First off: Aristo GTE/Auto with single 70 trim T4 and Tial 38 (10LB spring, Greddy Profec B to hold boost at 14 LBS), running stock 440's and an SAFC with a full 3 inch exhuast.

One day 2 weeks ago, I was driving my car to work and it started hesitating and acting strange, idling erratically and dragging no/light boost part throttle shifts out for wayyyyyyyy longer than normal. I immediately pulled the plugs to find that they were covered in oil, which was not much of a surprise because of my leaking valve cover gasket. I changed the valve cover gasket, the plugs, and did a compression test (180 across the board). After I broke all of the coilpack connectors and had to order new ones from Toyota, I plugged everything back in and took it for a spin, only to find immediate gayness.

Like I said, it idles like it only has 5 cylinders or a nasty cam, but only sometimes.... when the vacuum drops from 20+ lbs at 650RPM idle to about 12-15 lbs. It also causes my Air/Fuel ratio to go nuts... crazy lean or rich, depending on what seems to be its mood. OK, so it has a vacuum leak, right? The only leak I could find was my intake manifold gasket (using starter fluid while letting the car idle to listen for surge). There is just one hangup: Ever since it started doing this, my car will not hold boost below 14lbs, even with my boost controller turned off (running off of the 10LB spring alone). It will blow to 18-25 LBS IMMEDIATELY, provided the car is anywhere above 3k RPM. WTF?! Could an intake manifold gasket leak cause extreme boost spike?

HELP ME!

I plan on replacing the gasket and upgrading the injectors to Supra 550's (with twin DSM resistor boxes) when I pull the manifold.

Can anyone confirm or relate to this? Thanks in advance!

Lol@immediate gayness...



Did you check the map sensor vaccum?

Sounds like the hose going to the wastegate was melted by the exhaust manifold.

I checked all vac, but I will double check the map as well as the wastegate line.

Anyone else?

Sounds like there is a large crack somewhere in the intercooler plumbing. Check all your i/c pipes and couplings...

All intercooler piping is T bolt'ed w/ badass couplers.

Check you gasket between the turbo and manifold. Then check you wastegate assembly. I melted a #3 piston because the jam nut that holds the diaphram to he shaft lossen to point of falling off in the wastegate. sounds like your having the same simptoms.

Cool. Thanks man.

Well springs aren't 100% reliable so could your problem not be a stuck shut wastegate?

The idling problems are throwing a curve ball into the situ. A guy on our forum with an aristo is having idling problems and it turned out to be a dodgy injector electrical plug that was dropping out a cylinder.

Your fuel problems could be as simple as a dodgy earth or power supply on your SAFC install, in fact it would lose its programming and drive like a bag of ***** if you kept losing power to it.

^^^ This is very interesting.

^x2 check all that

yes soundslike a bad injector or more but i would double check on Ic pipes and vacum hoses ... i have the same problem also my car is running 700 degrees on my EGT @ 3k driving... i haven't drove with my new spark plugs yet.. but my motor doesn't boggle like urs.. def. check ur intake manifold and injectors... maybe one of ur injector clips came off when u were changine something... hopefully u dont have bad injectors or clips .. but hey with a 70 trimm turbo i would run nothing less then 550's, 650's tops depending what power ur making....... well good luck and please keep us posted so if happens to anyone else we can resolve the issue for the next force inducted maniac!!

okay i'm willing to make a bet on the solution of your problem lies in wiring or sensor.

what gap are your plugs, what kind? i would recheck the coil pack clips to make sure they are plugged in right and going to the right cyl. i've mixed them up before and it made the car idle just as you said.

check the turbo pressure sensor. make sure the sensor is connected securely and not coming loose. mine came loose and was barely able to drive, idle. there is a vacuum line on there as well that slips off easily. i doubt it'll be that or a leak but check that too.

an intake leak or boost leak can mess with your a/f for sure. i mean not to an extreme amount if it's something minor.

if your compression read well through out the cylinders, i wouldn't worry too much about your motor.

i can tell you it's definitely somewhere in the sensor or wiring. i've had my supra for over 5 years (sold) and went through A LOT of issues/problems. so i know how you feel

since you're running the AFC, check your splicing and wiring, if it's done correctly, wires can still come loose from the crimping. i've experienced this as well check your BCC or FCD if you have one. well, just check your whole ECU wiring with the piggy backs you have (afc, boost controller and whatever else).

it won't be a stuck closed waste gate or what not. it wont be anything mechanical or something broken. look specifically for sensors, wiring and possibly vacuum lines/leaks. there you will find your problem/s!!! good luck and post back up your results

^this post is from last month.

Savanna13, check in with us. What happened, did you get that *ish worked out ?

Semi-broken coil low tension wiring or,
a swopped wiring on one of the coils ?

I inadvertently swopped my wiring to coil number 4 one day
(flipped the plus to minus) and she idled very badly,
wouldn't drive right and would only "clear her throat"
at above 4000 rpm, in neutral....

Your coil wiring could also be contaminated with moisture
(creating a short) having soaked back thru' the heat shrink
you installed, many moons ago.