valkyrie03

Lexus LS400, '90. 190k miles on her.

I don't know what the hell happened, but I assume it's a result of my father powerwashing my car's engine block (for some strange and inarticulate reason). In any case, today, what I assume to be my cruise control kicked in when I began leaving for school this morning. I didn't even have my foot on the damn gas and I was booking 45 down the road in a matter of seconds- again, with my foot off the gas, which led me to believe it had to do with the cruise control.

I checked the manual to see if I could disable what I assumed right off to be the cruise control, but to no avail. The 'CRUISE' light didn't even light when I fidgeted with the Cruise control. I attempted to 'slow' the CC by slowing down the vehicle and then SET/COAST, but to no effect. When braking to a halt, I can feel the car fighting me, so I have to push down extra hard.

Furthermore, when I set the LS400 to park, it'll rev up to 1100~ rpm then stop, falling back down to an idle state, then back to 1100~ again. It will do this constantly until I switch to Drive/Reverse, etc. or turn off the vehicle. I assume this has to do with the cruise control itself, a symptom, rather than a separate problem.

My hypothesis is that the power wash busted loose some vital control mechanism that controls the cruise control and the vehicle itself. However, what research I've done suggests that that may not be the case, as the control module is in the driver's side kick panel.

Thus, to make it clear, I'd like a solution that stops this 'infinite cruise control' state.

PureDrifter

iTrader: (10)

sounds like there's a big vacuum leak, something mucking up the throttle cable/blade, and/or electrical damage from the water (ie-afm)

valkyrie03

Good diagnosis, PureDrifter; it was a cable connected to the Air Flow Meter (Part: FMZ3AYYI). We don't know if the damage is to the wiring itself or the meter, though. Chances are that it's the wiring, since the covering that surrounds the wires are cracked and old.

Anyway, disconnecting the cable from the AFM seems to stop it.

Can I live without this thing?

PureDrifter

iTrader: (10)

no .

RA40

iTrader: (6)

Disconnect the neg battery cable for a count of 15-30 seconds to wipe any stored memory. Check the engine bay fuse box for any signs of moisture. As you discovered, water in the engine bay of these old cars doesn't make for a nice existence. It should dry out and return to normal.

deanshark

As PD says, no. Actually you can live without it for very very little amount of time. As I've said in the past, mine is unhooked and it just causes many more problems. It runs very rich which will mess up the cat convertors, foul out the spark plugs, and give you terrible fuel mileage. I only get about 12 - 14 MPG but I drive it less then 20 miles a week. Also, I just read the other day, when you have a code set for the AFM or the IAT the car will run in "fail safe" mode.

valkyrie03

The problem with the cruise control seems to have subsided, however, another has cropped up in its place: upon ignition, my LS400 seems to not be able to maintain it and promptly dies. I can keep it alive by keeping it in park and slightly revving it for about a minute before it can maintain its 'on' state.

Furthermore, my RPMs are ridiculously low for some of the speeds I'm doing; (900 RPM for 60 MPH). And, this is a previous problem that has been there before, and we've left it alone, which may have cumulated to create the problem we have now, but the car runs somewhat hot. Not in the red zone, but just underneath the notch below the the red zone.

Help would be much appreciated. Thank you for your advice thus far.