whats going on with my egts?

[Doorslammer]

hey guys

im having a bit of trouble tuning the 1hd-ft in my 80 via the egts. a few details on the truck before i get into it, 3 inch exhaust, badboy gturbo running 20lbs, modified the fuel pin and have it set high, plazmaman WTA intercooler, 230k km's. injectors were serviced 15k ago and the fuel filter has 2500km's on it.

now, when im driving i get out of town, get out onto the highway and put my boot into it, egts have no problem getting to 700*c and will continue to climb if i dont let off, and thats how it stays.
i turn off down a backroad straight that i usually use to tune and can wind it out as its a long straight, i go for it and while holding it flat it wont get past 600*, all the way up to 140km/h (it struggled to get there) strange i think and turn around for another run. this time the egts rise to 700* then drop back quickly to around 620* and stay there, i can hold it flat like this for minutes with no change.
ive also had it sit on 600* then it will take off like a rocket at around 120km/h and the temps will climb quickly.

at first i thought maybe the intercooler wasnt efficent and i was seeing heat soak issues through it, allthough getting to the highway i would have thought it would have been coolest there when i first put my boot into it.
i am considering a large air to air cooler as i dont like the wta much.

i am thinking either the advance in the pump maybe sticking?
at first i thought it was the aneroid pin, i have modified it so the taper is followed all the way on the most gradual sloped side and wherever it is set it doesnt seem to change.

what does everyone think? should i look at getting my pump reconditioned, intercooler may not be working properly? any other ideas or tricks i could try?

cheers

 

[Tim-HJ61]

Have you asked Graeme for his thoughts?

Sounds too high for my liking.

In my 12h-t, different engine I know, I cruise at 100kmh at less than 300°C pre turbo. Really hard to get it to climb into the numbers you are talking about - for example long climbs at 110kmh with foot flat to the floor for several kms. These spots are hard to find around where I live, that that's the only way I can get my EGTs to climb to the heady numbers that came so easily prior to the gturbo and intercooler. My fuel screw is at maximum supply. Timing 1° advanced from standard.


What happens when you decrease boost to say, 15psi?
Or increase it to 25psi for testing?

What happens when you increase or decrease your fuel screw by half a turn to give less, then more fuel. Not familiar with your pump, so not sure which way is which.

Can you put a temperature sensor onto the inlet manifold, or even better, measure before and after the intercooler so you can see what is happening and see what the outside of the IC is showing. Better to put sensor in air flow, but that's likely much harder to achieve. Perhaps you can borrow a datalogger with some stick on sensors just for testing.

Just some thoughts on getting a handle on where your problem is, or if there is a problem.

You could post your query to the https://forum.ih8mud.com/diesel-tec...5371-gbentink-turbo-upgrade-users-thread.html and ask there as someone else is bound to have a similar setup.

Tim

 

[Tapage]

Fisrt of all can you trust / certify your pyro gauge reading .?

 

[Doorslammer]

went for another drive today.
at 100km/h boost is at 15psi and am running around 380*c. maybe my intercooler could be more effiecent... but thats another subject, im allready pricing up a large front mount.

i believe the pyro is correct. just on my drive today i had my boot into it, the pyro went to 620 and was staying solid. all of a sudden the egts climbed past 700 quickly. the motor changed pitch like it had more fuel/power and it started accelerating quicker.

its like even tho the pedal position doesnt change all the fuel pump is delivering more fuel, or less in the original post, and doing it at will.

ive also notice that when warm the idle went from 800 cold to 1000rpm when i pulled up back home.
i wondered if the acsd could have an effect on fuel delivery? allthough there is no white smoke at all and the idle is erratic or intermittent/rough.

cheers

 

[cruiser_guy]

Is it possible the wastegate on the turbo is sticky or malfunctioning?
EGT's are a function of fuel delivery and air delivery, they work together.
Usually high EGT's are caused by low air pressure/flow. The only time I've seen my EGT's spike has need when the air crossover popped off or burst on the intake manifold while under load. That also coincided with a sudden power loss (no surprise there).
If you have an OBD II port (i don't know if your truck might have that) see if it is throwing any codes or if there are pending codes.

 

[Doorslammer]

boost guage is tapped into the inlet after intercooler and just before the heater screen, and is at a constant 20psi, drops 2psi at close to redline. doesnt change with changes to the egts.

theres not a huge power loss, just slightly more when the egts rise.
im going to try take a video of it tomorrow.

no OBDII port either.

