When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I started taking the J&S safeguard out of the car, everything seemed fine and was easy to remove until the last bit, resolving the wiring for the knock sensor and setting it back to stock. There is an exposed wire (I’m wondering if this grounded out and threw my CELs?) and an unmarked box plugged in that I have no idea what is for.. hopefully someone has an idea lol.
here is the area we are looking in, just for context. The arrow points to the exposed wire and knock sensor, the unmarked box is circled: https://i.imgur.com/kemdLAO.jpg
alright, now the wiring. The wires that go to the SafeGuard (knock sensor + and - terminals on the Safe Guard unit) run to the greasy connector at the top right of the image. This seems to plug directly into the knock sensor itself. The unknown grey box (above) is connected via the corrugated wire insulator just below the greasy connector. One wire is very exposed, as noted above, and is connected to a nylock nut on the block.. I think this is the factory knock sensor ground? Maybe? The other wire is connected to a wire that runs under the intake.. I couldn’t chase it down: https://i.imgur.com/7ui8QIz.jpg
my theory is that the unmarked grey box is mimicking the factory knock sensor to fool the ECU so it thinks everything is fine. And I should delete the grey unknown box. That would mean soldering the wire running under the intake to the knock sensor and then soldering the ground wire off the knock to the nylock nut on the block.
edit: you know, maybe not. Looking at it, the wire I couldn’t chase down that runs under the block has a female spade connector (factory looking) and the nylock nut has a male spade connector. So maybe that plugs in there.. but then what is the unknown grey box doing? And where is the factory knock connector?!
Last edited by Kevin Ingraham; 06-06-20 at 08:16 AM.
Doing some research. It appears the factory Knock sensor that the ECU is reading is on the front rotor housing, so this looks to be an auxiliary knock sensor using the unused threads on the rear rotor housing.. so it seems to me I should be able to just unplug this thing and no worry about the wiring.. for now I’ll just tape over the connector for safe keeping and leave it; i don’t see the harm in leaving this sensor screwed to the block, unconnected.
that still leaves the question about what this unmarked grey box is though. Anyone have an idea?
also, here’s to hoping that is my issue... it looks like that wire is coming from the same wiring loom as the solenoids, And those are the majority of my CEL codes. Knock on wood, it’s that exposed wire above that arc’d or made contact with some metal somewhere and shorted.
Last edited by Kevin Ingraham; 06-06-20 at 08:15 AM.
Yeah, I think that box was for the water temp gauge. That's some old school mods there!
Basically one would do a small mod on the gauge itself then some people would make a box with a variable resistor in it to fine-tune the action of the gauge. The temp sender for the gauge is in the rear iron below the oil filter, it's a 1-wire connector.
I remember now that the J&S uses its own knock sensor. Yeah you can just leave that old sensor there until you get a chance to get to it, that's fine.
Yeah, I think that box was for the water temp gauge. That's some old school mods there!
Basically one would do a small mod on the gauge itself then some people would make a box with a variable resistor in it to fine-tune the action of the gauge. The temp sender for the gauge is in the rear iron below the oil filter, it's a 1-wire connector.
I remember now that the J&S uses its own knock sensor. Yeah you can just leave that old sensor there until you get a chance to get to it, that's fine.
Dale
Cool, good to know I was on the right track with my thinking!
unfortunately though, after removing the knock guard I got it back together, no change in symptoms. Same codes, I started it up, idle was rough and terrible. Damnit.
I guess it’s time to take the upper manifold off and see what’s going on in there.
there are a few wires with broken insulation/exposed wiring.. not the best. I can fix that, though no problem.
What I found though is a bunch of deleted solenoids/sensors. Here is an album (I tried to point to the deleted sensors and stuff with my fingers): https://imgur.com/gallery/pjbsHqs
from comparing it to the diagram I found, it looks like at least these are deleted:
turbo precontrol
wastegate control
relief valve
switching valve
egr
aws
some of that makes sense.. it has emissions deleted, I knew that. Some of these other things though, I’m not sure about. The weird thing is, the car drove perfectly fine for 2,000 miles or so.. so it WAS ok with these things deleted. I did disconnect the battery Not long before this started to install a different steering wheel. That would be crazy if that wiped some custom tune that was accounting for these missing solenoids though, right?
there are a few wires with broken insulation/exposed wiring.. not the best. I can fix that, though no problem.
