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TD05 late spool

JspecVR4

Member
Joined
Jun 19, 2022
Messages
15
Location
Australia
I recently installed a TD05 16g on my 1990 jdm vr4 and I am now experiencing abnormally bad turbo lag. On this current setup I will not see any positive pressure below 3k rpm. In 2nd gear at WOT past 3k rpm i will see about 0.1 to 0.2 bar between 3k rpm and 4k rpm. going up the rev range I will see about 0.5 to 0.6 bar at 5k rpm and I will see 0.9 bar of boost at around 6k rpm. This was done without a manual boost controller although the same problem happened with a MBC on the lowest setting. The car was previously running a TD04 with no issues whatsoever. on that setup I would see boost as early as 2000 - 2500 rpm given enough load and would see wastegate pressure, around 0.6 bar as early as 3500 rpm even when im not WOT. I could not find any boost leaks on the cold side and don't see how boost leaks could appear as the only piping I removed was the the piping from turbo to the metal intercooler piping and pre turbo.

I'm running stock exhaust, stock inter cooler and piping, stock injectors, walbro 255 fuel pump, stock O2 housing(although the housing was machined a little to account for the bigger sized hole of the turbine of the TD05).

I have seen some other people run into similar issues with other dsms and even other cars but could not find any solutions.

The turbo spins freely and seems to flow a good amount of air at idle and no load, and the waste gate seems to be closed shut. Im unsure what could be causing this issue. I know that TD05 would spool later compared to a TD04 but im not seeing any boost at all below 3k rpm and the boost slowly increases as I go up the rev range.

Any advice or suggestions would be greatly appreciated, Thanks.
 

turbofonz

Well-known member
Joined
Sep 27, 2006
Messages
467
Location
Granby, MA
I would verify that there is no pre turbo exhaust leaks and do a boost leak test . And even though you say the wastegate seems shut, it may not be. Take the 2 wastegate actuator bolts off and make sure it is kind of tight. Add a few washers underneath the flange to keep tension or add on the spring. I always shim internal gates to make sure it seals as well as it can. A gate that is stuck not fully closed is just going to make more lag.

A 16g should be able to make 20lbs by 3500rpm, more or less depending on airflow mods and engine mods.

So, a leak somewhere. Whether its an external exhaust leak (exhaust gasses being wasted and not making it to the turbine), boost leak (pressure to the wastegate is getting lost) or wastegate actuator, which would be literally an open wastegate.

I guess it's also possible if you left something in the intake that caused a massive intake restriction.
 

JspecVR4

Member
Joined
Jun 19, 2022
Messages
15
Location
Australia
I would verify that there is no pre turbo exhaust leaks and do a boost leak test . And even though you say the wastegate seems shut, it may not be. Take the 2 wastegate actuator bolts off and make sure it is kind of tight. Add a few washers underneath the flange to keep tension or add on the spring. I always shim internal gates to make sure it seals as well as it can. A gate that is stuck not fully closed is just going to make more lag.

A 16g should be able to make 20lbs by 3500rpm, more or less depending on airflow mods and engine mods.

So, a leak somewhere. Whether its an external exhaust leak (exhaust gasses being wasted and not making it to the turbine), boost leak (pressure to the wastegate is getting lost) or wastegate actuator, which would be literally an open wastegate.

I guess it's also possible if you left something in the intake that caused a massive intake restriction.
Thanks for the suggestions.

I did try starting the car cold and putting my hand around the exhaust manifold and could not feel any obvious leaks. I've also got a brand new aluminium radiator so I'd think I would see some carbon build up on the radiator as this happened with my old radiator.

From what I remember the wastegate actuator rod was pretty tight to put on and we had to put pressure onto the waste gate actuator first so that we could put the rod on. I could try adjusting the rod a few turns or putting washers like you said.

Im going to try and run the car without a line to the actuator and see if the waste gate is opening too early. If that doesn't make a difference ill try doing a pressure to the waste gate. Do you have any suggestions on how I could do that?

Also im still on stock 2 inch or whatever diameter stock exhaust is. I'm thinking of going 3 inch cat back and see if that will make a difference.
 

mooserage

Staff member
Joined
May 17, 2004
Messages
1,281
Location
Seattle, WA
Thanks for the suggestions.

I did try starting the car cold and putting my hand around the exhaust manifold and could not feel any obvious leaks. I've also got a brand new aluminium radiator so I'd think I would see some carbon build up on the radiator as this happened with my old radiator.

