BAD misfire **update* RESOLVED!!!

ok, so, i got about half way home and then all of a sudden i started getting weird random misfire and it was only coming from cylinder #2. SO, about 20 miles later it got REAL bad, and the SES started flashing(good thing i was right by an off ramp) so i got off right away, pulled over, and shut it off. Pulled up the codes on my scan gauge and they said P0300 and P1133. So i called my friend Josh in Iowa who works for Carmax, and he said the P0300 is for O2 sensor and P1133 is for ICM ( I believe).

SO, i got to thinking, the guy that owned this F1 hood before me cut out the inserts in the scoops and the passenger one is pointed RIGHT at the ICM/cylinder 2, 5 coil pack. So, I pulled off cylinder 2 plug from the coil and put it back on, thinking maybe the high winds and 75mph caused it FOR SOME REASON, to pop off and cause a horrible misfire. I drove it home on the side roads 45-50mph and no misfires.

So, i checked everything over and it seemed fine, started it right back up and it started fine but with LOW misfire this time, 6 at IDLE, once driving it was fine).

Now, im thinking I am going to have to plug up those inlets with something, but idk what to plug it up with or HOW to go about doing so....GRRR!

p0300 is random misfires but doesn't indicate what cylinder, could be attributed to the front o2 sensor.

For some reason I remember reading that the code is thrown when the PCM sees multiple random misfires under in the first few seconds of start up, but that may be for a similar code.

I don't believe wind resistance coming through your hood is causing this, I am leaning towards an o2 sensor.

P1133 is also to do with your front o2 (heated) it seems.

Double check your front o2 sensor harness. Something may have happened when installing the hood.

It may also be coincidence and just be time for a new front o2 sensor.

well when i was seeing the HUGE amounts of misfire i was actually looking at my scan gauge and WATCHING the cylinders and they ALL came up under #2.

Try covering the coils and wires up with a rag or something so that the wind can't get at them, keeping it away from the belts, and drive on the highway. I don't know how effective of a test it will be but...

well, what i think im going to do no matter what is find something and patch those inlets up because rain can easily get in there and cause problems as well as other debris.

So, now i just gotta find something that wont look bad at all and then cover it up with some mesh.

If that doesnt fix it then MAYBE ICM...?

Get some thin sheet metal, paint it black, JB weld or get some epoxy and glue the mesh grille over the black sheet metal and then epoxy the whole piece to the hood on the inside.

That way it looks like grille with nothing behind it, just shadows, and no water or anything will get past it.

hmm, i will have to do that.

FYI Tim your 02 sensor was hanging under your car when you left. might wanna crawl under your car and check it out.

thats how it is jeremy. it just sits that low cuz thats how jeremy welded in the O2 bung.

Oh, well EVERYONE thought it was hanging down when you pulled away one of the times.

ya thats how it sits. and thats the post cat sensor anyways.

Did you pull the ICM connector and see if water got in there?

no i did not. hmmm never thought of that.

ok, so the BAD misfire hasnt come back. I think it was just a bad connection. I just installed zzp 10.3's, thinking MAYBE i had bad wires, well thats not the case.

Im beginning to think it may be the crank position sensor because the misfire is random. Everytime it misfires its always a different cylinder.

Would someone be willing to help me out with the install of this sensor?

IIRC, I saw a write up, its a pretty dang big job, Well on my scanner I have 1-8 misfires at start up, but it never comes back. I dont both with it. It never comes back, Didnt you already have those wires before ? Those bad boys are expensive !

no, i had taylor 8mm's, those wires were crap! Ya, they ran me $95.56.

Ya, it is a pretty big job, you have to take the crank pulley off and other stuff.

I got 10.3 MM wires off of someguy that posted on here for about 3 posts, Lucky me !

Here ya go, Tim: http://mykidz.net/GTP/CrankPosSensor.shtml

thanks alot blackarrow! Now, i just gotta buy the sensor and find someone willing to help me haha. I dont want to do something like this by myself.

you just need a cps learn not a new cps, as far as I know... failing cps symptoms would be stalling with the tachometer dying.

ive done 2 case learns and not one of them cured my problem.

Zalfrin, I did a CASE learn when he came down here. Doubt it helped.


Tim, I'm begining to wonder if maybe your tune is just screwed up. How are your LTFTs?

k. doesn't really sound like CPS to me, but your call 01GT.

ok, so about 5 o clockish i decided to put the 3.6 back on. turned it on, had 2 misfires in the driveway, pulled it out of the driveway and it ran fine. did a couple hard pulls and nothing out of the ordinary(just a noticeable performance difference ). So, i let the car sit for a bit while i go inside and get ready for tonight, 40-50 minutes later, come back outside and start it up. 102 misfires, shut it off, looked to see if anything out of the ordinary happened, nope, nothing.

