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GTIRoids
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Discussion Starter · #1 ·
Uh OH! Helped a local sr20det owner put a new wastegate on his car Sat. The boost jumped to 1.4 bar. (17 psi I believe) This is on a BB with a bored MAF, 370 inj, 4 bar/JWT & T25. these were the 300zx Plats #6 gapped at .25 Today the car started sputtering. Checked the plugs and the elctrodes were completely burned off :confused:
Help!! what happened. Detonation?? Anyway we did a compression check and got 120/120/115/90 :( What's the diagnosis peeps? Piston rings, ignition system, head gasket? Help? GTIRoids
 

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GTIRoids
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Discussion Starter · #3 ·
myprojectB13 said:
Sounds like detonation to me. Not a headgasket or you would have low compression between two cylinders. Sounds more like rings. How many cars are you gonna blow up Joel? :)
Ha ha, not me this time man! I begged him to stay out of it. I said dude, it feels wonderful, but you don't have the fuel to support that psi. Don't drive it, if you do you'll race it! Needless to say he drove it :rolleyes:
So new rings only? Or pistons and rings?
 

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Wiggatastic!
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This happened to me when running a 100shot. Only the #4 cylinder was down on compression, but it had none at all. On mine, I think the electrode burned off and hit a valve, probably chipping it. Thats my theory, but I won't be sure until I get to tear it down.

~ Marcus
 

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GTIRoids
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Discussion Starter · #6 ·
myprojectB13 said:
Only one way to find out for sure.

Did you open the throttle all the way when you did the test? Also make sure its completely warmed up. The numbers all seem low. A perfect DET should read 156, maximum variance between cylinders of 14, and a minimum of 128.
Engine was warm and throttle was held all the way open. #4 is the one that really alarms me. 90 is super low. Now based on the fact that U said it should read a minimum of 128 all are low at 120. Rebuild maybe?
 

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getting close
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I burned off 1 of mine once, but all i did was replace the plugs and the spark plug wires and the car ran fine for 2 months, then i blew my headgasket, it might have been related to the spark plug electrode. I think it was just because of the mileage of the engine(turbocharged at 130,000mi blown headgasket at 155,000mi). I dont know what happened to the electrode, but i will find out when i am through tearing apart the engine. Oh well i am putting a new jdm de in, and building up my old engine.

Later,Jon
 

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Undecided
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You really think 17psi on a T25 with the 4 bar program is too much boost? If anything I think the turbo would puke before the spark plugs. Well, maybe it was just creating heat instead of more air. Does he have cams? The 4 bar should be good for 280whp which I'm sure a T25 isn't hitting w/o cams.
 

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97SE-R C2 said:
You really think 17psi on a T25 with the 4 bar program is too much boost? If anything I think the turbo would puke before the spark plugs. Well, maybe it was just creating heat instead of more air. Does he have cams? The 4 bar should be good for 280whp which I'm sure a T25 isn't hitting w/o cams.
The car he's talking about is actually me...lol We put in a new HKS wastegate and its boosting like a mopho. I haven't given it WOT at all because I was to afraid to. The highest I took it to was 1 bar and that was only for about 3secs. Right now, the car is driving on stock cams. The car seems to be running too lean.
 

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B15 Smack Junky
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hope ya didnt pay alot for that engine......

i know someone up here in ct that has a BB engine he is looking to sell :D
 

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Imma stock fuel pump guy myself.....lol but damm no way and hell will it support 4bar, its tuff supporting 9psi and thats with the pump re-wired to, see I can monitor such things as my o2 voltage which is a great indicator of fuel pump fall off equaly as telling you ur running to lean and you better get off the pedal. IMHO driving any other way is driving blind.
 

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Where the plugs missing the porcelin (or is is ceramic?) portion of the electrode too? I had a motor that blew 3 plugs up (ate the electrode), and the material from the plug ate grooves into the cylinder walls. This caused the same kind of compression results that you are getting.

Travis
 

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TT Tuning
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prob melted a valve
 

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unlucky said:
Where the plugs missing the porcelin (or is is ceramic?) portion of the electrode too? I had a motor that blew 3 plugs up (ate the electrode), and the material from the plug ate grooves into the cylinder walls. This caused the same kind of compression results that you are getting.

Travis
The electrobes were the only thing that seemed missing. Did your compression continue to drop?
 

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myprojectB13 said:
Only one way to find out for sure.

Did you open the throttle all the way when you did the test? Also make sure its completely warmed up. The numbers all seem low. A perfect DET should read 156, maximum variance between cylinders of 14, and a minimum of 128.
My W11 Avenir SR20DET read 155psi accross the board when I bought it, it now reads exactly 151 accross the board cold after 1 1/2 years of abuse.

P.S. But in my experience most DET's read in the 175psi range even cold, go figure.
 

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redrims said:
The electrobes were the only thing that seemed missing. Did your compression continue to drop?
Can you take a pic of the spark plugs? And post it here.. Thanks
Travis
 
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