How does a bad MAF act?
Thread Starter
Registered User
Joined: Nov 1998
Posts: 150
From: Murfreesboro,Tn
black smoke hmmm, means rich. I duno man maybe when the pump is failing the computer is trying to open the injectors more and more to give the engine more gas and when to pump finaly kicks it runs really rich untill the computer readjusts to getting fuel.
The one thing that is reall really weird is that you dont have any codes in the computer, a car running as bad as you are describing should be throwing several codes i would think.
When you unpluged the MAF did the check engine light come on?
Are you just guessing that their are no codes or did you have the car scanned?
If you are short on cash then i would wait untill you can have the car scanned untill you buy anything.
ANYWAYS to hook up the gauge, first off buy a fuel presure TEST gauge.
it will have a hose on it that will screw into a shard valve (the type of valve that is on a tire)
Behind the intake is where the LT1 shard valve is, it has a plastic cap on it that unscrews, just screw the fuel gauge into that (becarefull because some gas will shoot out).
Also if you have the cash ($75 each) buy the 2 upsteam 02 sensors (dont by the bosh ones they are crap) 90% of time if these are bad they will throw a code, bt it is way past due for you to change them.
Also when you did the tune up did you replace the coil?
Double check you coil wire is on tight.
The one thing that is reall really weird is that you dont have any codes in the computer, a car running as bad as you are describing should be throwing several codes i would think.
When you unpluged the MAF did the check engine light come on?
Are you just guessing that their are no codes or did you have the car scanned?
If you are short on cash then i would wait untill you can have the car scanned untill you buy anything.
ANYWAYS to hook up the gauge, first off buy a fuel presure TEST gauge.
it will have a hose on it that will screw into a shard valve (the type of valve that is on a tire)
Behind the intake is where the LT1 shard valve is, it has a plastic cap on it that unscrews, just screw the fuel gauge into that (becarefull because some gas will shoot out).
Also if you have the cash ($75 each) buy the 2 upsteam 02 sensors (dont by the bosh ones they are crap) 90% of time if these are bad they will throw a code, bt it is way past due for you to change them.
Also when you did the tune up did you replace the coil?
Double check you coil wire is on tight.
The SES light DID come on when I unplugged the MAF. I will buy the test gauge you mentioned. I dont KNOW that there are no codes in the computer, its just that the SES has not been on until I unplugged the MAF. I WILL get it scanned. I will also buy the O2 sensors this weekend.
Money isnt a REAL big issue, I just dont want to throw money at it, I'm an old retired guy that bought this car new and I still love it.
Thanks.
Ron
Registered User
Joined: Mar 2003
Posts: 1,146
From: Maryland
most parts stores will scan your car for free (dont pay the $75 some people charge.
Since you unpluged the MAF that code will still be stored in hte computer, so ignore it for now (but dont forget about it)
Do you still have catalitic converters?
Since you unpluged the MAF that code will still be stored in hte computer, so ignore it for now (but dont forget about it)
Do you still have catalitic converters?
Thread Starter
Registered User
Joined: Nov 1998
Posts: 150
From: Murfreesboro,Tn
I went to AutoZone to get it scanned but they said they cant do 95s, just 96s and up. I'll have to find a place to do it.
I DO still have a cat, the car came with a single cat and about 5-6 years ago I replaced it with a single Random Tech cat..
Thanks. Ron.
I DO still have a cat, the car came with a single cat and about 5-6 years ago I replaced it with a single Random Tech cat..
Thanks. Ron.
Registered User
Joined: Aug 2002
Posts: 2,325
From: BC
I'd replace the O2's and Coil. Sounds like its one of those 
MAF is OK(or at least not the cause of this problem) if it ran the same with it unplugged. Double check to make sure your not arching! Is idle smooth or shakey? If its shakey it sounds like you may have crossed wires...
If its breaking up at WOT only (high rpm) its the Coil - I've had this symptom twice.
If its breaking up when your just accellerating its either a really bad coil or more likely your O2's or perhaps your MAP sensor reading wrong.
Does this happen when the engine is cold or only once warmed up?
If it does this when cold I would lean more towards the coil or MAP.
There will be some some guesswork for you if you don't have access to a scanner
There are a lot of things which can cause your backfiring situation, and since you've changed the basics its almost for sure a sensor.
