WhiteRider1

Hi all, new to the forum, from England and running a Firebird.

Problem
I bought my 91 firebird 3.1 V6 over a year ago and have been driving it a couple of times a week just local, a change in circumstance meant it was parked up for a few months, I nicked the battery off it when mine died so sadly it sat there.
Now, some fresh fuel in it and a charged battery it started first time but when I put it into drive it cut out and refused to start, things got in the way so a couple of more weeks later I tried again, wouldn't start(I had added fresh fuel again) I had 3 brand new spark plugs so thought what the hell I will fit them and I ordered three more, the three removed from the drivers side were soot black, heavy in carbon. then I thought why not try to start it, so after a bit of a struggle it started and ticked over nice.
Got it to temp and thought I will take it for a run, everything seemed fine, no concerns.
Did 5 miles or so when I came to a steep hill(maybe coincidence) half way up this hill it seemed to feel as if it wasn't firing on all cylinders and a loss of power, it remained like this for the mile or so home, as I pulled up outside the house it cut out and refused to start.
I removed all the spark plugs to check, all seemed fine, checked around couldn't see anything obvious and tried to start it, it seemed very lumpy and didn't sound good but next thing it fired up and sounded fine.
Parked it up and left it running, no problems, came out later that night, damp everywhere and it still fired up and sat on tick-over fine, first thing next morning, fired up first go and sat for ten minutes ticking over, not a problem, later in the morning I went out, stated again no problem, thought what the hell, take it around the block, drove sweet, thought I would take it around again, that's when if I pulled up it would stall, every time I came to a junction it would attempt to cut out unless you pressed the gas and kept driving, got it home and it cut out as soon as I stopped, started up but wouldn't keep running unless you kept the gas on.
Any ideas?

I have a code reader but sadly dosn't fit the GM port:|

WhiteRider1

Tootie Pang

iTrader: (2)

Welcome!

MAF (Mass Air Flow sensor) maybe?

I think there is a diagnostic port where you can read the codes from a sequence of light flashes from the Check Engine Soon light on the dash.

Here's a link to the post. It worked for me yesterday. I needed to troubleshoot a code.

https://www.thirdgen.org/service-eng...t-error-codes/

zs&tas

Def check the codes first. Its easy, I carry a bit of bent wire with me to read codes whenever I'm out and about.
Im guna throw in guess that is meaningless really until you get the codes but if its staying in cold loop, it will be overfueling when warmed up and may have caused the old spark plugs to go dark on you. May be a coolant temp sensor.

OrangeBird

iTrader: (1)

91 is a MAP instead of a MAF setup ...

To the OP , Start with the basics , a good cleaning of the IAC valve and a fuel pressure check . The IAC is almost always dirty cause it's something most folks are leery of messing with , and cleaning it costs you pretty much nothing but time . The fuel pressure check will tell you MANY things about your car's fuel system if done right ; do you have leaking injectors / leaking fuel pressure regulator / weak fuel pump / etc , the fuel pressure test will examine all these and more and is one of the first things I do with any fuel injected car that is running bad & showing sooty plugs .

Welcome to TGO , and I wish you the best on your troubleshooting journey ...

WhiteRider1

Thanks guys, I did the code read and this is what I got, sound right?

23. Low temperature at manifold air temperature sensor OR Throttle position sensor error
I also noticed it put down soot on the ground from the tail pipes this morning.

zs&tas

Low temp will over fuel which is what's happening, as cold air is denser it dumps more fuel in . But if it does that but its not actually sucking cold air it won't burn the fuel. If the sensor reading actually happens to be around real air temp, int'l run alright. Which would explain the occasional fault.
Try a new sensor, shouldn't be expensive and tick it off your list .
Usautomotive in Bedford are very helpful but sometimes pricey I feel. Ultimate spares of america are more reasonable.
Also grab a manual, it will be very handy

WhiteRider1

Sadly not starting at all now, will have to purchase the sensors and see how I get on, don't have a multimeter to test the Throttle position sensor

Thanks I will price up the parts from them.

Has anyone got the GM part numbers for there parts?

Tootie Pang

iTrader: (2)

You can probably get those at O'Reilly, Autozone, etc.

OrangeBird

iTrader: (1)

If your running SO rich that soot is actually being deposited on the ground under the tailpipes you've got a lot more going on than just a sensor failure . The cold running rich mixture (the same effect a choke gives to an engine with a carb.) will only enrich the mixture to a pre programmed degree , and no where in that programming is the ability to dump THAT much fuel into the engine .

Now , there are two ways folks troubleshoot automotive problems . One way is to throw new parts at it that are likely contributors to the problem . This method , called the "shotgun" method , can get costly really quickly depending on your "luck of the draw" . Will the bad part be the first one you change ? The fifth ? What if you change ALL the likely suspects and it STILL runs poorly , then what ? ....

The second , much preferred method , is to actually troubleshoot down to the exact failed component and replace only that . Sure , it may cost a bit to rent the tools needed to do things like the fuel pressure check that I already told you to do , but these tests will produce the positive result of pointing out the exact failed part minus the costly replacememt of all the other parts till by luck the actual failed part gets changed .

PS , don't discount the possibility that there are more than one failed part(s) contributing to your problem . For instance , your MAT or TPS very likely could be failed according to your trouble code # 23 , but that alone shouldn't outright kill the engine , there are pre programmed "limp home mode" parameters covering both the MAT and TPS sensors that should allow the engine to at least run (at reduced power) . The fact that it won't run at all and was leaving the soot trail on the ground when it did indicates a huge amount of fuel being dumped and the fuel pressure test will show whether that is the result of leaking injectors or a ripped fuel pressure regulator diaphragm (the two most likely causes of THAT much fuel being put into the engine) .

OrangeBird

iTrader: (1)

PS , a VERY cheap check for a ripped fuel pressure regulator diaphragm is to unplug it's vacuum line going into the throttlebody and see if you can see/smell raw fuel in that vacuum line . Raw fuel in that line is proof positive of a ripped diaphragm , but the lack of raw fuel is not an indication that the regulator isn't mechanically hung up (stuck) . It's tests like this , that are mostly free , that can point you in the right direction .

If you choose to rent/borrow/buy a fuel pressure gauge let me know and I'll walk you through the tests/diagnosis it can provide .....

zs&tas

Agreed there if its that much, fuel pressure regulator needs checking. Still you want to know that the sensors are all good too otherwise it will never run right.
I highly recommend getting a multimeter for testing things down the line, at least you can check the tps then

WhiteRider1

Hi all, well I was working last few days so didn't get a chance to do anymore, I have roadside recovery and when I checked I have homestart, so that means a mechanic free of charge for one hour, called them and arrived sometime after.
He chacked the fuel, no problems with fuel delivery, he suspected the coil or distributor, sound right? will the error codes I had be correct or wrong or give a similar reading for the coil,dizzy?

zs&tas

He suspected the coil, did he check it ? I think the codes are seperate little issues mate. It should run with them .