Hey guys, I have an on-going fueling issue that I've had for nearly two years now and literally nobody can solve it. In all my previous attempts to solve it on here, I have probably waffled on wayyyy too much in my original post and confused the issue, so this time I'll try and keep it short and to the point (I hope!)

Basically, I have a MY00 Impreza Turbo 2000, mods are TD04 hybrid turbo, 3 port boost control solenoid, Ninja sports cat downpipe, afterburner de-cat centre section, hayward & scott custom backbox, STI version 8 top mount intercooler, cosworth panel filter, Nismo 550cc injectors, RCM fuel pump, NGKPFR7B spark plugs, Magnecor Ignition leads, Alcatek ECU. The car is doing 17mpg and this is driving around like an absolute granny, mostly off-boost. It is absolutely horrific on fuel, randomly difficult to start sometimes (just turns over for ages before it fires), and generally doesn't feel like it wants to go anywhere. I also have fuel in my oil somehow if that gives anything away? I've sent my injectors off for servicing and had them back with a full report saying they're all spot on, because I thought they might be leaking. I've also had a compression test done, which was bang on 150psi in all 4 cylinders - that was a massive relief! So, umm......how? What on earth could be wrong?

Any help would massively be appreciated, because otherwise I'm gonna have to get rid of it

 

[quote=simonds1;11460205]Hey guys, I have an on-going fueling issue that I've had for nearly two years now and literally nobody can solve it.

Given the modifications , you have also had mapping done.

I would think that a lot of us would like to see what torque/power curves you now have , as this will help diagnose if you have problems to burn the fuel. Can you put up a graph ?

Then given the tune it would be best to look at the WGDC and part throttle duty cycles. (Your engine mapper should help , if you still have contact after 2 years )

If you are over fueling , I would start by looking for boost leaks and (physical) waste gate control. Particularly in lower boost levels and low-mid rpm ranges. The static FPC pressure should be measured too.

Keep trying you will find it , by deduction. Linksfahrer.

 

Hi,

Don't know about imprezas, but most of the times when I met this issue on other cars, the fuel pump was the culprit.

Perhaps this may help you if you have a spare one to swap? Also has anyone checked your map for over-fuelling?

 

Ive seen this after someone fitted some new injectors, they had pinched a seal putting them into the rail. It may well be that they are not sealing in the fuel rail 100% and some fuel is weaping through.
A relatively simple thing to do would be to unbolts the inlet manifold and lift it up a bit, turn the ignition on to pressurize the system and look for any leaks.

 

It would be worth checking the fuel pressure both under vacuum and under boost to check it stays static against manifold pressure. A hole in the pipe that goes to the manifold may result is fuel pressure that works ok on boost but runs rich on low throttle giving you poor economy.

Also, a good fuel pump and a dodgy fuel pressure regulator that can't return enough fuel to the tank could be causing the fuel pressure to be to high at low engine loads.

It would definitely be worth checking fuel pressure so you can tick that off the list.

Presumably if you have an alcatek you're not using a MAF, as these often fail on this era of car?

 

No mention of mapping in the OP's post, although presumably it must have been at some point with the Alcatek ECU. Has the car been checked out by a mapper? First port of call really.

 

If its mechanically all correct (pump, FPR, injectors, etc) there's a few possibilities that could cause over fuelling:
1)It thinks there's more air coming in than there is - MAF sensor (not sure if MAP could contribute too?)
2)It thinks its running colder than it is - Coolant temp sensor
3)It thinks its running leaner than it is - O2 sensor
4)It's been remapped by someone who doesn't know what they're doing and its just a crap map.
5)?...

Feel free to correct me if I'm wrong on any of the above...

