So I pulled the motor out of my 99 2.4 ld9 and did a complete rebuild. Shortly after start up I had a p0300 code so I replaced the coil packs, spark plugs , spark boots, had the icm checked, replaced the crank and camshaft position sensors, checked for vacuum leaks and there went any, then I cleared the code and the cars still missing it does it at ilde and when I'm driving my afr at idle is about 13.0 and when I start driving it goes all the way to 10.0 and then all the way down to 20.0 and I have no power! But after that it goes back to roughly th 14's but it still misfires!
Here's the list of modds I have done
90mm wiseco 9.0:1 forged piston
Secret cams
Jbp oil pump
Jbp lifters
Eagle rods
Cosmetic head gasket
Water/meth injection ( haven't sprayed since rebuild)
Bbp header to 2 1/2 exhaust
B&m shift plus
True cold air intake
Parts I've replaced.....
Factory replaced crank
Factory rebuilt head
New timing chain set
New water pump
New alt
Replaced all the gaskets!
I've been working on this car for 8 day , been to 3 auto shops and then turned away for having aftermarket parts!
But the dealership did hook it to the computer and they said that all the cylinders are misfiring!
So my question is could lowering the compression to 9.0:1 cause the random misfire? How long does it take for nitrate steel ring to seat? Or am I missing something?
How many miles are on the motor? Did you do break in procedures? Have you done a compression check? Are you sure the timing was set right? What injectors do you have?
FU Tuning
160,xxx ,yep 35 to 55 then let off the gas and coast down to 35 do that 10 times! No compression check yet but the oil smells like gas! The timing is dead on took it apart to check ! Stock injectors
A mechanic at a speed shop told me that the rings may not have seated yet and that the compression maybe lower than 9:1 if it is he also said that might be causing the random misfire, but he isn't sure?
Also I've been running mobile 1 for 60k miles and after the rebuild I put mobile 1 back in it! Will it cause issues with the break in? The first time I rebuilt the motor was at 100k I had real bad blow by and just put stock parts in except for the cams I change them to the secret cams and I used mobile one for the break in last time!.......
So you have 160k on the rebuild?How many miles on this rebuild?
FU Tuning
I have a total of 160k when I did the rebuild.... I driven a total of 140 miles!!! a coworker told me it sounds like a fuel issue? So I was checking it out on my lunch break and I unplugged the vacuum line on the fuel pressure regulator and nothing happend.... Could a bad fuel pressure regulator cause my issue? On my way home today I noticed that if I gave it gas it would misfire! And when I was at idle it was doing the same.....
Did you replace the coil pack housing?
Unplugging the hose on the FPR you are not going to noptice a big difference. Do you have a fuel pressure gauge on the rail?
It could be fuel, but on stock injectors, and stock tune I doubt it.
FU Tuning
Yep replaced the packs, housing, plugs and icm tested so it all good unless the new coil packs were bad.... I'm starting to think it might b the head gasket ?
did you check the injectors that they are all firing do this by moving an injector thats missing to a different cylinder does the problem stay or does it follow, are your plugs good
if these are good check that the injector wires for contenuity incase 1 was broken when you pulled the motor and replaced it
JBO since July 30, 2001
Generally, a cylinder misfire is caused by three things:
1. Loss of Spark
2. A/F mixture too far out of balance to ignite
3. Loss of Compression
To break it down....
1. Loss of spark? Could be anything to do with the spark system.
-Plug wires or electrical wires leading to the plug. (did you remove the engine? Maybe a wire was pinched or broken in the re-and-re process.
- Coil Pack (if your engine has one), could be faulty
- Spark plugs. Did you replace these? Different kind? Is the gap different?
2. A/F mixture out of balance?
- Too Rich? (does it go lower than 10:1?)
- Too Lean? (Wow, a 20:1 A/F ratio could cause knock/detonation/misfire)
- Faulty Fuel injector? Do you get a lean code to go with that misfire code? Switch each injector to a different cylinder and see if you get a different code to let you know which cylinder the misfire is in.
