Does the Resistor Mod Actually Reduce EGTs?

[Jdub94]

As I'm sure many of you also know, the resistor mod seems to be a fairly popular and cheap modification for the 1KZ, especially in our wagons as folks complain about the power.

I have seen many people *claim* that it lowers EGTs. But does anyone have real world experience with this that has verified this truly does reduce EGTs? I have been hesitant to do this mod (my headgasket went right after I bought mine, so I replaced the head and turbo while I was at it and now I'm paranoid about it happening again), but if it truly does reduce EGTs it could be a worth while mod.

I understand it doesn't change the fuel pressure, just the timing for the common resistor mod. So, it's not increasing fuel and combustion, thus more heat that way - I am tracking there. But how would adjusting the timing cause for better out-flow of gasses when the change in timing is causing higher responsiveness?

 

[KiwiBogan]

As I'm sure many of you also know, the resistor mod seems to be a fairly popular and cheap modification for the 1KZ, especially in our wagons as folks complain about the power.

I have seen many people *claim* that it lowers EGTs. But does anyone have real world experience with this that has verified this truly does reduce EGTs? I have been hesitant to do this mod (my headgasket went right after I bought mine, so I replaced the head and turbo while I was at it and now I'm paranoid about it happening again), but if it truly does reduce EGTs it could be a worth while mod.

I understand it doesn't change the fuel pressure, just the timing for the common resistor mod. So, it's not increasing fuel and combustion, thus more heat that way - I am tracking there. But how would adjusting the timing cause for better out-flow of gasses when the change in timing is causing higher responsiveness?

These injector pumps are a low pressure pump and you can't actually create more pressure in the fuel delivery to get more power like you can with the common rail diesels. All you can do is adjust the amount of fuel being "spilled" (amount of time that the spill valve stays open per cycle) thus adding more fuel per combustion cycle.

What raises/lowers EGTs as far as I've experienced is the air:fuel ratio. I'm not 100% sure where the timing comes into it TBH. I've got my 1KZ-TE Prado Uni chipped and tuned and I observe when adding more fuel, the EGTs go up. If I wind the turbo up a few psi, they come back down again and I get more power. The Unichip Q4 also dynamically changes the timing according to throttle position to help with fuel consumption. The resistor mod sounds like it's a static setting so not sure what knock on effects that might have, say at idle for example. When I researched it a few years back, it all seemed a bit too "how-ya-goin" for me so went down the Unichip route instead. And bloody glad I did!

I've done heaps of mods to my 1KZ so happy to share my experiences (good and bad lol)

 

[Jdub94]

These injector pumps are a low pressure pump and you can't actually create more pressure in the fuel delivery to get more power like you can with the common rail diesels. All you can do is adjust the amount of fuel being "spilled" (amount of time that the spill valve stays open per cycle) thus adding more fuel per combustion cycle.

What raises/lowers EGTs as far as I've experienced is the air:fuel ratio. I'm not 100% sure where the timing comes into it TBH. I've got my 1KZ-TE Prado Uni chipped and tuned and I observe when adding more fuel, the EGTs go up. If I wind the turbo up a few psi, they come back down again and I get more power. The Unichip Q4 also dynamically changes the timing according to throttle position to help with fuel consumption. The resistor mod sounds like it's a static setting so not sure what knock on effects that might have, say at idle for example. When I researched it a few years back, it all seemed a bit too "how-ya-goin" for me so went down the Unichip route instead. And bloody glad I did!

I've done heaps of mods to my 1KZ so happy to share my experiences (good and bad lol)

Interesting! So doing a chip and tune on yours, you saw a benefit to cooling? I'm in Texas and basically any time I see a diesel chipped, it's an oil field roughneck pushing their 3/4 ton trucks to the limit. I always figured they were dangerous modifications. Interesting to hear the cooling benefits!

So far all I've done is new head and turbo as mentioned in the OP, but then new water pump and therm, snorkel, 10 blade fan done just last night. planning on straight piping exhaust since I can't afford a new one right now

 

[Finn1997]

I would also recommend turning the Turbo boost up to 14 psi with boost T. I don't know what the HP increase would be but I am thinking something like 180 HP is easily reachable with boost increase.

 

[Jdub94]

I would also recommend turning the Turbo boost up to 14 psi with boost T. I don't know what the HP increase would be but I am thinking something like 180 HP is easily reachable with boost increase.

