running rough!!

[Rootie524]

this sucks. my car now has NEW spark plugs, ignition wires, and coil pack with ICM and the problem remains!!!!!!

after the new wires went on i went driving around and it seemed to be fine and i could hear the occasional minor misfire. no big deal. so when i get close to home im at a red light..so im like what the hell..i pop it in first and there is no one behind me. so i go abour 25-30mph in first and pretty high RPMs and the problem that i've been having comes back. So under normal driving in D it didn't come around. but in one gear in high RPMs it comes around and stays around even when put back into D.

So..from this is most certainly should be a timing issue. so is there too much timing advance that would cause this? i've asked that many times but have yet to get a response. so can someone help me out..

its either timing or fuel..cant really be much else.

[SappySE107]

Tuning for 93 octane on 9.6:1 compression is not going to improve anything. There is no reason to increase spark timing compared to stock. I would guess this is your problem, or you have a bad plug, bad wire, or something in the fuel system. A datalog of operation would help a lot.

[Rootie524]

i got a new cam shaft so they had to tune it for VE..while they were at it they told me i should run 93 octane and they tried to get more power. in the end they got me about 7whp in advanced ignition timing. As soon as i got it tuned it ran great for a month and this only started happening recently.

all the plugs are new and even before the new plugs i had this problem, all the ignition wires are new, and before that i had this problem, the coil pack and icm is new (from junkyard) and even before that i had this problem. So everything spark wise is new.

I checked the MAF and tapped on it with a screwdriver handle and it did not change..i unplugged it and it ran even more rough..delay in throttle response, almost stalling, etc.. and when it was unplugged the MIL blinked on and off like the car does when it's misfiring like an SOB..so by that..it might be a MAF going bad. idk. A MAF at a junk yard is $16..maybe worth a try.

other than that i guess the fuel system is next. the pump is fine..shouldnt be a filter but why not replace it while im at it, maybe a injector or two took a shit on me. i am absolutely clueless.

VIDEO OF HOW IT RUNS NOW: http://www.youtube.com/watch?v=_JvRZBOyQ3A
VIDEO OF HOW IT RAN BEFORE: http://www.youtube.com/watch?v=WbvijFB-mEg

idk if u can tell a difference..it's hard to tell unless ur there..but i certainly notice it.

[prophiseer]

It's a little hard to tell based on the sound quality of the vid (even HD) . . . I'm thinking it's a failing MAF (which is actually quite rare, based on my experience), or possibly a horrible vacuum leak (although, it's really hard to tell without having a scantool to see the live data of what the PCM is seeing from all of it's inputs). Double check the breather port on the rear valve cover, that it hasn't popped out and the condition of all the other vacuum lines to make sure.

Curious, what kind of air filter do you have installed? If it's a K&N or other similar oiled high-flow filter . . . you might want to try and clean the MAF. Remove it, and carefully spray the resistors a couple of times with some quality brakekleen, then lightly blow on them to dry them off - would be a good idea to clean the IAT, too. Oiled filters are notorious for fouling the MAF and IAT and causing all sorts of odd headaches.

[Rootie524]

I'll try all that stuff then. It's not a K&N but its one like it..it's in the wheel well as you saw from the video so it's possible it's dirty.

the key thing to note here is it's on and off. sometimes it runs decent with minor miss and others it shakes the whole damn car. and lately when i start it and go to put it in gear it almost stalls out and has already a few times.

So I'm going to do some MAF tests and possibly just replace it. but im also thinking it may be fuel injectors..what do you think? could be clogged or just worn injectors that are slowly dying. i do have a scan tool for my computer that i can monitor live data from most all sensors. what should i be looking for.

[86FieroSEv6]

Transmission/Torque Convertor???

[Rootie524]

torque converter is why it almost stalls sometimes cuz its cammed with stock converter but that didnt happen much..it seems to be more now.

and if the torque converter or tranny were the issue, i would think it'd be ALL the time and not intermittent.

and it has the same issue in park at idle.

[prophiseer]

Well, TBH, the easy answer would be anything that seems amiss or out of range . . . but, it's easy for some of us to say that when we're accustomed to what "normal" data values are from working around cars all day

Honestly, as far as the values go, it'd be hard to say anything concisely. Reason being is due to the code - a P0300 is the PCM's way of saying "Hey! There's a problem over here!" But, there's nothing definitive enough for the PCM to pin it down to anything specific, and/or one specific cylinder. Whatever it is, it's causing an issue across the board. With GM's a P0300 is a blanket misfire code - it could even be an ECT sensor out of range. The only GM DTC that's more of a PITA to diagnose is a P0420 (Catalyst efficiency below threshold) - that's their real blanket DTC. Either way, it'd be near impossible for me to go through all the different inputs and what they should be based on your local weather (at time of testing), how warm or cold the motor is, run time, etc . . . at least, within the span of a post here.

