p0300 CE code

[I'm a dork]

Started after going wide open throttle at around 15.5 psi. After he hammered the throttle to about 5,000 rpm in 2nd gear the CE light came on. He pulled over, got the code, cleared it, and then it came back multiple times. Car idles like shit (around 4-500rpm), engine stutters like a bitch, no visible air leaks. We'll pressure test it tomorrow.

He datalogged o2's showed very lean .04-.06. No change on the S-AFC settings will allow the car to idle correctly, and he can't get the o2's to cycle at all at any correction.

This is DJ Auggie's problem, 96 vr4, mods are in his sig.


Matt

[Gray Haze]

"Bad gas has also been causing some false MIL lights. When the vehicle is diagnosed, the technician finds a P0300 random misfire code which would normally be set by a lean misfire condition due to a vacuum leak, low fuel pressure, dirty injectors, etc., or an ignition problem such as fouled plugs, bad plug wires, weak coil, etc. The OBDII self-diagnostics tracks misfires by individual cylinder, and considers up to a 2% misfire rate as normal. But water in the gas or variations in the additive package in reformulated gasoline in some areas of the country can increase the misfire rate to the point where it triggers a code."

P0300 - Random/Multiple Cylinder Misfire Detected.

[HellBringer]

I'd pull all of the plugs and make sure none of gaps have been closed, etc..

[DJAuggie]

Thanks guys. My car is broken down in a cemetary in the fucking rain. I dunno what's wrong but it happened after a WOT pull of 3 seconds. I pulled in and the CEL came on and the car just ran like piss. I have NO idea what it is. I doubt its trhe gas because I have 60 miles on this new tank.

The only weird thing lately is the car has been smoking a bit but I can't tell if its blue or white. It ONLY happens after sitting idle for about 5+ minutes. Other than that, its seen the track twice in the last month and been running strong... No changes to the s-afc can make the 02s cycle. i have no idea whats going on

[DJAuggie]

The plugs were installed in Feb. I shouldn't have more than 4K on them. They are gapped .28 I believe. I will recheck in the morn.

[msaskin]

Shawn,

I had a few ideas after speaking with you this morning. Do the obvious first: check plug gaps, check spark plug wires, etc.

If that's all OK, I'd lean towards it being a bad coil pack. With the car idling, pull the plug wires one at a time. If it gets worse, move on to the next coil, if it stays the same when pulling a plug wire, that's your fault wire/coil pack.

~matt

[Multiades]

Originally Posted by DJAuggie

Thanks guys. My car is broken down in a cemetary in the fucking rain. I dunno what's wrong but it happened after a WOT pull of 3 seconds. I pulled in and the CEL came on and the car just ran like piss. I have NO idea what it is. I doubt its trhe gas because I have 60 miles on this new tank.

The only weird thing lately is the car has been smoking a bit but I can't tell if its blue or white. It ONLY happens after sitting idle for about 5+ minutes. Other than that, its seen the track twice in the last month and been running strong... No changes to the s-afc can make the 02s cycle. i have no idea whats going on

Lean and O2s won't cycle, especially in combination with that "air noise" I heard over the phone is symptomatic of a BIG air leak -- most likely a big vacuum leak somewhere.

Check the brake booster and clutch booster hoses.

Check the upper to lower plenum seal.

Check the fuel injectors where they insert into the lower plenum.


While you have the plenum off, do a compression test with either the engine coolant hot or cold (but make sure it stays one or the other for testing each cylinder and each bank). What you are looking for is cylinder-to-cylinder comparison. After you mentioned the intermittant white smoke at idle, and the loss of coolant with no indication of where it's going, I'm thinking that you have a blown head gasket. Note that this blown head gasket is probably not keeping you from going anywhere directly, it's just something you probably developed while driving the car hard at high boost. When you're running around unable to be SURE that knock is not occuring, a blown headgasket can happen. It could happen without the knock too, but it is generally the product of high cylinder pressures (high boost, hard driving).

Let us know what you find.

-Chris

[DJAuggie]

Ok. I got to the car and started to look for any open air leaks. I found NONE visually. I started the car up with I'm a dork and the car ran absolutely perfect. I did have a CEL of P000 with a "[]" description. I've gotten that before after getting a previous CEL. I cleared it and it went away. The car did idle high which is normal after not being started/driven for over a day. Both Matt and I were absolutely stunned. We pulled the car from behind the shack by the cemetary (creepy sh1t). I checked the 02s and the 02s were cycling!

After 2 minutes of running and the CEL came on again with the "P0300". The car ran like shit again. I cleared the code and blipped the throttle and it went away again and the car ran good. Both Matt and I were stunned even more. We took the car and drove 100 feet one way and as we were coming back, the CEL came on again and the car ran like shit. The 02s went back down to .06 and .12 and no changes on the S-AFC would cycle them. As I give the car gas via the throttle, the RPMS raise and the skipping/misfiring is very evident.

I limped the car home with I'm a dork. Anubis came over and we swapped the MAF-T for the stock MAF and no change. We started to rip down the plenum to get to the plugs. I pulled all 6 plugs which were changed in Feb when I installed fuel mods at Feral. All 6 plugs looked very similiar, very black around the first couple of threads and a fairly white tip. Not WHITE WHITE but a bit greyish white. I believe that's similiar to my previous set. These COPPER plugs shouldn't have more than 4-5K on them.

Went over to my Supra buddy's house and he let me borrow a compression check. We removed the ECI fuse and the crank angle sensor(s) near the timing belt and cranked each cyclinder 5+ times until the compression gauge stopped moving. The car has been sitting for hours when we did this. All cyclinders were 155 except the two nearest the driver which were 135 at first and then 145 on the next try.

We replaced the plugs and gapped them to .3 and put the car back together. The car fired up and sounded as shitty as we started in the morning. My Supra buddy seems to think it may be the FP. I am completely lost. It sucks having a 11-12 second daily driver and not being a mechanic

-Shawn

[DJAuggie]

TTT Help please

[Feral]

Do you still have your old plug wires? Also I think an air leak is HIGHLY suspect myself ... but its hard to tell. What did you specifically change before and after? I know you have been doing some mods to the car recently.