Dream36

first off the car has always had a hesitation issue with the 15k miles I put on it (131k currently). The day before she was stolen from me I had done the BFI mod and didnt test drive it. The hesitation is actually much worse now. I cant tell if they did something to it when they "repossessed" it or if the BFI is making the problems worse.

Next up Check engine, TRAC off, and TRAC ligths.

The check engine ligth only comes on from time to time and it runs the same either way. I checked my codes a dozen or so times over the last few weeks and it always comes up with main o2. The trac off light comes on automatically with the check engine light. And the TRAC light has been on non stop since the theft (or repossession depending on whos opinion you ask).

I have changed my plugs and wires, with the number 8 cylinder being the worst plug but that was due to a duct tape repair from previous owner on the number 8 plug wire (yes he used duct tape to fix a split plug wire.

I have tested the MAF and the TPSs and they are in spec. I have also done the fuel ecu mod and that didnt fix it either.

Im totally at a loss here. I do not want to pull the cats to check them and the next step is to change the distros and coil packs. I dont want to do both at same time as they arent cheap so which should i do first?

oh, and to the dude from the "what did to SC" thread, I do not have a honey comb, I checked it a dozen times and it simply isnt there. either the PO removed it or my 92 didnt come with it.

any help would be appreciated, and I will monitor traffic here then go out and check since im at work and have access to a PC till 3pm

also, any reason the TRAC ligth wont go out? could it be low on fluid or something?


thanks
Shawn

Ali SC3

iTrader: (10)

you can check the codes on the trac light the same way you check the engine light codes. jumper and count the blinks and write them down, that may give you some insight to the problem.
I wouldn't jump to check or replace cats, they hardly ever get clogged.
Usually ignition problems are the cause of sc400 problems, and there is no way to replace the distributors, you just need to change the rotors inside them and the 2 caps, its under $50 worth of parts.
You should check the coils to see if they need replacing, there are like a 100 threads on checking the coilpacks on the sc400. IF you have a coilpack that's bad you are running on 4 cylinders then, and it should be replaced. judging by the ductape repair I would assume the previous owner never did the rotor and caps, and that can cause alot of issues on these cars when they are worn.

in short: pull the codes for trac, and check over ignition stuff.

Dream36

updated with information

ABS Code 17
TRAC codes 24, 26, 43, 47, 51

damn I was so happy to have this car back, now im not so sure. tranny runs fine btw, so I have no idea why all these codes popped up. I will reset the TRAC ECU and see if these codes are from forever ago/

Dream36

lol, I found the thread on how to pull the codes afte rI posted, I just spent the last ten minutes pulling them up and double checking. Problem is code 43, as it wasnt in the list.

Ali SC3

iTrader: (10)

are you sure you are getting a 43? don't see it on the trac code section.
from the other codes that are coming up, it seems like the second tps on your throttle body is bad, which is the one for trac control.
It happens from time to time, and will disable a bunch of stuff, once you fix it alot of your codes will go away if not all.
the abs one is kind of iffy not sure if its related as there is no abs 17 on the list, but I would start with the trac tps.

I had this happen on one of my auto SC's, its really not that bad but you probably wont have trac or abs until you fix it, so drive carefully.

http://www.lexls.com/tutorials/intro/codereading.html

TRAC OBDI Diagnostic Codes

11 - Open in TRAC brake main relay circuit

12 - Short in TRAC brake main relay circuit

13 - Open in TRAC throttle relay circuit

14 - Short in TRAC throttle relay circuit

15 - Electric supply to TRAC motor for a long time (fluid leakage)

16 - Open circuit in pressure switch circuit

17 - Pressure switch remains OFF

19 - TRAC motor ON and OFF operation is higher than a predetermined number of times (accumulator pressure leakage)

21 - Open or short in master cylinder cut solenoid valve circuit

22 - Open or short in accumulator cut solenoid valve circuit

23 - Open or short in reservoir cut solenoid valve circuit

24 - Open or short in sub-throttle actuator circuit

25 - Step motor does not move to a position decided by ECU

26 - Sub-throttle valve does not move even when the sub-throttle valve is controlled to fully open position by ECU

