The car:
1999 Cavalier z24
2.4l DOHC
5 speed manual
How it started: For a long while now I have noticed a definite power loss. It all started after my 99 cav blew its original engine with 55k miles on it. It spun a rod bearing. I had GM place a brand new 2.4l in it straight from the crate. When I got the car back it was spitting out oil or exhaust out of the EGR valve which was not blocked with the block off plate on teh new engine. I took it to them asking them why it was spitting out crap and they had no idea why and from looking at diagrams myself I saw no plate on valve that went in that location. Later on I was reading about how some 2.4's may have an EGR and some just have a block off plate. I had one custom made to put on. All this might be totally non-relevant.
Symptoms:
Funny odor coming from exhaust when driving.
Bogs down/almost stalls off the line unless I rev to 2k when letting out clutch.
Clutch is a SPEC Stage II, near life
Bad gas milage (Used almost twice the amount a similar modded cav on a 6 hour trip.
No check engine light.
It just has no power compared to what it did before (Ran a 15.2 at track with old engine and a 16.5 with new engine (All the same mods except went from a cold air intake to a Warm air intake because of rain)
AEM intake gets VERY hot to the touch.
Very low power on hot days
I have been trying to find the problem for the past year and have YET to come to a conclusion. I just want it to run like it did before, not for performance or racing reasons but just because I want to make sure its not running rich or lean or whatever because I may be hurting the engine bad. Please help me or offer me some ideas as to how to track down this problem. Could it be low/high fuel pressure, plugged fuel lines/ or filter, bad plugs, bad injectors? ANYTHING TO HELP!!!
Thanks!!!
PS: let me know if you have any other questions to solve my problem!
check ur cat it needs replace...
Yea that definitely just sounds like the cat. Smell like wrotten eggs?
definately check the cat man, its clogged.
01' Z24 5 speed
422whp/400wtq
T4 Turbocharged
Built LD9
HP Tuners
I'd go with cat as well. Even though the code isn't showing, it's probably still the safest bet.
" To study and not think is a waste. To think and not study is dangerous. "
I'm betting cat...Also check your TPS.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
why did first engine blow? did it run lean?
how old is your fuel pump?
i had simular syptoms like that and a big part of it was my cat. I wasn't getting a code for the cat either.
I have a Magnaflow High-flow Cat on it right now. It's been used for less than 6 months. It was performing bad before I even installed it too. Although when I had it installed there was a bung on the bigger section of the cat's body but the installer insisted that that one be welded shut because he said that it needed to be just as far AFTER the cat as the STOCK bung was from the stock cat. So he drilled a hole and welded another bung about 6" after the New Magnaflow cat. Would cause even more additional power loss?
It is probably the cat, but you have to wonder why it just clogged after getting the crate motor.
One other thing I would do is reset the computer. I bet when they installed the motor, they just started it up, revved the engine and drove it around. That is a big no go...
The correct way to reset is:
Disconnect the positive on battery for 10 minutes.
Connect positive.
Start engine and let idle for 5 minutes (do not touch gas, not even once)
Shut off engine.
Restart and drive.
The computer is not calibrated to the new crate motor. This will fix that, but it sounds like there is more than just this if there is oil shooting out and odors coming from the exhaust.
its a GM motor, and im willing to bet that GM took the ground wire off the Bat. when it was installed. so to say that "The computer is not calibrated to the new crate motor. This will fix that" gets a Big
i will be willing to bet that the tec\ servace wrighter cheeked VIS for any TSB's and maby flashed it too.
most GM dealerships have a back preser tester, thay will beable to tell you if the cat is cloged.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
Is there any way I can replace the Cat with a Resonator and if so where would I put the O2 sensor?
How can I check the TPS or where can i take it to get it check for cheap/free?
How can I check to see if it is running lean/rich or where can i take it to get it checked for cheap/free?
What else should I consider having checked?
A sincere thank you to everyone who has given thier input even if its just a guess. This will help me narrow the possibilites! I really just want my car running healthy again!
When I had an engine rebuild on my 2.5 Daytona ES, the motor stalled if I hit the gas at a stand still.
When I reset the computer, it never did it again.
