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P0300 code, hard start. NEED HELP!


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#1 Jgoodmon0001

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Posted 11 June 2012 - 06:56 PM

I have recently obtained a 96 V6, I absolutely love it. I have changed plugs, wires, cleaned the K&N air filter, currently running fuel injector cleaner through this tank of gas, checked and changed all liquids as need be. My car has a misfire which is barely noticeable at idle and at regular driving. The car falls all its face during hard acceleration especially during 1st and 2nd gear. I had a friend scan it (a somewhat cheap scanning tool). It through the dreaded p0300 random misfire code and bank 1 sensor 3 o2 sensor. Also, before we cleared the old codes, it said cylinder 6 misfire, after we cleared it we only received the random misfire code. Also it has a hard start, usually around 3 cranks, although sometimes it starts perfectly, as soon as you turn the key. Other times it has started really hard, 5 or more cranks. I am going to have it scanned at AutoZone to double check. I know the list of possible things are endless. I really love this car and it hurts my feelings knowing it is not running perfectly. Is the any tips or pointers anyone can give me? I really can not start dumping money into this car for things that I don't know if it will even fix the problem. ANY help is greatly appreciated. I want this bird flying high againPosted Image

#2 98firebird

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Posted 11 June 2012 - 07:03 PM

Welcome to FBN, Josh

Try checking your PCM's fuses (underhood). It really sounds like a failing ignition control module (ICM) though.
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#3 GaryDoug

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Posted 11 June 2012 - 07:54 PM

The problem with the generic misfire codes is that if you have more than one cylinder with misfires, it's reported as "multiple". With your v6, two cylinders share a coil, so a defect with one coil may just be reported as multiple misfires instead of #1 and #4 for example. Or #6 and #3, or #5 and #2. In your case it may be helpful to know exactly which cylinders are misfiring. If it is truly random, that signifies something else, than if only 2 cylinders are misfiring. More advanced scan tools and software will give you that information but at a higher cost naturally, typically $200 and up. If you have a notebook/laptop PC and about $15-30 to spend on an ELM327 OBD2 adapter, you can download my free OBD2 scanner program which you can use to determine which cylinders are exhibiting misfires (among a lot of other useful things in the future). If you have a smart phone instead, I think the $5 Torque app may allow the use of non-generic data retrieval (count of misfires for each cylinder for example), if you know the GM codes for that. However that requires the use of a more expensive Bluetooth adapter also ($30+?).
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#4 xgongiveittoya44

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Posted 11 June 2012 - 07:56 PM

I have the same problem it could be the ECT sensor also because once those go out they default to -40 degrees or something so the pcm floods the chamber on start up because it thinks it's -40 when infact its like 90+!!! Although some guy at tuffy told me its a faulty injector because he thinks its sticking open on start up and flooding the chamber that way... Its possible i guess but im not sure wheather to believe him my dad trusts him but im on the fence.

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#5 smokinhole

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Posted 11 June 2012 - 08:32 PM

For a hard start I would first check the fuel pressure, it should hold fuel pressure after shut off for quite a while. pressure should be 48-55
Assuming your pressure is good, a crank sensor on the fence can cause that code or the ignition module thinking about giving it up.

#6 Jgoodmon0001

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Posted 11 June 2012 - 08:52 PM

Hopefully AutoZone can give me more specific cyclinders. I feel like I should know what the ECT is....but I don't, I'm a newbie, sorry. Lol And are there any tests I can to see if it is a faulty crank sensor or ICM?(assuming fuel pressure is good, of course.)

#7 GaryDoug

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Posted 11 June 2012 - 08:58 PM

Hopefully AutoZone can give me more specific cyclinders. I feel like I should know what the ECT is....but I don't, I'm a newbie, sorry. Lol And are there any tests I can to see if it is a faulty crank sensor or ICM?(assuming fuel pressure is good, of course.)


Autozone only does the code readings, not data. They can tell you what an ordinary code reader will tell you, except with a little more detail perhaps, but nothing you can't find online. ECT= engine coolant temperature.
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#8 Jgoodmon0001

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Posted 11 June 2012 - 09:02 PM

Also, the fuses are all good. And oh okay, thanks. And I usually over around 210 give or take a couple degrees depending on how much are I push the pedal;). So I'm assuming the ECT is fine.

