NewHilux.net

Hi there
I have had my car previously tuned about 18 months ago and tuner said maximum boost is 18psi, I installed a boost gauge a few weeks ago and the highest it would get to is 16psi. Last week I installed a PDI Front Mount Intercooler and now boost can get up to as high as 21psi when loading up the car going up hills on the highway. Has anyone else experienced this and is 21psi with a stock turbo okay or will it need to be retuned?

Cheers

HiYa,
I'm not up on Turbo stuff myself, but I've seen them discussed a few times on this forum. Just thought I'd point out what time of year it is and hope you're in no rush, they might all be out playing in the dirt, but I'm sure someone will get back to you, if not sooner, then some time in the new year.
Take Care and have a good season.

21psi is past the factory turbos limits, 18 psi is around where most are tuned to for any longevity, My factory turbo did around 90k before getting the dreaded whine,

Where is the feed for the boost gauge?

Yes that’s what I’m hearing that max for standard turbo should be 18psi. I asked PDI if a retune would be required once there intercooler is installed and they said i won’t need a retune but more can be gained from a retune, my question is why would the boost increase from just changing the intercooler?

Feed for boost gauge is in the intercooler pipe just before the intake manifold, before the front mount it was teed into MAP filter, when it was tuned (12 months before top mount was installed ) tuner said max boost is 18psi

Put an OBD2 scanner on it and see what the electronic sensors detect. The ECU gets its measure of boost electronically and there may be a difference between electronic and analogue air pressure measurement. The ECU determines what boost the turbo makes via the variable vanes on the turbo using the electronic sensor and if the analogue gauge reads higher that may explain why. Also the FMIC is more efficient, that's why you put it on, so more cooling might be the difference. Also the tuners may have 'tricked' the electronic sensor into reading lower in order to artificially increase boost. As you said, the tune was done before the FMIC was installed.

Your last point makes sense ( tuners tricked the electronic sensor into reading lower) if they did this and now the more efficient intercooler is there it could be reading even lower temperatures.

I have asked the tuners via a message and they have said they don’t know why the boost would now be higher.

Another suggestion, see if there is an electronics or instrument shop near you and get your analogue gauge tested for accuracy. It would rule that out if it's accurate. Once you do this, the OBD2 will allow you to compare the measurements between digital and analogue. Remember though your feed for the analogue gauge is from a different source.

Remember also though, 21psi boost isn't likely to be a big problem because you're not likely to be at full boost very often and not for very long so it's really a moot point unless you thrash your Hilux regularly The problem becomes dangerous if you lug the engine at low revs and high boost settings. That's not very likely because the engine needs revs to make full boost. Use your gears to keep the revs up. The sweet spot is around 2500-3500 revs. Making your engine lug at lower revs damages all sorts of components not just the turbo. They love to spin because that's what they're designed to do.

I can do that but before the front mount was installed the analog boost gauge would get to a maximum of 16psi, then I installed front mount and now it goes up to 22-23psi and the only things that have changed is the gauge being plumbed directly into inlet pipe where as before it was teed into map sensor line which you would think would be the same pressure, would have to be a coincidence that the gauge went out of calibration when the intercooler a were changed

AC1981 wrote:I can do that but before the front mount was installed the analog boost gauge would get to a maximum of 16psi, then I installed front mount and now it goes up to 22-23psi and the only things that have changed is the gauge being plumbed directly into inlet pipe where as before it was teed into map sensor line which you would think would be the same pressure, would have to be a coincidence that the gauge went out of calibration when the intercooler a were changed

Just watching on with interest ... Any kind of blockage, crimp or kink between the two measuring points?
Sorry, just thinking out loud?

I can double check that but if there was I thought the gauge would read lower pressures

Possibly the more efficient FMIC improves air density therefore more boost? More likely it's the source point of the plumbing makes the difference. although the manifold air pressure should and I repeat should be the same wherever it's measured. Have you put an egr plate in? That makes a difference! Egr plate does reduce the map, bleeding pressure back into exhaust. Taking the gauge from the pipe could influence that? Thats because it's before the takeoff point for the sensor. At this stage I would put an OBD2 scan on and compare the boost indicated. Says Gipsy scratching his head
That's what an intercooler does... Increased air cooling leads to increased density equals more boost.

Yeah more efficient FMI improved air density so could be the reason for higher boost, I asked PDI multiple questions before purchasing it so you would think they would say you would see a higher boost, Place I got it tuned at said usually you see a slight drop in boost not higher.
I haven’t put an egr plate in, when it was tuned they said the maximum boost is 18psi, so with a slight pressure drop across intercooler and piping would expect boost gauge to read lower then 18psi and not higher?

Yes the FMIC does work more efficiently to cool the air from the turbo and in so doing it increases air density as well as providing more airflow which all adds up to increased boost but your different readings are probably due to where the gauge is tapped in. The electronic sensor is confounded by lots of other plumbing and the analogue gauge gives unadulterated boost from the turbo. Check it with the OBD2 reading and that may show the difference.