P0300 Random Cyl. Misfires with new IM?

[Ventmaster]

OK, too tired (and hot ) to safely work on this thing to day.

Still not convinced it's a leak. Once past idle she takes gas well and seems ready to rock & roll!

Could I have exceeded my tune's ability to match the flow at idle?

Did a freeze frame, if any of this can tell someone about what's happening please let me know! The P0300 is the only code I'm throwing.
Cylinder misfires were in #'s 1,3, and 5. Is this the left bank?

7E8: Engine

DTCFrzF P0300
Fuelsys 1 OL
Fuelsys 2 OL
Load-PCT(%) 74.9
ETC(*F) 100
SHRT FT 1 (%) 0
Long FT 1 (%) 0
Shrt FT 2 (%) 0
RPM 1063
Spark adv -20
IAT (*F) 91

MAF (lb/min) 2.373
TP (%) 35.3
RunTm (sec) 1
FRP (psi) 1263.3
EVAP_PCT (%) 0.0
FLI (%) 43.9
Baro (inHg) 26.9
VPWR (V) 17.960
Load-ABS (%) 57.8
EQ_RAT 1.027
TP_R(%) 21.6

AAT (*F) 93
TP_B(%) 35.7
App_D % 19.2
TAC_PCT (%) 31.0

I realise alot of this provides nothing useful, but I'm too desperate to leave out anything and assume!

Thanks for looking .

[Cyber Gray]

The leak codes are 3 (I dont recall the numbers) and I got them all at once when my IM & TB bolts were not tight. But Im sure that it wasnt P0300 !

It seems that you have a different problem here. Did you unplug any cables or plugs under the IM because the place is full of bolts, wires, and plugs so you might pressed on someting while installing the IM.

[Ventmaster]

Yeah the P0300 is generic and I think the specific codes are P0301 (cylinder1),P0303 (cyl.3), etc...

I've triple checked all connections and I'd had the Mace on for a long time (installed it myself without any issues).

Gonna order more new gaskets tomorrow and then try just the new IM w/Mace again.

[ChadG]

Originally Posted by Ventmaster

Yeah the P0300 is generic and I think the specific codes are P0301 (cylinder1),P0303 (cyl.3), etc...

I've triple checked all connections and I'd had the Mace on for a long time (installed it myself without any issues).

Gonna order more new gaskets tomorrow and then try just the new IM w/Mace again.

Try reflashing to stock tune and see what happens?

[NYJets77]

Originally Posted by Ventmaster

Yeah the P0300 is generic and I think the specific codes are P0301 (cylinder1),P0303 (cyl.3), etc...

I've triple checked all connections and I'd had the Mace on for a long time (installed it myself without any issues).

Gonna order more new gaskets tomorrow and then try just the new IM w/Mace again.

As a maybe last resort: undo everything, put the IM and plenum back to stock, make sure everything is good, then add 1 mod at a time until the problem re-surfaces. A lot of work but it should isolate the problem.

[Cyber Gray]

Originally Posted by Ventmaster

Yeah the P0300 is generic and I think the specific codes are P0301 (cylinder1),P0303 (cyl.3), etc...

I've triple checked all connections and I'd had the Mace on for a long time (installed it myself without any issues).

Gonna order more new gaskets tomorrow and then try just the new IM w/Mace again.

Vaccum leak codes that showed up to me were P0507, P2187 and P2189.

My problem was a leak caused by loose IM and TB bolts.

[Cyber Gray]

Technical Description

P0300 Random/Multiple Cylinder Misfire Detected
What does that mean?

Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.
A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.
Symptoms

Symptoms may include:

• the engine may be harder to start
• the engine may stumble / stumble, and/or hesitate
• other symptoms may also be present

Causes

A code P0300 may mean that one or more of the following has happened:

• Faulty spark plugs or wires
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector(s)
• Burned exhaust valve
• Faulty catalytic converter(s)
• Stuck/blocked EGR valve / passages
• Faulty camshaft position sensor
• Defective computer

Possible Solutions

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

[Cyber Gray]

Ventmaster, your problem is mainly electrical and has nothing to do with the IM. Check the article posted and once again check your plugs, sensors, and wires.

[hapisok]

i think part of the reason there isn't much useful data out of your freeze frame is because its still in open loop. at least thats how it appears to me. and since you've pulled your battery terminal and fuses, your fuel trims reset to 0 too. you'll need to let it run until it goes into closed loop to start pulling in data in order to utilize it for troubleshooting.

you also might want to check your cats...what are your cat temps? you could always let it run and check the flow coming from your exhaust in comparison to each other. if one flows more than the other...then you've found your problem. just thinking out of the box. not impossible to blow out a cat and i wouldn't suspect it right off the bat but its easy to check.

[Ventmaster]

Originally Posted by hapisok

i think part of the reason there isn't much useful data out of your freeze frame is because its still in open loop. at least thats how it appears to me. and since you've pulled your battery terminal and fuses, your fuel trims reset to 0 too. you'll need to let it run until it goes into closed loop to start pulling in data in order to utilize it for troubleshooting.

you also might want to check your cats...what are your cat temps? you could always let it run and check the flow coming from your exhaust in comparison to each other. if one flows more than the other...then you've found your problem. just thinking out of the box. not impossible to blow out a cat and i wouldn't suspect it right off the bat but its easy to check.

Thanks Hapi-

I ran it longer until up to temp, but then the scanner said it had no frezze frame to go with the new codes.

Pulled the IM today and found oil inside the IM.

Not from the crankcase vent hose I put a RX catchcan on a few hundred miles before installing the ported IM.

It seemed to be blowing up thru the #1 cylinder (passenger side, front cylinder- see pics) into the IM. The Rx spacer had also become loose- fell right off the IM!

Can a vacuum leak cause this?!

The Mace plenum spacer was glued on tight, but I had decided to go back to the 1" Mace insulator only and as I was taking the plenum cover off, a bolt broke .

Of course it sheared off right at the same level as the IM face- nothing to grab.

So right here I would like to publically endorse the Grabit Pro made by Alden . This thing shocked the shit outta me and worked like a charm...
Also got a full set of gaskets ( 2 for the insulator) and will endeavor to persevere!

But really- can a vacuum leak suck that oil out like that?

[derek19]

Wow.. How many miles do you have on that?

[Ventmaster]

Oh, about 3 miles since installing the IM.

About 8K on the car, which was running perfectly before this install... .

[dagolfguy]

It really looks to me like you had no seal around the cylinder in the top right there.
Leaking both to the outside, and also to the inside which would cause cyl to cyl contaminiation.
So, I have always believed that it is good to have found a (the) problem. I think you have.

[Ventmaster]

Yes, it seems I have.

But any idea what it means? Are things as dire as my imagination is making them?

Sure would like someone to tell me if I re-assemble correctly, everything will be good again.

Will be beginning in earnest tomorrow...