AgentLS1Z

I originally had a P0300 Code so I changed out the plugs and plug wires. Then I got a P0137, so I changed the 02 sensor, now P0301 keeps coming up. I also got a fuel injection service and cam and crankshaft timing from the dealership. I switched coil packs from 1 to 3 and P0301 still comes up. What's the next step? Should I check the spark plug again? When I started having my misfires P0301 would come up intermittently but P0300 was the main concern because all Plugs were shot. What else can be causing the Cylinder 1 misfire????

lt1pwr1

iTrader: (1)

So right now you are only getting a misfire on cylinder 1? Is it a dead miss or is it barely noticeable (but shows throws an SES light)? Can you feel it at startup but then is disappears or can you feel the misfire all the time?

You could try a compression check on that cylinder. You swapped coil packs, did you swap the plug wire as well? By fuel injection service, did they just put that cleaner through the fuel system? Did the dealer test cylinder 1 injector to see if it is getting power?

AgentLS1Z

Its a pretty bad miss. The car starts fine, then 1 minute later while driving the car will stumble bad. If i give it gas it feels like the car is trying to cough something out and if I keep trying to work through it the car seems to run fine on maybe 7 cylinders im guessing. After the stumbling goes away it runs pretty smooth but seems like it may be lacking power from that cylinder. When it first stumbles bad the SES light blinks, then goes away after it runs smooth. When the light is away and I scan the code, it's still there (P0301)...All the wires and plugs are new ACDelcos...Idk what exactly the dealer did. Next I guess is to check compression...

lt1pwr1

iTrader: (1)

Ok, a blinking SES light means multiple misfires. Try swapping out your MAF with a known good one from a friend or someone.

Also, you didn't use Bosch o2's when you changed them did you? You need to run factory AC Delco o2's on these cars. They don't like Bosch's and they will make you chase your tail.

AgentLS1Z

Yep I put a bosch 02 Sensor in, it took care of the P0137 code though. I unplugged the MAF to see if it runs better but so far still misfiring. I installed HIDs recently with harnesses and wired up a fog light switch for halos. When I wired the switch I used the orange wire from the radio and black for a ground. Also, I pulled out the PCM but replaced right away. I also connected the Auto headlight sensor wires together to eliminate the Auto headlight feature. Would any of that mess with the function of the car?

BLKSSLTT

iTrader: (10)

switch a say # 3 plug wire with #1 and see if it throws the code for that cylinder instead of #1 again. if so, maybe the wire isnt put together properly aka the wire inside the boot isnt touching the metal part that sits on the plug of vice versa for the coil end. PS. check the plug and make sure you didnt crack it when putting it in. i had the same exact problem and it turned out the ceramic had a hairline crack in the plug throwing the code. im gonna bet thats ur problem right there...

AgentLS1Z

I'll try it but P0300 came back...lol, this is bs

BLKSSLTT

iTrader: (10)

double check plugs and try your old wires if you still have them. taylor wires arent necessarily the greatest in the world and iv had bad luck with them before. double check each coil is firing each cylinder properly. get urself a harbor freight spark tester for $5 and check each cylinder if more than one if miss misfiring then its one of the sensors that triggers the computer to send spark to each cylinder. im not 100% but that might be either crankshaft positioning sensor or camshaft positioning sensor. someone with greater knowledge of the ignition system in these cars might chime in. but sounds like it started happening after the dealer dingbats touched timing cover. bet they pulled a wire end a tad far out of the plug on the crankshaft positioning sensor..

AgentLS1Z

Taylor wires were on my 98...I put ACDelco wires and plugs on this car. I'll get a spark tester. The car was missing b4 i brought it to the dealer. They did a fuel injection cleaning and cam/crankshaft timing.

joshp14

iTrader: (5)

When you say they did "cam/crankshaft timing", what are you saying that they did?

If the computer is setting a P0301, then I would go after the simple things first. As everyone said, start swapping things from one cylinder to another one at a time and see if the code changes. Plug, wire, injector. If problem stays with cylinder one I would go after mechanical, possibly a broken valve spring, worn cam lobe, bent pushrod, etc.