 

Hi guys, really appreciate all the replies so far, thankyou

Yes, sorry I should have mentioned in my original post that the car has been mapped. Many many times infact! Basically (I'll try and keep this simple!), the car has never ever put a foot wrong and has spent most of it's life with just the exhaust, spark plug, intercooler & air filter mods mentioned above, along with a walbro 255lph fuel pump and an EkuTek map on the standard ECU. Then came my desire for more power, which led to a VF35 turbo, some JECS 550cc injectors and an RCM fuel pump. Car has never been right since. Had it mapped with those extra mods initially on the standard ECU and mapper thought there was too much fuel and blamed it on the 'cheap' JECS injectors I had got from the states. He then said an aftermarket ECU would give him better control of the fuelling so I went for the Alcatek. Went back and had it re-mapped with the Alcatek and it was better, but still not right. It was then suggested that I should get the 'proper' Nismo 550cc injectors that were initially suggested to me by my mapper (I only bought the JECS ones because they seemed to be the same, but much cheaper - doh!). So I went back for another remap with those and it was better again, but.....I dunno.....still didn't seem right y'know? Every little mod I had made in the past had made such a massive improvement to the car's performance. The ninja sports cat downpipe for example, it was a different car after that! So yeah, after changing fuel pump, injectors, turbo and ECU......I was just left thinking it was pretty much slower than before to be honest. So that's when I changed mappers, just out of curiosity basically, see if anyone else could sort it. Again, left with a mystery non-performing car at the end of it. All the mods I had mentioned, along with a VF35 turbo, and it was only getting 283bhp and they were expecting more like 330 - 340bhp. So then I started going backwards - I thought if I put it back to how it was when it was good, I might be able to sort it. So I got a td04hybrid turbo (rather than getting standard td04 again) just to see if that would get rid of the turbo lag I was now suffering from. Went back for yet another map, and interestinlgy enough got 284bhp! 1 more bhp than before, after moving back to a smaller turbo??? So yeah, that's the state the car is still in now. Have thought about going down the road of putting standard injectors back on, going back to the walbro fuel pump, and even trying the standard ECU again.....but annoyingly I've sold everything apart from the ECU so it would mean buying everything again and I have just ran out of money to continually throw at it and so far I have literally got nowhere! I mean I have literally spend well over £2,000 making absolutely no difference to the car lol

Yes I have got dyno graphs at home for the VF35 turbo and also the TDo4h which I can post up later on. I'm still in contact with mapper yes as my last map was only in November now just gone. They are SO far away though it makes it difficult. 5 hour drive nearly

 

Just another couple quick thoughts , about your JECS 550's and your own thoughts on going back to original injectors.

I use the later version MY06 Denso' on MY05 But if some clown had de-capped them you'd flow more like 1000 cc and the tuner you would be struggling to get fueling right due to poor fuel atomisation character.

Another interesting comment about old JECS with new style being "resistant to electrolysis" caused by ethanol content can be found here :
http://www.z1motorsports.com/product...oducts_id=3348

Again this would lead to poor Atomisation ( spray pattern issues ). Read the sticky on Grahams Engine Mappers guide on that for some photo's of decapped spray pattern. Keep looking . Regards Linksfahrer.

 

Thanks for your reply mate, in answer to your questions....

1) I'm not running a MAF now because of the Alcatek ECU, but I haven't tried changing the MAP sensor.
2) I have changed the coolant temp sensor a few months ago when trying to solve the horrific fuel useage and that made no difference.
3) My latest map involved a new o2 sensor (bosch one recommended by mapper rather than genuine subaru) in a bid to eliminate that as a problem. I'm not sure if over-fuelling can kill an o2 sensor though? In which case I will be in a constant catch-22 of knackering every o2 sensor I put in!
4) Have been to two different mappers and neither have managed to solve it really. I mean if I left it with them both and had an infinite amount of money to throw at them, they would possibly get to the bottom of it. But so far, in a 'normal' look over the car, nothing.
5).....I've heard some people say that over-fuelling can knacker a cat? So the cat in my downpipe is probably knackered by now right? That would affect turbo lag and general performance wouldn't it? BUT....mapper tried putting on a whole different exhaust from turbo back temporarily to eliminate that and it made no difference on the dyno at all lol

I've had people mention fuel pressure regulator to me recently, which is an avenue I haven't explored yet. Should the standard one be able to cope with my current mods or do I need to get an 'uprated' one? If I do need to change it though, why have two separate mappers managed to not tell me that? Could it be sticking open/closed maybe? I don't understand enough about how they work to be honest

 

Hi Linksfahrer, yes my first mapper said to me that the problem with 'cheap' injectors is that they just have the ends cut off to make them flow more basically. But the flow is then horribly messy and will not have the correct atomisation characteristics for good running and turbo spool etc. That's when I changed back to the Nismo 550cc ones, which are what is on the car at the moment. I have a report saying that they all have excellent spray patterns when I sent them off for servicing. They all had new pintle caps and o-rings put on them etc. Thanks for your help

 

OK,

So we have tried 2 sets of injectors, not much difference?

