View Full Version : SR breaks up under boost?

06-27-2008, 11:58 PM
*posting for brother*

I have..

fresh swapped redtop
3" turbo back
255 fp

in an s13.

My car runs amazing at idle, no revving up and then dropping etc.. and when you rev with no load it runs perfect. but as soon as you put load and more than 1/2-ish throttle it starts to backfire/bog/get jumpy and lose power at around 4-5k rpm. it does it in first and second gear the most, but all other gears as well.. at first i thought it was the fuel pump, when i was running on stock, now i am on a w255 and it still happens. thought it was the alternator, got a better one, and still happens.

i have heard everything from MAF, bad gas, to sparkplugs (which have been replaced like yesterday with 7E's) to boost leak, to retarded timing.

let me know what you guys think.. hopefully i can get it running better tomorrow.

06-28-2008, 05:16 AM
So did you check your MAF at all after people told you that may be the problem??? Another good idea is to pull for codes on your ECU. The ecu will actually tell you whats wrong pending its not something stupid. And also did you fully check out a boost leak situation??? check every coupler through and through make sure you dont have any small cracks in your silicone couplers. Brake cleaner works good to located leaks.

06-29-2008, 03:19 AM
i have the same damn problem like freakin word for word!!

i'll check my ecu and MAF thought it was coilpacks i havent replaced spark plugs or anything...

06-29-2008, 04:18 AM
Things to try -

Check MAF connections, clean MAF element with brake cleaner/carb cleaner.

Checking wiring on coilpacks, re-earth coilpacks if earth looks dodgy.

Change fuel filter incase blockages.

Change plugs [think you did this already].

Change coilpacks, swap with a buddy to see if that fixes it.

Spray boost hoses/joins with brake cleaner to check for leaks.

FMIC or WMIC? WMIC are shit and leak, swap it.

If none of that works then fuck knows.

07-03-2008, 01:00 AM
try gapping the plugs around .030. mine ran fine for a while on .044 but then started misfiring 4-5k rpms and anything over 10psi. ran purfect up to 15psi after that.

07-03-2008, 06:48 AM
Either boost leak, make a boost leak tester and pressure the system to your required boost level and listen for hissing and tighten. Next thing would be to check your plug gapping.