lol.. dang, you beat me to it. [:'(]

 

So I took it to the shop but they only had time to do the diagnostic...they didn't tell me the code but they said the computer read it as a "random misfire"...im supposed to take it in Sunday and they said they'd start by checking the filter, spark plugs and wires. Im a little concerned because they said that if it was just the fuel filter the computer would probably give a fuel efficiency code rather than a random misfire one. If it was a bad fuelpump would the car be able to drive? Is it bad for the car if it's driven while misfiring? I had to drive it a long way to get back home yesterday.

 

Random misfire means that all cylinders are misfiring at random times. This is usually the result of having a lean fuel mixture, but could be ignition related, such as a position sensor or bad ignition module which affects the whole ignition system, Depending on how badly the pump is damaged, determines if the car is able to run or nut. Not a good idea to drive a misfiring car for a long distance because when a misfire occurs raw fuel is left in the cylinder and it washes the lubricant off the cylinder walls. among other bad things. Hav you tried changing the fuel filter??

 

No I haven't...is it something I could do myself? If so I'll give it a shot after work...i'm just not sure where it is or how to do it...

 

It would take you longer to get the tools and get the car jacked up, then it will to actually change it out. I'm unsure about where it is exactly. When you buy the filter, it would be a good idea to buy a Hayne's manual too. Lots of good info in them. Such as troubleshooting, step by step removal/installation, wiring diagrams, etc...

 

Yeah i don't have jacks or tools or anything. I'll probably hold off until Sunday and let my friend look at it...Problem is he's like15 miles away and I am worried about driving it that far.

 

Well, i took the car in yesterday. They replaced the fuel filter, spark plugsand spark plug wires. One of my spark plugs was cracked and one of my wires was kind of torn up. The car is a lot smoother now, but it is still shakier than it used to be and the check engine light comes on and flashes still. They still can't figure out what it is but insist it's not the fuel pump. One of the mechanics said it could be a coil or crank sensor and to take it back next week. Any other ideas?

 

Ok, so it's been a little over 2 months and I still have not solved this ...I have had the spark plugs and wiring replaced which helpeda little. The next week I had the coil for cylinders 1 and 4 replaced since it mine was not working...this made the car much smoother and seemed to add power, but it's still not quite back to normal and the CE light still flashes. They said something about acoil control module which may be faulty...but at this point i feel like i am just throwing parts at it without knowing for sure if that's what the problem is. Could it be bad gas? I still have the samegas in the car as i did that daywhen iran outandadded more (which is when all this started)...and would that cause my spark plug to crack, my wires to fry and my coil to go out? Thanks again for all your help

 

Dang its been a while with this problem. Try adding some of the Chevron fuel treatment. Drawing all the fuel from the bottom of the tank may have gunked something up. It would not cause the bad wires and plugs but they could have been bad and the computer compensated for it so you never really noticed it. I had 3 wires off of one back on a 97 4.3 and the OBDII computer compensated enough to make it run but a little rough. Was your fuel pressure tested? Engine off, idle and while cracking the throttle? Was the computer scanned with a scan tool or just a code reader? A scan tool would give you info on whats going on where a code reader just gives codes. My scanner will show wnat cylinders are missfiring and give the counts as it happens (amung other things)

 

At this point you need to have it evaluted like it hasn't been touched before. Take nothing that has been done into account and go threw the steps to find the problem. Just because parts are new doesn't mean they are good. The scanner doesn't tell you what's wrong, it tells you what is going on, testing tells what is wrong. Sure, once you see pattern failures you can be very sure of certain problems on certain cars but some testing still should be done to make sure.

Have the ignition scoped. Primary(not really primary but the cam and crank sensors also should be put on a scope to see their performance) and Secondary. Injector balance performed. If the person or shop knows the tricks with a low amp probe you can literally see if you have a weak cylinder by hooking the amp probe to the starter, disable the ability to start the engine, then turn it over. The amps will spike low on a weak cylinder because it takes less electrical power at that point turning the motor over. Or do it the old fashion way, compression check. Although if your scoping the secondary ignition you can see a weak cylinder and then check just the one. If you so choose or it's suspected it could be mechanical causing your problems.

Then, with gauges hooked up. As was stated by z28Pete, you need to find out if the fuel pump is performing. Fuel pressure and volume test. DeadHeading the pump by pinching off the return and watching for a quick pressure spike. Then you can again use a low amp probe to see how the fuel pump is drawing electrically. Nice, regular 2-4 amp draw is normal, spikes, high or low could be a sign of a weak pump.

With all of that, you may still not have a answer. Then your going into different tests. PCM checks, checking wiring (which should be done anyway) looking for "oddities" on the scanner, like low voltage or wierd readings then testing those parts. That is "if" you still only have a P0300 (random misfire detected). Don't bust their ***** to bad on this one. It may be a tough one and it may come down to trying some known good parts but it should be discussed if the known good parts don't solve things they shouldn't stay on and be paid for.