after ive replaced the o2 sensor, put new plugs, oil change...the car tried to turn over once..fired for a split second then died...later that night it started for like 2 mins then died...now im gettin a code 34....MAP sensor and MAF sensor...should i just replace them both?

 

I believe they use the same code 34 for MAP or MAF sensor, but your car will only have one or the other, not both.

How was the car running before the new 02 sensor, plugs and oil? Okay? Or did something about the way it was running prompt you to replace the 02 sensor?

Any chance you popped a vacuum line off to the MAP? (mounted on the firewall, I think)

 

well...im not sure where tha MAP sensor is, but i dont see any vacuum leaks around...all hoses attached..no holes or cracks..i think i might just go take a look at MAP, MAF sensors, and a new dist. cap...just to see.

 

What year/model/engine do you have?

 

the car will run with the MAP sensors vacumm hose disconnected. Mine did but idled extremely high. Is your car TPI? if its TPI then you have a MAF sensor but if you have a TBI car then you dont even have a MAF so that couldnt be the problem.

 

i have a MAF sensor its obvious..ill just replace it =\

 

Before you just replace the MAF, a little diagnosis might help. I'd hate to see you drop $180 on a new Wells MAF when a $10 relay might repair the problem. Exchange the MAF power and burnoff relays, clear the error codes, then restart the engine.

While you're swapping relays, it might be a good idea to check the MAF connector, and make sure the intake air hoses and ducts are sealed. Even a TPS that is out of adjustment can set a '34'.

 

A MAF is like $200. That's not the sort of thing you just up and replace on a lark. Don't do that unless you are sure it's bad, which you have no way of knowing yet.

Neither the MAP sensor nor the MAF sensor will cause the car to run and then die. There's still some other problem going on.

Make sure every vacuum line is plugged in correctly. The MAP (Manifold Absolute Pressure, aka vacuum) sensor is on the firewall not far from the distributor. It hooks to the plenum pass side rear IIRC. If you've been working around the distributor, there's a good possibility it's disconnected.

Sounds to me like you still have your original problem, and it's still fuel delivery. Sounds like nothing you've done so far has been a logical attack on the actual problem, but rather an attempt to shotgun the problem by just replacing parts until you accidentally happen to replace the right one. And at the same time, it sounds like as you've rambled around under the hood messing with stuff that was OK to begin with, you've created other problems that weren't there before. There's an awful lot of parts on that car and alot of them cost alot of money. It may take you a long time and a major wad of cash to get your car back on the road that way. You need to stop that, and adopt a mental discipline of actually zeroing in on the problem logically. Clear your mind of the "maybe it's this, maybe it's that" irrationality, or the notion that the computer is going to spmehow pinpoint the faulty component and tell you exactly what to replace; neither one will get you anywhere.

Go back to the basics. Fuel/air, spark, compression. Forget the computer and the sensors. The engine ran for a couple of minutes, so compression is probably OK. Right? now we only have to investigate 2 of the 3 necessary ingredients of success. OK? See how this works? Now... buy a can of starting fluid, take the air duct off the front of the MAF, and spray some of it in there. Try to start the car. One of 2 things will happen: either it will start, or it will not. If it starts, then you know you have a fuel issue, because now you know it runs when you supply it with fuel. If it doesn't run, then you know you have a spark problem, because fuel didn't fix it. It's pure logic, and cannot lead to a false conclusion, and will not cause you to spend money needlessly.

Let us know if it runs on starting fluid.

 

ok maybe i havent been detailed enough....the reason im goin around replacing all these parts is because im fiding out that they are bad, or almost bad...thats why im replacing them. ive already tried the starter fluid in the intake...nothing...ive also taken a spark plug out and put it on the wire and turned the key...no spark...i know its gotta be a spark issue. thats why i thought the dist. cap was bad, since i took a look at it...and no the vacuum lines on the MAP sensor are fine...maybe a few sliight tiny vacuum leaks..the car ran great before it suddenly didnt want to start anymore...im thinking it might be the coil since theresno spark. but i dont know if my coil is bad or not. before the car stopped starting, it would drive fine..then suddenly loose power..engine still on but when i hit the gas..nothing..the it would die, and start back up 10 mins later. i know its not a fuel issue because i can smell the gas when i try to start it. it sounds like theres no spark at all.

 

by the way if it helps its a 87 2.8L v6 w/multi port FI

 

OK, that's better. It helps when you tell us the whole story, we have no other way of knowing it.

Don't go changing the MAF just yet. That might just be $200 down the toilet.

A no-spark is almost always something in or around the distributor. You can take the distributor module to Auto Zone and places like that, they can test it. More than likely, if you have no spark and the rotor is known to be good (i.e. you just replaced it), the module is at fault. Take the coil with you and have it tested too if the module checks good. If the module and coil both test good, the only piece left is the pickup coil, which requires removal and disassembly of the distributor, at which point it's just about as sensible to replace the whole dist with a rebuilt one as it is to try to repair the one you have. But that's not real likely.

Like I said, there are so many parts in the control system on your car, if you just go changing everything you think might be bad, you can run up a thousand dollar ticket in a hurry, and your car still might not run. Get the car running before you go swapping computer control parts just becasue of the codes. The computer can only deal with diagnosing one thing at a time; the codes are only useful if everything else except that one thing it says is bad, is working perfectly. It gets just as confused as you do by a multiple-defects situation.

 

Check the air dcuting between the MAF and the plenum (guess it's a plenum on a 6?), also, disconnect the MAF electrical sensor to rule it out...but it sure seems like you have a leak between the MAF and the intake/plenum.

 

my car would have that problem too.
it would start, then die, sometimes it would have problems starting then other times it would not. when it did fire up it would stay on and run fine.
it was my MAF sensor
when they (dealer) replaced my engine they damaged my MAF sensor, lucky for me they replaced it for free, and the car ran fine.
I was also getting a code 34
biker

 

You might want to check the relay(or something or other)that is on the distributor shaft, when they go bad you will get random starting/no start/start run till warm then turn off and not start again etc, it is a 5-10$ piece but you have to pull the distributor and also for some reason at the same time check the fuel pump mine went wacky at the same time, guy at the dealership said it happens together for some reason I dunno, but those 2 problems fixed got me runnin again plus check the ICM while messing with the dist also, took me 2 of them to get a good one replaced, anyway hope this helps, I replaced everything from the MAF back till I had it figured out(cost me tooooo damn much, lol)
1988 Firebird 2.8

Also you will still smell fuel that is why I didnt think it was the pump also, but it wont keep pressure in the rail or to even barely run, kinda throws yah off huh,