FS-DE Running lean

bathtub · 10-01-2013, 08:36 PM

Hi guys,

Not too long ago I found a vacuum leak at the throttle body that was affecting my idle, so I pulled it off and installed a new gasket, which seems to have fixed the problem- apart from one thing. The car seems to be idling perfectly fine, but it seems to be running pretty lean, which still points to a vacuum leak. I've checked over all of my vacuum lines, and I can't for the life of me find a leak at the throttle body again. My plugs are super white and the motor is surging a little bit when held at a steady rpm - do you think it might still be vacuum leaking somewhere or could it be a different problem altogether? Seems to have only started since the issue with the throttle body gasket, but I'm not too sure, it could have been happening beforehand.

I'm really not keen on running motors lean, I've seen some pretty bad things happen. Anything you guys think I should be checking in particular?

Cosmo Dude · 10-01-2013, 09:10 PM

Once you fixed the old problem did you change the plugs?

bathtub · 10-01-2013, 09:24 PM

I didn't, would they not change color back after a bit of a run? Should I change them?

HAIGHIE · 10-01-2013, 09:34 PM

For the sake of 20 bucks just change then and clean your airflow meter and see what it's like, other wise get someone to chuck on a scantool and check the fuel trims and mixtures

bathtub · 10-01-2013, 09:47 PM

Okay, shall do

Is it going to do any damage to the motor if I run it as it is for a day or two?

Orion · 11-01-2013, 08:12 AM

Check for cracks in the corrugated pipe between the air flow meter and the throttle body - this is a common problem.

bathtub · 11-01-2013, 11:00 AM

Will do, I'll pull it off and have a look tonight. Appreciate the help!

bathtub · 12-01-2013, 08:57 PM

I've had another look around and I can't find a vacuum leak anywhere, but I did find the coolant feed into the throttle body was leaking, looks like I didn't put the hose clamp back on properly. Could that have any impact on the motor running lean?

Clean_Cookie · 12-01-2013, 10:30 PM

No. Did you check your intake pipe? That's number one on the list.

HAIGHIE · 12-01-2013, 10:45 PM

Yea check the intake pipe but that will make it run richer but check it anyways. Give the O2 sensors a clean aswell

bathtub · 13-01-2013, 04:16 PM

Intake pipe seems fine to me, there's no obvious cracks that I can see. Ill clean the o2 sensor as soon as I can get to Repco and buy something to clean it with! Electrical contact cleaner will do the trick won't it?

bathtub · 14-01-2013, 07:51 PM

New spark plugs installed and I've cleaned the MAF, so I'll see what it's like tomorrow morning on the way to work! Just a side note, I installed a K&N panel filter a while back and it was pretty covered with oil. Is there a possibility that it may have gummed up the MAF a bit?

Cliffandrews · 16-01-2013, 03:25 PM

I'd be wondering why the filter was oily. Its a fair way downstream of the TB CCase vent. Is the engine fuming heavily? That's the usual culprit, tho I hope not :-)

In some cases blow-by can alter the engine's performance as the fumes are mixing with the intake air.

To check fumes, you remove the 2 intake-manifold hoses and plug them with a golf tee leaving the rocker cover access venting to air. Idle the engine hot, and check for any fumes coming out that hole.

phildough · 16-01-2013, 04:25 PM

It is possible to over oil a K&N panel filter. This oil makes its way onto the MAF and causes erroneous readings to the ECU.
This is one of the reasons a lot of places do not recommend the use of oiled filters, they are also considered illegal in some states and countries.

bathtub · 17-01-2013, 06:50 AM

Mine came very oily out of the box. Once I cleaned the MAF, I plugged in a scantool and the fuel trims are fine. I'll let it run for a couple of days and see what the plugs look like - hopefully I've fixed it! Otherwise it could be my downstream o2 sensor sending wrong readings.

bathtub · 18-01-2013, 06:17 AM

My scantool is showing near perfect fuel trim, but my plugs are still white as!

