Boost leak/fuel cut

[gtevi]

Hey guys my gt starlet is hitting what I think is fuel cut at just under 5k with my foot flat to the floor.
Would it be worth getting a boost and vaccum leak test to check for any tiny leaks, all the hose are very old but I can't see any damage or cracks.
Is it something easy enough to do yourself or best to get a mechanic to do?
For reference I have a 94 gt with exhaust, decat, wepr mani hks adjustment actuator, ct9 (rebuild)with wastegate slightly ported.

 

[SKINY]

Hose leaks can be a nuisance to find on old hoses, you could try listening while blipping the throttle or some soapy water rubbed over them will soon reveal bubbles
You can do a smoke test yourself, plenty of videos on YouTube shows how it's done

 

[gtevi]

Yeah I've seen few YouTube clips but none on a 4efte. I know it would be the same situation for most motors but I'm far from a mechanic and a little paranoid ill do something stupid.
Skinny, you been a big help in my journey so far if I could judt get your guidance or steps as to how I go about it, it would be a massive help.
This is my girl. Cheers

 

[gtevi]

Yeah I've seen few YouTube clips but none on a 4efte. I know it would be the same situation for most motors but I'm far from a mechanic and a little paranoid ill do something stupid.
Skinny, you been a big help in my journey so far if I could judt get your guidance or steps as to how I go about it, it would be a massive help.
This is my girl. Cheers

Referring to the smoke test, couldn't find/hear anything with the motor on.

 

[SKINY]

Looks very clean
Smoke tests are done with the engine off

 

[gorganl2000]

have you done a diagnostic? any codes?
that might help us to narrow it down

 

[Badmoon]

Are you really sure you are hitting fuel cut? I had a cracked hose just before the MAP sensor and I never hit fuel cut... What it did, I believe, was to mess with the reading of the sensor which allowed higher boost pressure in the system, not hitting fuel cut and resulting in a broken piston in my case. When you hit fuel cut the engine suddently stops to produce power which results in a violent shake, its not something good to experience and neither do you want to hit it.

 

[gtevi]

I'm 99% sure it's fuel cut I does violently jolt at around 4.5k. I adjusted the actuator out 1 rotation that has stopped it. I would like to dos a proper smoke test to check for vac or boost leaks when I get the chance.

 

[gtevi]

Hi, sorry for the late reply. I've just done the engine diagnostic abd it's only giving me fault code 12.
I've also noticed its idling around 1200 rpm.

 

[SKINY]

Always a fun 1 that
Check condition of your dizzy cap, roter arm, king lead, connections etc, check the ignitor plugs too and wiring etc
Dizzy send a signal to the ignitor to let it know its turning then the ignitor sends the signal back to the dizzy to tell it to send sparks down the leads
Can also be a snapped timing belt, but car wouldn't run then and you would hear a difference with only the bottom end moving when cranking.

 

[gorganl2000]

to expand on Skiny's etc.---spark plugs, spark plug wires, distributor, coil,

depending, you could start with the cheap/easy ones first---rotor arm, dizzy cap, spark plugs, king lead & spark plug wires, connections/wiring/grounding,

then get to testing/checking the more expensive items---ignitor, coil, distributor

look for wear/hairline cracks/breaks in the rotor arm, distributor cap, spark plug wires...look for corrosion in the plug wire connections to the coil and dizzy....look for oil/residue in the distributor cap and distributor signal points

if you have time, you can change each item one by one...so you identify the problem

 

[SKINY]

Yea Buddy
Mine had a slight misfire that was only picked up on the dyno, didn't even notice it driving. It was the Dizzy cap and king lead end that had a badly corroded terminal, Jay lucky enough had a spare in stock that he kindly lent me until new stuff came from Toyota

 

[gtevi]

Check the dizzy and rotor are and they seem pretty good condition. What's the best way to check condition of king lead.
Also a little off topic but it's there anyone on here that can make or have a bracket for a rotated ct9 for a short route fmic piping? Should I post this elsewhere?

 

[gtevi]

So I've noticed that on initial cold start up idle and throughout the drive it'll idle at around 1200 (say a 20min to 30min drive) then turn the car off 20min or so, start back up the idle will drop really low 400/500rpm bouncing around that trying not to stall. Surely this has to be something pretty simple.
Skiny, I have checked what I can. Dizzy cap and points look fine and clean, spark plugs are fairly new.

 

[gtevi]

Could it be perhaps the icv starting to go or getting clogged, anyone?

 

[gorganl2000]

Could it be perhaps the iac value starting to go or getting clogged, anyone?

yes, its worth a try

the hunting idle does sound like a vacuum leak somewhere

 

[gtevi]

The idle is consistent on start up and when warm but only drops to almost what seems like stalling when car has been turned off and on again when still warm.