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what will the future hold
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Discussion Starter #1
Car is a 94 supra turbo. 720 cc injectors just tested for flow. Duel fuel pumps feed both sides of the rail. Center return. 67mm turbo. Heres the issue only spark plugs 1-4 are covered in soot. (rich) 5-6 are normal. Cant understand why cylinders 1-4 are rich and 5-6 normal. Reversed the coil packs and same results. Again had injectors flow tested. Side note I have a Hks DLI system so fire in cylinder should be the same. Any and all ideas welcome. Let the ideas flow.
 

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1994 Toyota Supra Turbo 6spd
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1,513 Posts
aem or vpc?

also check the pig tail plugs on the injectors to see if they are plugged in right
 

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what will the future hold
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916 Posts
Discussion Starter #3
VPC and replaced the pig tails after the rebuild 1500 miles ago. Compression is 170s across the board but slightly higher in those cylinders with soot. Thats understandable. Oh yeah car idles and runs great just the soot on spark plugs.
 

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What spark plugs are you running? I can't explain why only 4 of the cylinders have sooty plugs, but FWIW, my car runs beautifully on any plug I've tried EXCEPT NGK 3330s. 3330s turn completely black and sooty after < 200 miles. (and start idling and running a little ragged). 6097s stay nice looking indefinitely, as do Denso Irridiums. <shrug>

MKIVpowered said:
Car is a 94 supra turbo. 720 cc injectors just tested for flow. Duel fuel pumps feed both sides of the rail. Center return. 67mm turbo. Heres the issue only spark plugs 1-4 are covered in soot. (rich) 5-6 are normal. Cant understand why cylinders 1-4 are rich and 5-6 normal. Reversed the coil packs and same results. Again had injectors flow tested. Side note I have a Hks DLI system so fire in cylinder should be the same. Any and all ideas welcome. Let the ideas flow.
 

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Boost Junkie
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12,616 Posts
I also had problems with 3330s and switched to 6097s. I plan on trying the Denso IK24s once I get the Nitrous installed. I am also running a 67.

Steve K.
 

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Inline for the win
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4,727 Posts
I agree with the 6097's for reliabilty. I have had no issues with 1000cc, 6097's and dual pumps..... I just notice I tend to eat up the plugs more rapidly when running 30psi or higher.

DP
 

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what will the future hold
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916 Posts
Discussion Starter #8
Not understanding the front four being rich and the back two normal. That is even after I swap coil packs around and swap the plugs around. Any more ideas
 

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Check out the consistency of spark from the DIL by pulling the plugs and grounding them to look at the spark quality. It could be a a bad DIL or wiring, or a failing ingitor which is rare but can happen. If on AEM, each cylinder's fueling can be manipulated... Do you have any boost leaks? Pump up the system via compressor and check. Maybe a bad IAC or rear intake main vacume leak causing a lean condition on 5 &6? Are leak down test results possible?
 

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Garage Queen Club
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5and6 hooked up to an EGR? That thing functioning properly?
 

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what will the future hold
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916 Posts
Discussion Starter #12
EGR is blocked. Will try putting vacuum to system to check for leaks. Also will check DLI wiring although I must admit it hasnt been touched since the build.
 
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