Hard to start after Hewitt Bypass Module install

Got the codes for the stuck Air switching valve, etc., etc. Did my research and bought the Hewitt module that fit my truck. Install was easy but I took my time. I reset all the codes and they have not come back. Also no more limp mode. I drive it around for a while, no problems. The truck sits overnight and starts fine on my way out the door. I get to where I'm going and the truck sits for a couple of hours. I go to head home and it will crank but not start. I try again. Same thing. One more try and it cranks and runs fine. It drives home no problems. I let it sit for a couple of hours and try again. Same issue. Has a hard time getting started. Eventually each time it would start but it kinda sputters to life and then runs smoothly. Anyone have any similar issues with the Hewitt Module? I reached out to Hewitt via email but it is currently the weekend. 2008 Tundra 4.0l V6

 

Nope, why I'm waiting on tax return to put in shop with mechanic. Heard one guy say to disconnect the negative battery terminal and hold brakes for 10 seconds then you will be good to go, until you have to restart and do same thang again, but will buy you some time till you sort it out.

 

Hmm that’s odd, I haven’t had any issues with mine on my 4.7L. Curious what they say, they are pretty responsive on the feedback.

 

On my 4.6L 2010 bypass it worked great. Then when it got colder outside down around 30F and below I had starting issues but ran fine once started. They advised removing the purple wire to the relay and all was fine. The only thing you lose if removing the "purple wire" is if you put the key in accessory mode you have to cycle to off to start. If you go to start from accessory it won't work. That's no big deal, how often would that occur and you can just go to off and back to start and it engages start just fine. Anyway, if you have that purple wire try just disconnecting at the module and see if that resolves the starting issues.

 

@hewitttech

 

Interested in the response to this. I have the same issue with my 2008 5.7, trying to figure out if it’s a problem associated with the bypass kit or an issue with the fuel pump.

 

2009 4.0 L V6 , had Gen II kit installed by local mechanic, been 3 months runs great no issues.

 

Update: Here is the response I got from Hewitt. This seems to have fixed the issue. c Great customer service and a great product!

Thank you for contacting Hewitt Tech. We really appreciate the explanation also. It sounds like you may have one of the rare vehicles that has a temperature threshold that is slightly different than all the others we service. That can cause the start ability problem you have mentioned. Quick test to see if that is the case, you can disconnect the relay wire. Run the truck a few days this way and see if you still have any issues. If that remedies the problem then you can leave the relay wire disconnected. The module will still operate as needed. Anytime you start the truck the module will operate for 10-20 seconds keeping the SAIS from trying to run and our module will turn itself off. The relay wire was added so that if you were to turn the key just to the ON position after the truck has sat for 7 hours or longer, the module would have timed off by that point and would not prevent the system from operating, the relay wire was installed to restart the module any time the starter was engaged. Without the relay wire installed, you will just need to be sure to start the truck as normal but if you find you are in the key ON position for a bit, just simply key off and restart the drive cycle.
We also have our Gen II units that do not require a relay wire. We would offer an upgrade for the difference in cost of what you already spent and for the Gen II.

 

sounds like another reason to go with the Gen II

 

very satisfying answer

 

I had that issue on my '10 5.7 with the gen1 kit, disconnected the power wire and it fixed it, has worked perfect since.

 

I just purchased the Gen 2 Bypass. Will be installing it when I travel back home. Their customer service is great.

 

I just found this thread. I've been experiencing this for quite some time where if I drive the vehicle and let it sit for about 90 minutes, upon an attempted start, it may or may not start and acts like it's slightly flooded when it does. I've been focusing on trying to make note of the conditions in which this occurs to try to narrow down the temperature range as it seems to be happening more often in the 0-32F range for me (at least recently, I don't drive much). With this new information, I think that I'll follow the advice given by @Hewittech above and note what happens. My Hewitt device is scribed with: V5046/57H 0916. I suspect that 0916 is the manufacture date.

 

Why did you get this? I've never heard of it before I'm curious

 

This advice of disconnecting the relay wire has resolved my "flooded-like" starting mystery. It has not happened since I've done this.

 

I skipped it. Just gotta remember not to sit with your key in the ON position for very long.