What I can offer, though, would be to look for anything really amiss . . . for example, a sensor value that doesn't equate to the environment - like, an Engine Coolant Temp sensor reading of -70F when the ambient temperature is 80F. Or, a MAF reading of <5g/s with the motor running. Or, a BARO sensor reading (key on engine off) that doesn't correspond to your barametric pressure for the day/weather.

If your scan tool can take a print out, or record and save the data for print out (or even the freeze frame from the stored DTC), and if you had a way of displaying it here, that'd be great. As was mentioned before, the only thing better would be a video of the live data values

If the problem is still more on/off, that had me a bit confused, your last post made it seem more like it had become constant (or more constant). If it's really that intermittent, it's more than likely a sensor starting to fail and only acting up under certain conditions (heat, shock, etc.), or possibly an issue with sensor wiring somewhere. The PCM, though, usually will flag a sensor that's getting shitty enough to cause the motor to run like that, though, which is rather odd - in most cases like this, it's not actually a sensor, but something mechanical that's causing the problem as the PCM doesn't really see any issues aside from a random/multiple misfire.

[Rootie524]

well i would think if it's mechanical it would be all the time. and sorry if i wasnt clear but it is on and off but i guess what i was trying to say is its getting worse in the sense that it acts up longer before it goes away. it would make sense for it to be some sensor but the PCM isnt throwing a code for it which it should be.

i dont know much about LIMP mode but is it possible something causes it to run so poorly it runs in limp mode till the problem goes away then it goes back into normal operation? that's probably a dumb question but i have no clue anymore.

and would my fuel injector guess be a possibility? as mentioned in the post earlier..i was driving around without it causing a major problem..then i dropped it in first and stayed in first at high RPMs..and it started missing the a SOB and it caused the extreme problem that i'm having. it's hard to explain the noise im hearing unless you heard what it sounds like before and what it sounds like when it's acting up. idk if it could even be called a misfire. it is just so nuts. its like a very deep growl that stutters..my engine must be pissed!! haha

but im thinking a cylinder or two may not be getting adequate fuel which might just explain that. but first ill check the MAF..but i've never been more stumped in all my life.

[nixtux]

My 1995 Cutlass did something similar for 2 months before the transmission went out. Everything shakes, I'd give her a little, it'd wind up and go away. I only read the first page so I may have missed something.

[86FieroSEv6]

Barring any of that, reinspect the harnesses very carefully. What if the issue is due to engine movement causing an intermittent ground or other internal harness problem. Look for the harness rubbing against sharp edges or hot stuff. Sorry to sound so simplistic, I don't mean to be condescending, but I have been bit in the ass more than once for not taking a deep breath and starting over with a close careful inspection.

[91z24build]

Once upon a time I had a dodge shadow that did the same thing, it got worse and for longer times until one time it couldn't recover. The timing belt was jumping, it would jump a tooth or so then finally jump back and be perfectly fine for a week or so till it did it again. It finally shredded some teeth off the belt and that was that, there just so happened to be enough clearance with it being a 2 valve engine that it didn't bend any valves or hurt anything.

The only thing I can think that would stretch a chain enough would be a flat tappet cam installed in a roller tappet engine.

Another thing could be a broken sprocket dowel pin maybe the cam gets spun a little but if and when the pistons hit the valves its enough to spin it back without bending them.

Just thinking here, anything is possible

[86FieroSEv6]

What about lifter lock? Have you checked your oil pressure with a mechanical gauge to see if it's spiking? While rare, it has been known to happen, the lifter will pump out and not let the valve seat.

[Rootie524]

i dont think its my chain, but you never know..and i have the right cam installed in the right engine so i should be fine. i have a pre 99 (thicker) timing chain on my 2002 car and im running stock compression with a cam so it should be stretched too badly already.

but this lifter lock is starting to sound like a possibility. so your saying the cam lifts the lifter and the hole in the block the lifter sit in, it gets stuck in the hole in the up position keeping the valve open and the cam is unable to touch it at all. It's just stuck there? thats starting to seem like it might be the issue. would dirty oil or oil with debris cause that?

i wish i could say ur wrong cuz thats gonna be a PITA to fix..but it's starting to seem like the answer. i mean this car runs rough. its hard to tell of my idle videos but when your driving it growls like a SOB and shakes. and it sorta has a growl to it like when i mixed up my two pushrods. so that leads my to believe its possible its a valve/lifter problem.

[Rootie524]

removed valve cover in the front..ran it..problem remained and all valves opened/closed properly. i can do it to the ones in the back though because of all the stuff that would need to be removed it just wouldnt work. so fronts good, back is undecided.

also..when left in first gear and accelerated..thats when this growl and having little power happens. it sounds like i have 400whp when i dont and i dont go very far..but when i let off the gas and remain in first gear the exhaust tone sounds like it has. so that leads me to believe, if it is a valve problem, that the problem rests in a intake valve and nothing to do with exhaust.