27 - When power supply to step motor is stopped, sub-throttle valve does not reach its fully-open position

44 - During TRAC control, NE signals are not input to the ECU

45 - When idle switch is ON, main throttle position sensor signal is 1.5V or higher

46 - Main throttle position sensor signal is 4.3V or higher, or main throttle position sensor signal is 0.2V or lower when idle switch is OFF

47 - When idle switch is ON, sub-throttle position sensor signal is 1.45V or higher

48 - Sub-throttle position sensor signal is 4.3V or higher, or sub-throttle position sensor signal is 0.2V or lower when idle switch is OFF

49 - Open or short in engine communication circuit

51 - Problem in engine control system

52 - Brake fluid level warning switch ON

54 - Open in TRAC motor relay circuit

55 - Short in TRAC motor relay circuit

56 - TRAC pump motor locked

Always ON - Malfunction in ECU

Dream36

I agree as I checked it 3 times to verify and that is the code

I just went to three autozones and picked up caps and rotors. I'll report on that once I'm done. I doubt it's a coil pack as I'm running on 8cyl most of the time and 7ish when she pops.

I'll also recheck resistance to the tps on the trac. Thanks for the help so far, it's going to be a long afternoon.

Dream36

Caps and rotors replaced. No check engine light yet but she is still popping out exhaust. Didn't stall or hesitate during test drive. I assume once all that fuel gets burned out exhaust the popping will stop.

At this point I'm lost. I may have got the two tps's switched but the problems were before I tested them. My son grabbed them and I couldn't remember which was which so. Tps closest to IM is 89452-12050 (main tps) and the one closest to MAF is 89452-50010 (trac tps). Can someone check that for me?

Ali SC3

iTrader: (10)

that could very well be the problem, and sometimes the trac one is also sensitive to where you set it.
this thread has some info on part numbers, seems like they updated the main tps and you have them the right way as that appears to be the original part number, but the second tps number you have there I am not finding that it is for trac but it could be toyota uses many part numbers for the same thing.
https://www.clublexus.com/forums/sc4...ps-please.html

a good test is if you unplug it and nothing changes then it wasn't working at all.
when its bad the signal pin (one of the 2 center ones) will read a steady voltage for me it was 1.5V plugged in or not plugged in it made no difference. when plugging in a working one it immediately dropped down to < .5 volts on the signal pin.

Dream36

Yeah I got the same with a search.

Checking coils next. I can see if they are weak how it could be the problem but doubtful.

Oh, just to check is there a connector or vacuum or something that used to be connected to the resonator I may have forgotten abou when I cut it off doing the BFI mod?

I'm still actively searching threads but moved to my mobile while I try and figure this out today. If I can't get it today, I gotta wait two weeks before I can get in there, and I do bumper to bumper for an hour every morning. I can't stand wasti g fuel like this, it's keeping a tab on my wallet that I'd rather spend elsewhere. It's like every time I have to slam on the brakes, it literally costs $1 to get back up to the speed I was at before. Lol, I can count it up sometimes 1, 2, 3, sh!7, lol

Ali SC3

iTrader: (10)

generally the coils work or they don't. you can try unplugging one at a time and see if there is a difference.
There should be a difference obviously and if there isn't then that coil may be bad.
so you can smell the gas?? are any of your cats glowing? you could also have a bad injector that does happen from time to time. aside from the simple ignition tests, it will take some troubleshooting to get down to the specific problem, but even on a good day on a good running sc400 in the city you may not get more than 14-15 mpg. I think my brother used to average 12mpg on his with city driving, bfi and an exhaust, so also keep that in mind, but raw fuel smell and popping sounds like a problem. 1uz should be butter smooth no popping at all.

there is a vacuum line that comes from the power steering reservoir that connects to the intake piping, there is also a large breather line from the valve covers that connects to the intake pipe. Both of these must stay connected where they are after the maf or you will have issues.

have you ever done the o2 sensors, at 131k its just about time for those if they haven't been done, but in all reality, seeing over 15mpg in the city traffic would be pretty sweet for a sc400.
The tps could be causing your issues as well, as I said hard to tell but keep at it and if you have any questions post them up. whats your idle speed and pics and/or video of the problem usually help to figure it out as well.
may also want to pull a plug and check the condition and gap, if they are the OE platinums they are probably done for and need replacing.

