Idle/Running Issues

[SnowMongoose]

Hokay....
first off, background.
Engine out of supra C.
Harness and ECU out of Supra B
Installed in Supra A.

Mods: Intake, open 3 inch DP, EGR blocked off. No Cold start injector
Codes thrown: None that change engine running.
<speedo isnt hooked up, so it throws a speed sensor code>

Symptoms:
Idles high.... tach doesnt work, but I guess it is around 1500 RPMs.
Idle isnt very smooth, and occasionally it drops for a second, probably dropping a cylinder... only drops at idle, sometimes every 5 seconds, sometimes only once <at a light or something>
other than that, the car doesnt like the transition to compression braking very well, it seems to hesitate a little bit when I do so...<almost sputters>
last thing is that the throttle isnt very snappy on release... for example, if Im rolling along, then kick the clutch in and hold it, while off the gas it waits a second before the revs drop.

Stuff I've done/checked:
Cleaned the throttle body, nice and shiny
Replaced the ISC
Checked timing, its all good
99% sure its not a vacuum leak


Clifs: Car doesnt idle well, idles high, doesnt like being off the gas.

Im going to try a backup ECU, and different AFM electronics early this week...

ideas, advice, snide remarks, whatever, thanks!
Ashton

 

[shaeff]

i'd check again for vacuum leaks, as that's the most common problem for high idle. then i'd check all your intercooler pipes, just to be sure.

then, i'd place my money on the TPS. (throttle position sensor) that is commonly a problem for badly idling supras. chances are it's not bad enough to throw the code yet, but is probably on its way out. check the connection on it, too, even though you'd know if it wasnt connected (Check engine light).

now, you said the tach doesnt work? was your car origionally naturally asperated? if so, the tach wont work with a turbo motor, as there are different value resistors on the driver board. if you want to put different resistors in, you can find information here about it: www.4cefed.com

if you want to take the easy route, you can simply buy the tach driver board out of a turbo car, and slap it in your cluster. your tach will then work properly.

as for the throttle not being snappy on release, check the spring on the throttlebody, and make sure the throttle cable is well lubricated, so it doesnt bind up. chances are the throttle linkage mounted on the valve covers under the hood are badly worn out, or just sticky with grease/gummed up. clean that all up super well, and hopefully that'll cure that problem.

as for the idle dipping/dropping, how are your plugs and wires? that would be the most common problem for missing/hesitation. also, many people experience a miss at idle when they dont have the ground strap going from the coilpacks to the motor, to ground them. do you have that ground wire?

hopefully that'll get you started. good luck!

-shaeff

 

[SnowMongoose]

Thanks shaeff...
tach problem is just my being lazy and not wanting to yank the dash and toss in the turbo one...
plugs and wires are new, and the ground wire is there.

TPS, here I come...
mumble mumble vacuum leaks are a PITA.

 

[SnowMongoose]

Bump, some progress...

swapped in the spare Yellow plug ECU I didnt know I had...
not sure if resetting it via the EFI fuse will do anything, with how long it was out of a car, but we'll see...

car idles lower now, often on the onset of idle it struggles to be even lower, but eventually give up and idles up
<aka improvement>

also tried different AFM electronics, seems to smooth the car out a bit...

so now thinking its some obscure vacuum leak...
about the only idea Ive come up with for testing for leaks involves a smoke bomb in the intake, not sure how terrible an idea that is...
ideas?

Cliffs: Swapped ECU and AFM, works better, still idles high, less dropping of cylinders.