 

[Adam B]

Just to throw in what I can, based on my recent experiences...

Since you've got a WTA IC is it possible that you have a big air bubble somewhere that's causing the flow to start and stop? I went through that and thought the pump was dying. My intake air temps would be really high then all of a sudden they would drop right off and the intercooler water temp would start to rise. A minute later it would go the other way. Of course my EGTs would fluctuate based on whether the IC water was circulating properly or not. It was quite interesting.

So that's one idea, your IC may be failing to maintain constant IATs. You could test it to some degree by disconnecting the pump/fan to your IC. Your EGTs will be higher but for the sake of testing you might find that they're more constant without the sudden rise/fall. That would point you in a direction and you wouldn't have to worry about the injection pump (although you still might be on the right track with the ACSD, based on the unusual idle speed change you mentioned).

Similarly, you could have a boost leak but I'd think it would have to be intermittent to result in your symptoms.

On the topic of boost leaks, when I swapped intercoolers I had 4 x M8 mounting holes that I didn't realize were actually drilled through right into the end tanks so I effectively had a 5/8" hole in my intake. That's a pretty big boost leak and you could sure as hell hear it in the cab. The point is, my turbo had no trouble maintaining 20psi even with a huge leak but my EGT gauge could move almost as quickly as my boost gauge.

 

[cruiser_guy]

boost guage is tapped into the inlet after intercooler and just before the heater screen, and is at a constant 20psi, drops 2psi at close to redline. doesnt change with changes to the egts.

Boost should not drop as RPM's rise unless you let off on the throttle or the load decreases.

I've seen my wastegate stick due to rust on the pivot arm. Disconnect the actuator and see if the wastegate moves freely. It might not be possible to disconnect the actuator depending on the turbo design.

 

[Adam B]

Of course boost will drop as you get close to redline if you're running high boost. Try it with a stock CT26 around 15psi on a 1HD-T and you'll see that by 3000rpm it's already down to 12psi. You can't get to redline before it's below the stock setting of 10psi. With the stock CT26 the compressor just can't move enough lbs/min. Considering the turbo he has, that's not the issue. I'll bet his parts upstream of the turbo can't supply enough air.

 

[mudgudgeon]

Of course boost will drop as you get close to redline if you're running high boost. Try it with a stock CT26 around 15psi on a 1HD-T and you'll see that by 3000rpm it's already down to 12psi. You can't get to redline before it's below the stock setting of 10psi. With the stock CT26 the compressor just can't move enough lbs/min. Considering the turbo he has, that's not the issue. I'll bet his parts upstream of the turbo can't supply enough air.

Agreed re boost dropping off a bit at redline

Also, the comment on air flow restriction before the turbo could have merit. There has been examples rubber or silicone hoses collapsing/ being sucked flat by the turbo, if the air filter or air box is restricting air flow.

It would explain the sudden changes in EGTs and the sudden change in power.

Try pulling the lid off their box and filter out for a couple of runs the sake of eliminating it as a cause.


I used to do all my testing on a long hill near me with a consistent incline for a few km. I would be in 3rd gear at the bottom, wind it out through 3rd, then wind it out through 4th pulling about 110km/hr by the top of the hill.
You need a load on the engine for a more reliable indication of state of tune.

 

[Doorslammer]

Just to throw in what I can, based on my recent experiences...

Since you've got a WTA IC is it possible that you have a big air bubble somewhere that's causing the flow to start and stop? I went through that and thought the pump was dying. My intake air temps would be really high then all of a sudden they would drop right off and the intercooler water temp would start to rise. A minute later it would go the other way. Of course my EGTs would fluctuate based on whether the IC water was circulating properly or not. It was quite interesting.

So that's one idea, your IC may be failing to maintain constant IATs. You could test it to some degree by disconnecting the pump/fan to your IC. Your EGTs will be higher but for the sake of testing you might find that they're more constant without the sudden rise/fall. That would point you in a direction and you wouldn't have to worry about the injection pump (although you still might be on the right track with the ACSD, based on the unusual idle speed change you mentioned).

Similarly, you could have a boost leak but I'd think it would have to be intermittent to result in your symptoms.

