akhyakar

Hello all,

I switched out some injectors and when installing the intake plenum I lost a bolt that supports the plenum from the back, which is currently in the mail to me! I’m wondering if that support plenum OR the ground wire next to it is causing the problem below.

The problem I’m having though is that I now have two codes (p1135/p1155) which wasn’t there before. I’ve read that it could be the ground wire that is connected to the plenum from behind. I see that the ground wire is currently connected to a post and secured by a nut, but I see there is a recessed threaded hole which seems to be where it is actually supposed to be secured by a bolt, connected directly to the plenum. I checked the manual and that is what it looks like.

I already have replaced the a/f sensors recently so I am almost positive that is not the problem, and the fuses were fine too - I doubt the relay was damaged by me replace fuel injectors.

Can anyone confirm that this firewall side ground wire is supposed to be connected to the plenum by a bolt? And if so could anyone give me information on that bolt and part number?Attached is a picture showing the nut that was holding the ground on the post that is on that black and silver thing by my hand.

Thanks.

LeX2K

I'll look at my car in a bit.

akhyakar

thank you! It looks in the manual that it’s bolted down by that little raised up part on the plenum by a bolt.

LeX2K

Ground locations
https://www.japan-parts.eu/lexus/us/...wiring-clamp/8

The one coming from the engine harness to the plenum is critical (going from the nut then down) that grounds the entire EFI system under the hood

akhyakar

if I’m not wrong I have that one connected correctly. There is another one that is behind the plenum next to that support. Could you confirm? Attached is how my side ground looks without the nut. (The nut is currently attached, just showing this in case I have the ground and strap in wrong order) worth noting also the hose connected to PCV is pretty cracked, could that be causing the code?

akhyakar

attached are photos of the hole I think houses the bolt for the ground wire, and then a picture of where it actually is connected by a nut onto some post.

LeX2K

I know what you're referring to but I'll be damned if I can locate it on my car. The service manual shows a 2nd ground near the one pictured. I don't see it on my car in fact the one in your image is the same as what I have on the plenum nut/stud is it not?


What brand ignition coils are those?

akhyakar

NPauto. This whole fiasco started after I changed a ton of stuff for no reason trying to fix misfires which was actually caused by VVT solenoid. I’m a young guy and away from home having to work on car by myself and can’t afford mechanic. I took this to a mechanic and they only made it worse and I assume they put this ground on wrong.

LeX2K

I haven't tried on the 1MZ VVT-i but on other Toyota engines if that ground is not connected the engine won't run at all. Won't start. Those codes are O2 sensor heater circuit failure you might have a broken wire or connector.

....or poor quality O2 sensor might be the issue did you buy Denso?

akhyakar

Could be cheap sensors, but the problem only happened after I took off the intake plenum. I suspect since I’m still missing a bolt that connects the support directly to the plenum, and that this ground is connected to that support, that its not connected well enough to run smoothly, but we’ll enough to run. I have that bolt coming in the mail, and hopefully I can find the bolt size that goes to actually connect this ground wire to the intake.

Arsenii

Hard to tell from the picture, but there is indeed a threaded hole on the Back of the actual Plenum that the Ground wire attaches to, below is the picture of its general location. It could be quite tricky to reach, but is doable with enough patience, the biggest thing is to not get it cross-threaded while on the way. While it shouldn't play that much of a role, it is still grounded after all, there is likely a good reason Toyota chose that specific spot, even if I was quite tempted at some point to avoid it.



Been there, done that..

Can confirm, the car will start without the Ground on the back of the Plenum and even drive, though it will be a pretty questionable state as the transmission would have a time of its life trying to shift properly, throwing about a dozen codes. Came to learn it after doing the same thing OP did, replacing a whole bunch of stuff in one go, and not paying much attention to a lonely bolt left in a parts tray after I was done, it was 10 in the evening, I thought it was some hanger bolt..

[EDIT]:

Could be a bearer of bad news, but the Heater Element in those is controlled by Ground, and is grounded through an ECU, that's how it can modulate the amount of heat it produces, so I doubt that this is your issue. The heater element is usually simple enough to check with a Multimeter, check the Resistance between two Black wires on the sensor, and Voltage on the corresponding Engine wires.

It is a standard M6x1 bolt, about 10 or 12mm long, any Hardware Store should have it, even if it will look odd. I would go with a Stainless option if you decide to go that route, mostly because why not..

Hope this helps and best of luck!

My99ES300

Like Arseni's picture, the red circle is where that ground wire is connected on mine. The nut that yours is currently connected to is some a/c line which I believe is incorrect. What you can do is watch this excellent video from TRQ and go to 19:00 where he disconnects that ground wire. It'll be clear to you what's going on. I used this video to help guide me doing my left n right valve cover gaskets:


One other thing, you said "Attached is how my side ground looks without the nut. (The nut is currently attached, just showing this in case I have the ground and strap in wrong order)" . I don't think it should matter, but for what it's worth, yeah, yours are attached in the wrong order. The angled connector goes first, then the circular one on top.