running rich and rough
Thread Starter
Intermediate
Joined: Apr 2007
Posts: 30
Likes: 0
From: New Bern NC
running rich and rough
85 tpi did great yesterday!! another problem. it started running really rich today. i mean smoking exaust rich. never a code though. i pulled the fuel pump fuse while it was running and it cleared up till it run out of gas. did this three or four times snd same thing. i think this is why it ruined the other plugs. anything????
it has all of this new
injectors
egr
knock sensor
tps
iac
plugs
wires
cap
rotor
button
coil
all vacuum lines put back the way they went are new
cleaned throttle body and plenum and runners
all o rings on fuel rail
fuel filter
it has all of this new
injectors
egr
knock sensor
tps
iac
plugs
wires
cap
rotor
button
coil
all vacuum lines put back the way they went are new
cleaned throttle body and plenum and runners
all o rings on fuel rail
fuel filter
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
First check for any stored codes. Check fuel pressure if you have a gauge. There are a few things that can cause a sudden condition like that. I have read here before that when the members ECM crapped out, the engine ran pig rich with no stored codes. Just a thought.
EDIT: I reread and noticed where you stated no codes. So, time to check things that will not cause a code. Do you have a FSM (factory service manual)? You need to verify that the AIR system is not introducing air into the exhaust manifolds during closed loop. This will make the O2 sensor give a lean reading to the ECM and cause the ECM to add more fuel.
What size injectors do you have and where is your fuel pressure set? Any engine modifications?
EDIT: I reread and noticed where you stated no codes. So, time to check things that will not cause a code. Do you have a FSM (factory service manual)? You need to verify that the AIR system is not introducing air into the exhaust manifolds during closed loop. This will make the O2 sensor give a lean reading to the ECM and cause the ECM to add more fuel.
What size injectors do you have and where is your fuel pressure set? Any engine modifications?
Last edited by RRT vette; May 27, 2007 at 02:37 AM.
Thread Starter
Intermediate
Joined: Apr 2007
Posts: 30
Likes: 0
From: New Bern NC
it has open headers on it well... with collectors on them. it was like thiswhen i bought it and i plan to put exaust on it WITH CATS lol. would this have anything to do with it? its done it before but it doesent do it all the time. u think it would be worth it to just change the ecm? they are fairly cheap and worth it to fix the problem. but on the other hand trial and error is killing my pockets. the injectors are factory specs i guess. not performance or anything.
Thread Starter
Intermediate
Joined: Apr 2007
Posts: 30
Likes: 0
From: New Bern NC
oh i do have a haynes manual. im not sure about the air pump and all. i was reading the CAT thread an seen a little on it but i will read the manual tommorrow. thanks for your time and any help is appreciated. and it also has a new o2 sensor in the collector. they are for this car i was told. im not sure of the kind of headers do you recommend any certain exaust? i was reading and what ive seen its better to use x pipe over true duals????
Racer
Joined: May 2006
Posts: 281
Likes: 0
From: Urbana OH
I had this exact same problem and I fixed it yesterday. All mine needed was a replaced vaccum line. The line that runs from the fuel pressure regulator to the throttle body. Mine got broken and was letting all the air it wanted to into the system and I had the EXACT same problem you're describing. They don't make that hose anymore so I went to a junk yard and got the line off a camaro that was just sitting in the junk yard. They charged me $5 for it and it was fixed in 10 min once I let the motor cool down from driving it there. Car runs much smoother, more noticeable at idle and I picked up 6MPG. Only down side is I seem to have lost some throttle response..... :o Oh well price you pay for your car running right I guess.
I have the part number on that but it's out in my car. If you want it PM me or post it and I'll run and get the part number if you think it will do you any good.
Semper Fi
I have the part number on that but it's out in my car. If you want it PM me or post it and I'll run and get the part number if you think it will do you any good.
Semper Fi
Pro
Joined: Nov 2006
Posts: 638
Likes: 0
From: Plano TX
I had this exact same problem and I fixed it yesterday. All mine needed was a replaced vaccum line. The line that runs from the fuel pressure regulator to the throttle body. Mine got broken and was letting all the air it wanted to into the system and I had the EXACT same problem you're describing. They don't make that hose anymore so I went to a junk yard and got the line off a camaro that was just sitting in the junk yard. They charged me $5 for it and it was fixed in 10 min once I let the motor cool down from driving it there. Car runs much smoother, more noticeable at idle and I picked up 6MPG. Only down side is I seem to have lost some throttle response..... :o Oh well price you pay for your car running right I guess.
