stuttering at wot that comes and goes?

[JiveMasterT]

Ok, so I decided to take my car for a bit of spirited driving, which i hardly ever do and something weird is going on. I was in 2nd gear and I slammed on the gas at about 2200 rpms, and it took off wonderfully until about 3500 rpms, where it seemed to studder 3 times and i thought i heard backfires, and then right after that it takes off full speed. it made no sense to me... hits 15 psi just fine, sits at 20 vac at idle, and the car drives fine. im thinking maybe some sort of a mild intake leak or something? do anyone have any ideas?

(edit... last time i tried to submit this it didnt go through. hope it doesnt appear twice.)

 

[oldman]

Just some ideas.

1. Clean the air filter.

2. Change fuel filter.

3. Check condition of plug/gap and wire.

4. Leak test.

 

[JiveMasterT]

Just some ideas.

1. Clean the air filter.

2. Change fuel filter.

3. Check condition of plug/gap and wire.

4. Leak test.

just cleaned the air filter, plugs are brand new and gapped properly (im 99% sure), leak test should be done and the fuel filter probably needs to be changed. thanks for those ideas... i guess it is about time i did a leak test...

on a side note, how hard is it to change the fuel filter?

 

[oldman]

on a side note, how hard is it to change the fuel filter?

PITA but not impossible, removing the battery would help greatly. And yes, it's about time you do that leak test we talked about like a year ago.

 

[JiveMasterT]

PITA but not impossible, removing the battery would help greatly. And yes, it's about time you do that leak test we talked about like a year ago.

haha! did we really talk about a leak test a year ago? ive been considering one but im so busy I haven't gotten a chance... hence why my car is also nearly stock.

 

[JiveMasterT]

bleh, havent had a chance to do an intake leak test or go get a new fuel filter cause ive been so busy with school and work and the car still runs well enough to get me around

so, tonight my CEL came on again for my o2 sensor (the heater in it is bad so I've just been clearing the code) and after that the car started to run better at wot... makes me think it's an intake leak because when that CEL comes on the logger shows the car running richer and if it's able to run richer then I'm guessing the fuel filter might still be ok....... then again AFAIK it's never been changed and the car has 100k miles on it, so I'm not totally ruling it out.

Does anyone have any other things for me to check when I take it to my friend's garage?

 

[DsmPimp20]

sounds like plugs

 

[DGajre777]

My car started doing the same thing 3 days ago, sometimes hesitates in 2nd gear at WOT. I have 54xxx miles, new plugs and wires, still on factory fuel filter. It is acting the same way as it did when the coupler on my turbo had a tear in it about a month ago. I say intake leak somewhere.

 

[GSXTuner]

yeah sounds like a boost leak

 

[JiveMasterT]

well, I'm ordering a boost leak tester today....

does anyone know what size coupler I need to connect to the turbo?

 

[Strm Trpr]

I think the interval for fuel filters replacements is every 30k.
It is a PITA, but not impossible like "Oldman" said.
The hardest part is removing the metal battery tray.
If you have air tools it would be much easier.
I'm actually having the same symptoms right now, and I've got 40k on my filter and wires and about 20k on my plugs.
Needless to say I'll be replacing all of those parts in the next couple of weeks.

 

[DGajre777]

I think the interval for fuel filters replacements is every 30k.
It is a PITA, but not impossible like "Oldman" said.
The hardest part is removing the metal battery tray.
If you have air tools it would be much easier.
I'm actually having the same symptoms right now, and I've got 40k on my filter and wires and about 20k on my plugs.
Needless to say I'll be replacing all of those parts in the next couple of weeks.

I'm at work and don't have my owner's manual, but I remember reading the fuel filter replacement at every 60k.

 

[Strm Trpr]

You are correct, the interval for replacing the fuel filter is every 60k.

 

[Millerman340]

Now I'm used to speed density on turbo Dodges,but your telling me that with a mass air that the car will studder if there is a boost leak? My plymouth laser does the same thing but I assumed that it was bad wires but they are about new.

 

[oldman]

Now I'm used to speed density on turbo Dodges,but your telling me that with a mass air that the car will studder if there is a boost leak? My plymouth laser does the same thing but I assumed that it was bad wires but they are about new.

