2.4 running rough

Well, I just replaced the fuel filter.... No luck:mad:

I cut the old one out completely and spliced in a universal fit one with fuel line and the special fuel line hose clamps... kinda ghetto, but it works and will be super easy to change in the future.

I has to be that stupid cat! Is there a foolproof way of testing it before I pay someone to install a new one? Thanks again.

Oh yeah I also tried a new fuel cap with no change.:confused:
 
The previous owner tried some heet, and I put some injector cleaner in, but it didn't do anything. It runs too "consistently bad? to be bad fuel (in my opinion) I could try a new PCM from the boneyard for $15. Do you think its worth trying?
 
it's at the point where you need to take it..i hate saying that, but they have all the good equipment..it's worth it at this point
 
I just want to make sure I am not missing something before I bring it in. To recap this is what I have done:

Removed and cleaned injectors installed with new o rings
new plugs
2 new coil packs
ohmed out the plastic "distributor" thing where the coil packs sit
New ignition module
new gas cap
new map sensor
new tps sensor
new cam position sensor
new air filter
new fuel filter
cleaned throttle body
put heet in gas tank
tested compression
tried to test o2 sensor... not real sure about that


What is that other sensor on the throttle body? Its right on the front when looking it it. It has a big plug on it. It bolts right into the throttle body.
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throttle position sensor, you can take it out and clean it and take your intake hose off and clean the throttle plate.

15 bucks for a new to you boneyard pcm, i've spent more for less.

to test a cat you have to disconnect the exhaust pipe in front of it, should be nice and loud. but if you can go faster than 50mph chances are its not plugged.

did you ever check for vacuum leaks? spray ether or some cleaner spray around the engine when its running, it will change speed when you find a leak, how about the fuel pressure?
if you have more time than money its nice to do it yourself and learn, if your in a hurry and can afford it find a reputable shop
 
the iac and then theres the tps..you could clean the "idel air aontrol" out but that can b 80 to 100 bucks but if they went bad you would get a code
 
my brother had the same problem. he also has a 99 grand am 2.4L. it was also throwing the p0300 (random cylinder misfire). i figured out what the problem was after going through a complete engine rebuild that didnt fix the problem. it ended up being the ignition coil housing. this may sound stupid but it has several small copper stips inside it that make up the circuit providing power from the coils to the spark plug boot. over time these strips become brittle due to vibration and heat and they crack. this causes an open in the circuit. you can get this part from advance auto parts for $44. hope this helps.
 
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And i would get the pipe fix properly..1 day it will blow of from the pressure and you will of course lose the gas and it could light up...and it could also be the fuel regulator or the fuel pump..since its not throwing a code you could spend weeks figuring it out..GOOD LUCK
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In case I missed it, Have you checked the fuel pressure reg. Pull the hose off, if there is fuel present, replace.
 
Thanks for all the suggestions.

I did check fuel pressure regulator. No fuel in vacuum line. It should be good.

I tested the "coil housing" and I have good continuity between each spring and each plug boot. Do you think it could still be bad?

I tried to test fuel pressure, but there is no test port and the only place the adapters for the gauge would fit was on the end by the filter, which I cut off!. I could try testing now with the "inline" adapter that comes with it and hose clamps. I will have to check out the tester from autozone again.

I tried a new TPS and I removed the throttle body and cleaned it up real good.

I tried the "spray method" to find a vacuum leak with no luck.

I can go more than 50mph right now. Actually on the highway it seems pretty good. Its trying to get up to speed that is bad, right up until 3500 rpm then it takes off like rocket!
 
No more than 60 psi
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I think I will be fine then. I have a hose clamp on the main hose coming out of my 60 gallon air compressor which is at 120psi and it has been fine for years. I am pretty confident in the clamps and the way I clamped it. I guess I will find out in the future.

I am heading to the boneyard on Friday to grab a PCM, and a "distributor plate thingy" Hopefully one of these will fix it, otherwise the sawzall is coming out and that cat is getting removed. I will get this thing going sooner or later:D I bought the car as is for $350 and it is not my primary vehicle, so I can't complain.
 
I hope so..i'm just speaking from personal experience..i had to do the same thing on mine..but it was the quick release side and it leaked a year later even after tightening it down again..it's just with yours it's not flared..so if you look at all the pipes that has a hose clamp in use, they all are flared even where the hoses on the radiator go to prevent leakage..lol kinda sounds like a pampers commercial..it's just for your safety, i would hate for something to happen to you..a car can be replaced but life,when gone..are gone forever
 
Thanks for the suggestion. I will look into having a shop flange the ends out.

Guys:
Wouldn't a clogged cat cause the car to run worse as the rpm's increase? It just confuses me that it runs perfect after 3500rpm.

Could it be an injector? What should the plugs look like?
 
from what you say the converter is probably fine, did you change the spark plug boots? (wires) had to change them on my 2000 grand am, was missing but not as much as yours. if your fuel pressure was bad it probably wouldn't run well at high rpms either. i would think it is an spark problem, probably shorting somewhere, let us know what you find.
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I agree man, after thinking about it, I am leaning towards a spark issue as well. Maybe the PCM is bad. It seems like its running really rich at idle. probably no spark on 2 cylinders or something. I replaced both coil packs, ignition module and all 4 boots. The only thing I didn't touch was the plastic housing thing. I am going to grab one from the boneyard tomorrow if they got one. Only other thing I can guess would be if the injectors are functioning erratically or something. Maybe will grab those from the yard too. Thanks a ton for all the input.
 
what you could do is move the injector wire around with the car running and see if you hear a drop/raise in rpm..if nothing happens you should be good on them..and yes usually if the cat is bad you car would run better at high rpm do to the raise in back pressure forcing its way thou the cat and out the pipes..one way to see if you running rich, do to ignition failure is.. turn ur car on and smell the exhaust comming out..if you get a potent smell of gas, it could be because of your not burning it do to lack of spark..have you checked your speed sensor? it also has to do with the idi..it's located on the back, near the thermostat but on the transmission..and you should check your knock sensor too
 
well. I grabbed a pcm and a plastic coil pack housing thing from the boneyard. NO luck. PCM needs to be flashed I guess. (didn't know that) I may see if the dealer will do it for cheap. I tried the new housing with no change. I did verify spark on all four cylinders. I had my buddy turn the car over as I held all 4 plugs against the cam cover. It seemed to spark just fine and at different times. You could see the firing order.

Where is the speed sensor? I looked near the thermostat, but could not find it. Also, where would the knock sensor be? Thanks for the input.
 
I would still smell the exhaust..the speed sensor is right next to the passenger side halfshaft, right where the the shaft conects on the tranny under the thermostat..and the knocke sensor is on the back of the engine right under the exhaust manifold on the
side where the o2 sensor is..it only has 1 wire and it's pretty big for a sensor
 
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