mk3 breaks up under boost!
 

any suggestions ?...... breaks up ,miss fires under boost .. all stock except for hks turbo back... and cone filter

it sounds like you have a fuel cut out. check the filter, lines and pump.

i just checked the vacume lines.....found one cracked that goes from under turbo pipe to what looks like a check valve..pulled it off with out even touching clamps! lol thats how loose it was....well i replaced it and it pulls a lil harder but still breaks up a bit, not as much as b4 and i can rev higher too.

i just spoke to previous owner . he said it has a walbro 255 pump and ss braided line....so guess fuel isnt a problem.

Check for diagnostic codes:
http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx



A couple possibilities exist:

"Fuel cut" where the ECU cuts the signal to the injectors because it thinks or you are moving far more air through the air flow meter than there should be at a given RPM and throttle. This is a protective measure to prevent damage (see: engine meltdown). The most common causes of this are: a leak in the intake piping AFTER the air flow meter; increased boost pressure, whether intentional or due to malfunction.

NOTE: This is NOT what Toyota meas when they refer to fuel cut in ANY of their tech publications and service manuals.


Engine knock... not necessarily rod knock... inconsistent or premature ignition of fuel causes knocks which the ECU monitors for and adds fuel and pulls timing to eliminate. If you've got a bad knock (from running loo low of a grade of fuel, for example) or if the knock sensor(s) and/or it's wiring is bad the vehicle can falter severely and even become barely drivable after a while (see: limp mode). BTW, hot air makes knocking all the more likely... if your cone filter is in the engine bay either relocate it so it's outside of the engine bay or put the stock airbox on and use a good filter in it (NOT Fram). ;)


Other possibilities include: bad igniter, bad coil pack(s), incorrect spark plug gap, fouled spark plugs, damaged ignition wires, oil leaking in around the spark plugs and wires from the valve cover.

i havent put gas into it since just bought it last night, but i will put 93 in it tomorrow.

i changed the cheap autozone cone filter for a geniune greddy/trust airnex mushroom style sponge filter

i will check the plugs tomorrow

and i have no. check engine lights....the bulb works i checkd on start up

Did you actually check for codes? Very few stored diagnostic errors cause the check engine light to light up and stay lit.



As for air filters... If it's anything like the HKS then congrats, you've just bought a box of hype! ;) Do research, buy smart fix less... The only two aftermarket air filters I trust to run in my car are Apex'i Power Intake and AEM's DryFlow.

http://www.mkiv.com/techarticles/filters_test/2/
http://www.duramax-diesel.com/spicer/index.htm
http://www.bobistheoilguy.com/airfilter/airtest1.htm
http://www.supramania.com/forums/showthread.php?t=50900

I don't know how that filter compares and I am biased.

absolutly AEM is the only thing that gets run in my supras

its pretty good the sponge is interchangeble ....i got it with a greddy turbo kit i had for my acura.....

Sigh.... I don't care if it's got lights on it... if it doesn't filter well or has a reputation for caving in as it loads up it's still trash. ;) I'm not saying it's a crap filter, I'm just saying you should do some REAL research before committing your engine and turbo's survival to it's reliability.

If you're running stock boost and your ambient temperatures have been reasonable your car should run fine on 87 or 89 octane... unless it's old gas

Now, did you check for error codes?

lol......i guess its better then the autozone racing filter....lol.....but anyway i will check for stored codes tomorrow b4 work.....

i just picked up a used autometer phantom boost guage from my buddies at illgarage for 20 bucks ! now i will be able to see what psi it breaks up at....do all mk3 turbos come with factory boost guages? mine doesnt. now i just have to fix my oil psi guage! lol

if it helps i just found out its a jdm motor with new head gasket torqued to the new specs. any difference in the usdm & jdm motor besides the missing egr valve?

Not looking to hijack here but +1 on getting a decent (read-:PROVEN decent) filter. Just seen a turbo that's been run a few months on a K&N just like the one fitted to my 7m-gte & lets just say it ain't pretty!

I mean, I was under the honest impression that K&N was a fair bet but if you saw the dings & chunks of metal missing off this impeller you'd have thought someone ran gravel through the thing... :eek3::barf:The shopping list grows!

^^^ Yup, dust at the speed the impeller is moving is like making the turbo gargle B-Bs on weekends... it takes its toll quickly.