Has anyone had a Hewitt bypass quit working?

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F

folivier

Joined
Dec 15, 2020
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Location
Baton Rouge, LA and Gunnison, CO
Here's the story, my 2006 GX470 started throwing the codes and go into limp mode this past winter and a few times this summer. So I ordered the Firewater Marine bypass kit. When I installed it there was already a Hewitt bypass installed. I uninstalled the Hewitt bypass and installed the Firewater kit. I haven't put enough miles on it to know if it works or not and haven't had time yet to see if the block off plates are already installed.
Just wondering if I have a different problem or the Hewitt kit did go bad?
 
There are a few known incidents that Hewitt themselves know with first generation bypass. It can go bad. That is just from reading Paul Hewitt's comments on GXOR.

I am batting different issue with rutech bypass. Lately its been giving me P0113 for intake temperature sensor current high. Replace MAF sensor with OEM and it still comes back randomly on hot days.
 
folivier said:
Here's the story, my 2006 GX470 started throwing the codes and go into limp mode this past winter and a few times this summer. So I ordered the Firewater Marine bypass kit. When I installed it there was already a Hewitt bypass installed. I uninstalled the Hewitt bypass and installed the Firewater kit. I haven't put enough miles on it to know if it works or not and haven't had time yet to see if the block off plates are already installed.
Just wondering if I have a different problem or the Hewitt kit did go bad?
Click to expand...
I have a Hewitt kit on my 2007. It went into limp home mode 2X last winter, under cold conditions where I hopped straight on the freeway after starting the engine. However, I've also found that the ground wire for the Hewitt kit likes to come unplugged. So I crimped down the connector a bit more. Not sure if that was my issue or if the Hewitt kit is no longer working. I'll see how it does later this winter and then evaluate other options.
 
Jstawgn said:
There are a few known incidents that Hewitt themselves know with first generation bypass. It can go bad. That is just from reading Paul Hewitt's comments on GXOR.

I am batting different issue with rutech bypass. Lately its been giving me P0113 for intake temperature sensor current high. Replace MAF sensor with OEM and it still comes back randomly on hot days.
Click to expand...
It could be your MAF connector myself. I've had the OEM one go bad - and then my splice job on the replacement to bad later one. A bad MAF plug will cause all sorts of codes and issues. Others have also had this problem. I've since spliced in a new one, including making the connector easily replaceable by adding a Deutsch connector to the OEM harness, then another Deutsch connector to the MAF pigtail.
 
folivier said:
Interesting Rednexus. My MAF plug was broken and taped together. That could be my problem.
Do you have the part #'s for the plug you used?
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I used one from Amazon, but the pigtail was kind of short. Since your MAF wiring isn't pre-hacked/cut like mine, that might not be a big deal. You could cut off the OEM MAF plug, add a Deutsch connector in it's place, and then add a Deutsch connector on the end of the MAF pigtail. Or you can direct-splice, but the splices have to be really good to not have issues down the line like my rig did.

I'd post pictures of my new/improved splice job, but the forum is giving me a server error message. Here's the MAF connector.

Amazon.com: IXGKHC Mass Air Flow Sensor Meter MAF Harness Connector Plug 22204-31020 for Toyota Venza Highlander Matrix Avalon RAV4 Camry Corolla Sienna for Lexus is F IS250 IS350 ES350 GS350 and Scion xB xD tC : Automotive

Buy IXGKHC Mass Air Flow Sensor Meter MAF Harness Connector Plug 22204-31020 for Toyota Venza Highlander Matrix Avalon RAV4 Camry Corolla Sienna for Lexus is F IS250 IS350 ES350 GS350 and Scion xB xD tC: Mass Air Flow - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com

EDIT: Server is working.

Here is the new pigtail I made:
20250727_173536.webp

And it installed. The Deutsch connector on the ECU side can be seen attached to my ARB twin mount.
20250727_173540.webp
 
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Rednexus said:
I used one from Amazon, but the pigtail was kind of short. Since your MAF wiring isn't pre-hacked/cut like mine, that might not be a big deal. You could cut off the OEM MAF plug, add a Deutsch connector in it's place, and then add a Deutsch connector on the end of the MAF pigtail. Or you can direct-splice, but the splices have to be really good to not have issues down the line like my rig did.

I'd post pictures of my new/improved splice job, but the forum is giving me a server error message. Here's the MAF connector.

Amazon.com: IXGKHC Mass Air Flow Sensor Meter MAF Harness Connector Plug 22204-31020 for Toyota Venza Highlander Matrix Avalon RAV4 Camry Corolla Sienna for Lexus is F IS250 IS350 ES350 GS350 and Scion xB xD tC : Automotive

Buy IXGKHC Mass Air Flow Sensor Meter MAF Harness Connector Plug 22204-31020 for Toyota Venza Highlander Matrix Avalon RAV4 Camry Corolla Sienna for Lexus is F IS250 IS350 ES350 GS350 and Scion xB xD tC: Mass Air Flow - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com

EDIT: Server is working.

