P0300 and P0300 (PD)

ericv1984

ericv1984

New member
Joined
Apr 5, 2011
Messages
435
Reaction score
0
Points
0
Age
40
Location
Lacey, WA
My car started running like crap yesterday so I left it at my fiance's moms house so her boyfriend can work on it, meanwhile we are out of a car until it gets fixed.

When it started running like crap, I took it to autozone and got it scanned. Three codes came up, P0300, P0300 (PD), and not sure what the third code is but it was for the IAT sensor. I replaced the sensor with a new one from autozone.

My fiance's moms boyfriend is thinking that it's either the fuel injectors or the fuel pump, so I found a fuel pump on eBay or 20 bucks so I ordered it, but I was thinking about it and I don't think a fuel pump would cause a random misfire, or would it? Anyway, my money is on the injectors. We changed the spark plugs and then he took them out after driving it and he said the plugs in 1 and 4 were black after taking them out, so leads me to believe that the 1 and 4 injectors are fouled. He also bored out the cat cause he said it was glowing red, even though I looked at it and it didn't look like it was glowing red to me, but doesn't hurt to bore it out.

Anyway, what does the (PD) in the code mean?
 
It means there is a code pending being set in the PCM . The reason you have a p0300 set, and one pending is because if you have a few drive cycles that don't have a misfire, a p0300 will clear. If the pending code is experienced in several consecutive drive cycles, it will set the code. Fuel injectors can cause a p0300, but they are not at the top of the list of causes. You can get more info by looking here: http://www.obd-codes.com/p0300
 
Since I already bought the fuel pump, can a bad or weak fuel pump cause a random misfire?
 
Also, if the spark plugs were replaced then removed after a test drive, and number 1 and 4 were black, what would that lead you to believe is wrong with the car? Fuel injectors, ignition coils, spark plug boots, etc..?

Btw, it's a 1998 Pontiac Sunfire SE 2.4L
______________________________
 
I really don't think it is a fuel pump issue, but I guess anything is possible. What I think you need to try first is really check your coil packs. You can find the correct procedure here: http://easyautodiagnostics.com/quad_coil_test/coil_test_quad_1.php

If you find no problems with the ignition system, you next need to do a cylinder balance test, this will tell you if you have a bad injector. This procedure is explained here: http://easyautodiagnostics.com/quad_case_study/coil_case_study_1.php

Follow all these steps, including a compression test (also explained in article), and I think you'll be able to nail down the problem.

FWIW, from the description you give of the spark plugs, it sounds like you have a failing coil pack. Good luck, and please let us know what you find out.
 
msmith1956 said:
I really don't think it is a fuel pump issue, but I guess anything is possible. What I think you need to try first is really check your coil packs. You can find the correct procedure here: http://easyautodiagnostics.com/quad_coil_test/coil_test_quad_1.php

If you find no problems with the ignition system, you next need to do a cylinder balance test, this will tell you if you have a bad injector. This procedure is explained here: http://easyautodiagnostics.com/quad_case_study/coil_case_study_1.php

Follow all these steps, including a compression test (also explained in article), and I think you'll be able to nail down the problem.

FWIW, from the description you give of the spark plugs, it sounds like you have a failing coil pack. Good luck, and please let us know what you find out.
Click to expand...

K thanks. The car is at my fiance's moms house so her boyfriend can work on it. I didn't think it was a bad fuel pump but he said it was weak and since he used to be a mechanic I bought one anyway. The fuel pump is around a 250 dollar or more part but I found a brand new one on eBay for 20.24 with free shipping so it's worth a try.

Last night I was thinking it was a coil pack since it's the number 1 and 4 cylinder and I think 1 and 4 are on the same coil. 1 and 4 were on the same coil on my old 96 SE but this year could be different.

I'll most likely just go a head and buy a new coil pack since they're cheap on eBay, and if that's not what's wrong then at least I'll have one more new part on the car.
 
Also could be the "coil mounting bracket" aka the distributor cap. Or the plug boots.
 
Does anyone know how to test the ignition coil housing assembly?

Here's the part I'm referring to...
op3b4n.jpg
______________________________
 
msmith1956 said:
I really don't think it is a fuel pump issue, but I guess anything is possible. What I think you need to try first is really check your coil packs. You can find the correct procedure here: http://easyautodiagnostics.com/quad_coil_test/coil_test_quad_1.php

If you find no problems with the ignition system, you next need to do a cylinder balance test, this will tell you if you have a bad injector. This procedure is explained here: http://easyautodiagnostics.com/quad_case_study/coil_case_study_1.php

Follow all these steps, including a compression test (also explained in article), and I think you'll be able to nail down the problem.

FWIW, from the description you give of the spark plugs, it sounds like you have a failing coil pack. Good luck, and please let us know what you find out.
Click to expand...

I just ordered two coil packs on eBay at 14.45 each, brand new with free shipping. I was only going to buy one but decided to get both so I know both on the car are new and I've heard that it's a good thing to replace all the packs at once.
 
The car is at my fiance's moms house so her boyfriend can work on the car and test some things. He tested the coils and said they were ok, and said the gas in the tank was bad and probably messed up the pump so we have to drain it, put the new pump in, and fill it back up.

Gonna be putting the coil packs on anyway, since they are already ordered.
______________________________
 
Last edited:
Fuel pump didn't fix the problem, which I knew it wouldn't. Put on new spark plug boots a long with new coil packs and now the car runs good.

CEL is still on but haven't gotten it scanned yet to see if it's from before, which I think it is from before but just never went away since the CEL came on before for my IAT but after I fixed it it never went away until I erased it. I plan on erasing it tomorrow when I go to get it scanned and see if it comes back.
 
You must log in or register to reply here.

Share this page

Back
Top