On the topic of boost leaks, when I swapped intercoolers I had 4 x M8 mounting holes that I didn't realize were actually drilled through right into the end tanks so I effectively had a 5/8" hole in my intake. That's a pretty big boost leak and you could sure as **** hear it in the cab. The point is, my turbo had no trouble maintaining 20psi even with a huge leak but my EGT gauge could move almost as quickly as my boost gauge.

i like the bubble idea. ive had a little trouble with my intercooler cap, i will see if thats still causing a problem with air. are you running a overflow? does it have to be higher then the highest part of the cooler? i was thinking of teeing it into the engine overflow.

as for the boost leak, like you were saying i would have thought i could hear it being it has such a large effect as is intermittent. i will go through all the clamps anyway and see if i can nip the manifold up as it is weeping a little oil (still running a standard breather set-up)

out of curiosity what are you using to measure air/water temps for your intercooler?

Agreed re boost dropping off a bit at redline

Also, the comment on air flow restriction before the turbo could have merit. There has been examples rubber or silicone hoses collapsing/ being sucked flat by the turbo, if the air filter or air box is restricting air flow.

It would explain the sudden changes in EGTs and the sudden change in power.

Try pulling the lid off their box and filter out for a couple of runs the sake of eliminating it as a cause.


I used to do all my testing on a long hill near me with a consistent incline for a few km. I would be in 3rd gear at the bottom, wind it out through 3rd, then wind it out through 4th pulling about 110km/hr by the top of the hill.
You need a load on the engine for a more reliable indication of state of tune.

i will check the air filter (was also changed 2500k ago), snorkel etc for a restriction, i have seen the rubber silicon elbows get sucked flat, all a/m turbo kits but never a oem toyota hose piece.

unfortunatly there arent any hills around, i normally tune to egts and how the power is, then take it to the dyno and have it loaded up. allthough the most i ever tow is a 200kg ski on a small trailer.


im likeing all these ideas, but im still having trouble with the idea thhat when the egts rise i get more power, i can feel it, its as if im getting more fuel. if it was an air leak or restriction it would feel slower and have higher egts.

 

[Adam B]

but im still having trouble with the idea thhat when the egts rise i get more power

I think you are on to something. Maybe you're suddenly getting more fuel, so you get more power and higher EGTs. Someone who understands all the inner workings of the pump might have some insight as to how this could happen.

The alternative was that you were suddenly getting less oxygen so you still had the same amount of fuel, probably less power (might be very hard to detect), and higher EGTs. Less oxygen could come in the form of less boost or higher intake air temperature. You already know that your boost holds through most normal situations (close to redline doesn't count).

As mudgudgeon said, you really need to do testing with the engine under heavy load. Hills are good, weight is good, flat roads are tricky.

For my setup I am using a couple of K-type thermocouples under the silicone hoses pre and post intercooler. They're basically just a wire so they can be shoved under the hose with the end bent 90 degrees and right in the air stream. I bought some 1/8NPT ones to swap out next time I have the intake bits all removed, only because it's a little bit nicer and cleaner and I won't have to waste the time trying to get the thermocouple wires positioned just right. I'm using a digital unit from Omega ... HH12B on this page. The new thermocouples I'm going to install are these. You still need to get the yellow 2 prong ends to attach to them but the Omega website is pretty easy to use.

I haven't used an overflow in my intercooler system. Originally I bought the Denco kit and installed the supplied parts, which didn't include one. It does have a self-contained (not actually part of the radiator) rad cap that you're supposed to install at the highest point, and that cap has an overflow nozzle. I've since gone to larger everything (heat exchanger, cooler, fan, pump) and am still using that same rad cap up high on the firewall. Theoretically, small bubbles might collect there.

I can't share an overflow because my engine coolant is Toyota red, probably about 50/50, and my intercooler is mostly water with wetter and about 30% glycol because I experience a lot of nights below freezing when I'm camping at high elevation in April/May and Sept/Oct.

I might rig up a temporary overflow bottle just to see if it actually does get enough pressure to pop the rad cap. The highest IC water temp I've seen was 150F with the old system, and 125F with the current system. This is on long sustained hills in summer.

 

[Dougal]

Have you asked Graeme for his thoughts?

Sounds too high for my liking.

In my 12h-t, different engine I know, I cruise at 100kmh at less than 300°C pre turbo.

That sounds too cold to be trustworthy. Is your probe reaching the centre of the exhaust stream?
I run 380-400C at 100km/h with 9psi @2000rpm on a vehicle more aerodynamic than yours.

Doorslammer. I'd also be thinking heat-soak or fuel/water leaking into the intake.

 

[Adam B]

I might rig up a temporary overflow bottle just to see if it actually does get enough pressure to pop the rad cap. The highest IC water temp I've seen was 150F with the old system, and 125F with the current system. This is on long sustained hills in summer.