 

1/8/2021: I have a 2008 4.7L and had installed the bypass kit a month or so ago. The stuck diverter valve code was fixed but then got the new problem of an occasional hard start. It runs really nice but once in a while, after the truck has been sitting and temps are around freezing, the truck doesn't want to start. I let it crank for a few seconds longer than normal (not many) and then turn the key off as it's clear that it doesn't want to start. Try again. After 3 or 4 tries, it fires but there is a strong smell of gasoline from the exhaust that fades away quickly. I had this happen 4-5 times since installing the bypass about 6 weeks ago. I can say with confidence that temps around 30 degrees was the common theme.

Like others, I am having a hard time trying to figure out if the problem is somehow related to the bypass kit.

Based on the comments above, I just disconnected the purple wire from the module.

Will give it a few weeks to see how it goes and provide an update.

Thanks all for the advice and information on the board.

Update 1/31/2021: It's been a couple week since I've unplugged the purple wire from the module. The weather has been at or below freezing frequently lately but I have not had any further problems with hard starts. Everything is working well.

 

I installed a Gen I kit around a month ago. I had some odd start up issues that lasted about a week. The first few cold starts, the idle was very low. Then after a couple of days, the cold start idle was a bit on the high side. Again after a few more days it all evened out and it now idles like it should. I never had any drivability issues even with the odd idle issues. Maybe the computer had to relearn everything since I disconnected the battery long enough.

 

You hit it on the head. Disconnecting the battery deletes the learned values and the ECU needs some time to relearn. I've read of a suggested procedure, but normal driving accomplishes the same result in the end.

 

2011 4.7 DC. Installed the bypass kit as well in early May of last year. So far, no issues with anything. I did email HT and asked which kit would be better suited, they suggested the Gen II kit. A little more cost, but overall a heck of a lot cheaper than having to pay out of pocket for the whole SAIS replacement. Customer service with HT was great, and I have recommended them to other Tundra owners if they ever get into the same situation !!

 

I thought that the 4.7L only went to 2009...It went to 2011 in the LC though.

 

I know I'm reviving an older thread, but I'm having the same problem as everyone here after installing the Gen 1 bypass kit on my 2010 Tundra, and after following Hewitt-Tech's recommendation to disconnect the relay wire, I am still having trouble starting my truck. This happens regardless of temperature. I am also experiencing the odd idling issue where the truck RPMs will fluctuate and it will shut off if I try to drive the first few times I successfully get it started. Any thoughts? Thanks!

 

I also had installed the Gen 1 bypass kit on my 08 5.7 l . The codes stopped but there was a problem with starting after 1 - 2 hours later. Contacted Hewitt Tech and they replied right away. They said certain older trucks were sensitive to the starter relay bypass, having to do with timing and temperature, and suggested removing the purple wire. I've been driving for 2 weeks without issue. Very glad I found this post, as well as emailing their great service dept.

 

Hi all. This is my first post, nice to meet everyone.

I have a 2013 4.7L with similar issues, but the interesting difference is it only occurs when it is HOT. If I leave it in my work's parking lot on a hot day, it will crank and crank and crank, but never catch.

On the hot days, when this would usually happen, I found that feathering the gas right as I turn the key always gets it to start. If I put Premium gas in the tank, it starts about 70% of the hot days (without feathering). If I put in Ethanol-free, it starts 95% of the hot days (without feathering). If I run a can of seafoam, it starts 99% of the hot days (without feathering).

I wonder if my issue is similar to the issues discussed in this thread? The problem sounds similar - cranking but not starting - but I haven't seen any mentions of starting difficulties also being influenced by fuel quality.

I sent a message to Hewitt asking their opinion. I plan on disconnecting the purple relay wire to see if that has any impact on the situation. I'll drop an update here if I learn anything more... But in the meanwhile, I'd love to hear if anyone has any thoughts about this situation.

 

I have an 08 5.7, disconnected the purple relay wire, and haven't had issues for a year. Also, having the wire jammed under the relay doesn't allow full relay contact, it sticks up a bit. The only issue with removing that wire, is you must start the truck immediately from the off position. Happy to have this forum to pass on knowledge