Two mappers, both struggled?

Presumably they have checked the map, maf and throttle sensor readings were good when mapping

If it is overfuelling on boost as well as light throttle is is less likely to be the O2 sensor as it plays little part on boost.

So if the mappers needed to remove fuel to get it anywhere near right I would be looking at the fuel pressure regulator especially as the RCM fuel pump you have says it flows 4 times as much fuel as a standard one. If the regulator can't dump enough back to the tank then you will have too high a fuel pressure and overfuelling. Also check the vacuum pipe for holes and check its connected to the inlet manifold.

EDIT: I see you have written replies since I started typing, but I think most of the above still applies...

 

[quote=tjmatt;11460387]OK,

So we have tried 2 sets of injectors, not much difference?

Two mappers, both struggled?

Presumably they have checked the map, maf and throttle sensor readings were good when mapping

If it is overfuelling on boost as well as light throttle is is less likely to be the O2 sensor as it plays little part on boost.

So if the mappers needed to remove fuel to get it anywhere near right I would be looking at the fuel pressure regulator especially as the RCM fuel pump you have says it flows 4 times as much fuel as a standard one. If the regulator can't dump enough back to the tank then you will have too high a fuel pressure and overfuelling. Also check the vacuum pipe for holes and check its connected to the inlet manifold.


Seconded.

RCM FP is the one to look at first (its impressive).

So If I presume you have this one
here is why the above comment from tjmatt is tops to check out :


http://www.rogerclarkmotorsport.co.u...productID=2680

Best regs Linksfahrer

 

Hi there

If you are struggling with starting the car and you have poor mileage(MPG),I would suspect O2 sensor which can be faulty,but I wouldn't rule out fuel pump and fuel pressure

Are you running aftermarket FPR or do you running stock(OE) FPR?

Without the Wideband not sure,how you can check AFR during the off throttle or part throttle(cruising),with this you will know for sure if you are running lean or rich during those conditions

If you are running AlcaTek then you should be able to run Wideband which will only helps you and yours mapper and you will know for sure what AFR you running,speak with yours mapper about this

Thanks,Jura

 

You need to eliminate the basics and the injectors could be leaking as Ive said earlier. If the mapper(s) are struggling to get the fueling lean enough on this setup there is something fundamentally wrong. Any faults with lambda etc should be obvious to the mapper. I had a very similar issue with a Customers car, I'd built him an engine, he took it for injectors and a map, they couldn't get it to run right and blamed my engine build?? I went to have a look at it and check compresion etc and found the oil was stinking of fuel. The injectors were leaking in the rail.
It may not be that but before spending more time and money you need to eliminate it.

 

Hi, I think I have already eliminated the possibility of leaking injectors? I started off with a set of JECS injectors which were brand-spanking-new, so you would not be expecting leaks from them, even though I'm sure it is possible. I then changed to a set of 2nd hand Nismos which I sent away for servicing and I have a report showing they passed the leak test....



So, two different sets of injectors on the car and the problem has persisted with both, so that probably means it's not an injector issue surely? There is no visible fuel coming from any of the injectors or the fuel rail that I can see.

One thought I did have is that I only got the uprated RCM fuel pump and 550cc injectors because I had the VF35 turbo to go with them.... but now that's gone and I'm on a td04hybrid turbo. So the fuel pump and injectors I've got on there now are probably a bit overkill? I guess that shouldn't matter too much if it's been mapped to suit though?

In response to an earlier reply, here are my power graphs from my last two maps. This is with the VF35 turbo....



and this is with the td04hybrid....



If I'm being perfectly honest I don't fully understand the graphs. I don't know why there are two sets of data on the first one, and why one was done in 3rd gear and the other in 4th gear?! Makes it much harder to compare them to each other surely?

