at your tps with the key on ignition off? do you feel the stepper motor in the iac ticking? have you cleaned the port the iac sits in? also do you have a/c...if so does the idle recover when you turn it on? if the iac is not working as it should and funds are short you could try opening if the throttle body a smidge , then adjust the tps to correct levels. though I would first clean everything real good before you do that. Is there alot of carbon in the throttle body?

 

It stalls with foot still on gas. i have a/c but doesn't work right now. Im cleaning the iac port right now. when should the iac moter move. Tb is pretty clean inside tps is reading corect from what i can see

After she warms up every thing smooths out and she runs just fine

 

No I don't. I actually didn't know about this until reading another thread. She runs pretty good, goes through gas a bit quick and at times I think she is going to stall, but doesn't and like I said b4 the trouble codes and hard starting in cold temps. Also now that I think about it ( I haven't driven her since November) when I shift into gear the rpms drop from a good steady idle to around 400 to 450, then they come back up later. Also at 36 mph steady cruising the tcc shifts btwn gears and I have the tranny replaced twice so it's not that. And at the moment I am running a 305 prom.

 

Running a 305 calibration with 22#hr injector the engine will run rich. The maf code 36 will not be thrown if you are using the incorrect calibrator. You should go though the service trouble tree to diagnose the issue properly.

 

Already went down the trouble tree multiple times. Now I am looking for anomalies, PROM/mem cal, loose, bad connectors, k&n air filter oil on maf, etc. figured that code 36 and intermittent code 34 would/could/ might be tied to something else.

 

Intermittent issues are usually cause bye corrosion at under hood terminals, wire damage, fatly ecm or dcm ground.