Everytime I modded a car with either a bolt-on or did some porting, it changed the parameters and the car would not run so well until I reset the computer.
Also, it was not a statement of whether the computer recognizes the same type of motor, it was a statement that the steps of doing the reset was done WRONG.
How?
Of course they removed the negative.
But, read the part where they most likely revved the motor and did not let it idle for 5 minutes before driving around. Being a GM mechanic is not a certificate for being a genius as the oil shooting out of a new crate motor and running like crap proves. That can make a car stall and have spots of bogging down.
You may jump to say the cat is culprit 100%, but the cat wont make oil jettison out the EGR.
I feel there is a few problems in motion here, not just the cat.
well you can bang your cat and if it sounds like theres something in there bouncing around then its clogged. Also do the same with your muffler, it definitely sounds like your exhaust is clogged some where. Does it run rough or is it just plain power loss....like if your always trying to go uphill? do you have trouble going up hills? if so your exhaust is clogged
All of my exhaust is less than 6 months old. I dont think it's clogged. If it is there is another problem causing it to get clogged and that is what I'm trying to find. I feel that just replacing the cat may just fix it temporarily if there is a bigger problem...
Mike Tampa wrote:When I had an engine rebuild on my 2.5 Daytona ES, the motor stalled if I hit the gas at a stand still.
When I reset the computer, it never did it again.
Everytime I modded a car with either a bolt-on or did some porting, it changed the parameters and the car would not run so well until I reset the computer.
Also, it was not a statement of whether the computer recognizes the same type of motor, it was a statement that the steps of doing the reset was done WRONG.
How?
Of course they removed the negative.
But, read the part where they most likely revved the motor and did not let it idle for 5 minutes before driving around. Being a GM mechanic is not a certificate for being a genius as the oil shooting out of a new crate motor and running like crap proves. That can make a car stall and have spots of bogging down.
You may jump to say the cat is culprit 100%, but the cat wont make oil jettison out the EGR.
I feel there is a few problems in motion here, not just the cat.
Ok in J-body world the whole letting the car idle for 5 minutes is crap. Sorry.
I also agree that if the cat is clogged there is another issue. Cats do not just clogg on there own. Best bet would be to take the car somewhere (maybe a dealer, or another service place) and get it checked. Lot's of places will do a free check and tell you how much to fix. Sounds like you do not have the means of figuring this out yourself.
FU Tuning
Check your cat, and check your o2 sensors as well. With your exhaust being only 6 months old, something has to be clogging your cat or fouling out your sensors. Did you ever have have any problems running very rich or anything like that?
Id do a full tune-up, and maybe run some seafoam through your motor. Some people dont like it,but Ive used it through dozens of vehicles and always had good results.
Like mentioned before I have never had the air/fuel checked so I dont know if I am running rich or lean...also, what exactly is a "Tune-up"?
I just remember this as well.....
Every once-in-a-while my car decides it wants to idle at 1,500 RPM's at a stop. Could this mean anything or possibly narrow anything down?
Upon start up with a new motor, it should be reved to 2000 RPM for 5-10 Mins, to help with lifer pump-up.- GM
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
I personally would also look into the front o2 sensor to see what it's doing as well. But with it coming up to 1500 RPM I would look into a Throttle position sensor as well "TPS". If you know anyone that has a live data scanner, plug in your car and see if they can find anything.
2009 Ford Mustang V6
icemike89 wrote:Yea that definitely just sounds like the cat. Smell like wrotten eggs?
A rotten egg smell is due to a high sulfer content in the gas. This is normal. It does not mean the cat is clogged!
Most folks who do not know what they are talking about are always quick to say it might be a clogged cat. With yours being a high flow unit and your entire exhaust only six months old the problem is not with your exhaust!
More information is needed to properly diagnose the issue. You need to take it to a dealership and have them hook up their scan tool to see what your sensors are reading.
The only thing I can think of that you can do is just take a good look at all the wires going to sensors and make sure they are plugged in and that the wiring does not lok damaged in any way.
FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!
personally i would take it back to the dealership that installed it and make them fix the @!#$.
hey nick, sounds like you might have a problem with your cat.
