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I need to change my TPS but I can't seem to access it because of it's location. Does anyone have any experience or an idea on what to do so I can reach that spot?
Also some of the screws are so tight, I guess nobody ever changed anything in 175k miles. Anyone know how to loosen screws? I applied some WD-40 and hoping it penetrates them by the night..
Car is a 1998 SC400 (1UZ- VVTi)
I really need to get this fixed by tomorrow, any help would be appreciated.
The TPS is all the hidden at back (That silver device with the blue line on it)
Can't even take a picture of it clearly because it's all blocked up by other things.
Man, they really tucked it away on the later models. Have you tried a right angle screwdriver? Once you get the screws out, take them to the hardware store and find some higher grade allen heads of the same thread pattern. It'll be waaaay easier to work with in the future.
If it's that bad, and since you can't really get any leverage on it with angled tools, I would probably call a mechanic, machine shop, or any related outfit and see if they have mini air tools to get into that tight spot and break it loose with impact.
OP - if indeed you need to replace that sensor , don't you think it is a lot easier to take out the Throttle body ?... 4 bolts, one on each corner of TB then you have better access to whatever is on the TB.
What made you say that part is bad ? Usually the Accelerator Pedal Position Sensors on VVTi engines are the culprit before the TPS . It might be the tps on yours however, just trying to save you some work.
OP - if indeed you need to replace that sensor , don't you think it is a lot easier to take out the Throttle body ?... 4 bolts, one on each corner of TB then you have better access to whatever is on the TB.
Not a bad suggestion. Although, if it's anything like the earlier 1UZ setup with the nightmarish coolant routing (hint: don't bother trying to get the hoses off; just cut them and bypass the TB so you don't have to wrestle new ones back on), getting the TB off and back on could easily take longer than searching for a shop that can free the TPS screws. But, if that's the only way to get to the screws, it's better than nothing.
UPDATE: So I took gerrb's advice and took off the throttle body, it was pretty dirty so I decided to clean it up. The screws on the throttle body were so tight and a bit rusted that I had to go to a shop and remove them. Anyways, I swapped the old TPS with the new one and according do the GS400 forums, the absolute throttle position should be between 14.4% - 16%. I set it to about 15.1%, I used BlueDriver (OBDII) and figured out which percentage was the position at. I put everything back up and started the car, and it worked fine but I noticed that it slowly started to drop in revs after 2 or 3 minutes of idle'ing. I put it into drive and it almost shut off on me whenever the car was stopped. I park the car and then I changed my TPS to about 17.4% now, put everything back and started the car again. However this time the car started and stayed at 1700RPM with a new code that showed up, code P1128(Throttle Control Motor Lock Malfunction). At this point I am so lost, browsing through the forums both SC and GS, members are saying that you need to reset the ECU or reprogram the ECU since it's a new part and the ECU doesn't recognize it or something.
Anyways, I'm off to Autozone since I noticed one of my coolant hoses are leaking and I'll try removing the battery again tonight, anyone have any idea what possibly is going on?
P0121, I got that code a few months ago too but after a while it never showed, then a few days my accelerator just started to die out and the frequency of that happening just increased so I decided to change it because it seemed like a electronic issue.
I also want to note that my idle actually started to decline in the last month or so, I think that suggests that the TPS was actually going bad. Anyone have anything to chime on this subject?
The VVTi engines had incorporated the IACV into the throttle body . It is partly responsible for idle quality.
The first code you mentioned is P0121 which is either the pedal position sensor and / or throttle position sensor. The TPS is more likely not your culprit as I have mentioned . They do break but mechanical potentiometers like the TPS SELDOM breaks. Usually the Accelerator Pedal Position Sensor on a VVTi will be more the suspect than the TPS.
Now with your new error code of P1128 ... I wil suspect it is not also the Accelerator Pedal Position Sensor. In my opinion it is the Throttle Control Motor (IACV in VVTIs) that is your problem , affecting your idle quality.
It is the long motor just on the left of your TPS . That's a pricey part . Once you have confirmed it is the problem, your best bet is get a used throttle body with all those parts (Control Motor, Accelerator Pedal Position Sensor and Throttle Position Sensor) . It will be cheaper .
Just my $0.02 !
EDIT : also when taking out old hoses , before pulling them , get a channel lock , loosen the hose by rotating it after you have removed the clamp... then pull . It will be easier to remove the hose and less chances of breaking it. Patience is always your friend in old parts or you start breaking them.
EDIT : also when taking out old hoses , before pulling them , get a channel lock , loosen the hose by rotating it after you have removed the clamp... then pull . It will be easier to remove the hose and less chances of breaking it.
That works for a lot of stuff, but not so well for the 1st gen 1UZ throttle body. The coolant lines and crank case ventilation lock it into such a tight space, you can't really get any tools on it or wiggle it around to get anything started once the hoses have dried out a bit. There's barely enough clearance to slide a replacement hose of different wall thickness back on... When I had it off this last time, I replaced the crank case hose with a thin walled silicon hose that has the flexibility to conform to that ridiculous little space and not cook itself on.
That works for a lot of stuff, but not so well for the 1st gen 1UZ throttle body. The coolant lines and crank case ventilation lock it into such a tight space, you can't really get any tools on it or wiggle it around to get anything started once the hoses have dried out a bit. There's barely enough clearance to slide a replacement hose of different wall thickness back on... When I had it off this last time, I replaced the crank case hose with a thin walled silicon hose that has the flexibility to conform to that ridiculous little space and not cook itself on.
Yeah I still haven't gotten the hose replacement yet, turns out to be that the hose has to be a right angle one since that area is to tight that a normal hose bends really hard. You're right about the hose cooking it, it's so close to the metal which makes me think that's how the original hose leaked. Anyways, tonight I'll be hopefully get the proper replacement and then I'll update whenever I get that chance.
UPDATE: Well I just got the part replacement, had to get a proper angled hose. I'm having the exact same issue as mentioned before, nothing is different. There is the throttle motor lock code P1128 and it also seems like sometimes when I start the car it will die off if I don't press on the pedal. Any thoughts?
Exact description of a bad idle control valve , "need to press pedal to get it continually running at start up" . That is because your control motor is not regulating the air coming in through that control valve
Ok so I tried to turn it on again, it idle'd fine for about 2 minutes then the RPMs started to drop, I did notice I got codes P1120(Accelerator Pedal Position Sensor) and code P0120(TPS Sensor).
I tried to look more into the P1120 but I can't seem to find anything about it for the SC. Where and what is the accelerator pedal position sensor??
When you say the motor is not regulating the air coming through, what do you mean exactly?
12-06-15, 08:26 PM
Urgent help needed with TPS!!
(That silver device with the blue line on it)
