97 Yukon 5.7 P0300 code - Help

I've seen aftermarket distributor caps throw that code, same with those plugs, use Delcos, coils and the wirng too them are a common enough problem on those trucks, what do the cam and crank signals look like? Maybe they were disturbed with the engine re and re

Dear Mr Compton, Thank you for responding - I will carry this forum through until this miss is resolved. A bit more timeline background - At the time of the intake and transmission work.... I installed the new plugs as a matter of simple maintainance, as well as the rotor (Autolite, with Federal Mogul rotor). I thought the cap looked fine, and prior to the work the engine ran perfectly. Upon running the engine after the intake work and experiencing the miss, I had the local auto parts store do a scan, and the only code pulled was the P0300. Then (aside from the plug reading, vacuum check and fuel pressure check) my first steps toward correction were the new cap, an AC Delco rotor and the new premium plug wires. These had no effect on the engine miss. At the time of these initial checks, I did a visual on the plug wires in pitch-dark lighting, and observed some light ambient arcing in a couple of areas - this led me to replace the wires. The engine may possibly be running a tiny bit better in all driving conditions with the new wires, but a minimal perception. I think I will try the AC Delco plugs next. I don't have an OBDII analyzer, but if the plugs don't clear up the problem, I'm thinking of getting one of those setups where you put a program on a laptop and attach the appropriate cable. This to persue the cam position/sensor issue that you mentioned. If the cam issue is a fault, would it show up on a fault code scan? Discover more fuel Speedometer Forum Regarding the potential coil or coil wiring fault - again, would this show in a fault code scan? or is there an electrical test which can be administered to this area? I would like to be a thorough trouble shooter, rather than simply throw new parts at it. I'm an old school car guy, these modern vehicles and their "issues" are somewhat new to me.

try an a/c delco distributor cap!

I replaced the Autolite plugs with AC/Delco plugs, because it was one of two things that I did change during the top-end work, and resultingly could have been a potential cause. The A/C plugs made no difference whatsoever! The only other thing that I replaced during the top-end service work was the rotor. I had first replaced it with a quality aftermarket rotor. When I first re-started the vehicle and found the engine missing, I performed the tests noted earlier, and replaced the aftermarket rotor with an AC/Delco rotor. The Delco rotor made no difference. As I mentioned previously, the engine ran perfectly prior to my work, with the OLD plugs, rotor, wires and distributor cap (none of which were AC/Delco), all of which had over 70,000. miles on them. Again, the old distributor cap worked perfectly. I highly doubt that the new Premium NAPA distributor cap that I installed (which thousands of professional mechanics use quite successfuly every day) is the cause of the miss that I am experiencing. How about some professional troubleshooting procedure rather than "throw parts at it untill something works". Anybody?

okay so you're acussing of me of telling you to just throw parts at it! okay here's a suggestion, put all your old parts back on and take it to a professional! I was giving you the benefit of the doubt that you hadn't screwed up the distributor, cam timing or anything else and gave you some suggestions as too what I myself have seen fix those Discover more Jeep engine Ram Pickup codes on those engines but yet you choose to berate me! Go take your truck then to a professional and bother them for whatever they choose to charge you per hour and leave the people who try to help you for free alone, too many people get on these websites looking for the magic bullet, well there isn't any, None of us know the quality of your new parts or the compentency of the people doing the repairs, Maybe your engine is defective! We don't know but if it isn't and the code wasn't there with the old one then it must be something you did! You may have a problem with fuel volume and pressure, egr system, incorrect install of intake gaskets, cracked lines for the injectors, etc etc, etc! You're obviously the expert not me, you fix it then and be sure to enlighten me with what the successful repair ends up being! I won't hold my breath though. Not because I dont think you can't fix it but because if it is something you overlooked or caused it's unlikely most would admit it!

Your response speaks volumes. Troubleshooting recommendations, anybody?

97YukonBlues wrote: How about some professional troubleshooting procedure rather than "throw parts at it untill something works". Anybody? First of all, it does not pay to bark up a wrong tree. If you don’t like the advice given here then look elsewhere. I know Jeff is one of the elite members on this site with plenty of knowledge and experience under his belt. As for OBDII codes and scantools, they do not replace a trained mechanic. Codes simply tell you that there is a problem in a certain area/system. They are used to narrow down your search for the cause of the problem. Some codes are pretty precise but others like the P0300 is extremely general which means your search will have to be broader. So, your car has a misfire and being random does not help at all. You really need to do some data logging and go through some general tests so you can rule out some of the common failures/probems and this way narrow down your search. If you are looking at getting a OBDII interface with software for laptop, then check out Autotap with GM Manufacturer PID upgrade. It looks like a good package. But if you really want take advantage of everything OBDII has to offer, then get the dealer scantool. I can warn you not to expect too much from the scantools. They are great at providing codes, showing some data from sensors, and at running some tests. But they do not replace a good multimeter, fuel gauge and other test devices that are available at a shop. As they say you need the right tool for the job.

Seeking the next most logical troubleshooting procedure for the conditions that I have related.

* Compression Check * Minimum 100psi at 200rpm Perform at normal operating temperature, spack plugs removed and throttle wide open. The difference in pressure between cylinders shall not be more then 20%.

Yukonblues, Please tell me what you found out if any because I have the same problem after doing the same repair after replacing intake gasket

Problem Solved!!! Quick Answer= Misadjusted valve lash. Something that I had not mentioned in my earlier posts was that during the intake gasket replacement procedure I had adjusted the valve lash. I did so because in very cold weather, I was experiencing some lifter noise for up to a minute after a cold start. I assumed that in 170,000 miles the lash could use adjustment. As careful as I usually am, I had managed to maladjust one cylinder. This showed up in a compression check as being only 50 psi. in that hole. I corrected the situation and the engine runs perfectly now. No more Yukon Blues. Good luck!

oaky so like I said something you did wrong and neglectted to mention was the cause of your codes! Thanks at least for admitting it although the last thing anyone would expect to to tell you as a repair for po300 would be to recheck your valve lash after the intake job because it doesn't require changing it when you do the intake job!! Don't break your arm patting yourself on the back!

As the Sage has said: "If it is natural for the immature To cause harm to others It is wrong to get angry with them, Like resenting fire for burning." In this my final post, I wish all a wonderful life and many happy motoring miles. Goodbye

good riddance to you, try to be a little more thankful next time