HFS4 on 996tt
 

Hi all,

car is 996tt with gt30s turbos, upgrade fuel system 80cc injectors and trying to run in the end about 1.6 bar or more.

Car is running a bit rich even without meth, lambda set point is 0.8 and actual values are 0.78-0.8 most of the time

i tried with W60/M40 on defaul mapping (IDC) and after that W45/M55 on a custom mapping (MPS) and the same result, i see lambda going down to 0.73, engine load gets very high and engine is coughing

I am told i need to start injecting by 7 psi and full at 15 psi, any thoughts ?

thanks a lot

Fadi

Re: HFS4 on 996tt
 

Richard, can you help me please ? I used a basic kit instead of HFS4 and it works...
Isnt this kit supposed to be plug and play for basic users anyway?

Re: HFS4 on 996tt
 

Based on your is post, running rich is not good especially you injection water/meth on top. Reduce your fuel flow until you are running ~11.8 AFR

Re: HFS4 on 996tt
 

i used same aquamist pump, meth lines, injectors 2x1.2mm !!! and replaced your controller with a basic on/off boost switch at 10 psi reading boot from the intake and linked to the pump... car is running OK, i see much much better timing, better than with ms109 !!, perfect afr-not running rich anymore, but no iat drop, just slower increase of iat.... but i am able to run much more boost, so the problem is from the controller... are you sure the wiring diagram is correct ?

Re: HFS4 on 996tt
 

if you are running 2x 1.2mm jets and see no IAT temperature drop but much better timing, there must be something wrong with the temperature sensors. Send a picture of the jet installation.

Replacing the controller with a boost switch makes the car runs better, so there are really no problem to solve.

Re: HFS4 on 996tt
 

i bought the most advanced controller from aquamist, not a basic boost switch like 20 years ago, this is the problem


used both places to inject, see pics attached

Re: HFS4 on 996tt
 

The HFS4 can be triggered by boost and set to on/off mode. You have just wasted your money on a mechanical pressure switch?

Re: HFS4 on 996tt
 

I tried that just to make sure the system works, i had already that boost switch.

Seems i have found the biggest problem :

I just untightened the bypass screw on the pump and now IAT is dropping 10-15C, sometimes even bellow ambient temps, i think this was the problem... now i have to fine tune it, still getting rich but car is not bogging like before, maybe a bit less meth and maybe a bit later will do the job.

I would inject mostly by boost (P/I-R almost all the way to the left) but in the IDC and PWM mode, if this will be difficult i will switch to MPS/PWM and the last chance will be MPS/SSG and add later on all failsafes, i will still run with DFS on for now

Re: HFS4 on 996tt
 

if i switch to mps the amber led is always on and system is injecting all the time,any ideas ?

i tried different thres, gain, p/i-r setttings but no luck.

Re: HFS4 on 996tt
 

There is something very wrong on this.

Can you measure the voltage at test point 17 relative to ground (bottom left of the test points)

Re: HFS4 on 996tt
 

now is ok, was a wrong wire....like 1.x-2V at idle.. As i thought i am injecting too much meth I put just one 0.5 injector and car still boggs when kicking in... it can not be too much meth i supose.... we were running a very low mix like 30meth/70water. AFRs are going like 10.7, i am targeting and reaching 11.8 AFR on pump only. With 2x1.2mm we measured up to 7-800cc/min flow, injectors are 80cc and IDC at 1.5bar is like 70% peaking 75% sometimes

My install was also validated by another user fo yours cipsony who owns a very nice and fast audi ttrs, thank you Ciprian !


A 0.5 injector for this engine could do so much harm ? Besides retuning ??, i dont know what to do, i am lost......

Re: HFS4 on 996tt
 

I am very confused with your approach. Remember you insisted on using two 1.2mm jets? Now using one 0.5mm, you get bogging. What is going on here?

Re: HFS4 on 996tt
 

All I know is that Aquamist seems to work fine now, temporarly i have installed a secondary meth kit to double check WMI and my AFRs and everything with both of them, and in the engine keeping just Aquamist :) They dont run in parallel, just one enabled at one time. I was reducing the quantitiy of meth injected by reducing the size and number of injectors, that's why i ended with a single 0.5 now. IAT is dropping ok

With both systems, i saw HIGH ENGINE LOADS and 0.73 lambda with every combination of injectors (big, small, dual, single) and every combination of meth mix (30%-100%)

I dont know what is causing this, but if i will find out the answer i will know what to do next.

I target 0.8Afr (11.76) and this is also what i get on pump, on meth i target also 11.76 and i go down to 10.7 and high engine loads (240 instead of 170), any ideas what is the reason for this ?

Re: HFS4 on 996tt
 

I meant Aquamist is working fine as i think my problems arent anymore related to the meth system, maybe the tune or something else

Re: HFS4 on 996tt
 

It appeared you have some misfire fuel to weak spark (carob build up). or over-sized gap. It the fuel are not ignited properly, you get get excessive amount of oxygen, This could be the cause of low lambda value.

Get a new set of spark plugs and start again.