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Discussion Starter #1
OK, I've had my map driveability tuned and all is GREAT, EXCEPT that it sputters a little bit while cruising. Also, my car fouls plugs a lot (turns out only one plug). I've noticed that number 3 always looks BLACK (see pic compared to normal plug)



What are your thoughts? Bad coil pack? Bad injector? The car is great under boost and the car runs great otherwise. Anyone experience anything similar? Compression and leak down are great...

TIA
Peter
 

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T88 YOU
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looks like wet carbon fouling from excessive unburnt fuel... it COULD be an injector that is sticking open or just flows more than the rest, you can try swapping 2 injectors and see if it changes cylinders. if not then i would look at spark and try changing coilpacks... just change 1 thing to another cylinder at a time until it moves cylinders.
 

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Discussion Starter #3
Yea, that's what I'm thinking...I swapped coil packs and we'll see if that moves it. If not, injector swap time...
Peter
 

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T88 YOU
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luckily, its all really easy to do on these cars, if i had to do this on my truck i would just jump off a bridge instead. keep us informed as to what you find.
 

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OK, I've had my map driveability tuned and all is GREAT, EXCEPT that it sputters a little bit while cruising. Also, my car fouls plugs a lot (turns out only one plug). I've noticed that number 3 always looks BLACK (see pic compared to normal plug)



What are your thoughts? Bad coil pack? Bad injector? The car is great under boost and the car runs great otherwise. Anyone experience anything similar? Compression and leak down are great...

TIA
Peter
your lawn looks BEAUTIFUL. i can see every single blade of grass, its so green...mines kind of dying.

oh wait, spark plugs, yeah.

(jk :p the focus made me lol). +1 to supradupa's post, just to stay on topic.
 

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Boost Junkie
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Peter,

I had a similar problem and it turned out my 100k mile coilpacks were getting tired. Yours are a lot newer so I would think maybe an injector problem.

Steve K.
 

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Last stock TT on Earth
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Too much fuel. I just fixed my lawn mower which had the same exact issue, with the plug looking like yours. Ended up being a bad carborator gasket. My money is on the injector...
 

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Discussion Starter #9
Yea, I'm thinking it's an injector issue as well, but I swapped coil packs and drove the Supra to work today. When I get home, I'll pull them and look.

94 - hey bud, they are the RC 1200's

Peter
 

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Discussion Starter #10 (Edited)
Just checked the plugs...same ol' issue...number 3. Soooo, it's not the coil packs. I just swapped injectors 3 and 1 to see if it's the injector.

One interesting thing I noticed... On all the 1,200 cc RC injectors the area around to the tip of the injector is BLUE, but, on number 3, the area around the injector is BLACK. Coincidence?

Peter
 

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Just checked the plugs...same ol' issue...number 3. Soooo, it's not the coil packs. I just swapped injectors 3 and 1 to see if it's the injector.

One interesting thing I noticed... On all the 1,200 cc RC injectors the area around to the tip of the injector is BLUE, but, on number 3, the area around the injector is BLACK. Coincidence?

Peter

Sounds like you need a new motor :)
 

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Discussion Starter #12
LOL, I wish, then I would have motivation to do a 3.4 BUT sadly, compression and leak down are all great... :D LOL
Peter

Sounds like you need a new motor :)
 

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Discussion Starter #13
OK, swapped injectors, sure enough the BLACK plug moved with the injector in question. Back to RC!
Peter
 

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Peter are you running the RC 1200's? Or Bosch 1600's? I assumed with 1600's this was to be expected, even with the injector driver box. However, I don't think it would be only 1 plug consistently every time.
Just FYI - I run 1600's with no injector driver and I've never had a plug fouling problem. It's all in the tune.


Pete - Glad you got her fixed.
 

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Discussion Starter #19
OK, just talked to RC...turns out that one injector was in fact a 1,260-1,270 cc injector as opposed to a 1,200 like the others... As the pressure increased the gap b/w that one and the others increased exponentially. In any event, they are making a new injector and balancing the others to be virtually identical. I will have them all back in my hands by Friday... Thanks all!
Peter
 

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Glad to hear you're getting it resolved. RC quality control sucks....we had a dead injector at start up and another leaky one. Oh well, at least it's not something serious.
 
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