From what I remember the wastegate actuator rod was pretty tight to put on and we had to put pressure onto the waste gate actuator first so that we could put the rod on. I could try adjusting the rod a few turns or putting washers like you said.

Im going to try and run the car without a line to the actuator and see if the waste gate is opening too early. If that doesn't make a difference ill try doing a pressure to the waste gate. Do you have any suggestions on how I could do that?

Also im still on stock 2 inch or whatever diameter stock exhaust is. I'm thinking of going 3 inch cat back and see if that will make a difference.
Like turbofonz said, also do a boost leak test on everything after the turbo, soapy water and a spray bottle will help highlight leaks you might not even hear.

I recently tested my wastegate actuator using a bike pump, the clamp held tight enough around the hose nipple to hold pressure for the test and with a bike pump it was easy to gently add pressure and not overdo it. You can also just do a boost leak test and since the actuator is hooked up it should open at its normal pressure.

For the wastegate actuator, sounds like you have a modified or aftermarket actuator, since you mentioned an adjustable actuator rod. What type is it, or do you have a picture?
 

turbofonz

Well-known member
Joined
Sep 27, 2006
Messages
467
Location
Granby, MA
Thanks for the suggestions.

I did try starting the car cold and putting my hand around the exhaust manifold and could not feel any obvious leaks. I've also got a brand new aluminium radiator so I'd think I would see some carbon build up on the radiator as this happened with my old radiator.

From what I remember the wastegate actuator rod was pretty tight to put on and we had to put pressure onto the waste gate actuator first so that we could put the rod on. I could try adjusting the rod a few turns or putting washers like you said.

Im going to try and run the car without a line to the actuator and see if the waste gate is opening too early. If that doesn't make a difference ill try doing a pressure to the waste gate. Do you have any suggestions on how I could do that?

Also im still on stock 2 inch or whatever diameter stock exhaust is. I'm thinking of going 3 inch cat back and see if that will make a difference.
attachment.jpg
I use something like this for testing for leaks. Having a 25+ gallon air compressor with an adjustable regulator helps. Soapy water and a stethoscope helps as well.
 

Fourdoor

New member
Joined
Jul 30, 2020
Messages
4
Location
Palm Bay Florida
Another common culprit is a leaking BOV, could yours have been damaged when you replaced the turbo?

Keith
 

JspecVR4

Member
Joined
Jun 19, 2022
Messages
15
Location
Australia
Another common culprit is a leaking BOV, could yours have been damaged when you replaced the turbo?

Keith
I havent been able to fix it yet due to personal stuff. But to answer your question i don't believe that would have been the problem as my bov was recirculating at the time. Furthermore, the bov has been replaced and I now vent to atmosphere and the lag issue still persists. I will attempt to fix the issue again in the near future
 

slugsgomoo

Well-known member
Joined
Oct 16, 2003
Messages
3,749
Location
Tacoma, WA
It won't directly impact this, but if you didn't switch to GM MAF or speed density and you're doing VTA, you're only introducing problems for yourself.

Boost leak test is a good first step, followed by testing the actuator. If you want to do a quick and dirty test, and you're comfortable with watching the boost gauge and getting your foot out of it ASAP, unplug the vacuum to the wastegate actuator and see what it does. In theory with it unplugged you should free boost, which would make maximum sauce on the turbo.

Secondary question- is the 16g a genuine MHI unit, or is it a Chinese "evoIII"? Generally the MHI units should come with a stock actuator, rather than something adjustable, so that makes me wonder. Add some pics if you can.
 

JspecVR4

Member
Joined
Jun 19, 2022
Messages
15
Location
Australia
It won't directly impact this, but if you didn't switch to GM MAF or speed density and you're doing VTA, you're only introducing problems for yourself.

Boost leak test is a good first step, followed by testing the actuator. If you want to do a quick and dirty test, and you're comfortable with watching the boost gauge and getting your foot out of it ASAP, unplug the vacuum to the wastegate actuator and see what it does. In theory with it unplugged you should free boost, which would make maximum sauce on the turbo.

Secondary question- is the 16g a genuine MHI unit, or is it a Chinese "evoIII"? Generally the MHI units should come with a stock actuator, rather than something adjustable, so that makes me wonder. Add some pics if you can.

Im currently still on stock AFM atm, hoping to switch to link ecu in the coming months. What problems would be caused by VTA I've current had zero problems, On stock bov VTA I had problems with idle but on my current bov no such problems occur. I know people say the car would run rich because of on metered air, but its for such a short period of time when your off throttle. I havent installed my wideband yet to see the effect.

