Canister is in great working shape. Did all the tests and they all passed. i think i figered something out. I unplugged my MAF sensor and the thing runs great. Then when i plug it in, the engine does not run so well. I do notice it backfires now, is that because i have the MAF sensor unplugged and the check engine light is on for that. My egr valve is also shot but that shouldn't affect that right? How do i make sure that it is the MAF sensor itself and not something else. I am unplugging the plug that is connected into the intake hose. That is the MAF sensor. Any ways of testing this before i got out and spend another 100$? Thanks

 

You need to use a wiring diagram to locate the fuel pump relay, unless you already know which one it is in the front driver's corner of the firewall. Switch that relay with the relay that is located right next to the MAF, which is the MAF relay. If the MAF now works, the relay is bad, and if it don't, the MAF or wiring is bad. If the engine backfires, you have a timing problem, either too far advanced or too far retarded. Do not rely on the balancer to check the timing, as after all those long miles you engine has had, it may be slipping. Locate the TDC stroke on the #1 cylinder and do the timing adjustments from there. If TDC is identified on the balancer when the #1 piston is actually at TDC on the compression stroke, then you may use it to adjust your timing.

Also, remove the MAF and check inside to see if the orange film inside looks like the surface of a pool in that it is wavy. If it is, go get a new one. Also check this before you leave the auto parts store to make sure you have a good sensor. The thing about having to disconnect the battery when replacing the MAF is a myth so don't worry about it. That's what the relay is for...

 

I pretty sure my wiring is fine because it just started acting up. i do know where the fuel pump relay is seeing just replaced it. LOL. Where is the MAF sensor relay? So i just switch the relays around? What are they the same or something? Also can the whole MAF unit connected to the air box just go? I am unplugging the connector that plugs into that and that when it runs good. I am postive the car is in good time, I jsut noticed it back fired today in first gear going going down my street decelerating. I think it is do to the egr valve being bad and the maf unplugged. What do you think? Thanks again

 

The two relays are identical. At the end of the radiator, there is a little crevice, that starts the pocket where the air cleaner box thingy and the evap can are. If you stand to the pass side of the car and look at the air box, you will be looking into a corner where the sheet metal is welded together. You may need to remove the top of the air cleaner to see the relay. The relay is bolted to the short piece of metal that runs from the headlight support to the radiator support in the front to back direction. If you can't understand what I have just wrote because it's late and my tired brain can't write, just follow the red MAF wire and you will run into it.

For further reference, there is a battery power junction right below the relay.. don't short it out.

The EGR has nothing to do with the backfire.. if the solenoid works correctly it will close the vacuum to the valve when decelerating to keep the engine from bogging down and stalling out due to lack of fuel and air in the cylinders. The MAF should not affect the fuel air mixture at all when unplugged, because the ECM goes to a backup set of BLM tables for when there is no MAF signal, so that the engine will run. It will run kind of like crap with bad gas mileage due to the engine not knowing just how much air is coming in and approximating using the O2 sensor, but the MAF shouldn't have anything to do with it. I drove around this way for two months without any backfiring or problems (other than higher engine temps due to missing air dam) unless the timing went off.

 

Thanks again. Your helping me out alot here. Well i did what you told me to do (switching the relays) but it still isn't right. The rpm drops right off once it is plugged in. Is there a way to test the MAF unit itself. It looks clean but that doesn't mean anything. Thanks

 

Like I said before, you cannot test it yourself other than to check for current running in and out of it with a test lamp. Take it to autozone or a dealer and have them test it for either a low fee or free.

 

Alright. well right now it has a repair plate on it. So can't take i too far. My buddy is coming up with his MAF unit on his RS and we will switch them and see if that is the problem. Hopefully it is then i can replace it. Does the egr control throttle reponse? I think it does but just checking. Thanks again :hail:

 

The EGR does only one thing-funnel exhaust gases back into the intake to be burned to reduce harmful emissions. As far as I know, it has NO or very little effect on throttle response. That would be the TPS, fuel injectors, ECM, and the condition of the ignition, whether it is strong or weak.

Forgot to add... YOU HAVE TO SWAP IN A KNOWN GOOD MAF FROM a Firebird to test the old one! There is an elbow glued to the end of the Firebird MAF, that if removed, kills the MAF. There are supposed to be NO cracks or holes in the intake plumbing before the throttle body, because for some strange reason the MAF goes south almost instantly. I killed mine this way.

