88 Supra running lean/ Boost shudder?

Me[kk]A

New Member
Nov 16, 2009
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Toronto
Hey all! this is a poopy way to introduce myself. My Name is Chris, im from toronto Canada.

Bought a friends 1988 7MGTE mk3 recently and am in love. Sadly she is not in love with me! :: angry ::

The car has a built motor (trying to source the blueprints for the motor) the basics are eagle pistons, forged internals etc.

the fan has been replaced by a Howe aluminized rad and some lines running to the motor have been disconnected and modified to trick the system.

When i bought it the car had a modified fuel rail, modified for WOT stock wastegate(washers put in to open her up more), and afterkmarket fuel pressure regulator. the car is also using a MKIV fuel pump.

before any of these mods were addressed the car had a horrible idle, turbo did not want to spool steadily. it would horribly shudder, as the gas is applied imagine a machine gun going off in rapid succession. It was definitely robbed of power. It is also running lean.

Currently, i have installed a stock fuel rail from a 7MGE but used the turbo injectors. The wastegate has been put back to stock, i have checked the turbo elbow from the throttlebody and the intake arm before the maf for boost leaks, everything is as tight as can be.

since these mods have been put back to a stock setting the car has regained a lot of power however the idle is still irregular, at times it will steady if i give her gas but inevitably the near stall idle returns. The car still smells very lean, the spooling process shudders less but is still there.

im just not sure where to turn. I read through another gentleman's post of horrible idle and will pull the codes on this car after a reset to see what to look at next.

any suggestions would be appreciated.

thanks!
 

toolmaster

New Member
Jan 11, 2010
6
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pierce county
hello, did you ever find out what was wrong with your car? my son has an 88 we put together with a t3/4 turbo and intercooler and 550 injectors and it is running lean tried boosting fuel pressure but it only made the idle better. let me know what you found. dave.
 

toolmaster

New Member
Jan 11, 2010
6
0
0
pierce county
converted from N/A to aftermarket turbo. intercooler, 550 cc inj. lexus airflow meter, dbov, 50mm wastegate, 3"downpipe, stock wire harness for a turbo model. stock turbo ecu, and all the stuff needed like cam position sensor, igniter and coils, walbro fuel pump, afpr, afterthe stock fuel pressure regulator (not hooked to vacuum)... (which may be part of the problem not sure)...
 

toolmaster

New Member
Jan 11, 2010
6
0
0
pierce county
yes but i just read the article about doing the lexus af and 550cc inj and afp, and i will redo the way i hooked up the adj fuel pump regulator. and i will remove the j tube and fuel press dampener. then recheck my voltage on the o2 sensor to see what my af ratio is. maybe that will help?!
 

toolmaster

New Member
Jan 11, 2010
6
0
0
pierce county
i have not checked it . not quite sure how. they are supposed to make them run richer so it says...but my voltmeter says my o2 sensor is only putting out .04-.07 volts which is super lean. it should read .5 volts for ideal mixture. and my mixture gauge says it is very lean so they both agree with each other. thats how i know its for sure lean. guess i will check on how to check afm.
 

toolmaster

New Member
Jan 11, 2010
6
0
0
pierce county
timing is set at 12 , have tried 8-14 no difference in voltage on o2 sensor. one problem is that it dies right after it comes back to idle, i am sure its cause the mixture is too lean. we also have a fuel mixture gauge in the car, and it reads extra lean. i need to do more research.