What I found though is a bunch of deleted solenoids/sensors. Here is an album (I tried to point to the deleted sensors and stuff with my fingers): https://imgur.com/gallery/pjbsHqs
from comparing it to the diagram I found, it looks like at least these are deleted:
turbo precontrol
wastegate control
relief valve
switching valve
egr
aws
some of that makes sense.. it has emissions deleted, I knew that. Some of these other things though, I’m not sure about. The weird thing is, the car drove perfectly fine for 2,000 miles or so.. so it WAS ok with these things deleted. I did disconnect the battery Not long before this started to install a different steering wheel. That would be crazy if that wiped some custom tune that was accounting for these missing solenoids though, right?
most of the emissions sensors wont effect how the car drivet, things like the omp will though.and cause limp mode. but if u pulled codes u would of seen these codes before.
there are a few wires with broken insulation/exposed wiring.. not the best. I can fix that, though no problem.
What I found though is a bunch of deleted solenoids/sensors. Here is an album (I tried to point to the deleted sensors and stuff with my fingers): https://imgur.com/gallery/pjbsHqs
from comparing it to the diagram I found, it looks like at least these are deleted:
turbo precontrol
wastegate control
relief valve
switching valve
egr
aws
some of that makes sense.. it has emissions deleted, I knew that. Some of these other things though, I’m not sure about. The weird thing is, the car drove perfectly fine for 2,000 miles or so.. so it WAS ok with these things deleted. I did disconnect the battery Not long before this started to install a different steering wheel. That would be crazy if that wiped some custom tune that was accounting for these missing solenoids though, right?
First off, that diagram has a LOT of problems. Don't use that. Some of what you are working on is not right on that diagram. This is going to be more accurate -
One thing that may not be on that though is you have the air control valve (ACV) removed and blocked off. There is also on the forum a picture of the stock ECU harness with each connector labeled, that may be a good way to find out what was removed.
With removing emissions stuff with the stock ECU you would typically have to put resistors with each removed item so the ECU thinks it's still there. There are chipped ECU's but they can't have that programmed out, the chipped ECU's just have different fuel, timing, and boost maps.
Also, with no ACV you probably have no air pump. No air pump and the car will run like crap on a stock ECU - rough idle and rough on/off throttle.
Yeah, as I was Trying to figure this crap out last night I resigned myself to “I need a PFC now”. I was planning on it eventually anyways, but I guess it’s just time to accelerate that purchase. I’m gonna call my tuner on Monday and make sure he is cool with Power FC.. I’d so much rather run that. financially, totally.. but also I’m not going crazy with mods and don’t need all the features of a Haltech. I’m sure he has tuned on them before, but I figure call before dropping a grand on a stand-alone.
thank you for the better diagram! The simplified setup matches what’s going on in my car pretty closely. I also do have a deleted air pump, so that makes sense why it’s idling like ****.
in the meantime, I am going to delicately (Jesus the wire insulation on everything is so dry and brittle) resolve the spots where it has cracked/exposed the wire itself to keep it from shorting and get it put back together. That’s likely something I’ll have to replace in the future as well.. but I think for now it’ll be OK.
the mystery to me is how/why it ran so perfect, then all of a sudden 20 minutes into a drive it decided to hate life. Just kind of a bizarre occurrence.
I just removed a J&S knock sensor/controller from my car and I thought just unplugging it at the controller was fine. Turns out the system was installed to intercept/interrupt the lead coil signal wire to the igniter, so without the J&S controller plugged in, there was no signal continuity to the lead coil. Interestingly enough, the car will still run on just trailing, it'll just be down on power and response. I didn't realize this was an issue until I did a rewire for water injection and saw that this wire was being interrupted. Just thought you should know.
