Hawkeye WRX running about 400ish.

Harvey Smith TD05/06 20G
APS TMIC.

Fuel side of things
Fuelab FPR
Some modified injectors (flow matched etc from Lateral Performance)
Bosch 6 bar fuel pump

It's always had problems running lean since day dot. Tried several pumps and finally settled on the bosch. It has to be ok...

Had STi pinks, still ran lean. Onto modified injectors which Mark had flow matched and checked.

Fuelab...not heard of them going wrong often but a possibility.

It's recently been mapped by Bob Rawle (3 or 4 weeks ago).

OK, the scene is set....took it out on the LM-1 tonight and top end it's leaning right out. I'm fed up to be honest, apart from possibly scrimping on the injectors everything has been spot on. I've tried to do the best I can! Looks like over 5k rpm it goes to like 12 AFR.

Thinking of buying a new FPR this week and trying it. It's certainly the cheapest possible fix. Failing that it's injectors and remap...

Any more suggestions about what could be causing it to run lean?

Many thanks in advance!

 

Up to 12 is some cases is not a problem, that would be down to your mapper to decide.

Have you checked there is no voltage drop to the pump, also fuel filer? Fuel lab regs very rarely if ever give trouble in my experience, and if this was suspect I would suggest checking the diaphragm first.

It’s also good to recalibrate the LM1 on a regular basis to keep a constant accurate reading.

 

Yeah, everyone seems happy with the FPR and as far as I can see I'm getting good pressure. 3 on idle, rising up to 5+ with 1.5 bar boost.

Think I'll have to do some checking with regards to voltage drops. I've never been entirely happy with the power side of things (electrical power). Thank you for your suggestion!

 

Find out the current capacity of the pump, it's probably way higher than the standard item. I would almost suggest a separate feed via a relay and a hidden "kill switch " using the correct gauge of wire. And a similar earth lead too.

dunx

 

Anyone know what current they pull above a stock pump?

 

As SlowBoy said, check you LM-1, has it been recalibrated in free air recently? Can you check it against your stock O2 sensor, this is reasonably accurate to about 11.2-11.1 AFR, so could tell you if your WB is in the ball park.

 

We'll get the LM-1 calibrated and take it out on a known good car. Then take mine out. Just finding the time with quiet enough roads (so as not to kill ourselves).

Definately going to have to check the wiring thing though, been reading about how much current the bosch pulls at 5bar of FP and it's quite high. (checking for other sources).

Cheers
Stew

 

Are you saying it was known to be running lean before the LM1?
Was it spotted during mapping?

 

It's ran lean in the past. It's been mapped twice since, both times I've had suspected fuelling issues which have led me to get a remap (once changing injectors).

Maybe it's the LM-1. I need to get it checked on another one. That said, my mechanic has tried it on other cars and it's been spot on.

EDIT - Also had two rebuilds in 16k miles since new. First time fitted Mahle pistons, second time just replaced the knackered one. Ringland both times.

 

Please let us know what the current draw of the Bosch is !

TA !

dunx

 

Hopefully off to try it on another LM-1 on Friday. Will update.

Going to ask some of the lads at work the best way of checking the current while I'm at 5 bar of pressure.

 

Quick update.

Took it out on the LM-2 today (Thanks Harvey). Still running lean toward the top end (6k+) and appeared to be lean in the midrange too.

Current tasks are
Move FPR, replace hosing and make sure everything ok. DONE (No change)
Uprate wiring to Bosch. Doing tomorrow so we'll see what happens.

Thinking of putting a 8-10 bar Bosch in. Possibly changing FPR temporarily. Beyond that, not a lot more I can think of.

 

Quick dumb idea, swap the fuel connections and back flush the fuel pick-up, to clear any debris.

Mine is managing around 400 bhp on a Walbro.

dunx

 

How's an 8/10 bar pump going to help? Go back to a std 255 walbro.
Is the fuel pump controller still wired in to the current Bosch? If so then does it allow 100% voltage?

 

Today we rewired the pump direct from the battery with a relay for switching pump on and off using the standard wiring to switch the relay.

