pboxfun

iTrader: (2)

As the title states I知 having a pretty bad WOT misfire. This problem happens when I WOT from a dead stop it値l immediately start missing and won稚 stop till I let off the gas, and it値l also happen if I知 moving and I hit the gas it値l work fine until I get above 5k and it値l start missing and breaking up bad until I let off the gas. Other than those times the car will drive normally. It痴 only under WOT I have a problem. I replaced the opti, plugs, wires, and tps less than a year ago. But for all I know one of those things might have gone bad. I知 also not throwing any codes as well. Does anyone have any idea what the problem might be? I知 planning on checking the wires, coil, icm, plugs, and opti. Is there anything else I can check or I知 missing? Everything that痴 done to my car is in my signature. Any help would be great.

pillarpod

your on the right track. I would start with what you listed and see if that doesn't solve your problem.

SS RRR

iTrader: (2)

See what your fuel pressure is like during a WOT run. Get a tester, put it through the windshield so you can see it while driving and do some WOT runs.

guppymech

iTrader: (7)

The one time I had a misfire it was my plug wires, they all ohmed good but in the dark you could see them leaking sparks . I put some new wires on and that fixed it.

Pboxfun, That looks like a nice setup you have there. what does it run at the track?

Ed Wright

iTrader: (1)

Not likely fuel pressure. Fuel pressure dropping off usually makes them just nose over, not pop & fart. Ignition or valve springs. Most likely ignition.

pboxfun

iTrader: (2)

Thanks for the help. I'm going to try running it at night to see if I can see anything that shouldnt be lighting up. I've got a fuel pressure gauge in the car and i'm pretty sure thats fine, but i'll look at it more closely.

When it was running good the best I ran so far was 12.4 in the 1/4 with a 1.6 60"

TDavanzo

iTrader: (3)

Have you checked your plug gap? Always better to check the dumb **** first.

HarleyZ28

iTrader: (2)

My old 97z was cutting out past 5k rpms. Replaced the ignition control module and problem solved.

pboxfun

iTrader: (2)

Due to the nice weather today I致e finally been able to datalog my car. The car was in closed loop during these runs. The first file labeled misfire 1 is from a dead stop. I had a little trouble getting traction at first but once it hooked you can see it immediately started missing really bad, I had to let off the gas because it wasn稚 going anywhere. The second file labeled misfire 2 was from a roll. I had the car manually in 2nd gear from the beginning of the roll. The car took off fine but as soon as it got around 5k it started breaking up bad and wouldn稚 shift into 3rd. Once again I had to let off the gas because it wasn稚 going anywhere. Also I checked my electronic fuel pressure gauge I have in my car during these runs and it was fine. Does anyone have any ideas or can see something I知 missing????? Any help would be greatly appreciated.


Missfire 1

http://www.mediafire.com/file/gibx7o.../misfire1.xlsx

Missfire 2

http://www.mediafire.com/file/xadzuu.../misfire2.xlsx

Zlow28

iTrader: (11)

I had a similar problem not too long ago, and it ended up being my MAF sensor.

pboxfun

iTrader: (2)

How did you know it was your maf sensor and how did you fix it?

Zlow28

iTrader: (11)

Mine threw a code though at WOT. It was for being lean or something like that. I just cleared the codes, unplugged the maf sensor, and ran the car at WOT again. The car ran better had no misfire and didnt throw the same code. It just threw a different code for no voltage to the maf sensor.

Im just gonna buy a new MAF sensor to fix it. Im not gonna bother cleaning it.

pboxfun

iTrader: (2)

Well i'm still not throwing any codes

Zlow28

iTrader: (11)

You can still try and unplug the MAF sensor and run it how you would just to check for sure. Simple diagnostic but it will throw a code for sure. Only for the low voltage to MAF sensor. Could be deleted and it wont come back up after you plug it back in.

Just a suggestion.

sscamino

Mine did the same exact thing like 3 weeks ago.. it started out a few months ago it would start missing extremely bad once warmed up and I would get on it and after a few seconds it would go away.. Then that problem went away and it would only happen at 5000 rpm or above and then it slowly started creeping down, meaning it would start at 4500 then 4300 then 4000 rpm etc.. it would run like **** and to me seemed like an ignition problem because it felt like I was down a few cylinders, checked my fuel pressure and I believe it was around like 13LBS, so I did the trap door mod, new fuel pump and it fired right up and runs like a dream.. Fuel pressure is easy enough to check and after doing a quick read it doesn't seem like you have checked that so that's what I would do.. sorry for the long post lol

sscamino

Oh, and btw, mine didn't throw any codes either so check it!!

Edit! I re-read your posts again and saw what you said about having an electronic fuel pressure gauge, but I'd still want to check at the scharder valve on the intake just to double check, you never know might be something stupid lol

pboxfun

iTrader: (2)

I just tried downloading them from the links and it worked for me. If you or anyone else is having a problem I can email the datalogs to you. Just let me know.

Jason94z

iTrader: (3)

Nothing in your files jumped out at me.
I would guess coil / icm if I had to internet guess. Might not have enough voltage build time at higher RPM's because it's on it's way out. But just a lame *** guess.

Pull all the plugs see if any are different looking and take it from there?
Maybe that will show a bad wire or something.

pboxfun

iTrader: (2)

If the opti spark did go bad what would be the signs on a datalog?

Jason94z

iTrader: (3)

If the optical is bad it would throw codes. If the rotor/contacts are bad and arcing you would probably throw misfire codes. Test the coil, ICM, wires, and plugs first IMHO.