I just removed a J&S knock sensor/controller from my car and I thought just unplugging it at the controller was fine. Turns out the system was installed to intercept/interrupt the lead coil signal wire to the igniter, so without the J&S controller plugged in, there was no signal continuity to the lead coil. Interestingly enough, the car will still run on just trailing, it'll just be down on power and response. I didn't realize this was an issue until I did a rewire for water injection and saw that this wire was being interrupted. Just thought you should know.
thanks for the heads up! I did notice that when I deleted it.. and who ever installed this originally put spade connectors on the interrupted wires, so that made for an easy reconnection on the leading coil wire.
The last owner sent me the documentation for the car and it finally came in the mail.. holy crap, this car is well documented! Receipts going all the way back to brand new, original window sticker, two different manuals, all the instruction guides from all the parts put on it, and a ton of super hot 90s magazine cut outs, print-outs of different wheels one of the past owners was cross shopping... Amazing.
Looking through it, there’s no mention of a chip or tune. It seems like the car was relying on the J&S knock gused to just pull timing off it started knocking or running lean, Jesus.
regardless, I’m having a shop I’m familiar with do a once-over on it. They have one of the most knowledgeable rotary mechanics in the area, conveniently. But that’s really just to make sure it’s ready for a proper tune! The tuner doesn’t like tuning on Power FC and recommended Link. From my experience, if you want a good tune you listen to your tuner, so Link it is!
knock on wood they give it a full bill of health and we can move on to putting a proper, custom tune on this thing and get it running perfect and safe.
Thank all of you guys for the advice so far! I really appreciate all the thought and time put into helping me out this far. I’m sure it won’t be the last time I reach out to pull from the collective knowledge, here! Once it’s running, I’ll have to do a proper intro thread as well to join the community.
On the Link, I"m not super familiar with it. I would want to be certain that it can properly control the sequential system so the car still has it fully functioning. Don't let them try to go non-sequential, all that does is sacrifices low-end power.
If that is a problem you may still want to look at the PFC and find someone you can drive to for a tune. For your mods it shouldn't need much.
Yep, I plan on keeping the factory twins and they are aware of that. Looking at Link’s website, it says it supports NA, single, or twin parallel setups on the FD S6 model, so should be good. I trust this shop a lot, I have experience with them before. I know they’ve tuned and worked on a good amount of rx7s, too.
they use link because A) the tuner prefers it (he is one of the premier tuners in the Midwest, REALLY good at what he does, I want him to be the one touching my car), and B) it’s a drop-in board. So you take the guts out of the factory ECU and put Link’s board in the stock housing. So you dont have an adapter harness, it plugs right into the factory plugs and also you don’t have an additional box you’re trying to find a spot for or trying to make brackets in the factory ECU location.. the install is really clean. Seems like a great value too, just a couple hundred more than PFC and it is much more modern and has more features. I’m pretty stoked on it.
There isn’t a lot of information on forums about it, so it’s definitely not very common. I’ll have to talk to them about it more and try and get some more info about it and report back about it, get some information on here for posterity.
Just FYI, parallel /= sequential. I browsed the link website for the ECU and through the manual, did not see anything about it supporting sequential operations.
Yep, I plan on keeping the factory twins and they are aware of that. Looking at Link’s website, it says it supports NA, single, or twin parallel setups on the FD S6 model, so should be good. I trust this shop a lot, I have experience with them before. I know they’ve tuned and worked on a good amount of rx7s, too.
they use link because A) the tuner prefers it (he is one of the premier tuners in the Midwest, REALLY good at what he does, I want him to be the one touching my car), and B) it’s a drop-in board. So you take the guts out of the factory ECU and put Link’s board in the stock housing. So you dont have an adapter harness, it plugs right into the factory plugs and also you don’t have an additional box you’re trying to find a spot for or trying to make brackets in the factory ECU location.. the install is really clean. Seems like a great value too, just a couple hundred more than PFC and it is much more modern and has more features. I’m pretty stoked on it.
If you want to keep the stock turbo setup, that is a sequential setup not a parallel setup. From the few threads I can find about the Link, it doesn't seem to support the stock sequential setup.
The Link G4 plug-in ECU doesn't support sequential turbos. That's a shame! I wonder if there is a way to get it to work, there's basically 3 or 4 solenoids that just need RPM switches for the sequential system to work right.
06-05-20, 10:04 PM
. That sounds pretty slick.
