92 supra is breakin up when revved.

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shutupnshift04

New Member
Dec 15, 2008
21
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NJ
Hello everyone im new to the supra comunity. I just purchased a 92 turbo with a blown headgasket. I replaced the headgasket and added a fmic, divorced catless downpipe, blitz nur spec catback, hks bov, walboro 255. and i custom made a 3 inch intake for it since my stock one was shredded. Now the problem is it breaks up even in nuetral if you give it full throttle past 3500 rpms. If its in gear it studders and bucks but only when you give it full throttle. I know i know i thought it was a boost leak too but i checked everything countless times. I thought it was the coilpack too so i replaced that ( a couple of the harness wires looked iffy). I was wondering if maybe its breaking up because i didnt delete the j tube or do the 12v fuel mod when i installed the walboro? its gotta be that or the maf sensor I cant think of anything else. Sorry its so long just tryin to be descriptive.

Oh and i forgot to mention that it sounds amazing at idle and part throttle its just wot that it sputters.
 
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shutupnshift04

New Member
Dec 15, 2008
21
0
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NJ
Sorry that I forgot to mention that. There are no codes what so ever! Thats why im going so crazy. It threw a code after I got everythin together and it was the o2 sensor plug that had become unclipped put that on and there was no more codes. So now I have no idea what the problem is. I consder myself a good mechanic nd checked a lot of things nd everything seemed fine. I'm going to do a compression test today nd delete the j tube to see what happens. Please keep ideas flowing in though. Thanks guys this is def the best mk3 forum out there.
 
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shutupnshift04

New Member
Dec 15, 2008
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NJ
Also i have not pressurized the system how would i go about doing that? I assume a compressor nd some type of wide rubber stopper to let pressurized air in and not out?
 
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shutupnshift04

New Member
Dec 15, 2008
21
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NJ
Okay so today I took the spark plugs out and they looked pig rich. I then gapped the plugs which have like 20 miles on them to .029 (they were all around .040). I then deleted the J tube which was quite easy might i add. i also did a compression test and everything came back normal. now im officially stuck. After i got the car together i started it up and sounded fine then I gave it gas and it broke up (sounds kinda like a 2 step launch controll) after it warms up it doesnt break up as bad i can give it more throttle before it does. then i took it on the road and the car drives fine at about 25% throttle then once you give it gas and the turbo begins to spool it bucks and trys tofall on its face. Could it be the timing?
 
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shutupnshift04

New Member
Dec 15, 2008
21
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NJ
can a bad o2 sensor cause this? When i removed the stockexhaust i remembered that there was carbon CAKKKKKEEEEDDDD on the 02 sensor and i cleaned it with carb cleaner. also my stupid step brother sprayed the maf sensor with carb cleaner when i wasnt looking and thought that might cause it to read wrong?
 
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suprahooked

Built 7M
Jun 20, 2006
1,160
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pa
shutupnshift04;1230686 said:
can a bad o2 sensor cause this? When i removed the stockexhaust i remembered that there was carbon CAKKKKKEEEEDDDD on the 02 sensor and i cleaned it with carb cleaner. also my stupid step brother sprayed the maf sensor with carb cleaner when i wasnt looking and thought that might cause it to read wrong?
Click to expand...

Carb cleaner is a big no no, it probably wasted your afm.
 
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shutupnshift04

New Member
Dec 15, 2008
21
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NJ
I checked the timing and it was HORRIBLY off i tryed adjusting it to 10 btdc but the car didnt wanna idle? I think i was jumping the wrong test conections. The reference i used said to jump e1 to T but there was no just plain T to jump it to? there was a tt but thats it? what are the proper connections? I used this as a reference http://www.supra.co.nz/timing.htm
 
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shutupnshift04

New Member
Dec 15, 2008
21
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NJ
Okay so i redid the tiiming and its still breaking up. Im lost at this point. Its a little better but and i can bring it up to redline with partial throttle but whenever i go past about 25% even in nuetral it breaks up. I was thinking posible boost leak the whole time but the only reason i ruled that out is because it does it in nuetral too.
 
Nghty89

Nghty89

Zombie Chicks Are Hot
Mar 26, 2008
978
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7 Cities, VA
I have to agree, try a new MAF sensor. I 'cleaned' mine before I knew anything when i first bought my car and it toasted it completely. Even with good electronics cleaner. Mine had the same issue afterwards until I replaced the sensor.
 
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