- Fuel filter? Did you replace it since the rebuild? when was the last time you replaced the filter?
- Fuel pump? (would cause a general misfire, rather than in certain cylinders, aka, a P0300)
Are you getting an EGR code as well as a misfire code? Could be a leaky EGR Valve (if your car has that option)
3. Loss of compression? (meaning a cylinder lost most of it's A/F mixture before it can be ignited)
- Burned exhaust valve (did you re-use the stock valves with the new cylinder head? Did you "prussian blue" the valves against the head, and Lap them in with compound to maintain a good seal? You can't just throw in old valves and call it a day...)
- Blown head gasket
Does it misfire when Cold? Warm? Under load?
I would hook up a fuel pressure gauge to the service port, and check fuel pressure at "Key-on" and "Start-up/Idle" conditions, then report back to us with that answer, as well as as much as you can answer from above.
It's hard to give a diagnosis without being there, and the more information, the better
oh crap,
just read your post about noticing that your oil smells like gas.
I'd check to see if there actually IS gas in your oil, or it just smells like it.
If you are getting gas in there, it could be caused by fuel seeping past the pistons.
How were the pistons installed?
Condition of cylinder walls?
Did you hone?
How were the piston rings installed? Gapped properly? Ends spaced out around the piston properly?
If you have a buddy who can help you check the compression, I would do that too just for peace of mind.
Erik
Pistons were installed using a ring compressor and the ring were gaped using a feeler gauge and yes they were spaced out to manufacturer spec. The cyclinder walls were honed using a ball hone. As for the condition of the walls they looked alright.
*watching this thread*... i have a similar issue with my 00 2.4... however i have higher comp pistons (11:1), .430 lift cams, LSJ injectors, and a partial tune, and my misfires are part time...
Alright went to the speed shop this morning and we got to talking about proper break in and oil! Come to find out I didnt know that synthetic oil is bad for breaking in and also it has no zinc ! The guy did a oil change to conventional and added Lucas break in additive and said to drive it for 1k miles and if nothing changes come back! He also said that the rings prolly haven't seated yet being I have only gone 150 or so miles.....
Could I do a computer tune to get rid of the misfire?
Everyone stop throwing around heresay...
You put cams on a motor that has no tune and is used to a standard lift cam and expect the PCM not to freak out?
Get a tune... Your rings are already seated, and I WOULDN'T go back to whatever speedshop you went to.
Buildin' n' Boostin for 08' - Alex Richards
Alex
The cam that are in it have been in for a while going on over two years and im pretty sure the cams arnt the problem .... I've had the cam in for about 50k miles I reused the cams for this build
Screaming for Mercy!! wrote:Alex Richards wrote:Everyone stop throwing around heresay...
You put cams on a motor that has no tune and is used to a standard lift cam and expect the PCM not to freak out?
Get a tune... Your rings are already seated, and I WOULDN'T go back to whatever speedshop you went to.
Secret cams really???
QFT...
Hense why I created that huge post about other potential problems. Alex, Look at my build. I ran that on Hahn 32lb injectors, with a stock tune, with no misfires during the initial break in procedure (no boost). I really don't think that his cams are causing the problem.
Gosh I need to figure something out quick! I barily made it to work this morning the misfire was so bad the car wouldn't make it over 40 mph ?
Blair Birch wrote:Gosh I need to figure something out quick! I barily made it to work this morning the misfire was so bad the car wouldn't make it over 40 mph ?
If it is that bad you should not be driving it. Is the chec engine light flashing why this is going on?
What spark plugs are you running?
FU Tuning
No check engine light! The only light on is the etc light and I'm getting fed up with it!
Spark plugs are acdelco double platinum
Blair Birch wrote:No check engine light! The only light on is the etc light and I'm getting fed up with it!
That makes no sense. IUf your getting misfires that bad you should have a flashing CEL.
Really need to see some datalogs of the car.
FU Tuning
What else could it b if it's not throwing a code? If it was the coil packs or a fouled spark plug should it throw a code and like I said it's all new!