So, i started it back up, gave it some gas and they went away!! Pulled it out of the driveway, gave it some gas and they went away, ONCE i stopped for a stop sign, they came back! Fuel pump?!?!?!!

Im really confused now! I called john(lonezerg) he said hes never heard of anything like this, and he said he wants to pull the crank pulley off and take a look at that cps, and maybe the ICM is bad.

check fuel pressure, could be a regulator

how do i check fuel pressure without a fuel pressure gauge?

osmosis? :rolleyes: or borrow or buy one.

well, i currently dont have money for anything. I need someone to help me out. I called john, so I will see if he will be able to come up and help me out again.

Thanks john for all the help with my POS! haha

You wanna talk about a POS ?!

Look at this 4dr GTP in my driveway !

**update**

I just took the car out for a drive and code p0171 popped up. so i brought it home and looked up the code and this is what it reads : P0171 - Fuel Trim System Lean Bank 1.

Someone explain to me whats going on here!!

Means your motor is missing and/or knocking because she's not getting enough fuel.

You gotta pull your LTFTs up on your scan gauge and tell me what they are at idle.


But honestly, all these signs are starting to point to a lack of fuel due to a bad fuel pump. Did you get the pressure checked like I asked you to?

Your car is angry for the top swap, it misses being N/A.

no i didnt get the pressure checked because i didnt have time today, and im not knocking because I am not registering any kr on the scan gauge.

Could you make a trip up here on tuesday John? Is it the fuel pump or is it the fuel pressure regulator?

I don't get off of work until 7:30 tuesday night.

I'm really thinking it's the fuel pump. It's the only part of our cars that tends to work some times and not others.

And your car won't even look for knock until it's up to running temperature.

You never did replace regulator, did you, when you found the milky fuel while replacing fuel filter.

no, the regulator has not been changed. I am going to take it to a shop tuesday and have them take a look at it. I am done putsing around with it.

A quick and easy way to check the regulator is pull the vacuum hose going to it when it's not running. If gas comes out, it is bad. Normally that would dump too much gas though.

ok, so ive decided im just going to buy an OEM l36 pump and buy the zzp rewire kit. Would someone in the area be willing to help out with the install?

Why not an L67 pump?

because, i was looking on zzp and l67's have differenty stuff in the fuel pump system "extras" that l36's dont have.

So if your reg is blocked, whats a new pump going to do?

i have no idea if the reg is blocked steve. I never once stated that it was blocked. I have no clue what is wrong. Im guessing its the pump....

I'm stating, the milky substance when changed the filter, is not passed the filter and in your regulator. So whats good a new pump is, if the rest of the system won't allow the pump to do its job?... You dig Timmy!

L67 fuel pump is a 2-speed pump designed for a boosted engine, if you're changing yours I would highly recommend using the L67 pump and enabling it in your bin.

well that does me no good now zalfrin as i ordered the l36 this morning. No one responded to this yesterday to tell me about the differences, so nothing i can do now. If it will be that big of a deal I will also order the fuel pump rewire.

steve, i will soon find out if the pump is good or bad. if the pump doesnt fix it, then i will be buying a new regulator.

Sorry for trying to be helpful, you're the one throwing parts at it willy-nilly. I'll keep my opinion to myself.

i sent you a pm zalfrin, to keep this thread clean.

i said something about the L67 pump.

you never gave me reasons as to WHY i should put one in.

Well its kind of obvious why, your boosted now, you should have the boosted fuel pump.

code 0300 just popped up : Engine Misfire Detected

I wouldn't continue driving it until you get this figured out, p0300 only pops if you get a ton of activity on your knock sensors.

I know shops don't want to work on a modded car, but it seems like you would be able to find one that would just do a fuel pressure test for you so you can make sure you're attacking the right system. Not like you're asking them to do debug work, just a test.

k. im done driving it then.

I thought you were going to keep your opinions to yourself? LOL j/p.

Tim, I think you are on the right track with it being a fueling issue.

Good luck!

i mean, when i was driving it, the misfire goes away when i press on the throttle. I texted lonezerg and he asked what my ltft's are at idle and they are 16.4. The idle trims have been at that number since i did the swap 2 months ago.

