my car is still on the lean side. it has a walbro fuel pump, new fuel filter, pressure gauge reading 42psi at idle, and an hks afr that is running at 47% and still leans out after 10psi. now do i need bigger injectors? or is my fuel pump weak? or maybe something else? im looking to run up to 15psi and i cant even get passed 10, any help appreciated...

 

Perhaps it is your injectors or did you rewire the system when you added the Walbro? Good luck/skill!

 

Get some bigger injectors and an S-AFC

 

he has an AFR its the same thing.

 

mabye the injectors are 100%?

mike

 

will 4 680cc injectors be enough??/

 

Just curious......what are you using that tells you that the car is running lean?????

Just from my very limited experience, I've never seen my car run anywhere close to lean at 10psi using the stock ECU and stock injectors. But then mines a series four and maybe? the lower compression is why.

 

Hailers beat me to it. How do you know you're lean? I'd be very surprised if you're running lean unless the tuning of the AFR is completely hosed up. What do you mean when you say it's "running at 47%? Was it dyno tuned?

Also, is that a stock turbo? 10psi is OK, but 15psi is asking for early turbo death. I wouldn't want to run 15psi through the stock IC either.

 

i have a haltech haltuner a/f guage, its very accurate, i only trust it now because when i did have it dyno tuned my guage was dead accurate. im going to run a constant 12 psi on the stock turbo with a spearco front mount. and the 47% is the increment i am running on the hks afr ( max is 50% ) at 5k rpm+, once my car hits 4k rpm and up it starts to lean up a bit, to about 12.5- 13:1 all the way to 6k, i dont redline my car ever cause of it being lean.

 

In reality, you have a glorified voltmeter hooked up to a sensor that is very inaccurate at WOT. That sounds OK. Something is very wrong here. If you're increasing fuel flow by 47% it should be pouring out the tailpipes. Or am I misunderstanding how the AFR works? 10psi with a Walbro and that much correction should NOT be lean; quite the opposite. You'restill well within the limits of the injectors. I think a trip do the dyno to confirm those mixtures with a wideband is a good idea.

 

yea i agree, i am taking it in this weekend to have it on the dyno. now if it really is lean with all the settings the way they are what could be my problem? faulty injectors? i thought i wasnt going to need more then 30-40% to run safely at 10 or 12 psi, i only followed this guage because when i did have it dynoed it was right on the mark. but its probably off. when i am at wot it stays in the rich area just not maxed out ( 11.5:1 ). its like 3-5 bars short. ( 12.5-13:1 )

 

Most people reduce the fuelling when they use fuel controllers. The factory mixtures are already very rich at full load, so more power can be found by leaning them out a bit. Blown engines from lean outs are usually caused by running to much boost on the stock fuel pump. It's not the ECU or the injectors that are the problem. You've upgraded the fuel pump so that should be OK.

Fuel flow could still be a problem. How long since the filters (tank and engine bay) were replaced? Have the injectors ever been professionally cleaned? What's the fuel pump voltage?

 

Most people reduce the fuelling when they use fuel controllers. The factory mixtures are already very rich at full load, so more power can be found by leaning them out a bit. Blown engines from lean outs are usually caused by running to much boost on the stock fuel pump. It's not the ECU or the injectors that are the problem. You've upgraded the fuel pump so that should be OK.

Fuel flow could still be a problem. How long since the filters (tank and engine bay) were replaced? Have the injectors ever been professionally cleaned? What's the fuel pump voltage?

 

i changed the engine bay filter but i didnt change the in tank filter, neither did i check voltage on the fuel pump. i figured it was new so it would be fine. i do have a pressure gauge on there reading 42psi at idle. as for the injectors being cleaned , that has not been done. also where can i check the fuel pump voltage?//

 

also just curious but how much hp should i be pushing? heres the list

88 t2 stock engine 110psi on both rotors
stock turbo ( 9 psi )
stock intercooler
no air/pump p/s a/c
elec. fan
walbro
hks afr
3" tid
dual pulleys + underdrive
2.5" dp
2.5" bonez high flo cat
apexi dual n1 cat back
act 6 puck
jacobs ignition
jacobs 8.5 wires, ngk 9's

to come:

spearco front mount
12 psi

 

also manual boost controller. and will be pushing 12psi when i hit the dyno

 

It's an easy job to clean it. A clogged tank filter can make a real difference to flow. It's not the pump that's the problem, it's the wires feeding it. With the age of these cars and the fact that the charging system isn't the best, you'd be surprised how low the voltage at the pump can get. Low voltage = low flow = dead motor... That's good but it doesn't matter. It's the full load pressure that is important. This should be done. Most people (including myself) report a noticable improvement in performance afterwards. Really dirty ones could cause lean mixtures from restricted flow. You need to check it at the pump itself. The connector is on the left rear strut tower. Go for a drive with a DMM plugged into it and see how low it goes. Try it with all the electrical accessories turned on. For more info and a way to fix the problem, read this page on rewiring the fuel pump.

 

what's your fuel pressure at 10psi?

or is it under the hood?......

so you are saying you are adding 47% fuel?? and if it was set at 0 it would be stock?

at 10psi mine is leaned out more then stock...

 

ok i will have to do all that over the weekend its raining here for the next 3 days. as for the injectors i think i am just going to upgrade already. what is a good set up to go with? next year i want to put on a t-66 or something that size and a shot of n2o.

 

I agree with NZConvertible. Wait until you get your car on the dyno, and try not to push your luck. Its possible you're running very lean, and its possible you're running VERY VERY rich.

You might have a half-dead injector... or one that doesnt flow well enough.

But there's no way to tell at this point. And no O2 gauge in the world is accurate unless on the other end is a wideband O2 sensor.

 

You should be seeing about 50psi fuel pressure at 10psi boost. REwire the fuel pump for a solid 12 plus volts at all times.

See http://techedge.com.au/vehicle/wbo2/default.htm for some piece of mind.

Clean/replace the fuel pump strainer/filter in the tank. Thirty minute job.

Just a repeat of the above.

Oh, and when you do you dyno thing, just for grins, turn you headlights on and any and all other things (can't spell accessories). For the obvious reason. The alternator may not be keeping up and the fuel pump voltage may be dropping quite a bit.

 

Have you pulled a spark plug for a look-see just to make sure you aren't actually running very rich as mentioned above?

 

ok checked my fuel pump today. now with no accessories on at idle it reads 9.25v, under full boost it reads 12.10v. with the accessories on, lights, hid lights, turned on all my inside lights (because i dont have a radio right now). it read 8.75v at idle, and under full boost 11.66v. looks a little low, i think i am going to rewire it to get somewhere near 12.5-13v. i just got a brand new alternater along with a battery so its not that.

as for my spark plugs i just changed them about 50 miles ago so i doubt there is much on them. last set i removed though were lean burned.

also going to change injectors. whats a good set up to go with.

 

also i was looking a the page to rewire my fuel pump. i noticed its has the wiring for the factory resistor. i dont have one of those on my car, how do i go about rewireing? just skip all of that part??//

 

Are you sure? All Turbos had them. That's what causes the fuel pump voltage to drop to ~9V at low load. Yours is doing that, so it must be somewhere.