I recently installed the new Haltech plug and play on my JWT TT G35. I previsouly had the old red box Haltech, and while I liked it, I disliked having the stock ECU in there as well, and using Uprev Cipher on the stock ECU to hide some codes it would throw.

The new Haltech ('silver box') is great, and I have the tune down pretty well, although I am taking it to Dynosty in a week or two to get a good dyno tune. The new settings with the silver box really allow you to fine tune a lot of things that you couldn't touch before, and it is nice not having to cram the box in there behind the dash along with the stock ECU.

One problem I am having, though, is that desptie using the same settings as my old red box (boost control proportional, deriviative, and integral, along with base duty cycle, etc...) is that while the red box (using the same boost solenoid) would not overshoot the target boost of 9.0 psi, the new silver box overshoots it by about 1.5 psi before dropping back down to 9.0 psi. I was having some problems with the redbox with boost creep after holding steady boost (in 4th, 5th or 6th gear) for long periods, but I haven't seen that here (mostly because I am not holding it in boost long enough to do so until I get a good tune); what I am seeing is that as boost builds quickly, it overshoots to about 10.5 psi before dropping back down to 9.0 psi.

Anyone have any insight as to what settings I should be looking at to prevent the overshoot? I do have the overboost limiter set to 11.0 psi, but thats a hard cut, and only there as a safety factor, not as a control.

 

I am not a haltech expert but in a PID system you have overshoot from D being too high. Try reducing or even zeroing out D. In many systems I've designed D wasn't even needed.

 

I believe the current settings I have are 75/25/0 (PID), but I would have to check them at home to be sure. So, deriviative is already zeroed out.

 

Try reducing I then P. PID tuning is a PITA.

 

what is your wastegate duty table set as? you might have the wastegate duty to base boost set too high.

if you go to open loop boost control, what does the curve do?

dont touch the PID until you confirm that open loop is hitting exactly 9psi.

 

base duty is the same as it was on the red box Haltech, 25. I tried lowering that to 20, and it didn't seem to make a difference. Base duty of 25 on my red box hit 9 psi, never overshot, and held it solid.

I have not tried tuning it on open loop, always on closed loop.

 

I am surprised that you are not having more issues than just a tiny overboost if you just copied all your settings over to a completely electronically different ecu.

Start with the basics. run open loop and go from there.

 

I probably wouldn't say 'completely electronically different' as they can use the same maps, and use the same tuning software.

But anyways, thanks for the advice, I'll see what I can do.

 

ya, i agree with rich. My first line would be to log output duty cycle for the boost control and look at those when boosting. That will tell you what duty cycle it needs to hold 9psi. Then from there I always stay 5-10% duty cycle under that to start off. Depending how fast the boost builds. Also, check what your boost controller state psi is. You might have to start it sooner so it doesn't overshoot.

That is where I would start before messing with PID settings although the new box might control PID differently than the old units.

https://my350z.com/forum/tuning/4854...-settings.html is a thread about them. Setting them from scratch might be helpful. Your numbers seem really high compared to what mine are. I think from setting mine the I is what brings it to the desired target.

also, be careful on calling the new silver box "the new unit". I have the older version but it's in the new silver case. It's deceiving.

 

Thanks for the info, that thread is a good read. Also, I didn't know there were old models of the Haltech in a silver box. I'll have to figure out the proper terminology, I guess

 

I think they call them "ecu replacement" ones now. they should have called them something like haltech V2 or something. The first edition uses the red and the silver cases.

Hope you get it figured out. Let us know how it goes.

 

I would try a lower base duty cycle and basically start over. but what do I know, I still cant get mine perfect. lately ive been having issues with getting the same boost when in lower gears vs 5-6th gear on the freeway. I keep overshooting and hitting my boost cut in 5th and 6th when rolling into boost cruising on the freeway. but down low, I undershoot my target boost.

 

more load in higher gears so you will need less duty cycle.

not sure how you have yours set up. If you have your PID set properly it should be able to maintain your boost even with the higher load. You need to set your base duty lower then the closed loop will add more to it in lower gears and it will be spot on in upper gears with less correction. So that means you have a "target boost" but you need to set your target duty cycles in the target boost map lower and you can make a 2d map associated with speed so it will use less duty cycle with higher speed (meaning higher gears)

 

i wouldnt even spend too much time trying to correct a 1psi overshoot. even on the most efficient setup thats maybe 40hp, probably much closer to only 20hp.

if you AFR's are getting outta whack, then your map isnt tuned properly or doesnt have enough resolution.

My overboost is set at like 4-6psi over target.

 

AFRs are fine, map is good resolution; I have the load colums under boost set for every 1.5 psi, and there is plenty more resolution if necessary.

It's a stock block, so I would rather not have boost spikes over 9 psi, though.

 

how much whp are you making at 9psi? 10.5psi? 450ish?

regardless you have to set open loop and redo your base boost tables.

 

last dyno was about 4 years ago, at 6000' altitude (yes, I know it affects a FI system less, but it still affects it) and it made 390 at 9 PSI

 

It's hard to keep a boost controller perfectly steady. 1psi swing isn't bad and if it's at the beginning you can increase the start point of the boost controller (default i think is 3psi before boost target). Try 4psi before target, change target base duty cycle down a couple of percentage so it doesn't come in too hard as well.