I'm not too considered with the HP increases - I drive fairly conservatively and it reached 75mph at a decent pace. I have always been weary of the boost increases -- but if it lowers EGTs with a tune it might definitely be worth looking into

 

[KiwiBogan]

Interesting! So doing a chip and tune on yours, you saw a benefit to cooling? I'm in Texas and basically any time I see a diesel chipped, it's an oil field roughneck pushing their 3/4 ton trucks to the limit. I always figured they were dangerous modifications. Interesting to hear the cooling benefits!

So far all I've done is new head and turbo as mentioned in the OP, but then new water pump and therm, snorkel, 10 blade fan done just last night. planning on straight piping exhaust since I can't afford a new one right now

Thought I sent this the other day. Opps!

Ahh ok, sorry mate I thought you were wanting to modify for performance. Chips can absolutely be safe if you have your supporting mods in place and they're tuned on a dyno. I'd be wary of the plug n play type chips that have a generic tune that doesn't take into account your engines condition/transmission type etc.

In terms of cooling, are you experiencing overheating? Or just wanting to take some preemptive measures? The cooling system chats I feel like we've done to death in recent times both in here and over at the KZ-TE_Owners sub on Reddit if you're keen to go back and have a look through them.

But right now as the ambient temperature is quite cool here in South Australia, I'm running my Unichip on full power and turbo boost at around 22-24psi. Absolutely no signs of overheating whatsoever. Not even close. I have forgotten what the stock figures were like but my engine was not in great shape when I first bought the car so it wasn't really a great reference point to work with. I reckon I've read of others with stock engines mentioning running temperatures slightly in the high side stock and I was always under the impression the 1KZ did run slightly warmer than you would like. (I've got my own theories on this)

So yeah, I'm not really answering your original question as I don't actually know 100% what advancing the timing alone will do. But I'd consider the resistor mod more risky than a chip and tune on a Dyno.

 

[Jdub94]

Thought I sent this the other day. Opps!

Ahh ok, sorry mate I thought you were wanting to modify for performance. Chips can absolutely be safe if you have your supporting mods in place and they're tuned on a dyno. I'd be wary of the plug n play type chips that have a generic tune that doesn't take into account your engines condition/transmission type etc.

In terms of cooling, are you experiencing overheating? Or just wanting to take some preemptive measures? The cooling system chats I feel like we've done to death in recent times both in here and over at the KZ-TE_Owners sub on Reddit if you're keen to go back and have a look through them.

But right now as the ambient temperature is quite cool here in South Australia, I'm running my Unichip on full power and turbo boost at around 22-24psi. Absolutely no signs of overheating whatsoever. Not even close. I have forgotten what the stock figures were like but my engine was not in great shape when I first bought the car so it wasn't really a great reference point to work with. I reckon I've read of others with stock engines mentioning running temperatures slightly in the high side stock and I was always under the impression the 1KZ did run slightly warmer than you would like. (I've got my own theories on this)

So yeah, I'm not really answering your original question as I don't actually know 100% what advancing the timing alone will do. But I'd consider the resistor mod more risky than a chip and tune on a Dyno.

Thanks for the reply!

I am not experiencing overheating that I know of -- but I bought the Prado back in August, and I either bought it with a bad head gasket or it was already on its way, because once it got cold the symptoms were more visible. I replaced the head and the turbo back in December/early January.

That was the first time I've ever done any kind of work on a car before in any significant manner, and it was definitely pushing the limits of my capacity. I was just completely exhausted from stress by the end of it. All that being said -- I have been trying to do everything I reasonably can to help with cooling that I can afford; today even - I just straight piped my exhaust because I can't afford a full new setup, so just doing what I can. I kept seeing people mention "lower EGTs" when talking about the resistor mod, but I have yet to get a legitimate answer to how or even to verify that they actually experience lower EGTs.

So, I was primarily asking because if it really did reduce EGTs then I was going to consider it. I want this truck to last me at least 5 years and hopefully another 200-300Ks. And I bought it with the purpose of doing some moderate off roading and overlanding. So -- just mainly paranoid lol but tomorrow will be a good test. Going to a nearby offroad area that has a very steep descent into the canyon that will require 4L and L gear, and then some pretty decent trails that will likely be close to the limit for an IFS on 33" tires. If it does well tomorrow, then that will give me a lot of peace of mind.

 

[KiwiBogan]

Thanks for the reply!

I am not experiencing overheating that I know of -- but I bought the Prado back in August, and I either bought it with a bad head gasket or it was already on its way, because once it got cold the symptoms were more visible. I replaced the head and the turbo back in December/early January.