If it sets a P0300 instead, you could monitor misfire counter on scan tool if you have access to one...or you could unplug injector while its missing and see if engine idle changes.

BTW, crankshaft position sensor determines spark. Camshaft position sensor is used to determine the position of the valvetrain in relation to the crankshaft.

BLKSSLTT

iTrader: (10)

hmm good i had the right idea in my head. just didnt want to throw out un-educated information. thanks for clarifying ... start simple then get deeper and deeper until u find the problem. you'll get it, just keep pluggin away at her til you get it!

lt1pwr1

iTrader: (1)

I think what the dealer did was just a crank relearn procedure with the Tech 2 scanner when they say they re-timed the cam/crank sensors

Everyone has good advice hear but I honestly would get rid of that Bosch o2 and get a delco/denso.

You say it runs fine when cold at startup then a minute later starts misfiring..? That has o2 written all over it because it starts misfiring when it goes into closed loop mode is what it sounds like.

O2Form

An 02 wouldn't cause just one cylinder to missfire and the flashing check engine light is warning the CATS are in danger of damage.

Kevin01Z28

iTrader: (8)

So there is a way to time the cam/crank sensors? I've never had this done when replacing them.

I just replaced both of mine with bosch, so far so good. Wanted the densos, but they didn't have them. Whats the deal with boschs, I keep hearing this now after I read about them?

AgentLS1Z

The guy at the dealership said the cam and crankshaft timing was a little off so they would adjust it...and he said the fuel injection was pretty dirty. He said either that was the problem and/or the plugs and wires needed to be changed. They were gonna charge me $600+ to change them, so I did it. Car is still misifirng, its Definitely a Multiple miss. Like I said, it starts goodruns good for 1 whole minute then it starts to stumble bad (shakes bad) light blinks. I'll give it gas and it starts to work through the misfires and runs good after about 1 minute of playing with it.

I dont have access to a "scan tool", do you mean HPtuners?
If I unplug an Injector what would that prove? Could it potentially idle normally?

AgentLS1Z

Yeah, it misses basically after 1 or 2 mins. I heard after closed loop. I put Bosches on my 98 when I had longtubes and had no problems with them. I was getting a P0137 but it went away when i replaced it with the Bosch

joshp14

iTrader: (5)

If it runs fine in open loop then as soon as it goes to closed loop then I would suspect o2 sensors. However, typically it wont pick on just one cylinder.

A tech 2 scan tool, efi live, hp tuners, etc to monitor misfire counts. It will tell you exactly which cylinders are missing.

Typically if an engine is missing, and you dont know which cylinder is missing, you can start unplugging the injectors one at a time. If the idle drops or the engine runs worse when one is unplugged, then thats NOT the cylinder thats missing. If you unplug an injector and nothing changes, then typically that IS the cylinder thats missing. This method works best if one cylinder is missing. A lot of times if you have a o2 sensor causing misfires, it will cause all cylinders on that bank to misfire randomly.

AgentLS1Z

It's definitely not 1 cylinder. At first the P0301 code came up but now its strictly P0300 every time. I listened to all injectors with a screwdriver, theyre all ticking...I replaced the Post cat drivers side 02 with a bosch, is there any way of checking theyre bad without simply replacing them and wasting money? also could the cats be bad?

Kevin01Z28

iTrader: (8)

I don't think there is a way to check resistance of them with an volt meter. About the only thing you can do is find someone with a scanner and check the o2 mv's running, or use tuning software and force the car into open loop and see if the miss goes away. Other than that your just gonna keep going in circles. P0300 is just that random misfire, so it doesn't really point you in the right direction. I JUST had P0300 code, very similar if not identical symtoms that you are having, and it was my passenger side o2.

I completely understand you not wanting to waste money, but so far you have bought plugs, wires, a fuel injector service, cam/crank sensor re-timing (still have no idea what that is). If I was gonna shoot in the dark I would pick an o2 sensor. Not much else it could be at this point

BLKSSLTT

iTrader: (10)

++++1 above