Hi I have searched and seen many people with this issue and every case seems to be a bit different and so far ive had no luck getting my car back running the way it was meant to and I hate driving my 4 door family car everyday so any help would be greatly appreciated.

First things first what it is doing, first a misfire on #3 and #6 so replace coil pack, CEL goes away, few months later im getting a random misfire CEL code and have no clue what to do next, idle is sitting at 1k rpms even on a cold start no fluctuating really sitting steady, was dropping a little before i replaced the weak battery. Car is sluggish from a stop and any time you accelerate and car is just running rough with a minor shake in engine.

What I have done so far not in order but, oil and filter change, air filter, fuel filter, plugs and wires, all 3 coil packs now, pcv valve and gasket, small elbow in vacuum line was cracked so I replaced it. Ive ran injector cleaner, 93 octane all the time, replaced battery, sprayed carb cleaner all over manifold looking for leaks and found none, even used baby powder as well to do this (not at the same time lol). I have not checked for burnt valves but seems to run too well to be a valve just yet, the next guess i have is to clean the injector tips by soaking them in trans fluid and ohms test the electronics on them and replace the seals while im at it. After that I will try a new crank position sensor as well unless someone has another idea or anything you can do to help. I just want the t-tops down on my car again and running on all 6 cylinders.

 

check fuel pressure, test evap system, how did the plugs look that you took out? where they fouled? check your 02 sensors to see if they are fouled. check all wires and connections you can. have you considered sending your injectors in to be cleaned and flow tested. doesnt cost that much and will take them out of the equation.

 

Had that before with a random misfire, where I pretty much determined the injectors were the only thing left that it could be. So I unplugged each injector one by one while the engine was running till I found one that didn't make a difference. A couple tankfuls of injector cleaner in the tank didn't do squat. What did fix it was removing the injector, and soaking it in carb cleaner for a half hour or so, swishing it around periodically. I wouldn't use trans fluid.

 

Sorry it was late, I did check the fuel pressure, cant remember now what it was, but it was slightly low so I changed the filter it looked original to the car and sure enough the flow was much better and in the normal range. The plugs I pulled out were a little bit wet with fuel but not real bad. Gap was correct on them. I would assume it has to be more than one injector causing the issue for it to be a random misfire but correct me if thats not the case. ive got an extra set of fuel rails and injectors from an 01 camaro 3.8 car Engine was bad but thought it might be helpful for parts clean this set thats already out and swap them one at a time and see what happens. Any idea what it costs to have the injectors tested? Ive already sunk more into it than what I would like right now but Ill do what I have to, to fix it.

 

random misfire is usually a lean condition. check egr. i sent my injectors in for cleanin and testing. cost was very reasonable like 15 bucks each.

 

I'm not an expert but if the EGR checks out ok and your misfire continues after having injectors cleaned, I'd do a compression test and check for a burnt valve just to be safe. Again, not an expert but had this same thing happening and final diagnosis was a burnt valve after I changed EGR, fuel filters, plugs & wires, and cleaned injectors.

 

One badly spraying injector can trip a random misfire code. If you have an injector that is clogged, or not spraying fully, the oxygen sensor will read a lean condition and trip a code. Since the computer can't know which cylinder is lean, you get a random misfire code. Although a random misfire could happen in more than one cylinder, the code doesn't automatically mean it's more than one. Generally, a random misfire code is the computers way of saying, "at least one of your cylinders isn't right, and best of luck finding which one".

 

I had the same exact issue just yesterday. Had recently upgraded to full MSD coil packs and wires and Bosch Iridium plugs. Couple days later, yesterday, I went out to grab a bite to eat and my car was running amazing. As I left it was sputtering and backfiring bad. Parked it and gave a call to my mechanic because I was at a loss. Come to find out my Ignition Control Module was the cause of the problems. He picked a used one up, swapped it out and now my car runs perfect again.

 

Ok just got on here I founda good price on injectors just have to wait 8 days to get them delivered to the local parts store. Today I did manage to find one halfway taped vacuum line, not sure what it went to but was two different sizes and connected on passenger side almost under the dash. with a falling off piece of electrical tape the two hoses were visibly open so redid their connection and made it secure, replaced the camshaft position sensor, swapped the MAF, and double checked the throttle body wasnt dirty since i had never taken any of that apart since I got the car. I will get the injectors in just over a week from today. I guess the best way is to try it in each one and see if that clears it up one at a time or is there a better way? knowing there is a possibility of multiple being effected. Its just hard to spend 352 dollars plus tax for 6 injectors up front however on the positive side everything but the engine block will be new by now.

 

i bet these guys could have them to you on tuesday for way less. http://fuelinjectorconnection.com/shop/