shaodome

iTrader: (3)

92 SC300 Aristo GTE
JDM ECU / MAP Based

So driving along this evening on the highway, get to the off ramp and sitting at the light I notice the idle is VERY low. like AT ZERO. Car is missing and I can see smoke out the side mirrors. Its dark so I couldn't tell what color the smoke was, but it smelled like rich smoke.

As I limped it the next 1/4 mile to my garage it got worse adn worse to the point where I couldn't pull it in my garage. WOT yeiled 1100rpm and a lot of sputtering and smoke.

I just got done swapping in the tranny and went for a quick little test drive and after pressing the clutch in 3rd I heard a pop and just figured it was the charge piping as I couldn't make any boost. These JDM turbos always had a little whine to them, I'm wondering if they finally **** the bed? Would it cause the car to stall and barely move, not hold idle, etc?

I checked the charge piping and it was all still connected as was the map sensor vac line and the IAT sensor.

It's almost like the MAP sensor was disconnected or something? Do the JDM ECUs have a limp mode if the MAP sensor failed?

O. L. T.

iTrader: (17)

OH-MY-GOD.......... I think your hamster broke it's leg.


However, before we assume a clean break...... It just dropped out of nowhere, right? No bumps you hit, no change in anything, no goosing it on the drive home before the fault occurred? Nothing that would bring it on at all?

If you have unplugged the battery in the last 5 months or so, it is likely not a bad MAF. The engine ECU pre-loads settings for the MAF unless the memory is cleared so if it goes bad, it still works unless it completely dies and you should have symptoms beforehand.

shaodome

iTrader: (3)

For the record...Hamster = stock POS JDM turbos?

The only time I got on it was right when I got the new trans in, just a quick pull 2-mid/high 3rd gear....to when I thought I heard the coupler pop. Even after that I had to drive the car a little distance and it cruised on the highway just fine at 70mph with all the power and glory that beholds an NA 2j :-/

This car has no MAF as it is on the JDM ECU which is map based.

O. L. T.

iTrader: (17)

It actually does the same in the USDM cars (reading from memory as I was saying above), but uses the MAF as well.

I wish I had some help, but all I can do is respond so it goes up.

tavarish

iTrader: (2)

Here's a few quick tests you can do:

1. Unplug the MAP sensor while the car is running, see if the idle and rev changes.
2. Check the coilpacks, they could be grounding out against the valvecovers (common). If there are cracks, seal them up with either epoxy or electrical tape and try again.
3. Your sparkplugs could be fouled out by an inconstant spark. Check them.
4. Your ignitor could be on its way out (common). Move it around and see if the idle changes while the car is on. if it does, replace the ignitor.
5. Do a boost leak test. Just because your couplers havent blown off doesnt mean you're not leaking from somewhere.
6. Check your TPS to make sure it's within spec.
7. Also, double check your wiring for any connections that have come loose, this has happened to me a few times.

Hope this helps.

shaodome

iTrader: (3)

OK, so I had to leave town for work for a week or so and didn't get any chance to look at the car.

Tonight I finally went over to the garage and figured at the very least I would install my cold cathode gauge back lighting (which came out awesome)...that's another thread though.

Car started right up! had a little misfire at around 1100rpm (warmup idle). I didn't get a chance to check the plugs as I figured they where pretty fouled up and that is what was causing the miss. Car drove pretty normal for a quick jaunt around the block. At least the stock twins are still working. Bad news is, back to square one in solving the problem. I HATE the uncertainty of a problem of this magnitude (undrivable car) as it can leave you stranded in the middle of nowhere and lets face it..the South Florida Lexus Crew likes to drive long distances.

I did eventually find a popped coupler, but I started the car up BEFORE reattaching it just to see and it went right to warmup idle and revved OK (unlike before where it wouldn't rev at all).

This is my first factory speed density (MAP) based car, but in every stand alone ECU i've tuned if the charge piping blew off, the car drove just fine in the n/a part of the fuel maps. Is Toyota different somehow? I mean I did have to drive the car about 15miles with a charge pipe disconnected, but I didn't think anything of it, since the MAP sensor is at the intake manifold and I would just drive the car home in vacuum the hole time.

What I'm getting at is, would the charge pipe being off for that period of time cause it to run so rich it would eventually foul out the plugs? In that short period of time?

shaodome

iTrader: (3)

Well it DEFINITELY was running rich...so rich in fact the plugs are fouled....figures. Gonna change those out tomorrow I guess.