FutureSC

iTrader: (1)

Hey all, on my 1jz auto swapped sc300 I've been having a stuttering issue at low rpms and at idle. When I start it up it idles fine but after driving it for a little while the stuttering kicks in. It progressively gets worse as time goes on. Also at high rpms it goes away.

When I replace the plugs it temporarily fixes the problem but then the problem comes back after a little while.

Here are some things that I've replaced/done with no avail:
1. Fuel filter
2. Vacuum lines
3. Poured in some fuel injector cleaner
4. Changing the plugs

Upon searching, I've found that it could be the TPS, injectors sticking open, bad ECU, spark plug wires ect. But it seems that no one really knows what fixes it.

If someone could point me in the right directions that would be awesome.

Thanks in advance

topdog849

iTrader: (1)

had this problem awhile back





pm if you need help

FutureSC

iTrader: (1)

Thanks so much man, I was actually going to do that today but the diagram makes it all that much simpler. I'll be sure to post back up with the results.

sc-driver

iTrader: (7)

You should try seafoaming the car and see if there's an exhaust leak. I'm having the same symptoms and 90% sure its an exhaust leak after seafoaming.

FutureSC

iTrader: (1)

So my idle is right at 700 and playing around with the tps did not help at all so it's still sputtering. I'll look into seafoaming the car too sc-driver.

Other symptoms include:
burning through gas (like a full tank in a week) possibly getting 13-14 mpg
clean startup but more stuttering as the engine gets warmer

Also, when the car stutters, the AFR jumps up a little bit (0.2-0.5). I do have it tuned a little richer at idle on 14.0 than the suggested 14.7 just so I'm not running it lean

RyanV

iTrader: (9)

No, dont seafoam it yet.

You should also pull back the boots on each coilpack and check the coil for stress cracks. Its common for the coils to crack, get hot, then arc out of the cracks.

The wiring to the coil packs can also get damaged.

RyanV

iTrader: (9)

Are your CEL code working? Do you know how to check for codes?

Use a wire or paperclip at the diagnostic port in the engine bay to these two pins. E1+TE1

, key to on, count flashed or continuous flash for no codes.

FutureSC

iTrader: (1)

The check engine light was pulled before I got the car so I need to get a bulb in there to check any codes. I know how to but I simply can't at the moment.

I've also considered that it could be the wiring to one of the coil packs as cylinder 1's plug wiring is shotty and doesn't have the clip. (is suprastore the only place to get them?) I never checked for any cracks in the coil packs but I'll be sure to pull them out tomorrow and check.

Thats what I get for buying an already swapped SC I suppose :/

Thanks Ryan, I've always looked up to your SC ever since I've started creeping on the forum

RyanV

iTrader: (9)

Hey no problem, thank you. Definitely look at those coils...someone else had the exact same issue last week.

You can get all the clips.

click for part numbers
http://www.supraforums.com/forum/sho...ight=coil+clip

RyanV

iTrader: (9)

I just realized that is a 2jzge and he has a 1jzgte.

sc-driver

iTrader: (7)

Why not? This would be an easy and effective way of determining if he has an exhaust leak or a vacuum/boost leak. Run it through the brake booster.

I DO recommend you try this. Have someone with you looking around to see any white smoke from the seafoam. I did this and found a leak in my exhaust that was causing the exact symptoms you described.

If you try it, and don't see a leak then maybe it could be dirty injectors, water/humidity in the gas tank, or even bad fuel.

Good Luck!

UTSC300

iTrader: (4)

y don't u just fix the cel light , and actually check for real problems. It's worthless to spend all this time guessing.

FutureSC

iTrader: (1)

Just as an update, it was the coilpacks.

Two of the 6 had hairline cracks on the stems and I put a couple of layers of electrical tape around all of them the the stuttering is completely gone.

No low rpm missing and no high rpm cutting out.

SC-driver, I do suspect there is an exhaust leak and that seems to have always been there. I'm planning on a 3 inch single exit and I'll deal with that leak when I install that.

Thanks for all the replies everyone

bryan767

iTrader: (6)

wanted to bump this thread because i had the same issue you described down to the very last detail.

However, mine got progressively worse. At first the missing only happened between 2100rpm and 2600rpm. This then started to spread higher up to about 3.5/4k and then even when i was in a high rpm range, say the 5-6k range it would still miss on occasion. So if your driving around and after about 15-20 min you start sputtering/stuttering/missing from 2k-3k your probably going to need to replace the coils. I put electrical tape on mine which barely helped, but i did notice the missing was more stable and i wasnt losing as much boost between each misfire. This lead me to believe the spark was being shielded by the tape somewhat, and was helping.

Also, It would miss at idle, and it also didnt matter if i was in boost, out of boost or under load.

Ended up getting a set of 2jzgte coils from a buddy of mine for 100 bucks and threw them in. What a difference

As for cracks, I honestly didn't really see any. And if your running electrical tape and thats it, i really suggest you only run it for a day or two because it WILL melt. Pick up some 1" Inner Diameter heat shrink and use that with either liquid electrical tape or nail polish