anyone know what it is? I don't feel like going to get my tech manual, esp when I'll just come here to find out how to fix it once I know what IT is :lol:

Code 34 on my 85 occasionally on startup. Thanks :cheers:

 

O2 sensor??? I don't remember the codes for that vintage...

 

Code 34= MAF '85-89(or MAP'90-91) circuit - voltage low

 

Jenn, Mr. Mojo is right this is a MAF code and means the ecm believes the air flow going throught the MAF is too low (or reading too low) based upon other sensors it is monitoring.

This can be a difficult code to troubleshoot, especially on an 85. The problem can be with the MAF sensor itself, with the connections to the MAF, or with just a host of other sensors or modules. Don't mean to discourage you, but this is what your are up against; could be simple or hard.

I don't know the 85 well, but I think it has a seperate module for the MAF, but this may just be for burn-off. This could potentially be the problem, but I don't know how to tell you how to figure it out. We need David F or perhaps Craig (did Craig have an 85 or 86?), or one of the 85 folks to help you out here.

Personally I would remove the MAF connector and make sure the connections are clean and tight. More then one code 34 problem has been just from loose or dirty connections to the MAF. Make sure the connections in the female end are all seated fully in the connector and right up to the end of the connector.

Other things to check are air leaks inbetween the MAF and throttle body, leaks in the throttle body, vacuum leaks. maybe even a really dirty throttle body or IAC. Erratic idle can cause a 34. I'm hoping David F can tell you why you might get a 34 on start-up.

Sorry I'm babbling a little, had to go to Vegas for dinner last night and just got back. NEED SLEEP! Hit the airport at 3:00am, 12 hours after arrival. That too much from the east coast!

At least this brings it ttt!

Hope it's simple,

Pete

 

Meant to edit my last post, Oh well wrong button.

Do a search from about 3 weeks ago on code 34, lots of discussion. Maybe ever over the last couple of months.

Be careful of years, you need general info but there are specific differences just in 85!

 

Pete, thanks, we have the 1985 Service Manual so I'll have my hubby look at it this weekend.

 

In my 86 I got the code 34 sometimes during startup also. My starting was dragging a little also. I put in a new starter and no more code 34. May not help you but it worked for me.
Good luck,
Mike

 

Need to know if when this code sets was there a problem starting? A code 34 is most commonly caused by excessivly low idle, yes it can be caused by other things but for the most part it's lower than normal idle that will cause it. You may also need to check the snorkel inbetween the MAF and throttle plates or any other large vacumn leak. Poor connection at MAF could be another possibility but would think it could happen any time not just after start up, but do take a look at the harness going to the MAF and it's connector and terminals. PeteL is correct in that 85 uses a MAF Modual instead of the relays that were in use after that. A code 34 could be relays in a 86 to 89 but none are used on a 85. MAF sensor is a possiblity but again with it only happening intermittenly on start up I think we need to look else were, first thing we need to know how the car started when the code set, if it fired up and then almost died then there is a cood chance that was the cause of the code then all we need to do is find out why that happened, but let us know how it happened.

David Fulcher

 

thanks David, I'll print this out and show it to my hubby. I didn't notice a low idle at startup when the code set but now I'll be on the lookout for it and let you guys know.

 

I'm having the same problem on my 87 on start up sometimes the check engine light comes on and code 34 is the only code stored. Every time I start my car I have to have my foot on the gas and it still takes a long time to start. If I don't put my foot on the gas it takes even longer to start. This is the way I bought the car and I haven't really got into trying to fix it yet. but now that I got other things fixed on the car I want to fix this. About a month ago the car died on me. That led to the tap test on the ECM and sure as poopie the car stalled when I tapped on the ECM. I installed a new ECM and Prom. So I know that is New from GM so that is singled out. I'm a Pontiac Tech so I have a 87 Firebird Manual to go by but was not sure the codes were the same on a Corvette. A guy at work said the TPS might be causing the long and stepping on the gas starts. I'm taking the Throttle body off tomorrow and cleaning it and checking the IAC motor. Please guys would love some more advice. Thanks

 

:confused:

 

There is a chance that because you are having to press the pedal to get the car started you could be setting the code, It will look at TPS in determining air flow so if you give it throttle and when it starts you have to keep the throttle open for a while that could be all that is needed to set the code you need to take a look at the IAC, I would just replace it, also clean the throttle plates and if you know how you may after you get it running check the min idle air speed. Do you work at a dealer? If you do you can go to SI2000 and look up the bulletins for an 87 there are a few good bulletins in there about working on MAF codes 33,34,and 36, but remember for the most part 34 is set because of near stall condition, yes a TPS can cause the same problem but if the car has a neer stall fix that first then see if it still has the same problem. The code will for the most part be the same, location of relays may not.

David Fulcher

 

David the code only comes up if I start the car and the idle drops really fast and almost stalls. Like if I have my foot on the gas when I start it and I let it right off. but when I start it and let it idle around 1,000 rpm's the light with never come on. Only when the idle gets low and jumps around. I still have not cleaned and checked the IAC motor yet. and I'm also going to do an injector balance test.

 

And also David with my car what I don't understand when I try to use the tech 1 on the car it always says waiting for data and that's all it does I have never got it to work. even with the new PCM still didn't work.

 

You have to use the "E" pin adaptor that should be with the Tech1, but then again there are so many adaptors it's hard to keep them in order.

David Fulcher