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290cc injector tuning & purge valve question

8K views 50 replies 6 participants last post by  craighome125 
#1 ·
Hi guys!

I've recently boosted my 2L G4GC Tib using an Evo 4 TD05 and have a question or two.

So I've been doing a lot of research here as wow there is sooo much info but there is just one thing that I can't seem to find an answer to and that is the EVAP purge system and boost! Is the purge valve able to handle boost?

And the other is I have installed the Sonata 290/310cc injectors and dialed the piggyback (Ecumaster DET3) in by originally putting -34 across the closed loop part of the map. Still tuning this part...

I found that since the injector install, the car is running great and AFR's are looking decent but one problem that I seem to have now is a bit of rev hang when changing gear at low RPM ~2000-3500. Now is this a symptom of too much fuel or too little? Or maybe a vacuum leak?

Also a side note, this rev hang doesn't happen while the car is warming up in the morning...

Any ideas?

Craig
 
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#3 ·
Ah good to know about the EVAP valve, couldn't find any posts about it so thought that was the case!

I seem to be hitting boost at about 2800-3000 rpm, I did install a thin plate with 2x 1/4" holes (from memory!) on the IAC a couple years ago to stop the standard rev hang which did the trick perfectly but now since the injector install it seems to be back...

Oh I also did slacken the accel cable and clean the IAC recently as I thought it might be sticking but made no difference at all.

The car is MAF, had it just before the TB (blow though) for some time with the crank breather inlet to atmosphere with a little filter and suspected that that was the unmetered air coming in causing this but have since changed to a recirc BOV with a catch can system taking clean air from after the MAF and moved the MAF pre turbo but changed absolutely nothing.
 
#4 ·
I had a problem with rev hanging and a strange idle with my car, the culprit turned out to be a vacuum leak where the brake booster vacuum hose attaches to the rear of the upper intake manifold. Apparently somebody before me over tightened the hose clamp and smashed the metal fitting kinda flat shaped.

You can find a vacuum leak with a propane torch, turn on the gas and obviously don't ignite it and run the tip around all your vacuum lines, if you have a leak it will make your engine increase RPM's when you find it. Its probably not very safe, but it works.
 
#5 ·
Yeah thats what I was thinking but I did spray a little industrial IPA around areas I thought might cause a leak a while back and nothing. Only thing left could have been the EVAP system but seems it cant be that.

I did check the brake booster pipe as I have tapped into that for my vacuum manifold but its all secure.

I reckon I need to try some propane! :smile2:
 
#6 ·
I would rather suggest brake or carb cleaner, they are a fuel that is a bit more tame than propane.
 
#10 ·
I think I'll still go with the brake/carb cleaner as its easier to come by here in the UK.

I've put a brass T in the brake booster pipe before the check valve and all the connections have miniature T-bolt style clamps so shouldn't be leaking. I was thinking of drilling and tapping the intake manifold for a dedicated barb for the vacuum manifold - might do this sooner!

I'll have a look around that area again just in case I've missed something.

Thanks for all the suggestions guys!
 
#12 ·
I have the T in between the check valve and manifold.

I have been thinking...dangerous I know! :smile2: so the rev hang started almost immediately after the 290cc injector install so it must be fueling issue surely!

The plan is to try the suggestions here and search for a vacuum leak and if nothing is found then check the throttle body to make sure its closing 100% and then make some changes with off throttle fueling and see if I can clear it up.

If all else fails then I'll live with it until summer as its pretty much brought the stock rev hang back and the cars running fine in all other areas.

Oh one last thing before I forget, it def seems to do it more around 3000-3500rpm when I lift off the throttle as boost is climbing - don't know if that means anything haha
 
#13 ·
Where does your recirc line go? It should go in between maf and turbo inlet. How is your catch can plumbed? You should be using one in between the PCV valve and intake manifold and it should be one that can be pressurized. You can also have one on the breather line and that one can go to the same place as the recirc line. I don't recommend that though as you can pressurize the cylinder head with the air from the bov. I also recommend a PCV valve from an evo 9 since it's designed to hold boost pressure.
 
#14 ·
Yeah the recirc is between maf and turbo inlet.

