What is wrong with my car? [Archive] - GrandAmGT.com Forum


View Full Version : What is wrong with my car?

12-31-2003, 08:37 PM
Ok, I posted a while ago what my symptoms were, and everything pointed to an o2 sensor.(low gas mileage, black soot from exhaust)

Well, there are no codes thrown, and apparently I don't have an o2 sensor problem. But i'm still having the above problems. I did a test just to see how bad my gas mileage was.

I did the test twice to make sure the results were the same.

Keep in mind I have the 2.4 engine, with a 5-speed transmission. I filled the gas tank completely, and for the duration of the tank, drove very easily. Never went over 65, and the engine never went above 2500-3000 rpm. And both times I got roughly 190 miles a tank.

190 miles a tank?? From a 2.4 5-speed? This is a freakin' joke. I used to get 340+ from a full tank of gas. My mileage has been cut almost in HALF! And noone can tell me what's wrong.

I need your help here guys. What the hell else could it be?

Is it possible that no codes are being thrown, and everything LOOKS fine, but I still have an o2 sensor problem?

It has also been suggested to me that my timing could be somehow way off, and I need to adjust it.

Any other ideas? I need to get my car running normal again here.

Oh, and as far as mods, I only have an exhaust. That's it. The rest of the car is bone stock performance wise.

Thanks for any input you guys may have. Anyone that helps me out gets a cookie.:D

And if someone figures the problem out, damn i'll give you a whole batch of cookies!

12-31-2003, 10:36 PM
I'm not exactly sure about this, but have you replaced your fuel filter lately? Or how about the oil filter, or even the air filter?... maybe even all 3? Have you noticed a decrease in performance? If so, maybe you need new spark plugs, like maybe your car is not firing on all cylinders. My brother-in-law has a 6 cylinder Chevy motor and his spark plug wires burnt up and his gas mileage went down from about 260 a tank to about 170. Because his motor wasn't firing on all cylinders, a lot of gas was going through the motor without burning and just exiting through the exaust. I'm not sure, but maybe check it out.

12-31-2003, 11:10 PM
Yes, performance is definitely decreased. Quite a bit, actually. Hmmm....I did replace the air and oil filters at my last oil change, but not the fuel. I have a fuel filter in my back seat, just haven't done it. I also have not checked the plugs. I have the day off tomorrow, so I'll do both and see what happens.


Any other ideas?

12-31-2003, 11:46 PM
The only thing I can think of is your fuel pump. Lets hope its not that though..... lotsa $$$.

01-01-2004, 12:10 AM
your driving a 2001, do you still have warrenty?

01-01-2004, 12:28 AM
Very possible an O2 sensor is still your problem... it can get bad but still work enough not to throw a code. Have had a very similar problem in truck of a friends, no codes, but replaced the O2 and got back all kinda of mileage and power. Black soot at the exhaust, your definitely running rich... replace that O2 sensor and see if that doesn't help. Changing the fuel filter wouldn't hurt, but I don't think you could have a filter hurt your mileage that much and still have the car start and run ok. I'll be waiting for my batch of cookies, I like MnM's. ;)

01-01-2004, 04:56 PM
Maybe you could pull the spark plugs and see if any/all are fouled. It can tell you if it is cylinder or system specific problem.

01-01-2004, 08:10 PM
I'm not sure, but it may be that the catalytic converter is plugged or has fallen apart inside.

01-01-2004, 08:15 PM
Disconnect your battery and go do something for about 30 minutes. Then reconnect the battery, drive it for awhile and see what happens. Something may have gone thru the fuel system messing up the computer and restting it may help....Even if I am wrong it's a free idea.

01-02-2004, 10:16 AM
I drive A 2000 2.4 l but an auto... I noticed al lot of soot from my exhaust (at least it bothered me cause the stainless tips were dirty, and I used a fuel system cleaner (slick 50 fuel system plus) and saw dramatic results I has shortly after had a tune up and they said my injectors were in need of replacement, thank gawd I was still under warranty. Its not a free attempt but it couldn't hurt. right?

01-02-2004, 10:22 AM
my guess is somewhere along the lines of a cylinder not firing correctly. check that spark and fuel.

01-04-2004, 03:37 AM
checking the fuel/air/oil change at all have u replaced the spark plugs, the o2 sensor would not have that but a mass air flow sensor might have a problem or cloged injectors do a cleaning too a little upkeep will keep u going longer farther...
2 cents fell keep it clean :)

01-04-2004, 10:12 PM
Does the car still run smooth, and build power smooth? How does it run when its cold, before it goes into closed loop?

01-05-2004, 10:41 AM
Power buildup seems to be all out of whack actually. When I shift into 2nd, the car just bogs. If I don't shift at 4000 or higher it feels like it wants to stall sometimes. And remember, I have the 5-speed, so the 1st to 2nd transition issue doesn't apply to my car. That and it never happened before this problem started.

The car is very weak. My gf drives a 15 year old civic with close to 200k on it and needs a new clutch that has more power.

The car does seem to have a bit more power when cold, but it goes away quickly.

Don't know if this makes any sens eto any of you, 'cause it sure doesn't to me.

BTW, the car just hit 27k miles. Still practically new.

01-05-2004, 10:13 PM
I've got money on an o2 sensor, especially if it seems to run better till it warms up. See, the car will not use the O2 sensor till its warmed up, so thats kind of an idicator, IMO. If its starting and running ok, but just lacking power and getting horribe mileage, I'd be inclided to think its a sensor. If you had a cylinder missfiring, you'd feel it, especially with a manuel. It could still be something else, but I'll bet its a computer control related problem.

04-18-2005, 08:51 PM
did you ever find the problem? i'm having the same problem w/my 89 2.3 quad le. all of a sudden it has no power and sounds like its bogging alittle more when its cold but not much. just prior to its running like this, i noticed more smoke coming out of the tail pipe after which i removed the air intake hose from the tb to see how it would run without the air filter. that's when it seem to f.u. i swapped another air flow sensor from my 92 2.3 gt, no change. also changed the o2 sensor, no change. i suspect its the cat or the fpr because when i disconnect the vacuum hose from it, the car runs better or about the same not worse. please remember this was a sudden change in a car that was running perfect the day before. anyone have any suggestions?

04-22-2005, 04:58 PM
Power buildup seems to be all out of whack actually. When I shift into 2nd, the car just bogs. If I don't shift at 4000 or higher it feels like it wants to stall sometimes.

Sounds like a clogged Catalytic Converter.
Get it checked !

05-30-2005, 07:06 PM
Play nice. If you don't have something civil and/or constructive to say, don't say it at all.