Has My Car Been Chipped Or Piggy Backed Ecu

mafp · March 20, 2015

Dear Members,

i am after your collective and wise help, i purchased recently a W reg IS200 1GFE engine, the vehicle i bought for a reasonable price (i thought) and been fixing it since. it has had a new radiator, cat converter, manifold including precats, and injector seals so far.

since having the car the the ABS and TRC light are on, my OBD does not read any error codes??? further to that if the cam sensor is disconnected the engine runs, if connected it does not start, and will cut the engine out if connected when engine running, i have checked the resistance on the sensor and is working, at least is between the resistance value on the BOOK. is there any possibility that somebody connected a piggyback or has chipped the engine, although the ecu is stock and there is nothing obvious inside the engine compartment, ECU box, passenger footwell fuse box, and behind glovebox, ia am comming to the end of my tether looking for this source of fault or lack of, not to mention the hemorrhagic pace of at which money has been spent on this vehicle. which is not that good an example anyway......please help.

Stuno1 · March 21, 2015

Sorry to hear you are having so many issues. I know you don't want to hear this but maybe take the car to toyota/Lexus or an independent for a look over? Given how much you have already spend it can't hurt to let them look the car over for a few hours?

Stu

ColinBarber · March 21, 2015

The IS200 ECU cannot really be chipped, so if there isn't a piggyback then it should be standard.

Is the vehicle a UK one? A Japanese import wouldn't support OBD II at that age. I cannot remember which OBD II protocol the IS200 uses but I suspect your reader doesn't support all of them.

I believe the sensor detects the 3 teeth on the intake camshaft - worth making sure those teeth aren't damaged.

mafp · March 31, 2015

thanks for the reply.

an update. I managed to get flash codes from the ecu, and the result was a abs sensor dirty, checked the condition and cleaned it and was good to go. cleared tge error using procedure on book. shorting certain terminal on the OBD connector and press brake pedal certain number of times. the cam sensor was a bit trickier. after much fault finding and reading it became apparent that the timing must be out, considering that the cam and cranck shaft timing should match. anyway after dissasembling the valve cover I foung the gears out by one tooth. this has no been remedied. this afternoon I should complete the job and the mil should exinguish it self and should also have lots more power at low revs. wish me luck...

thanks all.

it been an interesting learning curve.

ColinBarber · March 31, 2015

sounds promising :)

mafp · March 31, 2015

little update.

completed the work today. connected the camshaft sensor back on and tried to start the engine, no luck at all, engine would turn over very well but would not fire, prior to trying to start the engine i cleared any error by disconnecting the Battery for 15 minutes. when the sensor was disconnected the engine fired after a bit of turning. i took the car for a quick spin and has more power than before at low revs, but when it reaches 3k 3.5k the power surges, this suggest that the cam lobe design is working at it's best at those RPM, and well clearly nothing is happening at low RPM when the OCV should be controled by the cam sensor. i will replace the sensor for a spare i have, although both the sensors i now have have the roughly the same ohm reading. the plot thickens.

just when i thought all issues where getting resolved.

Regarding the ABS/TRC, the flash codes do not identify any issues with anything on the system, TRC light comes 10-20 seconds after starting the engine, ABS/TRC light extinguishes themselves off after turning key to ON as described on the BOOK, this suggests that there is nothing wrong with the system.....any ideas?

mafp · July 6, 2015

Quick update.....it has been a few months now, and my car is working fine. In the end by using an oscilloscope the signal from the camshaft sensor was monitored with the engine running, and with the use of the repair manual which indicates the correct sensor signal (analogue DC, that oscillates between + on approach & - on moving away from sensor, depending on distance between sensor and lobe), I managed to identify that the sensor polarity was the inverse of what should have been, this erroneous signal will shut the engine down to prevent engine damage; which is what was occurring when connecting the sensor; under normal correct operation this erroneous signal will indicate the wrong camshaft position relative to the the crankshaft, this will potentially destroy the engine (as the 1GFE is an interference engine). Once the polarity was reversed the problem was repaired. Unfortunately I now have a foreign cable running from the sensor to the ECU, as there is just not enough room between the fire wall and engine to make the a proper repair, i guess this will have to wait until I disassemble the intake manifold for access. it has been now almost 4K miles and working nicely, i get between 26-30 MPG. just recently a changed a vacuum pipe between the rocker cover and throttle intake, this has now improved low end power, will monitor MPG for the next refuels as usual.

Thanks all for lending a hand.