Dang, i wish i knew what i was doing with a tuner, because than i would putz with it myself. I hate having to ask people constantly to help me out with my problems.

fyi, shop manual diagnostic aids for random misfires are:

check grounds (clean and tight)
abnormally low maf reading causing engine to run lean
damaged accessory belt or device connected via accessory belt
vacuum leak or malfunctioning crankcase ventilation valve
fuel pressure
injectors
bad fuel
leaking egr
dirty o2 sensor

what were the operating conditions when the check engine light came on?

we made up.

Tim, misfire only at idle/low rpm and low ECT points to dirty o2 according to shop manual. Supposedly you just need to run at > 15g/s MAF at operating temperature to eliminate the deposits.

did the CEL just illuminate, or flash?

the car was idling when p0300 popped up. i had over 50 misfires.

no flash. just illuminated.

when did you last change o2?

good that no flashing, flashing indicates cat damage possible.

16.4 is what the LTFT's MAX at.

Your car is starving for fuel and I believe it's the reason you are getting misfires. The PCM is dumping in 16.4% more fuel to the A/F mixture to try and reach stoich. You are running mad lean.

Are you sure you don't have a vac leak?

Like Zalfrin pointed out it could be a dirty or failing o2.

What are the LTFT's when cruising or WOT? Or is it at idle that you only get misfires?

yes, running lean is why it is misfiring, 16.4 LTFT is a symptom of the air/fuel/sensor issue.

ive never changed the o2. Its only at idle that i get misfires.

but, why out of NO WHERE would it start misfiring this bad?

sorry, I'm a little behind and haven't been following the thread too much other than page 4.

Tim, things do just malfunction and break out of nowhere.

On your scan gauge do your o2 voltage readings constantly switch back and forth from 0 and another number?

idk randall, i havent checked out many readings. I will wait until lonezerg stops up here so he can check everything out.

lol im too nervous to touch this car anymore....

i used to be that way too lol...

so, i just talked to a friend of mine over in colorado who has a 98 swapped gt, he said that with the symptoms i am explaining, that it is most likely a bad o2 sensor.

I explained to him that for the first minute after a cold startup it runs fine and once it warms up than i get the bad idle. I also said that once i give it gas, it will go away.

He said that for the first minute after a cold startup the o2 sensor is in closed loop and after it warms up it becomes open looped, which explains the bad idle. He than said, once I give it gas in drive the reason it goes away is because it goes into PE.

lol SO, i just bought an o2 sensor from zzp.

** I checked all wires for the sensor and they are all intact, no melting or anything, so no signs of grounding out.**

How did you extend the o2 harness? Did you buy the extension harness, or cut and splice?

no, we unwarveled the original engine harness and pulled it out and un tangeled it and extended it. There was no cutting or splicing that took place with the extension of my harness.

Tim, I'm looking at your .bin right now and something seems really off.

Your MAF table starts at 3.09gps. That's 2 whole grams more than even my MAF table. And it keeps going up. Your MAF table is quite a bit higher than mine actually.

Who tuned your car for you?

ZZP

Off the shelf or did you have them dyno it? I can't remember.

it was dyno tuned.

Wasn't there an issue prior to the dyno tune? That was supposed to get fixed while at ZZP?

misfire at idle.

Actually, it is open loop at startup and closed after warmup, but otherwise correct. As for PE thing, I don't know what your enables are set for, but light throttle should not put you in PE, over 50% certainly will.

well either way im going to replace the o2 now. haha

worst that'll happen is you'll be out $100 and you'll get better gas mileage.

yep.

well, i just got the fuel pump, so now all im waiting for is the front o2 which will be here sometime tomorrow from ZZP.

could have jusy gone to napa or similar for that

Yep sometimes paying the extra dollar or two is worth it.

well napa wants $120 for the front o2. i got it for $55 shipped, sorry not paying close to $70 extra just to save on one day of shipping.

Ya I thought you can get from ZZP for arond $50, screw $100+.
Think my sensor may need replacing.
R.S.- I thought -16.4 was max too, but i've seen mine in the -22 range before!!

-22.6 is the max the motor can pull. +16.4 is the most the motor can add.

well i got the o2 sensor. Just waiting for you to stop up here sunday. Boosten should be here also, unless he decides to head back to chicago sometime sunday.

Just get under the car and do it. You don't need extra hands for those jobs.

i am waiting for him so he can do a maf tune, because zzp tuned the car with a bad o2

No, they should tuned your car with their own wideband o2.

Your car is not running properly because it's not getting enough fuel.

