Running Lean... Really Lean

[solitaire]

Hey...

Me Again...

Car: 1990 MR2 Turbo 3SGTE

I did a dyno run a torque performance and my A/F flutates between 12 & 13... Very lean...

This car has had no mods, apart from a k&n pod and ive only had the car for a few months... Is there any way to rich it up a bit? ive just put a boost controller on and took it for a little bit of a blat and it went like stink on 14psi... but ive turned it back down to 10 as im worried it will grenade... obviously id love to turn it back up...

Im gona replace the fuel filter but does anyone have any sugestions? Any suggestion not involving buying a new ecu are valued

[sergei]

It should not grenade with good fuel/timing on 12-13:1 a/f ratio. I would be woried if it was above 13...

[solitaire]

It should not grenade with good fuel/timing on 12-13:1 a/f ratio. I would be woried if it was above 13...

Really? I was told that 11.5 was ideal... any way for me to tell what my timing is like? you think it will be ok on 14psi boost?

[Caveman]

Simple way, use an adjustable fuel pressure regulator and bump up the base pressure

[solitaire]

Simple way, use an adjustable fuel pressure regulator and bump up the base pressure

A higher base pressure will force more fuel in? (sorry i got no clue as you can tell)

[Ako]

Extra simple way: Change your fuel filter, taking a wild guess here but 9 times / 10 they never get changed (why bother? The next owner can do it!)and will cause a car to run slightly lean. Every car I've ever bought has never had the fuel filter done, especially if its' in a bad spot.

A stock MR2 shouldn't be that lean, no way. Even running big boost they have quite rich mapping.

[Caveman]

Simple way, use an adjustable fuel pressure regulator and bump up the base pressure

A higher base pressure will force more fuel in? (sorry i got no clue as you can tell)

Yes more pressure in the rail will mean more fuel through the injectors at the same duty cycle. Increase the pressure at a linear rate with boost.

But ako is right, do the maintenence first, might fix the problem.

[MR2SIK]

A stock MR2 shouldn't be that lean, no way. Even running big boost they have quite rich mapping.

hmm does sound odd, mine was sitting at 10:1 while boosting 17.5psi- even a spike to 19psi didnt phase it
still stock fuel system afaik

[solitaire]

A stock MR2 shouldn't be that lean, no way. Even running big boost they have quite rich mapping.

hmm does sound odd, mine was sitting at 10:1 while boosting 17.5psi- even a spike to 19psi didnt phase it
still stock fuel system afaik

Right... ill do the fuel filter... thanks lads

If i need to upgrade the regulator what do i buy? just walk into repco or what?

[Ako]

The reg shouldn't be an issue - its more of an upgrade than maintenance.

Cheapest decent adjustable reg is the SARD reg - around $230, plus a fitting for your fuel rail, plus a wee bit of fuel hose. I can supply it - but you don't need it.

Do the maintenance - get a new filter in there, your pump maaaay be on its way out (I've seen it before, mainly nissans and subbies though) but I wouldn't put money on it just yet.

Do the cheapest things first, if they weren't the problem - its at least stuff which probably needed doing anyway and will be contributing.

Also... Check that the dyno was using a WORKING, CALIBRATED 02 sensor. You may be spending money for no good reason.

Another thing to check is the fuel pressure - the garage who did your dyno run can do this for you. If you've got the right pressure across the rev range, then the issue is somewhere else entirely, the engine will be recieving enough fuel. If you see the pressure fall over up top, my guess is on a dieing fuel pump. If its low all over, I'm picking a blockage from the filter.

[Caveman]

Another maintenence issue which could cause the problem is dirty injectors. Costs about $100 to get them cleaned, new seals, new seats and flow tested. If your worried about piece of mind you should do this eventually.

[solitaire]

The reg shouldn't be an issue - its more of an upgrade than maintenance.

Cheapest decent adjustable reg is the SARD reg - around $230, plus a fitting for your fuel rail, plus a wee bit of fuel hose. I can supply it - but you don't need it.

Do the maintenance - get a new filter in there, your pump maaaay be on its way out (I've seen it before, mainly nissans and subbies though) but I wouldn't put money on it just yet.

Do the cheapest things first, if they weren't the problem - its at least stuff which probably needed doing anyway and will be contributing.

Also... Check that the dyno was using a WORKING, CALIBRATED 02 sensor. You may be spending money for no good reason.

Another thing to check is the fuel pressure - the garage who did your dyno run can do this for you. If you've got the right pressure across the rev range, then the issue is somewhere else entirely, the engine will be recieving enough fuel. If you see the pressure fall over up top, my guess is on a dieing fuel pump. If its low all over, I'm picking a blockage from the filter.

Legend, Thanks mate... im defintely doing the fuel pump... just wanted to check about the other thing while i had a captive audience

Im going to torque performance next run so ill see if they will check the fuel pressure as well...

[solitaire]

Another maintenence issue which could cause the problem is dirty injectors. Costs about $100 to get them cleaned, new seals, new seats and flow tested. If your worried about piece of mind you should do this eventually.

cool thanks mate any mechanic will do this?

[Caveman]

Another maintenence issue which could cause the problem is dirty injectors. Costs about $100 to get them cleaned, new seals, new seats and flow tested. If your worried about piece of mind you should do this eventually.

cool thanks mate any mechanic will do this?

They could but I would take it to a specialist, better service. There are a few in auckland, one on kyber pass which I got mine done for $120.