Car ran spot on. 11.2 ish. Then we got a CEL. I think it was "Fuel Pump Primary Circuit" but will check with laptop in the morning. From then on, car ran lean again. Not dropping below 12. Ran it on LM-1. Same, so at least my LC-1 is working. Cleared the CEL and tried it again. Ran spot on, leaning out at top end as expected, but 11.2 until 6k rpm. Light keeps returning, so clearly a fault in the wiring is causing light to come on and car is entering a "limp" state. Only symptom is lean running. Still boosts etc.

Also, the hose from the tank cover to the pump was seriously degraded. Possibly been ballooning up in the tank and causing problems. This MAY be the root cause of the issue!

Anyone know how to resolve the CEL? Got a wiring diagram for that end of the car?

I'll never use a walbro ever again after a failed one taking an engine out and probably causing a second to go. Too many horror stories for me! Lots of people using them without issue, but it's a case of I've had my fingers burned, never again!

 

Well...it's back (the problem that is).

Sorted the pump/relay wiring. CEL cleared and gone. Grommets in fuel tank cover leaked when I filled to the brim so we sealed that up properly. Gave it some WOT and seemed sorted. Driving to work today, 11.2...11.5...11.9...12.0 CEL back! ARRGGHHH. What a proper ballache. Ran lean after about 4.5k but probably due to CEL. Guess it retards the fuel supply somehow when it's on. Anyone confirm? No other symptoms.

I'm really at the end of my tether. Spent about 24 hours this weekend moving FPR, rewiring pump, fannying on...still no further forward really.

Think I'm going to have to start throwing money at it, but don't know where to start.

FPR, Injectors, Pump?

Exhaust Gas Recirc system has been brought up. Any ideas on whether that could be defective somehow?

Many thanks
Stew

 

MAF scale.

It needs a bigger MAF tube and rescaled to suit in the map.

 

..

 

The fail safe fuel map would and should be much richer than the std one - it wont be that.

 

I think you need to be plumbing in a fuel pressure gauge you can read IN CAR to tell you whether it's a pressure issue or not.

Where are you based?

 

I've stuck a Defi gauge with the sensor screwed into the Fuelab regulator on mine, to monitor the differential pressure boost/fuel, this way the gauge just sits at 3.8 bar, and any movement downwards = weak mixture = ALARM !

HTH

dunx

 

Having looked at the logs now and as suspected this is topping the maf scale out - that is causing the leaning out.

The WRX ROM turns over at the top anyway and with you hitting the 295.11 max level at about 5100 it has no idea of any airflow above that and thus doesnt know that it should be adding more fuel.

You could tweak it in the map but I reckon that wold be a bodge - bigger MAF tube required (remap to suit) and job done.

 

Thanks for checking that out Duncan. Will speak to Bob about getting a slot booked in.

I've asked on the other place, but any recommendations for a bigger maf pipe/intake?

Cheers

 

Hyperflow & APS 70mm wing mount intakes spring to mind.
Surely this hasn't been the cause of all the engine failures you've had?

 

Just talking about that now...done some logging and posted on 22b. MAF certainly looks maxed out. Wouldn't be surprised if this was the root cause.

Going to ring Dave Stone tomorrow about the APS kit.

 

If it is definitely capping at 295.11 grams/sec (which by the sounds of it and from what I have seen it definitely is).... the worrying thing to me is that this affects the load calculation in the other maps aswell with most of the other important maps such as fueling and timing being related to engine load. If the MAF grams/sec reading is capping at 295.11 then going by what I think is a 400 bhp car - the MAF reading would generally be equivalent to the power at the wheels - ie around 350 grams/sec.

Therefore the car is underestimating the air flow in by 55 gram/sec - and would be going lean (dangerously lean)

Depending on how the map was done (I am led to believe not all mappers rescale the loads columns fully) it may be in a completely different load cell for timing (ie running more timing than it should) and fueling (possibly running leaner still) aswell as running leaner from the under read on the maf.

Was it the same turbo and map on the other engines?

 

Same turbo. Yeah.

Learn something new every day really

 

350 g/sec - so it could be a bit more than a 400 bhp car then , but a figure that may not have been anticipated during mapping?

Nick

 

airflow is an indication of power potential so might not be more than 400

 

It would be a pretty good 20g set up to knock out 430 bhp.
Semper, what boost profile are you running?

nick