 

You CAN use a maf from a camaro, it just doesnt have the bend.
Your EGR CAN affect idle if it gets stuck open at idle. Its easy to check. Push up on the bottom of the diaphram with the engine at ilde and see if it was already open.

also cracks in the intake rubber pipe DO NOT kill the maf instantly
IT just doesnt get a correct reading. I had a crack in my pipe when i first got the car and left it like that for 2 months. BTW last time i checked a bad maf threw a code.

My problem wich was simular to yours was due to me plugging the vaccum line that went from the evap can to the TB. Seems like the ecm takes this extra intake of air/fumes into account and the lack of it made my car idle too low at lits and stall sometimes.

I didnt hook the evap can back up instead i just opened the vaccum hole back up. Car doesnt stall now, problems fixed.

If i remember correctly you said if you create a vaccum leak it runs better?
Its probably a clogged(possible?) vaccum line or a bad evap

 

I didn't say that a crack in the intake piping kills the MAF instantly. I just said that it does kill the MAF if left unchecked for a long time. He asked whether the EGR has an effect on throttle response not idle. Yes it does have an effect on the idle, like I stated before.

And you can also test the EGR valve the same way you did the evap can. If you hook a vac pump to the valve intake port and apply vacuum and then suddenly release the vacuum and the valve has a slow response, then the valve is going south.

 

If the egr sticks at idle it richens the mix correct? and too rich of a mix affects throttle responce.Also air leaks after the maf wont kill it. Look at the stock pcv hose, its routed to the ruber hose infront of the TB AFTER the maf.

 

Look at the date when you started this post. Seems like people are guessing as to whats wrong with your car. As much as i hate them i think you need to go see a mechanic.

All this time this thread has been open you could have rebuilt the motor.

 

EGR does not richen the fuel/air mixture in any way. It just takes up room in the combustion chamber that would normally be taken up by more fuel and air, which would normally create a much hotter flame and increase nitrous oxide emissions. The only way the EGR would richen the mixture is if it had excess hydrocarbons (aka unburnt gasoline) in the exhaust it is passing through to the chambers.
You do know that that is engine vent air and is considered not affecting the MAF in any way, right? It is too close to the throttle body to have any effect on the MAF, and it is that dirty disgusting air that comes from inside the crankcase anyways, not fresh, non-acidic air coming from the outdoors. Put a crack or two in the big black air box in between the MAF and intake bellows and then see how fast the MAF goes south. Been there, done that. Still don't have a working MAF, not that it matters now anyways...

 

Your wrong on the egr AnD maf to a point,

I had a huge crack in the rubber hose for two months when i got the car, put over 1000 miles on it during that period and the maf is fine. Just because there is air comming in after the maf doesnt mean the maf is gonna "burn out" or something, it just wont get a proper reading for the ecm.

His car runs rich-!

The egr send gas and unburned fuel (because hes running rich) back through the TB when its normally supposed to be closed AND RICHENS THE IDLE MIXTURE!

 

Guys don't be fighting. I am happy with all the advice i get. I am sure it is the maf unit itself because th ecar runs liek crap once i plug it in. That is the problem. It runs so much better unplugged. I think the whole unit is gone. What you guys think? I am also sure the egr is bad because it doesn't even open, it frozen. So i will replace this. Any other things you guys think i shoudl check that could be related to the MAF? Thanks

 

Go unplug you iac with the maf unplugged and see if it runs good also.
I havnt done it yet but ive been told the ecm goes into limp home mode when a sensor is unplugged. When i was having my problem i unplugged my iac and it ran better BUT that DIDNT mean my iac was bad because as it turned out it wasnt!

So just because it runs better with it unplugged doesnt mean its bad. It would suck if you spent money on a part that wasnt bad. Before you go buy a new one try out your friends maf in your car.

 

I have the definition for what the EGR posted and you still say it richens the idle mixture, or any mixture for that part. It takes up the space in the combustion chamber that would normally be filled with fuel and air, lowering the temperature of the flame due to less combustible material in the chamber. That is all it does unless the fuel mixture is already too rich, and only richens the mixture a small amount more due to the excess hydrocarbons in the exhaust gas. Go look it up in your Haynes manual if you don't believe me...

And as for the MAF, if you get a new one and it still doesn't work the way it should, go have the ECM tested. That is the only other thing that can be causing probelms because your IAC, TPS, EEC can, and MAF are good, and that leaves only the ECM to be causing your pain...

