87 GT4 Has code 52 - knock sensor signal open or short circuit, since i've had the car and however long before. I've tried another second hand sensor but no change. I will try it again with the new wire to be sure. I have run a new wire 3 times, the one i did today is shielded, it's shield is grounded on to wire E1 coming off the ECU and not connected to anything at the plug end. Is this the right way to do it? Checked cam timing, it's spot on. Dizzy timing is 10BTDC with T and E1 bridged in the diag box. - was 15deg, fully advanced, to make up for the retarded timing from the knock sensor - i guess to get it sold Knock error still happens when cold and warming up. When it was fully hot i turned it off and on again, no error and made it a few kms to home. Idled in the driveway for a few mins, temp gauge dropped a tiny bit, then took it around the block, the code came up at 1.5 k rpm taking off slowly. Turned it off and on again and drove a bit quick and no error for a couple kms, made it home and idled and still no error. I will try it again later today when its cold. Heres the noise i'm hearing 1.5-2k rpm it could be setting the sensor off...but not when hot. So, possibly -rattling noise in vid -knock sensor loose until it heats up to temp -engine pinging when cold -ECU - It has run perfectly when not throwing a code, I will find another or take this one apart as a last resort -clogged fuel filter-running lean? would the ecu compensate for this by fuel pressure? -broken catalytic converter core rattling around -TVIS butterfly loose/broken rattling around -thermostat broken and rattling around I've got a lot of ideas of what it might be... working through them easiest first Anything else? Cheers
I am attaching this page on Toyota knock sensors.. The sensor shielding is grounded to ECU and to the back of the intake manifold Good Luck! 1
I have been having this cursed issue forever except mine is always there no matter what. Replaced wire, sensor, even the ecu and still can't get it to go away. But I've seen daily driving it for the past few years. I just gave up on fixing that damn code. Sent from my SGH-T769 using Tapatalk 2
Its hard to diagnose though since you replaced all to include the ECU.. have you checked for electromagnetic interference from the alternator? Sometimes this can be an issue.. consider the fact that the knock sensor is simply a microphone.. when the ECU hears or sense tones at the 7000 MHz it is interpreted as knock .. now have you ever been in a car that had an aftermarket stereo system and you were able to hear a humming tone that would increase in pitch as the car accelerated? Same concept except instead of that sound going to your speaker its going to the ECU.
Yeah I know what you mean there. But how can you diagnose that, or even fix it. Sent from my SGH-T769 using Tapatalk 2
A PDF document explaining on how to test for ripple voltage from your alternator. https://www.google.com/url?sa=t&source=web&rct=j&ei=oCTNUsfCMMrSsATsgoCoDg&url=http://www.pvv.org/~syljua/merc/TooSeptST07.pdf&cd=7&ved=0CEEQFjAG&usg=AFQjCNH0elt6XLMWeeeQg_jLpmVLQio0QA The above may be overkill though it would not hurt to check .. I have one major concern since you replaced your wire to the knock sensor.. what kind of wire did you use and what did you do with old wire?? It ties back in the harness and the insulator ground loop wire is also tied to the distributor, O2 sensor and Something else.. but I can't really remember.. though they went to that same ground pin at the ECU.. so saying you ran an independent wire to the knock sensor and back to the sensor ground .. the old ground loop wire could still be injecting emi into that sensor if that old ground loop was not corrected because that sensors ground is at two place .. behind the intake manifold and the ecu . So potentially any of the other systems that shared that loop can be injecting noise to that sensor.. they are still tied at that ecu pin where you grounded with the new independent wire.