I have also disconnected the vacuum line to the waste gate actuator and the car behaved the same, didnt see a difference even all the way to redline.

Finally it isn't a genuine MHI 16g ;(. I have a genuine 16g that is from a another VR4 but it requires a rebuild and I cannot find any rebuild kits for it at it has different dimensions. I might make a follow up thread regarding that turbo.

Thanks for your input:)
 

slugsgomoo

Well-known member
Joined
Oct 16, 2003
Messages
3,749
Location
Tacoma, WA
Im currently still on stock AFM atm, hoping to switch to link ecu in the coming months. What problems would be caused by VTA I've current had zero problems, On stock bov VTA I had problems with idle but on my current bov no such problems occur. I know people say the car would run rich because of on metered air, but its for such a short period of time when your off throttle. I havent installed my wideband yet to see the effect.
While you aren't having the issue at idle because the valve is staying closed (the problem you likely saw with the stock BOV), if you're actually making boost, and the valve opens when you lift, you can get stalling or stumbling- additionally with a small turbo, recirculating will have a positive impact on boost recovery between shifts.

I have also disconnected the vacuum line to the waste gate actuator and the car behaved the same, didnt see a difference even all the way to redline.
If the wastegate is disconnected and you're still seeing the same boost, you either have a massive boost leak, an insane exhaust leak pre-turbo, or a turbo that simply doesn't work.

Does it sound like it's spooling up/making a noise? Have you tried building a boost leak tester, and testing the pressure side for leaks?
Finally it isn't a genuine MHI 16g ;(. I have a genuine 16g that is from a another VR4 but it requires a rebuild and I cannot find any rebuild kits for it at it has different dimensions. I might make a follow up thread regarding that turbo.
What's the shaft play like (in & out, up & down there will be some because it's journal bearing, but it shouldn't be extreme)?

I know you can do a rebuild with FP for a reasonable amount, but it's probably much cheaper to buy a kit or a good used unit, since you'd be dealing with international shipping. That said, there are quite a few diagnostic steps left to do before you start throwing money at the car.
 

JspecVR4

Member
Joined
Jun 19, 2022
Messages
15
Location
Australia
While you aren't having the issue at idle because the valve is staying closed (the problem you likely saw with the stock BOV), if you're actually making boost, and the valve opens when you lift, you can get stalling or stumbling- additionally with a small turbo, recirculating will have a positive impact on boost recovery between shifts.


If the wastegate is disconnected and you're still seeing the same boost, you either have a massive boost leak, an insane exhaust leak pre-turbo, or a turbo that simply doesn't work.

Does it sound like it's spooling up/making a noise? Have you tried building a boost leak tester, and testing the pressure side for leaks?

What's the shaft play like (in & out, up & down there will be some because it's journal bearing, but it shouldn't be extreme)?

I know you can do a rebuild with FP for a reasonable amount, but it's probably much cheaper to buy a kit or a good used unit, since you'd be dealing with international shipping. That said, there are quite a few diagnostic steps left to do before you start throwing money at
I haven't experienced/noticed any stalling or stumbling when I lift.
I also didn't notice a difference on boost recovery when I went VTA but that's probably just because of my laggy turbo hahaha. I will look into recirc vs VTA when I fix this lag issue.

I will eventually do a proper boost leak test when I have the time but I'm currently sorting out personal things but it is definitely something I want to do at some point. My current theory is that the internal wastegate on the turbo is faulty and is basically always partially open or something along those lines.

I can't really hear the turbo spool until late in the RPMs maybe because of my stock intake setup I'm not sure. However, if I try brake boosting, the boost will go to about 0.6 bar in second gear and I can definitely hear the turbo spinning.

When I got the turbo the first thing I checked was shaft play and from what I can remember there was basically little to no shaft play at all or not enough for me to notice/care about.

Also I'm quite jealous of you American folks and your FP stuff. It's so hard to source any good second hand 1g 4g63t parts here in Australia, all I see is late evo stuff :(
 

Turbo99

Well-known member
Joined
Oct 9, 2013
Messages
66
Location
Haverhill, MA
Also I'm quite jealous of you American folks and your FP stuff. It's so hard to source any good second hand 1g 4g63t parts here in Australia, all I see is late evo stuff :(
If you are in need of anything specific let me know. I'm happy to see if I can find affordable shipping options and get stuff to you.
 
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