Having just racked my brain to figure out things that would have been easy 20 years ago, I think I've determined that the intercooler water would have to be heated to 186F in order to increase the pressure enough to pop a 9psi rad cap. I have to check what mine is but that's the lowest common one I've seen, many are 13 or 15psi. To pop the 15psi cap you'd need the water around 212F. I think with a functional radiator in your intercooler system there should be no need for an overflow and I think I'm going to plug mine now.

That applies to pure water, but I think the result is extreme enough that my 70% water mix is covered...

 

[mudgudgeon]

went for another drive today.
at 100km/h boost is at 15psi and am running around 380*c. maybe my intercooler could be more effiecent... but thats another subject, im allready pricing up a large front mount.

i believe the pyro is correct. just on my drive today i had my boot into it, the pyro went to 620 and was staying solid. all of a sudden the egts climbed past 700 quickly. the motor changed pitch like it had more fuel/power and it started accelerating quicker.

its like even tho the pedal position doesnt change all the fuel pump is delivering more fuel, or less in the original post, and doing it at will.

ive also notice that when warm the idle went from 800 cold to 1000rpm when i pulled up back home.
i wondered if the acsd could have an effect on fuel delivery? allthough there is no white smoke at all and the idle is erratic or intermittent/rough.

cheers

What are boost pressures doing when this happens?

The lack of load while testing bothers me, you just won't get a true indication.
My testing example above, at 110km/hr under load, WOT, I would see temps over 900c, and boost peaking at 22psi (this was way to much for my setup)
On flat highway at 110km/hr boost could be as low as 10-12psi and EGTs around 300c.

What has been changed or adjusted on your pump? You say you modified the taper on the aneroid pin, I'm assuming you reground it? Is it polished smooth?
I am wondering if the pin that follows the taper may be getting caught?

Did you change the pre-load on the aneroid diaphragm spring? Once boost pressure overcomes the spring pre-load, the android pin moves to increase the fuel available. I'm wondering if something is binding there and releasing suddenly?

Also wondering about fuel filters, fuel pick up in tanks. Are they all clear and clean?

If the ACSD is functional, idle should be lower once It's warm not higher.

 

[Tim-HJ61]

That sounds too cold to be trustworthy. Is your probe reaching the centre of the exhaust stream?
I run 380-400C at 100km/h with 9psi @2000rpm on a vehicle more aerodynamic than yours.
.

Yes Dougal, the probe tip is in the centre of the mouth of the turbine housing.

EGT probe locaction - full size image


I've no reason to believe it is inaccurate. It's a VDO brand. Each time i have made an improvement/ adjustment the EGT have responded predictably.

Tim

Sent from my iPad using IH8MUD

 

[Doorslammer]

What are boost pressures doing when this happens?

The lack of load while testing bothers me, you just won't get a true indication.
My testing example above, at 110km/hr under load, WOT, I would see temps over 900c, and boost peaking at 22psi (this was way to much for my setup)
On flat highway at 110km/hr boost could be as low as 10-12psi and EGTs around 300c.

What has been changed or adjusted on your pump? You say you modified the taper on the aneroid pin, I'm assuming you reground it? Is it polished smooth?
I am wondering if the pin that follows the taper may be getting caught?

Did you change the pre-load on the aneroid diaphragm spring? Once boost pressure overcomes the spring pre-load, the android pin moves to increase the fuel available. I'm wondering if something is binding there and releasing suddenly?

Also wondering about fuel filters, fuel pick up in tanks. Are they all clear and clean?

If the ACSD is functional, idle should be lower once It's warm not higher.

boost pressure stays the same.

as for the load, i have no way of testing it untill i get it on the dyno, i want to get it close then check it. if the egts were changing from load then i would be happy to put it on the dyno and fine tune it. but it feels as if its something else, once this is sorted i can load it up and finish it properly.

i modified the pin a while ago, and was running it that way before, i continued the taper past the cutoff flat and polished it smooth with a crankshaft polishing belt. i have raised the pin a little higher, i might lower it and see if the problem is still there.

will have to check fuel filters when i get back from perth. also when it is warm the idle is deffinently higher, also the a/c doesnt raise the idle when kicking in allthough i just think the linkages are loose.

 

[Adam B]

The AC idle-up is pretty "touchy". It's only moving the throttle a small amount so any time you mess with your main fuel screw or idle stop you usually have to adjust it.