big problem

gomezmk · 10-04-2006, 05:49 AM

I have a 1987 supra turbo, mods are 2.5 inch inner cooler pipe, mbc 10psi, 3 inch full exhaust, adustable fuel regulator, no boost leaks for sure, foam air filter. Engine runs perfect, pulls ok under boost up untill I hit 5,000 rpm then the motor just starts back firing like crazy. I have a super monitor on the dash to check codes by pressing the buttons it will tell me the codes and the dash says, eng- ok. I don't know what to do. Am I crazy to think my foam filter is restricting air. Help me!!!!!!1

suprra_girl · 10-04-2006, 08:42 AM

sure you're not hitting rev limiter (oddly enough) early?

is it fast backfiring or consistent or just all over the place?
what codes did you pull, in your post do you mean the codes were clear?

gomezmk · 10-04-2006, 06:14 PM

The wierd thing is that when my engine was all stock at 6 psi of boost, it never did it that bad from 5,000 rpm to six, it use to just pull very slowlly from 5 to 6 so thats why I think my foam filter might be the problem because since I'm running more psi now more air has to flow through my filter which is probably now restricting the air even more. I have completelly no codes existing in my diagnostics check.

gomezmk · 10-05-2006, 10:31 PM

I ran the car without the filter and I noticed a torque increase but still would cutout at 5,000 rpm. I remembered that I installed bosch platium spark plug and I did researh and learned that they are no good for turbos so I installed ngk plugs, i'll see what happens now.

gomezmk · 10-05-2006, 11:40 PM

well i ran it with new plugs and it still does it wtf!!!!!!!!!!!!

gomezmk · 10-06-2006, 06:37 PM

Next is to try to readjust the tps, thats all I can think of.

suprra_girl · 10-06-2006, 08:25 PM

i think if it was the tps it would throw a code of some sort

can you describe the noise any better?

is it a slowish type cut or is it really fast?
is it the same cut as with the old plugs? or has the sound changed

nelly26 · 10-06-2006, 09:42 PM

have you had fuel cut off bypassed if not, if you exceed the psi on turbo more than 10 psi it will cut out so will have to get the ecu chipped to bypass

suprra_girl · 10-06-2006, 09:49 PM

^ i'm confused

what has that got to do with his misfiring?

and just for future reference you can't "chip our ecu's" as such

fuel cut is not boost/psi referenced it is by hz which is what our afm measures and the hz frequency of fuel cut can vary it is generally between 11-13 for stockish vehicles and can be very low for high air flow vehicles

nelly26 · 10-06-2006, 10:03 PM

when i had my boost put to 15 psi i found when it got above 10 psi she would cut out and miss fire i had her chipped and has been runing sweet

10-04-2006, 05:49 AM	#1
gomezmk 3" Exhaust Join Date: Jul 2006 Location: Santa Rosa, CA Posts: 70	big problem I have a 1987 supra turbo, mods are 2.5 inch inner cooler pipe, mbc 10psi, 3 inch full exhaust, adustable fuel regulator, no boost leaks for sure, foam air filter. Engine runs perfect, pulls ok under boost up untill I hit 5,000 rpm then the motor just starts back firing like crazy. I have a super monitor on the dash to check codes by pressing the buttons it will tell me the codes and the dash says, eng- ok. I don't know what to do. Am I crazy to think my foam filter is restricting air. Help me!!!!!!1

10-04-2006, 08:42 AM	#2
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	sure you're not hitting rev limiter (oddly enough) early? is it fast backfiring or consistent or just all over the place? what codes did you pull, in your post do you mean the codes were clear? __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

10-05-2006, 10:31 PM	#4
gomezmk 3" Exhaust Join Date: Jul 2006 Location: Santa Rosa, CA Posts: 70	I ran the car without the filter and I noticed a torque increase but still would cutout at 5,000 rpm. I remembered that I installed bosch platium spark plug and I did researh and learned that they are no good for turbos so I installed ngk plugs, i'll see what happens now. Last edited by gomezmk; 10-05-2006 at 10:31 PM. Reason: add letter

10-06-2006, 08:25 PM	#7
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	i think if it was the tps it would throw a code of some sort can you describe the noise any better? is it a slowish type cut or is it really fast? is it the same cut as with the old plugs? or has the sound changed __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

10-06-2006, 09:49 PM	#9
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	^ i'm confused what has that got to do with his misfiring? and just for future reference you can't "chip our ecu's" as such fuel cut is not boost/psi referenced it is by hz which is what our afm measures and the hz frequency of fuel cut can vary it is generally between 11-13 for stockish vehicles and can be very low for high air flow vehicles __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

10-04-2006, 06:14 PM	#3
gomezmk 3" Exhaust Join Date: Jul 2006 Location: Santa Rosa, CA Posts: 70	The wierd thing is that when my engine was all stock at 6 psi of boost, it never did it that bad from 5,000 rpm to six, it use to just pull very slowlly from 5 to 6 so thats why I think my foam filter might be the problem because since I'm running more psi now more air has to flow through my filter which is probably now restricting the air even more. I have completelly no codes existing in my diagnostics check.

10-05-2006, 11:40 PM	#5
gomezmk 3" Exhaust Join Date: Jul 2006 Location: Santa Rosa, CA Posts: 70	well i ran it with new plugs and it still does it wtf!!!!!!!!!!!!

10-06-2006, 06:37 PM	#6
gomezmk 3" Exhaust Join Date: Jul 2006 Location: Santa Rosa, CA Posts: 70	Next is to try to readjust the tps, thats all I can think of.

10-06-2006, 09:42 PM	#8
nelly26 3" Exhaust Join Date: Oct 2006 Location: UNITED KINGDOM Posts: 58	have you had fuel cut off bypassed if not, if you exceed the psi on turbo more than 10 psi it will cut out so will have to get the ecu chipped to bypass

10-06-2006, 10:03 PM	#10
nelly26 3" Exhaust Join Date: Oct 2006 Location: UNITED KINGDOM Posts: 58	when i had my boost put to 15 psi i found when it got above 10 psi she would cut out and miss fire i had her chipped and has been runing sweet

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