Hewitt SAIS Bypass Question for Cold Climate

-New member here, I just made my introduction thread before this.

I've owned my 06 for about a month. I noticed the high pitch vacuum sound at start up and distinct vacuum shutoff sound after 20-30 seconds. It has not thrown any codes for this yet. But I want to be proactive and take care of this issue as I want this to be a reliable adventure vehicle.

I've done some research on the Hewitt bypass kit and read that some have issues with the P2445 cold weather glitch. To my understanding this code has nothing to do with the Hewitt system, and as long as I don't have this code I should be fine to run the Hewitt system in negative temperatures? I live in Minnesota and it is frequently below freezing and even negative.
Just wondering if there's anyone who lives in a freezing climate and have had success with this kit.

Also, I might try to skip the blocking plates. Those nuts will be a nightmare for me to get off, I'm sure all 4 would probably snap off. I've read that as long as you don't have existing codes that a lot have had success not using the blocking plates as the valves should already be closed and the bypass kit will keep them closed.

I did call Hewitt and ask them this question. They were nice, but didn't seem to have a confident answer. That's why I'm asking here to see if anyone has any experience with the kit working well in cold climate.

Thank you for any help. I tried to research as much as possible before making this thread.

 

No problems in NC winters. I broke 3 out of 4 bolts.

 

That would potentially be a very fucking stupid thing to do, based on other complaints we've seen on here, specifically ....

I've seen several people come here bitching about the Hewitt kit not working and throwing codes, only to find they didn't install the plates, and installing the plates fixed it. At least 3, if not 4 or 5 people now in my time here since registering. There are also some success stories without installing those, but that's another story. The Hewitt kit works by tricking the vehicle into thinking the temperature is (low enough?) such that it doesn't need to run the pump.

But seriously, why not just replace the pump? It won't kill the truck to run without it, let it die, swap it out. Deal with it again in 15 years without rigging up the truck.

 

Well the pump itself is $390 from Ourisman Toyota. But once you add in the check valves, hoses, gaskets, tax, shipping, and all other recommended things to replace when doing this job it adds up to a little over $900 from Ourisman. Unless you think I should just replace the pump only and reuse the current check valves and hoses? Asking that as a genuine question. I do agree, I would prefer to not rig up the truck, but $150 vs $900.

 

Chances are you only need to replace the pump. And only if it fails. Can’t hurt to replace the rubber hoses on the solenoids and over to the valves from those solenoids.

 

Should I just leave it then and wait until it fails? Have you heard of people who’s pump is noisy and it’s lasted for years? I thought that usually meant it was on its way out. Sorry for all the questions, I just don’t want to be hundreds of miles away from home in limp mode.

 

More than one person has popped up on here to say they’d been hearing the sound and it was bugging them after going for so long. As if it’s been a long while.

I also distinctly recall @Dakillacore mentioning his was noisy, and it got cleaned up rather than replaced. And the noise went away? I forget. He’d need to fill in those blanks.

 

Alright, appreciate the replies @shifty`

I guess I’ll just leave it for now and hold off on the kit. I’ll replace the pump at some point, probably when ourisman or some other dealer runs a 25% off.

 

Nah, not me. Might be someone else. I do hear the sound at start up, but it goes away after a bit.

 

Damn now I’m gonna be sitting here wondering who the hell it was

How long you been hearing the sound?

 

It's fairly recent. Within a month or two. It's a loud whistle and then it goes away.

 

Edited for clarity:
@Lucky2 Minnesota native here too.
I have installed SAIS bypass kits by Hewitt Tech, Rutech , and Fire Water Marine on two vehicles. After my 2009 gx470 started throwing SAIS related codes, I installed a Rutech kit but then switched to an upgraded Hewitt Tech kit. I also installed block off plates after paying to have exhaust manifolds replaced at a garage so it was easy to do after it all had just been apart.

As a proactive "repair" on my FGT before any codes, I installed the significantly cheaper Fire Water Marine kit without block off plates. My understanding is if the valves are functioning and therefore closed on the SAIS, it should be fine to skip the block off plates. I live in the commie republic of New Jersey so rust is a big issue and I had to weigh the significant risk of snapping exhaust bolts.

 

I’ve read the majority of people have been fine doing this. I’ve found one expample of where someone’s valves @Rph74 magically opened again when they were 750 miles away from home and he had to reset code 15-20 times to get home. Although I believe this was on a 2nd gen with the 5.7. I haven’t found any specific examples of people skipping them with the 4.7 and then having issues.

All I risk is just ruining the check valves? Or is the other sensors not associated with the sais system that I could ruin. My thought process was be lazy and do the cheap fix now, and down the line if those valves magically open then I’ll go in there and fix the entire system and be down $900. But if I could get 2-3 years being cheap, that would be great. Truck is new to me and I just want to drive it and see what I got. I got more important things like a potential rack and pinion I got to do. If it proves reliable then I’ll do the correct fix later on. Thoughts @shifty` ? I know you’re pretty opposed and I understand.

Did you have this code prior to putting the kit in? The cold weather glitch code for the tundra is the P2445 which can happen in 05 and 06.

 

Yup, TSB for that is here: https://www.tundras.com/attachments/sb-10075945-0699-pdf.856874/

 

Up front, I want to apologize for muddling this issue. I misstated the original problem. There was another SAIS related code for 08/09 gx470 that I needed to address by buying the updated Hewitt Tech kit. From HT website, "if you were install a competitor’s kit or Gen 1 (V36) on a model year ’08 or newer, you would get the error code P011B – Temperature Correlation Error." This is why I got the updated HT v54 vs the v36 kit.

I actually got the cold weather glitch code for the first time this winter which can be avoided by restarting the vehicle after warming up prior to driving off in 30 degree weather. Otherwise, the vehicle goes into limp mode and must be cleared with an OBD reader. The SAIS bypass kits from any maker do not address this factory ECU programming flaw. HT website states, "***There is a known “Cold Weather Glitch” on some older 4.7L engines. If the vehicle is tripping a P2445 and it is caused by this glitch; the Hewitt Technologies SAIS Bypass Kit will not resolve the issues." I didn't expect to have this problem because I've got a 2009 gx470 but I definitely have this cold weather glitch.

Since installing the SAIS bypass kit on the 2005 Tundra, I've have had no problems. I recently installed the starter relay wire without issue.

https://hewitt-tech.com/product/sec...47ha1y/?sy=2009&sm=Lexus&smodel=GX470&se=4.7L

 

I don’t believe I have this issue. Truck is originally a Montana and North Dakota truck. So it’s spend its entire life in the cold. I’m sure if it had that issue over the course of 20 years, it would have been fixed. I think i’ll go ahead with the kit and come next winter I’ll find out once and for all if I have the cold weather glitch. If so, I’ll get a new ecu or see if a dealership can flash mine, I saw a site shifty linked on an old thread to get one for $250.

 

I haven't had the cold weather glitch this winter since buying my 2005 Tundra last summer. Like I said above, simple work around is just to restart after it's warmed up or clear the code with a OBD reader. As I recall, the code is only tripped on cold start after 7-8 hrs since prior start in 30 degree weather. So it might be possible for you to drive to work, park for 8+ hrs , and then throw the code again but most often this is just a morning cold start issue

 

I went with the Hewitt kit, primarily cause I didn't feel confident tackling that job myself, . . . that along with the cost for OEM parts + labor in my area was ridiculous . . . I was quoted north of $3K . . . f-that.
Not to mention Toyota never upgraded that crap system . . . so who knows how long a new 'SAIS' system will last.