#9 Jgoodmon0001

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Posted 12 June 2012 - 03:20 AM

I was wondering about the coils, but didn't know which one or how many to change. Maybe since the old code rea cylinder 6 misfire.....change the one that controls it?

#10 Ivan

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Posted 12 June 2012 - 04:30 AM

I was wondering about the coils, but didn't know which one or how many to change. Maybe since the old code rea cylinder 6 misfire.....change the one that controls it?


I think you are on the right track, if your car turns on and works fine sometimes I will check the coils. One coil (bad or intermittent) can kill your car, even a bad spark cable (it happened to me). Remove the coils and the control unit under it and inspect for rust on contacts and also check coil impedance (Ohms) with a multimeter. Original coils have the spark number on top (1-6).

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#11 Jgoodmon0001

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Posted 12 June 2012 - 05:42 PM

UPDATE

Tested the coils by pulling the wires one at a time and brake torquing the car to see if the car ran worse or the same. The coil that runs cylinder 6&3 didn't change the engine. Replaced the coil ($33). No miss at all. Burnt rubber for the first time today.

#12 Madman95

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Posted 12 June 2012 - 05:53 PM

nice find man,good thing it was nothing major

#13 Jgoodmon0001

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Posted 12 June 2012 - 06:43 PM

Thanks Bryan. My hard start wasn't completely cured though. I got the TPS code today. So maybe that is the problem? Also if I double prime it usually starts within 2-3 cranks...not too bad but not perfect. If I don't, it takes longer. That look like TPS or maybe possibly fuel pressure regulator?

#14 Injuneer

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Posted 12 June 2012 - 08:34 PM

Check your fuel pressure. Turn the key to on, without starting the engine. Pressure should rise to at least 40psi (48-55psi applies to the 98 and newer cars, not to a 95-98 3.8L). Turn key off. Pressure should not drop rapidly. If it drops rapidly, could be a faulty check valve in the fuel pump, a faulty fuel pressure regulator, leaking injector(s) or leaking fuel lines. The faster the pressure drops, the harder it will be to start.

If you have leaking injectors, it will make it even harder to start, since the pressure will be dropping and a cylinder or two may be flooded with fuel. Next time you attempt to start it, hold the accel pedal on the floor BEFORE turning the key to run/start, turn the key to start, and continue to hold the pedal on the floor until the engine starts. If the engine starts quicker, it may indicate leaking injectors. Putting the pedal on the floor puts the PCM in "clear flood" mode.
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#15 98firebird

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Posted 12 June 2012 - 10:10 PM

I had a similar problem with a TPS, I believe I had 3 codes pertaining to it. I removed the sensor, shot it with some electrical cleaner, and like magic my car was running and starting smoothly again.
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#16 Jgoodmon0001

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Posted 13 June 2012 - 05:11 AM

That's a good idea 98. And if this doesn't work, I guess I'll be testing the fuel pressure.

#17 djfirebird93

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Posted 13 June 2012 - 04:09 PM

Your other thread has valuable information to your question. http://www.firebirdn...nent-slip-code/
The TPS could very well cause a hard shift. The computer could think that you are applying full throttle when you actually aren't. (Higher pressure in the valve body when you floor the car). The transmission sees this as "Holy crap, i'm shifting too hard" and will give you your code. Do you remember the exact code? as well as the TPS code?
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#18 Jgoodmon0001

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Posted 13 June 2012 - 05:10 PM

I agree but nobody was replying on that post so I asked here also. (hope that doesn't violate any forum rules) But te codes were P0122 and P1870.

#19 djfirebird93

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Posted 15 June 2012 - 11:54 PM

Here's some good info about the p0122 http://easyautodiagn...t_bad_tps_1.php
As for the p1870, that is for "Trans Component Slipping" and most likely means your trans is on its way out. Fix the TPS issue first, and clear the codes, then see if the p1870 code comes back.
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#20 Kelly Rivas

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Posted 5 days ago

Any updates on what this was?






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