I've taken my truck to two places to have my P0300 diagnosed, both have decided the injectors to be the most likely suspect. The one I put in was from autozone, and when the smoke test was done, it was leaking pretty bad. So now I'm going to go with an AC Delco one, wherever the shop gets their parts from quoted it at $696 for the part. The one I found on RockAuto comes up for $380. It sounds kind of crazy that I'd be saving over $300 on the same part. Is this right? If so, is there a lower price I can get?

Also, what else should I have replaced? I don't want to pay to have the intake removed multiple times if I don't have to. I'm really hoping this works out, and if so I'm sticking with no AutoZone crap in my engine. If not, I guess I'm back to square one with emissions in two weeks, wish me luck! Thank you!

 

Change it yourself.... get the spider assembly and the "nut kit", the lines that bring fuel to the spider inside the intake. these generallly get brittle over time and dont like to move around or be detached adn re-attached.

its really simple to do. all you need is an 8mm and 10mm deepwell socket. took me maybe 30 mins the first time I pulled my intake to change my FPR that was leaking.

 

MakaveIi, please put your vehicle information in your signature.

schollianmj, since his truck is a 2001, there won't be a "nut kit".

I actually, believe it or not, got the best price on the MFI spider from the dealership here in town. If I remember correctly, I paid $250 and had the part in my hands the next day. Haggle with them on price. The guys at the parts counter at my dealership know me by now and give me their best price when I get there. If I find the part cheaper online before going there, I'll tell them exactly what it would cost me. If it's something I can wait for (typically is with my repairs), I buy online.

 

Just curious how can you smoke test the injector system? Just trying to wrap my head around it?

 

oops... my bad. thought i knew something. Hey at least I tried to help rather than just shout SEARCH!

 

They weren't smoke testing the injectors specifically, but when they hooked the smoke test up, lots of it came out of the injectors, and they were able to show me. Correct me if I'm wrong, but I believe the MAP sensor is what's right above it, and that's what they had off to look at the injectors, so course it's just a tiny space to see through but that's what it looked like.

Alright I'll update my sig and check out the dealership on Monday and see what they say. Thanks!

 

Just curious is all... I have heard of smoke testing intake systems just never the injectors. Sounds now like a intake leak that should be addressed and could cause all the symptoms mentioned... These are just my ramblings. Good luck

 

Yeah, definitely a possibility, they said my PCV valve was going crazy, maybe when the upper plenum is off we'll see something wrong.

 

$186.35 with free shipping: Amazon.com: Delphi FJ10565 Fuel Injector: Automotive However, if there's a problem with an injector, it's likely to set a cylinder specific DTC, not P0300.


So before you just replace it, keep in mind that P0300 is almost always caused by a fault in the secondary ignition system: Spark plugs, spark plug wires, distributor cap, rotor, possibly worn distributor shaft bushings, ignition coil, and in some cases, low fuel pressure. These 4.3's are real fussy when it comes to ignition and fuel delivery parts... they like AC Delco and Delphi, aftermarket stuff, not so much

 

Cylinders 1 & 6 are misfiring like crazy, with misfires on the other cylinders every so often. More than anything it acts like a leak. There were a couple times before I overheated it that I would start it up and it ran like there was a major vacuum leak somewhere, but then I'd restart it a couple times and it would be fine. After the overheat now that happens sometimes when I let off the gas when in reverse or just shift into reverse, but the rpms pick back up and it will run fine. Then once it heats up it starts misfiring. While it's heated up if I try to start it again it doesn't stat immediately like when it's cold, it stumbles until it can hit the 550-600 rpms. I know for a fact there's an AC Delco Cap and Rotor, and I was told the plugs and wires were too, but I wasn't there to confirm when they were put on. Ignition coil is out of my 97 Jimmy which was running fine when I took it out. Once I get my school stuff in order I want to swap my ICM, MAP sensor, PCV valve, and IAC with my Jimmy to see if there are any changes, but I just don't have the time yet.

Glad I waited to buy, that's a great price, and I might have them erdo the gaskets too since the Fel Pro ones are only $65.