Hello and thanks in advance for reading this long post and possibly helping me figure this out. Ive been searching but have done everything Ive seen listed.
To start, I have a 99 Z24, About 2 years ago I swapped in a 97 Grandam 2.4 due to noises that I have since found out was nothing.
The 97 motor had about 30k miles less than my 99 did. Cooling fan quit working even after changing the relay, fan motor, and the coolant temp switch on the head. So now have it hooked up to a switch in the car to manually turn it off and on.
On to the problem.
Ive been having an onging issue for a few months now and its driving me crazy that I cant figure out what it is.
My problems started one day when the car was running real bad, exhaust smelt like unburnt fuel. First check was the fuel system, found the regulator to be bad, was spitting fuel. Replaced it with the one from my 99 motor and the car ran great for a while.
My strutts were bad so I replaced all 4 with KYB strutts and ground control coil overs. I also redid ny warm air intake with a new one with a 1 piece pipe with mandarel bends. Along with the strutts and Intake I changed the coil housing (factory one from 99) and changed the plugs since they hadnt been changed in a couple years.
About 2 weeks after changing those parts the car starting having an intermitten miss. No check engine light yet. A couple days later I went to Ace Hardware to get some bolts and the car started dieseling real bad and had no power. I had a spare ICM from the 97 parts I had so I swapped it thinking it may be the issue. Still same thing. I pulled th eplugs and found only 1 was real wet with fuel where the others werent bad. I changed the plugs again, and bought 2 new coils even though the ones on the car tested within spec of the chiltons book. Problem still existed. By this time the car is now throwing a p0300 code, as we all know it is for random missfire. I started thinking back to what I change last before it started real bad. Only things that would affect this are the plugs and the coil cover. Luckily I still had the old cover in the trunk so I swapped it out. The car ran much better. Upon further inspection, there was a flaw in the plastic of the cover that must have been arching. The code stayed after removing the battery cable but the car ran fine so I didnt worry about it.
Here it is about 3 months later, CEL is still on, car still has a slight miss and its driving me nuts! There is no power loss, just a slight miss at idle. I checked all the parts to make sure there are no issues, the plugs look good. I even changed out the coil housing again, from a different parts store and put in a set of new e3 diamond plugs.
I got a code reader and cleared the p0300 code and it seemed fine for a day or 2 and the light popped back on and the car has the slight miss again.
Here is a list of things changed and checked:
New coil housing
New coils
New plugs
Checked ICM (2 of them actually)
New coolant sensor
New crank angle sensor
New Cam angle sensor
Checked the FPR, works ok, not spitting fuel.
Tapped on ECU to see if car would sputter, did not
Compression test was good, 180 across the board, no more than 3 psi between highest and lowest.
Im at my witts end on what to try now. Only things I can think of are bad injectors, bad ECU, nad fuel pump, or bad CAT
Is there anything I am missing or anyother tests that can be done to figure out the issue? I havent verified the puel pressure yet but I dont hear the pump whining at all.
Again, thanks for the help,
Thomas
99 Z24
Phoenix, AZ
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
I also forgot to note that both o2 sensors were replaced when the FPR went bad.
Thomas
99 Z24
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
Really? No one has any info after 2 days? Someone has had to deal with this issue before.
Thomas
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
change spark plugs to just normal delcos... nothing fancey. Sometimes its the crazy plugs that actually cause the problem.
The LD9 is known for having issues with platinum plus 2 etc etc etc plugs.
Sounds like it could be a bad injector. I would try to replace the one for the plug that was wet.
2.2 97 Cavalier......the "Crapalier"
Thanks for the input so far.
I originally had regular autolite copper plugs in the car the first time I changed the coil cover. It wasnt until this last time that I put the fancy plugs in the car.
Once the first replacement coil cover was replaced I didnt have any issues with wet plugs the 2 times Ive checked them (most recently yesterday).
Im starting to lean towards a bad ECU, headed to my buddys house yesterday after work I was cruising along about 70mph on the freeway and my speedometer started going crazy, was bouncing from 70 to 0 and back and forth a few times. I have a video of it on my cell phone that i see if I can convert and post. That along with the cooling fan not working is what leads me the think the ECU. I can get one from Checker Auto for like $130 so I guess its not too bad, would suck though if thats not.
Anymore ideas out there?
Thanks,
Thomas
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
Don't you 2.4 guys ALWAYS have trouble with those plastic covers?
See about picking up an ecu from a yard, see if that fixes the problem if the 130 is too much.
What about the coil cover connectors? The 4 boots that go to the spark plugs?
Im glad to see the last 2 posts I made didnt actually post, I love wasting my time. LOL
The boots were replaced when the coil pack housings were replaced. I assumed that was standard practice when changing the covers so I didnt bother typing it.
I dont mind paying $130 for the ECU if I know it is the issue but hate to waste it if it is not the issue. I would try one from a junk yard but none of the junk yards around me have z24s to get one from.
I have been getting the weird spedometer issue almost on a daily basis now. It really only does it when I am cruising at a steady speed, usually between 70-80mph. Im not sure if it is a ecu issue, speed sensor issue or a cluster problem. My fuel, temp and speedo have been off for some time now, Ive just adjusted to it and know were it should be when everything is normal.
I have one other issue that could be related, my car DID NOT have an EGR valve on it from the factory, atleast it didnt when I bought it in 02. Around the time of the first coil pack housing change I made a plate to cover the egr port on the head by the intake manifold. Could putting that plate over the port cause some issue? I was reading that a bad or clogged EGR valve can also throw a p0300 code.
Im running out of ideas and really appreciate the help so far.
Thomas
99 Z24
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
DSM skyline whats the latest on your car? i just started to get the 0300 code tomorrow morning i will start to take it a part and find out my problem.
~1996 Cavalier LS 2.4L (auto)
Sorry for not posting an update. Code is gone, car seems to be running good, still have a slight miss at idle but I can live with it.
Been a little busy with my new project... a 16' Ski boat I picked up dirt cheap.
I kept going over what would cause a 0300 code and called a couple dealers and talked to several different service techs to pick their brains as well.
When I installed my intake I decided to make a block for the EGR port on the head to keep the exhaust from blowing all over the engine bay. My car never had an EGR valve on it from the factory but the Pontiac motor I have installed did. When I put the Pontiac motor in I did not put in the EGR valve. This turned out to be my issue.
One reason for an 0300 code is clogged or blocked EGR valve. I removed my block off plate, pulled the negative battery cable and just like magic, the code went away!
It always sucks when you try to make something better and end up causing an issue that makes you crazy trying to figure it out.
If I were you, I would definitely start with a new set of plugs, coil cover and boots and see if your issue goes away. That seems to be the biggest issue. Also, if you have an Autozone or Advance Auto around you, take your ICM to them and they can test it to make sure it is working properly.
Keep us updated on what you find out.
Thomas
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
hey what is the ICM stand for?
~1996 Cavalier LS 2.4L (auto)