Here is the new pigtail I made:
View attachment 3967766
And it installed. The Deutsch connector on the ECU side can be seen attached to my ARB twin mount.
View attachment 3967767
Click to expand...
i broke the MAF plug on my tacoma, and I got a pig tail but i didnt splice it in. i depinned the old connector and just used the new connector body and plug the old pins into new body and everything worked fine. didnt have to splice anything and worry about it not being working right
 
wrmathis said:
i broke the MAF plug on my tacoma, and I got a pig tail but i didnt splice it in. i depinned the old connector and just used the new connector body and plug the old pins into new body and everything worked fine. didnt have to splice anything and worry about it not being working right
Click to expand...
My connector was not broken and physically looked fine. It also snapped onto the MAF fine as well. I think the issue was the actual pins/wires inside of the connector. For both instances, the issue fixed itself as soon as I put on a new MAF connector. The MAF wires are only 24 or 26 ga wire so the they are rather fragile when they get old. Or, perhaps the connector pins aren't gripping the pins of the MAF very well. The MAF is pretty sensitive; if there is a poor connection or slightly higher resistance due to a wiring issue, the ECU will mis-read engine airflow and cause all sorts of strange problems.
 
I have a 2003, so no SAIS on mine.

However, Hawkeye Garage just posted a YouTube video and posted on GXOR about his new fix for this issue.

He had problems with bypass kits, so he and his buddy posted what they call a permanent fix that you can DIY

 
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HomersCanyonero said:
I have a 2003, so no SAIS on mine.

However, Hawkeye Garage just posted a YouTube video and posted on GXOR about his new fix for this issue.

He had problems with bypass kits, so he and his buddy posted what they call a permanent fix that you can DIY

Click to expand...

I had one of those that was previously sold by slyfox75 on eBay. He's NLA, perhaps he got a nasty letter from USEPA. It also threw the PO2445 code, which is why I tried the Hewitt. Not sure if I had a wiring issue with that kit or something else.

Can't help but wonder if this is a ECU issue caused by my tune. Maybe the ECU tune of my rig has the SAIS "bug" in it, as I don't ever recall having SAIS issues prior to loading a tune on the rig. Some more experimentation this fall might address it. I'm also not opposed to pulling the intake off and fixing the SAIS parts as opposed to bypassing the system.
 
I replaced the MAF connector plug, cleaned the contacts, then hooked up the new Firewater Marine module. Started up and my GX ran rough at higher rpms, and threw the same codes again. So I unhooked that one and hooked up the old Hewitt module. It ran great, no codes, drove it 150 miles yesterday from the mountains to town, towed a trailer with my Rzr back to the cabin. No codes. Hmmmm.
 
Hewitt is redeemed.
 
Is this SAIS bypass considered preventative maintenance at this point. Hewitt kit is 2-5 hundred depending on which kit you choose; Gen 1 or Gen 2.

Kinda expensive for a maybe event? If vehicle goes into limp home, clear codes and restart the vehicle?
 
Limp mode is (at best) a major inconvenience. If you're on a highway, it will limit your power severely - to the point that you will have a hard time going faster than 45 mph with your foot on the floor. Can you clear it? Yes, but you'll need to pull off the road to a safe space, plug in the code reader, let it link, and then clear the code. That's what happened last time mine went into limp mode. Luckily I was on a rural 4-lane highway with big shoulders and not much traffic. I'd really hate to have it happen on a busy interstate going fast.
 
Good point. I hadnt even thought of it from a highway safety point of view. I have experienced it myself before - cant remember the circumstances but do remember it being quite a shock. I think it was in an old Ford Windstar.

Anywho, Im considering doing it with some upcoming exhaust work. I am doing research to see if I should bundle cat replacement with bypass since Ill be working in the same area.
 
Happened to me in my '06. Had it in storage for the winter, started it up and drove off on a 4 lane highway. Came to first hill and couldn't get over 45 mph. Had to pull over, hook up OBD reader and clear codes. Was ok until it happened again. Look at my earlier post for my solution :)
 
Beej said:
Good point. I hadnt even thought of it from a highway safety point of view. I have experienced it myself before - cant remember the circumstances but do remember it being quite a shock. I think it was in an old Ford Windstar.

Anywho, Im considering doing it with some upcoming exhaust work. I am doing research to see if I should bundle cat replacement with bypass since Ill be working in the same area.
Click to expand...
If you are going to do the cats, you should bundle that with short tube headers.

The bypass is a pretty easy install. <1 hour. Although, you may not find a shop willing to install it so you might need to DIY it (not sure if you were planning on having a shop install cats or doing it yourself). It is, after all, a emissions defeat device. While I can't imagine that this administration is enforcing that part of the CFR very much, it would still be (on paper) a Clean Air Act violation.
 
Rednexus said:
If you are going to do the cats, you should bundle that with short tube headers.
Click to expand...
Oh, Ive read your build thread, @Rednexus . There are better goodies in there for me than headers. Believe me, you've got me in plenty of trouble as it is but I appreciate the encouragment.

If this is a 1ish hr DIY, I may just wait. I'm collecting parts for my builds and Im not sure this SAIS is up near the top of the list since it doesnt same me time/money bundling with exhaust.

I do DIY but this new truck is going to my mechanic. I need to get my p0430 and p0420 out of the way so I can register/plate this truck by end of next month.
 
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