Dream36

Thanks again. I am going to run injector cleaner like crazy for the next week or so since I'm stuck now as it sits (ran out of funds till payday again). I'll keep fiddling with the tps's hoping it helps too. I'll make videos and such an spots them tomorrow at work.

My idle is around 900 when I start it up and smooth with an occasional pop once every ten seconds or so. Once it's warmed up it drops to 500 and sputters for a but and when it pops it near stalls then shoots up to 1300 rpms before settling down. I'd say it does this every 30 seconds it so. I usually shift to neutral at lights and it isn't near as bad but still does it.

When I hit the throttle hard I can clearly feel all 8 firing but it will sputter up to speed. If I'm light on throttle it is very lacking and will sputter stall if I don't ease into it right.

It's real annoying. It is definitely running better with new wires, plugs, caps, and rotors. But way under par to where it should be (or when I first got it).


Edited. I forgot to add this car sat a few years before I bought it. So I did the fuel filter early on.

Ali SC3

iTrader: (10)

both of your idles are actually low beleive it or not, it should be close to 12-1400 cold start and closer to 900 when getting warm, and then when it hits closed loop (usually when the tamp gauge is starting to register almost a quarter way), it should then idle down max 650-750.
you shouldn't have to throw too many parts or money at this problem, its just a matter of narrowing it down.

I would suspect you need to turn your tps some more at the least, when turning clockwise it should raise the idle some (magic I say), and when turning counter clockwise it should lower some (crazy how it can do that right without changing the amount of air entering the engine). If it turns the same way as the sc300 (pretty sure it does), you will figure it out pretty fast playing with it, just loosen the 2 screws and start playing with it. I have never used a multimeter or a feeler gauge to set a toyota tps, you can do it by feel, its pretty easy.
if you have it turned to the side that gives you the lowest idle, it may stumble when blipping the throttle that means the idle circuit is not engaged at all. all the way to the other side the rpm's are at its highest and the idl circuit is also not activated and you will notice when blipping the throttle here it will be the smoothest it has ever been because the ecu does not think you are idling it thinks your foot is on and you want to accelerate at an instant.

what you want is the spot thats the most towards the lowest idle, that still revs properly when you blip the throttle as right after the lowest setting there is a sweet spot where the idl circuit is activated. By blip I mean a quick flip of the throttle cable bracket by hand.
If it hesitates as in the idle will actually lower for a split second before it goes up, keep going to the point it stops, then turn it a hair back.
The intention is to be on the IDL circuit, but with any touch of the throttle it is instantly off the IDL circuit.
This is usually ~ 1/3 of the adjustment range from fully counter clocwkise on these throttle bodies. 2jzgte turns the other way compared to the 2jzge and 1uzfe so if you have a gte its actually all backwards (how fun is that).

also do the coilpack test its free, and you do have alot of the symptoms including low idle and gas smell. I would rule it out at the least, since you remove the tps's it may be a simple fix if the tps is not set right you get alot of wierd symptoms at idle and partial throttle.

I'm starting to feel like I know too much about the toyota electronic systems...
I actually prefer the carb on my truck, all I need is a flat screwdriver and I can fix everything that goes wrong.

Dream36

Coils came out to spec. One wire was shorting on the block but I fixed that by putting the plastic tray back in place.

Retested my tps and got no readings, in fact it only shows a reading at one position and it is way out of spec and it is where the car runs worst. So, I'm driving to Maryland to check the salvage yards as they have two sc400s currently

Dream36

Tested a set of sensors from a ls400 boom! They tested perfect. Lets hope nothing else slows me down. Now I gotta drive 35 minutes home lol

Dream36

Installed new tps's, the trac light went out and the main tps appears to function (unlike the last one) however it is still stumbling and sputtering. This is really pissing me off. I guess it's the injectors or something. It still backfires if I floor it from idle. It will stall if I hold it to floor after the backfire.

I have this guy feeling the timing is off. Is there a how too on checking mechanical timing? How about testing injectors?

Brb