One of the things I made sure was to get the Evo PCV part no. MD152772 - hopefully thats the right one, funny enough the Hyundai PCV looked identical!

My catch can setup is a bit weird but I have found it works well and takes fresh air after the MAF, the cam cover has a straight barb so no restriction.

The idea of this sealed catch can is to pull vacuum from the intake until the PCV closes then the turbo intake starts to pull vacuum.

Don't forget I had the rev hang issue before I installed the catch can with this design, it was also there with the blow through MAF hence why I thought changing to this setup might solve it as all air is now metered.
 

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#15 ·
The turbo will not generate enough vacuum to open the PCV, especially not the EVO one as it has a stiffer spring in side. As long as your PCV catch tank is good then you only need the lines from the cam cover and intake manifold. The line to the turbo inlet does nothing. Also remember your boosting a motor than never came that way. At best the MAF sensor will read 2-3psi before pegging its voltage range. What are you clamping the MAF voltage to in the DET3?

Also remember that unless your forcing open loop under boost or modifying the O2 signal under boost the OEM ECU will attempt to trim fuel out to reach its closed loop AFR targets.

Another thing to consider is how long the vac hose is to the DET3. I recommend no longer than 3ft otherwise you'll get slow response time from the DET3's internal MAP sensor. This could cause issues like your seeing. Are you intercepting or just tapping the crank sensor?
 
#16 ·
Sorry the diagram isn't as clear as it should be, the two one way valves coming from/to the intake piping are actually brake servo type check valves that I bought on a whim and found they open VERY easily but close very securely the other way around. The only valve that I feel isn't really required is the one going towards the cam cover. The EVO PCV is only between the intake manifold and catch can.

One of the catch can lines is right at the turbo intake so as to have the best vacuum and the fresh air line to the cam cover is right after the MAF further down the intake piping so as to cause a greater pressure difference - the catch can seems to be filling up a little quicker since doing this, thats what made me think its working better now.

These are the one way valves I am using: https://www.ebay.co.uk/itm/6-8-10-1...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

MAF voltage is clamped at 4.7v and at WOT boost is 0.23 bar/3.3psi @ 6500rpm its about 4.5 volts but the DET3 is currently scaling down to 4.2v

Strange thing is boost is 0.42 bar/ 6psi from 2800-4700rpm and tapers down to 0.23bar @6500rpm as above - should it not be constant to redline?

The vacuum hose is 2 foot away from the DET3 and I'm intercepting the crank. I had the DET3 wired up for a good 6 months when I was still NA just to make sure all was working ok before the turbo install. During that time I did advance the timing slightly in the lower rpms as I found it increased torque nicely with 98 octane fuel here in the UK. Since the turbo I did zero out the values to put it back to standard timing.

With regards to open closed loop, I have tuned the open loop area of the map but have yet to sort out the closed loop. I have been making sure I don't sit in boost at closed loop due to the AFR being way too lean ( I change gear before then!) I only drive about 10 miles a day currently in heavy traffic so for a short time should be ok.

The plan in next week or two is to have a small relay that gives the TPS a 4.7v signal to force open loop just before I hit boost. I'll be using an output on the DET that will activate the relay just before positive pressure comes in. Then I'll tune that area.
 
#17 ·
In the future lead with info like that. ?
I'm assuming you have a 6psi wastegate? If so than your loss of pressure higher up could be due to too much back pressure or an improperly adjusted actuator arm. What size is your down pipe and exhaust? Did you port match the manifold to the head? An Evo manifolds ports don't exactly line up so they must be port matched.
 
#18 ·
In the future lead with info like that. ?
I'll try my best! :grin2:

I have a 0.3bar/4.4psi spring in a Kinugawa wastegate but have tweaked the boost up with a manual boost controller teed into the boost line to the wastegate. I did originally adjust the wastegate to hold closed a bit more according to online advice so should be fine - pin sits halfway on the eye of the wastegate from memory...

Exhaust is 2.75" downpipe to the resonator and then 2.5" right to the aftermarket backboxes (large bore)

I did port match the exhaust manifold a "little" but must admit its not perfect and could well be the cause of the boost dropping in that case. I have another EVO 8 manifold here that will be getting ported a bit better in future.
 