 

IF you READ like I told you too in the past you'd see he said hes running rich already! SOOOOOOOOOOOO a stuck open egr will cause extream rich condition ALSO that could explain why when he creates a vaccum leak it runs better BECAUSE hes adding more air to the gas rich mixture. E xhaust G as R ecycler
SOOOOOOOOOOO lets think about this, if car run richs and egr is stuck open at idle the engine gonna get a **** load of rich mixture and not enough air.....A vaccume leak makes it run better ei MORE AIR TO THE RICH MIXTURE..............I think the egr CAN be the blame for the problem, I can post this in arabic if your having a hard time reading english....Unplugging sensors is not the way to solve a problem.

This thread reminds me of that person who swore a 60* and 90* 700r4 were interchangable

 

Well, I guess I should start posting in Spanish or something so that you can read that THE ENGINE RUNS BETTER WITH THE MAF DISCONNECTED, SO THEREFORE, HE HAS A BAD ONE!! The ECM cannot tell exactly what the amount of air is that is coming into the engine, coupled with a possibly faulty TPS adjustment, it is only approximating how much fuel it should add to however UNKNOWN amount of air there is in the plenum and manifold, therefore it adds TOO MUCH GAS to the little amount of air coming through the throttle body, and Voila! It runs rich as all hell. AND THE EGR IS NOT OPEN AT IDLE!

And that was me, you idiot! We'll see which is interchangeable...

And it's not RECYCLER, it's RECIRCULATION SYSTEM! Maybe I should learn Arabic so I can tell you things PROPERLY!!

 

Guys, All I am looking for is advice! Thats it! Stop fighting between you two. I did the test that i was told to do on the emisions can. Good shape. My IAC is brand new. So no problems there. I think it is prob the MAF because they are known for causing a bad idle. So i will have to figer out the deal there. Always something. Never easy. I don't think unplugging the idle air would tell me anything because it is new. So can't be that and I know the maf relay is good. Any other ideas?

P.S. Guys i need all the invo i can get, don't be fighting over things.

 

I am seriously leaving this post behind now. It seems that everyone only wants to insult me lately....

350man, if you need any more help, you can PM me.

 

Guys this is a friendly post. Just helping a guy out with his car. Don't be fighting over this stuff PLEASE. That is little kid stuff. Combing ideas always helps out and we all learn knew things. Don't be mad at each other.

 

dp

 

Maverick just because the car runs better with the maf unplugged DOES NOT mean its bad when you unplug a sensor the ecm goes into limp home mode.
unplugging the iac WOULD HAVE THE SAME EFFECT! THEREFORE WOULD THAT MEAN THE IAC IS BAD TOO NO!
the egr should not be open at idle but how do you know his isnt?
did you check it?
didnt think so!
IF his egr is open at idle it could effect his car to the point where it runs as he is saying it runs now THATS WHY I SAID CHECK IT!

DAMN now i see why your car doesnt run! AND BTW
No one is picking on you, your just spreading false information and people get tired of it!
Like your 60* trans that bolts to a v8, IT DONT! NEVER HAS NEVER WILL!

camaroman DO NOT go by a maf just because unplugging it makes the car run better, that IS NOT how you check it.

If you unplug the iac the ecm goes into the same mode and the car will run the same way, does that mean the iac is bad also?
NO!!!!
Im not mad or am i picking on anyone,im just tired of reading post after post of WRONG information!

 

Wow, definitly a lot going on here, but I think what might be the easiest thing is to say that it could possibly be your MAF, but might not be.

the car does go into limp home mode once a sensor is unplugged. it could be running better due to limp home mode overriding some other circuit or due to the limp home mode taking the place of the MAF circuit.

before you spend your money, it is best to do all the checks you can to be as confident as you can that what you think is wrong actually is. i'd really reccommend putting in a friend's MAF if it's available to check it still. if you don't have a good MAF to put in there to check with, well, maybe buying one would be best and if it isn't that...at least you know you have a new MAF and a spare one in case one or the other craps out on you.

 

amen!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

What EXACTLY does a MAF sensor do? I'm a little rusty on these computer controls and I'm trying to re-educate myself in this area.

If there were a tear in the air connector hose after the MAF sensor, would it cause the vehicle to run rich? I just discovered the tear when I was tearing off my upper plenum. My injectors are most likely leaking , but I'm curious as to whether this could be a major contributor to the rough idle that I'm encountering.

 

Mass Air Flow sensor. tells the computer how much air is going through the intake. someone please correct me quickly if i'm wrong, but a tear after the MAF would cause it to run lean.

 

well going to try another MAF unit off a 1989 RS this weekend and see if that is it. I need to get some money if it is thought More money. I can't find any other way to test it besides that way. So i will see what happens.