 

Hi there

I don't think yours current fuel pump and injectors are overkill,you have more headroom for future upgrades

Those graphs are power graphs,first one is overlayed with yours probably first setup and do you have AFR graphs too?

Injectors can be OK,but I would check at least injectors seals,but still I wouldn't rule out fuel pressure and O2 sensor

Last thing check fuel pump connection inside the tank,if hose is connected or hose is intact plus check fuel pump sock etc

Not sure if you can borrow at least wideband and check AFR,this would at confirm at part throttle you are running rich

Thanks,Jura

 

The injectors may be ok but leaking where they sit in the rail. As Jura says the setup is pretty std and should be fine, certainly mappable to get correct AFR.
Just reading your post again, you say you can't see any leaks, but have you lifted the manifold off the heads to check, thats where the problem would be. If you don't fancy doing that, leave it ticking over for a minute or so then take the plugs out and see how clean/wet each one is.
Another thought, when it struggles to start, does it miss fire a bit once it does start up?

 

I don't think it missfires as such, but unless I give it a bit of throttle, it does kinda tick over at hardly-any-rpm for a while before it idles normally. I took a video to show this (Ignore the horrible rattling sound, that isn't my engine! Just the vibrationn of the barely-ticking-over causes everything to rattle like hell)....



That is when I park at work, which is on a slightly downward facing slope so the rear of the car is lower than the front. Pretty much every night I leave work it's like this to start. At home on my driveway, which is flat ground, it's okay

 

Also guys, I just wanted to show another video. Ever since I changed to the Alcatek ECU, there's been like a small 'mechanical' sound a few seconds after I've turned the engine off. It sounds like some sort of electric motor is turning or moving something, and I was gonna question whether it was normal or not to my mapper at the time but I never got around to it and then I didn't really think anything more of it. But literally today now I noticed for the first time that the noise has changed quite a bit, and it now sonds like it's some cogs trying to turn that are missing teeth sorta thing?! What on earth is this noise, and has anybody else got it on their car?! I can't really tell exactly where the noise is coming from, but I just pointed my phone at the general area where it seems to be....



I'm sure it's probably completely un-related to my fuel useage problem, but thought I'd post up just incase.

 

Thats just opening as a picture for me? Do you get any exhaust smoke on startup?

 

Oh, it opens as a video for me? I don't get any exhaust smoke on startup, no. Well, I say that - I am normally sat in the car when I start it, and then I drive it away so I don't really get to see. But yeah, nothing that I've ever noticed.

 

Something that was mentioned to me when I had my car mapped because it was under power was change the up pipe, the mechanic seemed to think they can cause issues, something to do with the cat collapsing inside it and part blocking it

 

Hello Simon , Thanks for putting the graphs up. These are indeed interesting as they show pretty well the torque development of a TD04 hybrid as superior to the VF35 in the low rpm band , none of our 2.0 ltr engines do particularly well don low. But the Turbo you are using does show good heathly torque , so nothing to worry about on that. Just for your understanding the earlier higher curve is torque and the later post 5200 is showing your brake horse power. TD04 rarely get to 300 bhp on a 2 liter due to the maximum flow that they can achieve , but that's not the whole story for a quick , but drivable pleasurable feel. Here the earlier in the rpm band the torque is developed the better.
If anything is at all surprising it is that your VF35 did not get to 300 bhp.

Importantly I can see nothing in these graphs to show a problem in fuel delivery. The report on the injectors kind of points to slight spray pattern issue on 1 injector but , if you can see the flow all at 72 , at 5 bar test then I assume all is well with them , what they do a lower pressure would be almost more interesting however shame you do not have a result a 3 bar.

So after this information you are now looking to the way in which the fuel pump / injectors are fitted and if the ECU / Map is trying to compensate for other issues.

Jura gives you plenty on that .

 

I think I mentioned this earlier , and it would still make sense to take the down pipe off and take a look that the top of the cat is free from any debris ,
idle level would suffer if the downpipe cat is partially blocked but you would also notice a considerable power loss when on boost , higher up the rpm.

Best regs Ralph