#19 ·
If the actuator arm fits easily over the flapper arm pin the that's your problem. You should have to pull it out a bit to get it on. Otherwise it will open too easily. It needs a certain preload on the spring. Also make sure your boost source for the controller comes from the intake manifold and not the compressor housing.
 
#20 ·
Yeah I had to pull on it a bit to get it over the flapper pin, will try the actuator piping to the intake manifold first before anything else - makes sense as thats after the IC where you could get pressure drops and thats the actual pressure being put on the engine.



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#21 ·
So just a bit of an update

Since last time I've done extensive checks for vacuum leaks with butane gas and found nothing. I saw that I had a small exhaust manifold leak on one of the corners so installed new gaskets on the engine and turbo side just to make sure the lambda wasn't reading air from outside and throwing the AFR off.

I've also got the DET3 to send a WOT signal to the ECM as boost builds so got full control now and the wastegate actuator is now plumbed to the intake manifold so the boost goes from 0.43 to 0.37bar - both worked a treat and happy with the outcome!

Next step regarding the vacuum leak was to try isolate all the piping coming off the intake manifold one at a time and see if that made a difference, the only one was the EVAP line which once clamped seemed to make the car idle much smoother and the STFT also seem more stable so I decided to take a drive and see how things were while clamped.

The car drove smoother and the rev hang got a LOT better but still not quite as it was before, the biggest thing that happened is boost suddenly shot up and I hit an AFR of 14:1!! :surprise: I quickly let off the throttle and luckily all is ok!(I've now added fuel to compensate) So I've been driving 2 days with the EVAP line clamped and no CEL which is weird and the rev hang seems to be getting less and less but will only see in a couple days - Think the ECM is learning...might need to do a reset.

So I'm off to my homelands, SA from Thursday so won't be able to do anything more for a couple weeks, I suspect the EVAP valve is stuck open so I'll order up a new one once I'm back.

Hopefully this is the problem!
 
#23 ·
Thanks mate! Yeah hopefully this is the issue or at least whats been causing me to not tune the lower RPM properly.

And on that note!! :grin2:

I now am having an issue where I can't add any more fuel at high boost between 3200-4500RPM! Even if I'm pushing my MAF voltage to the ECM to its max of 4.7v -see the attached pic

And excuse the tune, it need refining...
 

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#28 ·
And now I can't seem to get my AFR to safe levels even with the boost turned down to 0.3bar!! Would it be possible that the faulty EVAP valve was causing me to boost into the tank and "helping" the fuel pump? And strange that the EVAP system hasn't thrown a code yet with the pipe clamped...

Looks like I'm going to have to remove the clamp for now until I get a new purge valve and install the 190lph pump.

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#30 ·
Do you not mean the long term trims? As I have them at -2.34 at the moment, the short term trims are mostly stable but I have seen them go as high as +5 around mid load/rpm. I force open loop just before the onset of boost via TPS and relay and can confirm it is showing 92% TPS across the map in boost.

I'm thinking of doing an ECU reset and seeing if that changes things as I haven't reset since before the clamping of the evap line.
 
#31 ·
When you say unsafe AFR what do you mean? And I was talking about STFT because that gives you and accurate idea of what is going on at the moment.
Also I don't think you ever said what year your car is. 07-08 2.0s ECU programs are much more strict than the earlier ECUs. They may be fighting you. I would suggest throwing in that 190lph pump for now and see how it does. The stock pump may not be able to push the pressure you need under boost.
 
#32 ·
AFR of 13.5-13.9 from 3200rpm to 4500rpm then it drops to 12.8 which is another strange thing as shouldn't it be getting leaner to redline? Maybe exhaust not flowing well at that high rpm??

Don't the STFT's zero out in open loop? I can check this in the morning to confirm it is zeroing in boost as I've not checked this!

Car is a '07 2L manual UK version

Yeah fresh fuel filter and 190lph pump will hopefully sort this out! Time to turn that boost down methinks!
 
#33 ·
New fuel pump should definitely help. If your AFR is that low under boost you will be in open loop. Good thing is that timing is pulled as well. Another thing to remember is air temp will affect afr as well. Warmer temps will make it leaner as the ECU will pull fuel. Do you have any temp compensation?
 
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