The computer uses your o2 values to determine whether to add or remove fuel. For some reason, your computer is adding all the fuel it can, based on lean o2 readings, and it still isn't enough.

That is why you are replacing your fuel pump. The computer is seeing a lean condition because your fuel system isn't flowing enough fuel to the injectors. This is causing your system to run lean, which is observed by your o2 sensor. Your computer is compensating for this by flowing as much fuel out the injectors as it can. However, it isn't enough.

That is all assuming that your tuning isn't just really freaking screwed up, but I've checked on that. And what I've seen is that a lot of your tables seem to be adding more fuel than normal. More fuel because your fueling system isn't working properly. Hence, the importance of the fuel pressure test.


For example, in a perfect system, your fuel pressure is 60psi. Your injector pulse width is 2.1ms at idle based on the o2 readings as well as tuning tables like IFR, MAF, etc.

However, let's throw a wrench at that system. Your fuel pump isn't working the greatest and it can only provide 48psi of fuel. The tuning still says that your injector pulse width should be 2.1ms at idle, but because of the pump, those same 2.1 milliseconds aren't flowing enough fuel. The o2 sensor reads that as a lean condition. It will adjust the fuel cells to add more fuel. Now your injectors need to be open 2.8ms to flow enough fuel.

That is what is wrong with your car Tim. Only in your case, it's so bad your computer can't flow enough fuel to fix it.


I'm positive that once we put that pump in, I'm going to scan your car and she's going to be PULLING fuel because your tables are set so rich due to a failing pump. Probably enough fuel that I'm going to have to drop your MAF table to stock and scale your IFR down for your L67 injectors just to have a baseline for how bad it was in the first place.


To be perfectly honest, your o2 sensor is probably fine. But don't worry, if it is I'll buy the new one off you because I *do* need a new one.

Whats his IPWs at idle?

another possibility is that the car is running fine and the o2 sensor is bad, causing the PCM to think there is a lean condition, so now you're drowning the engine in fuel. like you say, fuel pressure would tell you whether its fuel or sensor related.

ok, well you guys have told me to not drive the car until its fixed, therefor i have not driven it....

Did you install sensor yet?

Oh yah, since you don't have leisure time to drive, update your sig photo!

everythings going to be installed this evening.

Did you get everything done last night Tim? If I had checked this out over the weekend, I could have come put the o2 in no problem. Guess I need to check the boards more instead of playing games all day. Lol

Tim needs to learn how to turn a wrench and apply the info he seeks on here to his car!!!
LOL

Think he got is squared away.

It's all good to go. I'm going to go up there tomorrow and get a good scan in, make sure the ZZP tune is all good to go.

As far as the solution went? Let's just say we learned a valuable lesson here

weak, Tim needs to make an update since you guys won't.

Simple Vac leak I believe.

nice.

Where was it at ?

evap line was cracked on the throttle body.

Gald to see you got it all worked out.

Now that the issue is taken care of, no holding back at the Drive the Mile event next year! :p

well now, like zerg, code 1133 popped up.

Just delete the evap. and plug the line at the throttle body.

zerg said that its the front o2 sensor and insufficient switching....

Insufficient switching of what?

i have no idea. he said he would explain it to me after he got off work, but i work tonight so i dont know how this will happen.

check o2 wiring, if no problems, replace o2 (front)

lol i JUST replaced it with ZZP's o2...

P1133 HO2S Insufficient Switching Sensor1

The PCM monitors o2 Sensor activity for 100 seconds, and counts the number of times o2 signal voltage crosses from rich to lean, and lean to rich thresholds. If the PCM doesn't see the o2 sensor switch enough times, P1133 will be set.

Lean to Rich: Less than 300 mV to more than 600 mV
Rich to Lean: More than 600 mV to less than 300 mV

ok, so how does this get corrected then?

Replace the O2 sensor or the harness.

alright, i will do so.

I asked in the other thread, but I don't know if it was answered, how did you extend the harness from the o2 sensor?

It looks like a ZZP plug-and-play extension harness.

That o2 sensor is brand new out of the box from ZZP. There is no way it's bad.

the odds are low but it is possible.

New doesn't mean it's good. Even AC Delco has their bad days, like any other company.

well, the code just went away by itself today on my way home from working a half day.

Depending on the code, once the problem is fixed the light may go out after several trips, and erase the code from memory after 40 key starts.

well, hopefully it fixed itself and everything is good now.

CEL clears when you've had 3 successful tests in a row

ok, so i take it, its good lol.