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I can spell you.....
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Discussion Starter · #1 · (Edited)
code = P0300. Got it with a OBDII reader. Says something like "rapid/multiple cylinder misfire" in the manual.

???What would you check???

The car was sitting w/ stone cold engine idling VERY rough (I was letting the engine warm up) when the code come on.

2 major problems with my car:

#1- cold engine bucking then stalling
#2- 'extremely' choppy idle (like aggressive cams, but I only have 91's) **started after the cam install.

I hope this code will solve one of these two problems....

Thanks in advance for any help :)
 

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I can spell you.....
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Discussion Starter · #2 · (Edited)
Hmm, search engines provided me with this...
A random misfire problem (code P0300) means the misfire is jumping around from cylinder to cylinder and that multiple cylinders are experiencing a misfire problem. This is usually due to a lean fuel condition, which, in turn, is being caused by a vacuum leak, an air leak in the intake manifold, dirty injectors, low fuel pressure or an EGR valve that's stuck open and leaking exhaust into the intake manifold.

A "random misfire code" (P0300) is even harder to diagnose because there can be numerous causes. A random misfire usually means the air/fuel mixture is running lean. But the cause might be anything from a hard-to-find vacuum leak to dirty injectors, low fuel pressure, a weak ignition coil, bad plug wires or compression problems.
Why can't it be more specific!!!???? :mad:
 

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I can spell you.....
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Discussion Starter · #4 ·
Storm88000 said:
Are you the same guy who posted that his car stutters when cold? Perhaps you found your problem....
Yep! I'm the gal that's been trying to figure out my cold engine stalling/bucking for over a year now. :(

If it solves one of the two probs above, I'll be ecstatic!! :D :D
 

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From the 1997 FSM:

P0300 Possible Causes:

Improper spark plug
Insufficient compression
Incorect fuel pressure
EGR valve
Injector circuit is open or shorted
Injectors
Intake air leak
Ignition secondary circuit is open or shorted
Lack of fuel
Magnetized flywheel (drive plate)

There is a three page diagnostic procedure:
- Check for intake air leak by listening for the sound of a leak
- Check for exhaust system clogging by checking for dents
- Power balance test by disconnecting each injector harness connector to see if there is an engine speed drop
- Check spark plugs for fouling, etc.
- Check ignition spark by getting a good spark plug, putting each plug wire in turn on the plug, putting end of the plug on a good ground, crank engine and check for spark.
- Check each injector to see if it is making an operating sound (clicking) at idle. (Requires a mechanic's stethescope)
- Check EGR Function (This is a long separate procedure)
- Check fuel pressure by installing a fuel pressure gauge in the line between the filter and the pressure regulator. Should read about 34psi at idle.
- Check compression. Should be 178psi with a minimum of 149psi and a difference between cylinders no greater than 14psi.
- Check ignition timing
- Check MAF (Requires Consult or OBD-II monitor)
- Check ignition wires for cracks. Check resistance of wires between the spark plug end and the inside of the distributor cap. Should be 4.15-5.61 ohms/ft. Move the wire while measuring to check for intermittent breaks. If resistance is high, check for good distributor cap connection.

Lew
 

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chucky200sx said:
^^
Thanks SO much for taking the time to give me all that information Lew. It's really appreciated! :)

*** Looks like there's a few things that need to be tested huh?
When I am faced with a large number of possibilities like this, I ask myself, "What is the cheapest, quickest, easiest thing I can do?" That's what I do first.

In this case I think checking the condition of the spark plugs is it. If there is an air leak, the car will be running lean, and all the spark plugs will be white/blistered due to the high combustion temperatures caused by the lean condition. If an injector or a wire is bad, then one spark plug will be different from the rest. If the electrodes are missing entirely, then aliens from space have stolen your car during the night. :D

Lew
 

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lshadoff said:
When I am faced with a large number of possibilities like this, I ask myself, "What is the cheapest, quickest, easiest thing I can do?" That's what I do first.

In this case I think checking the condition of the spark plugs is it. If there is an air leak, the car will be running lean, and all the spark plugs will be white/blistered due to the high combustion temperatures caused by the lean condition. If an injector or a wire is bad, then one spark plug will be different from the rest. If the electrodes are missing entirely, then aliens from space have stolen your car during the night. :D

Lew

I do most of the work on chucky's car (though she's learning rapidly herself :D ) and this is what I've found...