I have the part number on that but it's out in my car. If you want it PM me or post it and I'll run and get the part number if you think it will do you any good.
Semper Fi
I have the part number on that but it's out in my car. If you want it PM me or post it and I'll run and get the part number if you think it will do you any good.
Semper Fi
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Thread Starter
Intermediate
Joined: Apr 2007
Posts: 30
Likes: 0
From: New Bern NC
i will look for thwt but driving it to the junkyard is a problem. it dont have any throttle at all. it bogs when i hit the gas. i could makt it there at probally 30 mph or so. still sound like the same problem? thanks for the help.
Racer
Joined: Aug 2006
Posts: 408
Likes: 1
From: Gun Barrel City Texas
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
There are a few ways to check the cat. Hit it with a rubber hammer or block of wood and listen for rattles, look at it at night after the engine is at operating temps for it glowing, take the cat off and look, or use a backpressure gauge.
If the exaust flow out of the mufflers is not good or the engine chokes down past half throttle, I would check out the cat.
A scan tool would help in the troublesooting of the sudden rich condition. If the plugs are gas fouled...forget looking at the cat.
If the exaust flow out of the mufflers is not good or the engine chokes down past half throttle, I would check out the cat.
A scan tool would help in the troublesooting of the sudden rich condition. If the plugs are gas fouled...forget looking at the cat.
Very good point. Your plugs can tell you a bunch about what your engine is doing.
Thread Starter
Intermediate
Joined: Apr 2007
Posts: 30
Likes: 0
From: New Bern NC
"it has open headers on it well... with collectors on them. it was like thiswhen i bought it and i plan to put exaust on it WITH CATS lol."
i mean the car has no exaust right now headers and collectors is all
could this be the problem? it doesent do it all the time the plugs itook out were gas fouled. i know its getting too much gas i just dont know why.i plan to put exaust on it but im working on the body too and plan to do it after the car gets painted. so ...... checking the cats is out of the question
i mean the car has no exaust right now headers and collectors is all
could this be the problem? it doesent do it all the time the plugs itook out were gas fouled. i know its getting too much gas i just dont know why.i plan to put exaust on it but im working on the body too and plan to do it after the car gets painted. so ...... checking the cats is out of the question
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
Hi I have an 85 with headers.
There are some reasons for the car going rich and one main reason is that the O2 sensor gets too much oxygenand therefore increases the fuel amount. WHere is your o2 sensor ploaced. You have only one on the 85. If it is at the collector it it might be too near the opening and can get stray air in to it and therefore get rich. You have also the air valves in the air system that can be bad. There is ways to check this. The air shall under some circumstances go in to the manifold and if they are leaking it might be a reason. The same if the control valves controlled by the ECM just in front of the throttlebody. Check so everything is ok there This is ofcourse only on the side of the engine where the o2 sensor is placed.
Good luck
There are some reasons for the car going rich and one main reason is that the O2 sensor gets too much oxygenand therefore increases the fuel amount. WHere is your o2 sensor ploaced. You have only one on the 85. If it is at the collector it it might be too near the opening and can get stray air in to it and therefore get rich. You have also the air valves in the air system that can be bad. There is ways to check this. The air shall under some circumstances go in to the manifold and if they are leaking it might be a reason. The same if the control valves controlled by the ECM just in front of the throttlebody. Check so everything is ok there This is ofcourse only on the side of the engine where the o2 sensor is placed.
Good luck
Thread Starter
Intermediate
Joined: Apr 2007
Posts: 30
Likes: 0
From: New Bern NC
u sound like you are hitting a nerve thats causing my problem with the running rich. so back pressure could pull oxygen in and cause the o2 sensor wich is right in the middle of the collector to say its lean and send more fuel in? maybe thats it. im not sure about the air pump at all. it should send air to the intake? or the exaust? the o2 sensor would make alot of since since its pushing alot of smoke like out its so rich and throwing no codes. but when i pull the fuel pump fuse it clears up no smoke miss or anything. thanks so much i will check it out. any way to bypass the o2 sensor just to see if this is the prob?