Yes, because you're losing metered air which was counted at the mas that ecu thinks is still in the system, it then injects fuel for air it thinks is still present causing your car to bog due to running rich. Even with speed density, you want to keep your intake tract leak free so you don't over spin the turbo causing either turbo failure or blowing hot air being out of its efficiency range.

 

[Millerman340]

It doesnt really feel like a bog, almost like overpowering the clutch and shuddering. but the tach says it's not. But the tob just started grinding so it will get a new clutch regardless and rule out that one.

 

[Talon_BodyMan]

Man sounds like this is a pretty common problem because my Talon is doing the same exact thing. At WOT the car jolts back and forth pretty bad around 4000 rpm, just like everyone else said I think its time for a leak test.

 

[DiamondStarM]

Just some ideas.

1. Clean the air filter.

2. Change fuel filter.

3. Check condition of plug/gap and wire.

4. Leak test.

Did you do number 3, mainly the wires, if they arc to the valve cover you will bog down under load. Sometimes you can see it arcing at night, have a friend rev while you look or just swap wires with someone to test.

 

[JiveMasterT]

Ok, so I have a theory... sorry I've been inactive in this thread.

Anyhow, my car's front o2 sensor is kinda wacky sometimes, so it mostly relies on the o2 sensor behind the cat (that I don't have). Well, last week, i was driving home from my girlfriend's and realized that the car was really loud up front and I was like "wtf is that?!" so I got it home, put it up on the jack, looked under the car and I had a huge hole in my downpipe.

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Looks like the jackass who put the pipe on didn't bolt the bracket that was there on, and then it banged against the block a few times, breaking off, then taking a huge chunk of pipe with it.

My theory is that it has been developing slowly and I just didn't notice, therefore making the car think it was running differently than it actually was, or trying to compensate because one o2 sensor was not reading properly.

tomorrow I'm taking it to my friend's dad to swap the downpipe for me while i'm at work (he works in the garage of the same complex that I work at) so i'll post if it makes any improvement. if not then I'll get new plug wires, change the fuel filter (which I should do anyway) and run the boost leak test.

 

[oldman]

The rear o2 plays no role what's so ever in close loop fuel trim adjustments, it's only there to tell the ECU that you have a functioning CAT. Did you make that leak test your new years resolution?

 

[JiveMasterT]

The rear o2 plays no role what's so ever in close loop fuel trim adjustments, it's only there to tell the ECU that you have a functioning CAT. Did you make that leak test your new years resolution?

I realize it plays no role in close loop fuel trims, but I forgot to give an update... I don't have to be at WOT for this to happen... If I'm at %75+ throttle it will do it as well...

I didn't but I'm making it right now. Within the next few months, I will definately do a leak test... I have a shiney new compressor and all I need to do is order the $20 leak tester thing and a coupler and I should be set.

I thought about making one, but my local home depot makes me want to commit suicide whenever I walk in there and they never have anything that I need so I'll save myself the trouble, wait till my next paycheck comes, then get the leak tester and maybe some new plug wires and a fuel filter.

 

[oldman]

Within the next few months, I will definately do a leak test....

You kill me

 

[JiveMasterT]

Ok, I lied about getting it put on tomorrow.

I got bored tonight so I convinced my dad to come out and help me put the thing on. She's purring like a kitten again. So I took her out for a beating and lo and behold, no more studdering at wot... actually, it rips now. Quite suprising.

It does feel a bit shitty when it first starts though so I think I do need new plug wires. Will get some and let you know how that works. Any recommendations?

 

[DGajre777]

I have NGK Premium wire set on mine, $59.00 at www.extremepsi.com

 

[JiveMasterT]

1. I'm ordering the wires like right now.
2. Anyone know where to get a fuel filter? and how much?
3. I know this is probably common knowledge, but whats the inlet size of the t25? my leak tester should be here in a week or two and I need to order a coupler for it to go to my little tiny t25. The tester is going to be about 3 inches around.
4. I'm going to regap my plugs and clean them off when I do the wires. They have about 3k miles on them.

I'm dominating this problem.