Personally if money is not that big of an issue (and you don't have access to a scanner)I would replace the O2's, MAP, Coil, Coil Wire since it doesnt sound like you know when they were last changed. It'll give you some piece of mind for future problems as well
MAF is OK(or at least not the cause of this problem) if it ran the same with it unplugged. Double check to make sure your not arching! Is idle smooth or shakey? If its shakey it sounds like you may have crossed wires...If its breaking up at WOT only (high rpm) its the Coil - I've had this symptom twice.
If its breaking up when your just accellerating its either a really bad coil or more likely your O2's or perhaps your MAP sensor reading wrong.
Does this happen when the engine is cold or only once warmed up?
If it does this when cold I would lean more towards the coil or MAP.
There will be some some guesswork for you if you don't have access to a scanner
There are a lot of things which can cause your backfiring situation, and since you've changed the basics its almost for sure a sensor.Personally if money is not that big of an issue (and you don't have access to a scanner)I would replace the O2's, MAP, Coil, Coil Wire since it doesnt sound like you know when they were last changed. It'll give you some piece of mind for future problems as well
Thread Starter
Registered User
Joined: Nov 1998
Posts: 150
From: Murfreesboro,Tn
I'd replace the O2's and Coil. Sounds like its one of those MAF is OK(or at least not the cause of this problem) if it ran the same with it unplugged. Double check to make sure your not arching! Is idle smooth or shakey? If its shakey it sounds like you may have crossed wires...
If its breaking up at WOT only (high rpm) its the Coil - I've had this symptom twice.
If its breaking up when your just accellerating its either a really bad coil or more likely your O2's or perhaps your MAP sensor reading wrong.
Does this happen when the engine is cold or only once warmed up?
If it does this when cold I would lean more towards the coil or MAP.
There will be some some guesswork for you if you don't have access to a scanner There are a lot of things which can cause your backfiring situation, and since you've changed the basics its almost for sure a sensor.
Personally if money is not that big of an issue (and you don't have access to a scanner)I would replace the O2's, MAP, Coil, Coil Wire since it doesnt sound like you know when they were last changed. It'll give you some piece of mind for future problems as well
MAF is OK(or at least not the cause of this problem) if it ran the same with it unplugged. Double check to make sure your not arching! Is idle smooth or shakey? If its shakey it sounds like you may have crossed wires...If its breaking up at WOT only (high rpm) its the Coil - I've had this symptom twice.
If its breaking up when your just accellerating its either a really bad coil or more likely your O2's or perhaps your MAP sensor reading wrong.
Does this happen when the engine is cold or only once warmed up?
If it does this when cold I would lean more towards the coil or MAP.
There will be some some guesswork for you if you don't have access to a scanner
There are a lot of things which can cause your backfiring situation, and since you've changed the basics its almost for sure a sensor.Personally if money is not that big of an issue (and you don't have access to a scanner)I would replace the O2's, MAP, Coil, Coil Wire since it doesnt sound like you know when they were last changed. It'll give you some piece of mind for future problems as well
It acts up mostley when the car is warm, the idle is always smooth. I replaced all this stuff, plugs, wires, opti trying to fix this problem but I dont feel bad about putting the money into it because everything has so many miles on it anyway. My wife can drive it and she never has a problem, but she drives nice and slow. I dont have to leave like a race car for it to do this, just running up through the gears makes it do it for me.
I'm going to pick up a coil and both O2 sensors today.
Thanks a lot.
Ron
Thread Starter
Registered User
Joined: Nov 1998
Posts: 150
From: Murfreesboro,Tn
update!!!
Here is the latest. I replaced the O2 sensors, no change. I replaced the coil, no change. I finally took it to another shop to read the codes, no bad codes, nothing unusual. So, I left that shop wringing it out, about a half mile from the shop I get a huge backfire with flames and the whole bit, the car died and wouldnt start, no fire at all. I got it towed back to the shop and told them to fix it whatever it takes. It seems it was a good thing that it finally quit completly since now they could trace the no fire problem. It turned out to be the ignition control module, its finally fixed!!
Thanks for all the help guys.
Ron
Thanks for all the help guys.
Ron
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