Ice88 · 18-01-2013, 07:39 AM

You know the stock tune runs reallly lean at 3-3.5k yes?

Can try unplugging 2nd O2 sensor i think it is, should richen the mixture up.

bathtub · 18-01-2013, 08:39 AM

I didn't! My scantool only does realtime display of data and no logging, so I'm pretty limited in what I can actually see..

I just want to make sure that I'm not burning up valves and all of that nasty stuff!

marcs_sp20 · 18-01-2013, 09:20 AM

What temp plugs are you running?

bathtub · 18-01-2013, 09:23 AM

I'm pretty sure they're heat range 5?

10-01-2013, 08:36 PM	#1
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	FS-DE Running lean Hi guys, Not too long ago I found a vacuum leak at the throttle body that was affecting my idle, so I pulled it off and installed a new gasket, which seems to have fixed the problem- apart from one thing. The car seems to be idling perfectly fine, but it seems to be running pretty lean, which still points to a vacuum leak. I've checked over all of my vacuum lines, and I can't for the life of me find a leak at the throttle body again. My plugs are super white and the motor is surging a little bit when held at a steady rpm - do you think it might still be vacuum leaking somewhere or could it be a different problem altogether? Seems to have only started since the issue with the throttle body gasket, but I'm not too sure, it could have been happening beforehand. I'm really not keen on running motors lean, I've seen some pretty bad things happen. Anything you guys think I should be checking in particular?

10-01-2013, 09:10 PM	#2
Cosmo Dude コスモ Join Date: Dec 2002 Location: Location: Vic Car: Mazda '95 Astina I4, '86 B2K and '10 3 MZR-CD Posts: 7,888 View Photos By: Cosmo Dude	Once you fixed the old problem did you change the plugs? __________________ My 'stina Hatch

10-01-2013, 09:34 PM	#4
HAIGHIE Senior Member Join Date: Jun 2010 Location: wollongong Car: 99, BJ 323 astina hatch Posts: 1,506	For the sake of 20 bucks just change then and clean your airflow meter and see what it's like, other wise get someone to chuck on a scantool and check the fuel trims and mixtures __________________ Cars .. 1: 241kw Turbo 1999 BJ 323 Astina . 2: 1983 ke70 Corolla. 3: 2011 PK Ranger Wildtrak (tow car )

11-01-2013, 08:12 AM	#6
Orion SP20 Member! Join Date: Nov 2006 Location: Brisbane Car: Mazda SP20 sedan Posts: 1,769 View Photos By: Orion	Check for cracks in the corrugated pipe between the air flow meter and the throttle body - this is a common problem. __________________ Exhaust: Autoexe headers; Custom midpipe; Racing Beat catback Engine: AWR mounts; Twiggy cams; Custom CAI; RR Racing UDP; Mishimoto rad EMS: Microtech LT-10; J&S Safeguard; Gearbox: MSP LSD; Fidanza flywheel; 5th gear Rims/Suspension: MX-5 rims; Tokico Illuminas; Eibach Pro-kit; Progress RSB; AutoExe STB Exterior: MSP front lip & rear spoiler; Matt V headlights; AutoExe grill; EDM tails Interior: JVC AVX-77; Autometer gauges; DaveBs; B&M shifter Projects to come: Engine rebuild

12-01-2013, 10:30 PM	#9
Clean_Cookie obsessed-incomplete-broke Join Date: Oct 2008 Location: Brisbane Car: BA Hardtop/Hatch Posts: 5,441	No. Did you check your intake pipe? That's number one on the list. __________________ Worklog

10-01-2013, 09:24 PM	#3
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	I didn't, would they not change color back after a bit of a run? Should I change them?

10-01-2013, 09:47 PM	#5
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	Okay, shall do Is it going to do any damage to the motor if I run it as it is for a day or two?

11-01-2013, 11:00 AM	#7
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	Will do, I'll pull it off and have a look tonight. Appreciate the help!