That was the first time I've ever done any kind of work on a car before in any significant manner, and it was definitely pushing the limits of my capacity. I was just completely exhausted from stress by the end of it. All that being said -- I have been trying to do everything I reasonably can to help with cooling that I can afford; today even - I just straight piped my exhaust because I can't afford a full new setup, so just doing what I can. I kept seeing people mention "lower EGTs" when talking about the resistor mod, but I have yet to get a legitimate answer to how or even to verify that they actually experience lower EGTs.

So, I was primarily asking because if it really did reduce EGTs then I was going to consider it. I want this truck to last me at least 5 years and hopefully another 200-300Ks. And I bought it with the purpose of doing some moderate off roading and overlanding. So -- just mainly paranoid lol but tomorrow will be a good test. Going to a nearby offroad area that has a very steep descent into the canyon that will require 4L and L gear, and then some pretty decent trails that will likely be close to the limit for an IFS on 33" tires. If it does well tomorrow, then that will give me a lot of peace of mind.

Ahh ok, that's a better picture.

Best thing to do is install a Boost and EGT gauge (2 in 1). That way you have another method of monitoring what the engine is doing. You'll eventually end up driving to this gauge, especially on hills and towing in warmer weather. As long as your cooling system is in good condition, you should have nothing to worry about. Theirs a few things at play that affect the combustion temps but it can really be broken down into a simple statement. More fuel = More Heat.

So yeah, grab yourself one of those 2 in 1 gauges and start observing engine temps. Then you can install a cheap boost t and start winding up the turbo a bit and observe how it effects EGTS. From memory, I found 16psi to be a sweet spot for my engine before I upgraded intercooler. Another mod which I really appreciate on my bus in the summer is an aftermarket water temp gauge. I have mine plumbed into the top radiator hose measuring the coolant as it pumps straight from the head to the radiator. It's bloody reassuring being able to see it rise and fall during hill climbs, towing and such.

 

[Jdub94]

Ahh ok, that's a better picture.

Best thing to do is install a Boost and EGT gauge (2 in 1). That way you have another method of monitoring what the engine is doing. You'll eventually end up driving to this gauge, especially on hills and towing in warmer weather. As long as your cooling system is in good condition, you should have nothing to worry about. Theirs a few things at play that affect the combustion temps but it can really be broken down into a simple statement. More fuel = More Heat.

So yeah, grab yourself one of those 2 in 1 gauges and start observing engine temps. Then you can install a cheap boost t and start winding up the turbo a bit and observe how it effects EGTS. From memory, I found 16psi to be a sweet spot for my engine before I upgraded intercooler. Another mod which I really appreciate on my bus in the summer is an aftermarket water temp gauge. I have mine plumbed into the top radiator hose measuring the coolant as it pumps straight from the head to the radiator. It's bloody reassuring being able to see it rise and fall during hill climbs, towing and such.

The day on the trails was a huge success. It was a relatively cool day, but I won't ever be down there when it's probably over 90F.

Did great on the trails, and then the slope climb out was a little more of a task than normal as it was raining on us and so it was slick. Went 4L and L gear, O/D off - kept it around 3200rpm easy and it climbed right out, no temp issues!

 

[KiwiBogan]

The day on the trails was a huge success. It was a relatively cool day, but I won't ever be down there when it's probably over 90F.

Did great on the trails, and then the slope climb out was a little more of a task than normal as it was raining on us and so it was slick. Went 4L and L gear, O/D off - kept it around 3200rpm easy and it climbed right out, no temp issues!

Great news! Happy wheeling!

 

[Sparkxy]

As I'm sure many of you also know, the resistor mod seems to be a fairly popular and cheap modification for the 1KZ, especially in our wagons as folks complain about the power.

I have seen many people *claim* that it lowers EGTs. But does anyone have real world experience with this that has verified this truly does reduce EGTs? I have been hesitant to do this mod (my headgasket went right after I bought mine, so I replaced the head and turbo while I was at it and now I'm paranoid about it happening again), but if it truly does reduce EGTs it could be a worth while mod.

I understand it doesn't change the fuel pressure, just the timing for the common resistor mod. So, it's not increasing fuel and combustion, thus more heat that way - I am tracking there. But how would adjusting the timing cause for better out-flow of gasses when the change in timing is causing higher responsiveness?

He said tracking. I know that verbiage anywhere

 

[Jdub94]

He said tracking. I know that verbiage anywhere

I'm confused lol

 

[Sparkxy]

I'm confused lol

Are you military?

 

[Jdub94]

Are you military?

No sir haha

 

[Rootless]

Ahh ok, that's a better picture.

Best thing to do is install a Boost and EGT gauge (2 in 1). That way you have another method of monitoring what the engine is doing. You'll eventually end up driving to this gauge, especially on hills and towing in warmer weather. As long as your cooling system is in good condition, you should have nothing to worry about. Theirs a few things at play that affect the combustion temps but it can really be broken down into a simple statement. More fuel = More Heat.

