My car has been idling bad in Park and it goes dead at redlights once it heats up. Yesterday I got a Code 34 (MAF, Low voltage High Vaccum). I have checked the connections and they seem to be okay. Is there a way to test the MAF or the MAF burnoff relay?

 

Does this car have the stock computer and if so do you still have the prom chip in it that ame with the car in '85?
Those chips were bad from the factory and one of the problems they caused was a false code 34.

 

The problem is that the car idles really bad and dies at redlights. I don't think it is a false code. It has only thrown the code once but the car continues to idle bad and die.

 

The code 34 is just one of the symptoms of the chip. It is a problem where the chip is slowly corrupting and the car gets worse and worse over time. It took mine over 3 years to get the first symptoms.

If you think it is the MAF, try rapping (lightly) on the MAF housing with the engine running and see if that makes a difference in the way it idles.

Oh, and your setup doesn't have a burnoff relay. You have a MAS module that is piggybacked on your ECM, it supplies the MAF power and burn off function for the MAF, and it costs somewhere around $800 from GM.

 

That would really suck it that is the problem. What would happen if I tap on the MAF? It already idles like crap. Will the engine shut off? What else would you suggest in determining what the problem is?

 

Okay, so I lightly tapped on the MAF and nothing happened. What does that mean?

 

If the idle didn't change at all it doesn't really prove anything, but if it had changed it (gotten better or worse) it would have proved it was bad.
Do you know anyone that has an 85 MAF car you could borrow the MAF from? If so and that makes no difference, I'd change the prom chip. When I replaced my prom it cost $44 from GM and cured all of the problems I was having. It could also be the ECM that is causing the problem.

How old are your plugs, wires, cap & rotor and coil? If the coil is origional I'd replace it, 18 years is a long time for it to last.

You could also try setting the minimum air and TPS.

 

If there is anyone on here from the Richmond, VA area that will let me borrow their MAF for a few minutes I would appreciate it greatly. I did a complete tuneup just a few months ago. This didn't start happening until after I replaced the transmission. I don't know what that would have to do with it though. I also removed some of the AC stuff but again, what difference would that make.

 

The only thing I can think of is that maybe some wiring got pinched and is grounding, Thats about all you could mess up doing a tranny swap.

 

Yeah, that's what I was thinking but I checked all the wires and they are good. I got 15V on E and 5V on C. D had nothing but this is with the connector unplugged. I couldn't get a good reading with the connector plugged. Couldn't get the leads into the back of the connector. Could an exhaust leak cause a code 34 and cause bad idle. I don't think I have an exhaust leak but I'm not sure. Just trying anything possible.

 

code 34 here too, doesnt really die, just sometimes "misses" at random occasions, and after it starts up after night its real ruff, but once warmed up its' fine..

id let you use my maf but it's a v6 so...that wont work

 

I haven't found that the burnoff circuit is likely to cause a 34. My Burnoff issues have always kicked a 36. That's not to say it can't happen, but....

I would look at other areas. Having a spare relay is a must-have for anybody with TPI anyway, so pick one up and try changing the MAF power relay. I would think this relay is your culprit. If that doesn't fix it, you may want to try and find a spare ECM to swap.

I was having all sorts of MAF & code 34 problems, and the behavior was different with the Wells MAF than with the stock MAF. It was driving me crazy because I couldn't diagnose it. I finally determined that the ECM and the MAF Power relay were bad. Once I replaced both instead of just one, my MAF problems disappeared.

 

I have a question to ask you. Do you use a K&N air filter? One problem I found was that I get a code 34 just a couple of days after I clean and re-oil my K&N's...... Found out rather quickly that spraying the MAF with electrical contact cleaner was way cheaper than replacing the MAF......

I've owned an 85 TPI for the last twelve years so I have just a tad of background with this problem.......

 

You've got to be using way too much oil. I've had K&N's on my 85 for 16 years now and never had a code 34 from cleaning and oiling them.

 

I've only actually had it happen a couple of times. But the first time I bought a new MAF becaue I was way out of town and couldn't take a chance on getting stuck. Once I figured out what it was, like looking at all the oil on the inside of the MAF, I knew what to do.... Forget turning it in for the $25 core charge... Gut that puppy and use it at the track!!!!!