12-01-2013, 08:57 PM	#8
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	I've had another look around and I can't find a vacuum leak anywhere, but I did find the coolant feed into the throttle body was leaking, looks like I didn't put the hose clamp back on properly. Could that have any impact on the motor running lean?

12-01-2013, 10:45 PM	#10
HAIGHIE Senior Member Join Date: Jun 2010 Location: wollongong Car: 99, BJ 323 astina hatch Posts: 1,506	Yea check the intake pipe but that will make it run richer but check it anyways. Give the O2 sensors a clean aswell __________________ Cars .. 1: 241kw Turbo 1999 BJ 323 Astina . 2: 1983 ke70 Corolla. 3: 2011 PK Ranger Wildtrak (tow car )

13-01-2013, 04:16 PM	#11
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	Intake pipe seems fine to me, there's no obvious cracks that I can see. Ill clean the o2 sensor as soon as I can get to Repco and buy something to clean it with! Electrical contact cleaner will do the trick won't it?

14-01-2013, 07:51 PM	#12
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	New spark plugs installed and I've cleaned the MAF, so I'll see what it's like tomorrow morning on the way to work! Just a side note, I installed a K&N panel filter a while back and it was pretty covered with oil. Is there a possibility that it may have gummed up the MAF a bit?

16-01-2013, 03:25 PM	#13
Cliffandrews Junior Member Join Date: May 2012 Location: Dubbo NSW Australia Car: Mazda 323Astina 2002 Posts: 37	I'd be wondering why the filter was oily. Its a fair way downstream of the TB CCase vent. Is the engine fuming heavily? That's the usual culprit, tho I hope not :-) In some cases blow-by can alter the engine's performance as the fumes are mixing with the intake air. To check fumes, you remove the 2 intake-manifold hoses and plug them with a golf tee leaving the rocker cover access venting to air. Idle the engine hot, and check for any fumes coming out that hole.

16-01-2013, 04:25 PM	#14
phildough Banned Join Date: May 2006 Location: Brisneyland, Queensland Car: 2002 Mazda Frankenstina Posts: 2,868 View Photos By: phildough	It is possible to over oil a K&N panel filter. This oil makes its way onto the MAF and causes erroneous readings to the ECU. This is one of the reasons a lot of places do not recommend the use of oiled filters, they are also considered illegal in some states and countries.

17-01-2013, 06:50 AM	#15
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	Mine came very oily out of the box. Once I cleaned the MAF, I plugged in a scantool and the fuel trims are fine. I'll let it run for a couple of days and see what the plugs look like - hopefully I've fixed it! Otherwise it could be my downstream o2 sensor sending wrong readings.

18-01-2013, 06:17 AM	#16
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	My scantool is showing near perfect fuel trim, but my plugs are still white as!

18-01-2013, 07:39 AM	#17
Ice88 Senior Member Join Date: Jun 2008 Location: Auchenflower, Brisbane Car: Blue SP20 Posts: 2,782	You know the stock tune runs reallly lean at 3-3.5k yes? Can try unplugging 2nd O2 sensor i think it is, should richen the mixture up. __________________

18-01-2013, 08:39 AM	#18
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	I didn't! My scantool only does realtime display of data and no logging, so I'm pretty limited in what I can actually see.. I just want to make sure that I'm not burning up valves and all of that nasty stuff!

18-01-2013, 09:20 AM	#19
marcs_sp20 Moderator Join Date: Oct 2005 Location: Ipswich, Queensland Car: 2002 Mazda Astina SP20 2006 Mazda 6 GY Wagon Posts: 9,769 View Photos By: marcs_sp20	What temp plugs are you running? __________________

18-01-2013, 09:23 AM	#20
bathtub Junior Member Join Date: Dec 2012 Location: Adelaide, Australia Car: Ford Laser SR2 Posts: 105	I'm pretty sure they're heat range 5?