So yeah, grab yourself one of those 2 in 1 gauges and start observing engine temps. Then you can install a cheap boost t and start winding up the turbo a bit and observe how it effects EGTS. From memory, I found 16psi to be a sweet spot for my engine before I upgraded intercooler. Another mod which I really appreciate on my bus in the summer is an aftermarket water temp gauge. I have mine plumbed into the top radiator hose measuring the coolant as it pumps straight from the head to the radiator. It's bloody reassuring being able to see it rise and fall during hill climbs, towing and such.

Any links to Boost/EGT gauge? I need to get one.

I looked on eBay for the Boost Tee and they run from ~$25 to $100. Anything to look for when selecting?

Also any alternatives to Unichip? Unichip tuners - https://www.tundras.com/threads/unichip-tuners.47932/

Thank you.

 

[KiwiBogan]

Any links to Boost/EGT gauge? I need to get one.

I looked on eBay for the Boost Tee and they run from ~$25 to $100. Anything to look for when selecting?

Also any alternatives to Unichip? Unichip tuners - https://www.tundras.com/threads/unichip-tuners.47932/

Thank you.

This is th one I had: SAAS Genuine 2in1 Diesel Turbo Boost and Exhaust Temp 52mm Gauge EGT Pyro | eBay - https://www.ebay.com.au/itm/143213824643?mkcid=16&mkevt=1&mkrid=705-154756-20017-0&ssspo=_Gw_iGKzRSi&sssrc=4429486&ssuid=xQTZgYlSTs6&var=&widget_ver=artemis&media=COPY

Pretty sure they're an international brand.

Unichip alternative? Not really. DP Chip is the only other safe chip I know of but it's a plug and play style chip so it has a generic tune built in. Not sure id trust that?0/ It would come with some extra work of course. Once you increase fuel, you need to increase air aka turbo boost, improving intake airflow etc to keep EGTs down. It opens a can of worms. I'm drunk now from a big night out with friends but happy to share some of my experiences over the weekend if you want to know more.

 

[Rootless]

I couldn't find any SAAS available on eBay outside of AU. I did find this one: W PRO 52mm 2 In 1 Boost PSI & EGT Pyrometer °F Exhaust Gas Temperature Gauge | eBay - https://www.ebay.com/itm/234210505614 that looks like it will work for less than shipping from AU.

I grabbed this Boost Tee too: TurbosportX Boost Tee Manual Boost Control Kit MBC Black - FAST USA Shipping! | eBay - https://www.ebay.com/itm/185439451863

As for chipping, the Tundra forum made it seem that Unichip was not really a safe option. I'm also struggling to find a vendor for a decent price.

I think finding the 3 Bar MAP sensor would be the next thing, before the chip. I'm having a hard time finding/identifying the correct 3 Bar version. I've found these, but I'm not sure if they are 3 Bar or not.

Pardon Our Interruption...

Pardon Our Interruption...

Pardon Our Interruption...

All of my experience with chipping is on Ford 7.3L Powerstroke diesels. This my first time doing any mods to a 1KZ.

Thank you so much for responding.

 

[Finn1997]

I couldn't find any SAAS available on eBay outside of AU. I did find this one: W PRO 52mm 2 In 1 Boost PSI & EGT Pyrometer °F Exhaust Gas Temperature Gauge | eBay - https://www.ebay.com/itm/234210505614 that looks like it will work for less than shipping from AU.

I grabbed this Boost Tee too: TurbosportX Boost Tee Manual Boost Control Kit MBC Black - FAST USA Shipping! | eBay - https://www.ebay.com/itm/185439451863

As for chipping, the Tundra forum made it seem that Unichip was not really a safe option. I'm also struggling to find a vendor for a decent price.

I think finding the 3 Bar MAP sensor would be the next thing, before the chip. I'm having a hard time finding/identifying the correct 3 Bar version. I've found these, but I'm not sure if they are 3 Bar or not.

Pardon Our Interruption...

Pardon Our Interruption...

Pardon Our Interruption...

All of my experience with chipping is on Ford 7.3L Powerstroke diesels. This my first time doing any mods to a 1KZ.

Thank you so much for responding.

Hey Rootless,

Are you located in China?
How is it?

 

[Rootless]

Hey Rootless,

Are you located in China?
How is it?

I need to update that. I'm not in China anymore. I'm in Arizona, USA now. China was fine. Big differences depending on where in China you are.

 

[KiwiBogan]

Here's the map sensor I bought