Spark plugs are white and have signs of light detonation. The timing was set to frickin' 28 degrees BTDC, presumably by a retarded shop (the distributor was cranked WAY forward). I reset it to 15 degrees BTDC and set the base idle again.

The cap and rotor seem to be very worn and there's deposits on the points in the cap. And something seems to be triggering the knock sensor to retard timing - when I watch the timing I can see it randomly jittering about 5 or 10 degrees back. Phantom knock caused by engine noise, a faulty knock sensor, or genuine knock - who knows?

The engine compression tested at 182-186 psi across the board and leakdown numbers were between 2.5% and 6% across the board. The engine's healthy.

Disabled the EGR system and changed the fuel filter, no change. I personally think the car is possessed by space monkeys that are drinking the gas before it reaches the cylinders. But I'll install a fuel pressure gauge and make sure before applying anti-monkey cream.

If I unplug the knock sensor will it put the engine into backup mode or just trigger a CEL?
 

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raene said:
And something seems to be triggering the knock sensor to retard timing - when I watch the timing I can see it randomly jittering about 5 or 10 degrees back. Phantom knock caused by engine noise, a faulty knock sensor, or genuine knock - who knows?
If the timing is bouncing around, then you do not have the car in " set timing " mode.

How could someone have a stalling problem for a YEAR without doing simple things like cap, rotor, timing, base idle, aac check?
 

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I can spell you.....
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Discussion Starter · #10 · (Edited)
cnynracer1 said:
How could someone have a stalling problem for a YEAR without doing simple things like cap, rotor, timing, base idle, aac check?
Ok, here's a list of what's been done over the last year:

-tranny/tranny comp assessment
-alternator checked
-new sparkplugs
-cleaned the aac valve assembly
-checked for vaccum leaks
-O2 sensor replaced
-fuel filter replaced
-squeezed the PCV valve tube shut. (dropped the idle about 100 rpm/normal)
-plugged EGR (no change)
-reset base idle (many times!)
-cleaned throttle plate
-reset ECU (many times!)
-tested ECT sensor
-starter fine
-battery fine
-compression and leakdown test = fine

Not like we haven't done anything to try and fix this. I just don't have a lot of money to be replacing random things, so we go off of what could be connected. Plus it stops stalling in the warmer months. Unfortunately things have just gotten really bad/escalated the last couple months. So now that we see the cap and rotor needs to be replaced, that'll be done in a few days, the other things you listed have been done.
 

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Enjoy the GTR Matt!
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You've got to make sure you put it into timing mode first, it shouldn't be roaming all over.

You found a major problem, set that timing, change the cap/rotor/plugs, check the fuel pressure, and report back. Shouldn't cost too much to do that, call Greg V. over at quality nissan - he is a great guy and hooked me up on parts cheap.
 

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I can spell you.....
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Discussion Starter · #12 ·
R0b_ said:
You've got to make sure you put it into timing mode first, it shouldn't be roaming all over.

You found a major problem, set that timing, change the cap/rotor/plugs, check the fuel pressure, and report back. Shouldn't cost too much to do that, call Greg V. over at quality nissan - he is a great guy and hooked me up on parts cheap.
Yep, when it is in timing mode it's jumping when it knocks! makes it hard to set the timing. So in the next week, I'm going to do the cap & rotor and get new plugs and check the timing again to see if it has advanced.

Something with the fuel pressure though.... when the car stalls, and I start it up again, I have to gas it in order for it to start, otherwise it sounds like it won't run unless it gets more fuel. It's only started having problems starting after stalling lately, b4 it would start up just fine. We'll have to see if changing the detonated plugs and old cap and rotor fixes that... but it's really starting to look like the 20% lean condition is the cause of the stalling. But what is causing is to be so lean?!

In addition I'm going to hook up a air/fuel gauge and see what those pretty LED's tell me.

BTW Rob_ I can't use U.S. Nissan Parts places, I'd get robbed with exchange, shipping, and UPS border fees... "I am canadian" :D Thanks anyways!
 

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cnynracer1 said:
If the timing is bouncing around, then you do not have the car in " set timing " mode.

How could someone have a stalling problem for a YEAR without doing simple things like cap, rotor, timing, base idle, aac check?
We HAVE done these things... 'cept the cap and rotor, 'cause as chucky said, she's broke :( Poor student and all that... but those are being done soon :)

IMO that's unimportant though (besides the fact it needs doing) as the car is dying due to a lack of fuel, not an ignition problem. Cap shmap, rotor shmotor, it's leaning out and dying and that's why it sounds like it's a cammed Camaro at idle.
 
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