super lean AFR/bogging/lost power

the98stang

Active Member

Aug 12, 2005

2,408

0

47

Clovis, CA

Oct 24, 2007

#1

• Oct 24, 2007

• #1

Ok I changed my plugs a few days ago and I got on it today and in the upper RPM's it bogged down. It felt like it was missing. I heard a ticking noise, but it didn't sound like a ping. My last fill up of gas was some cheaper 91 octane gas (Valero), but usually my car runs fine with that gas. My AFR is REALLY lean, like 12.5-13 AFR in the upper RPM/high load. So wtf can cause such a huge lean spike all of the sudden? Maybe I got a bad batch of gas? It'll build boost but then all of a sudden it'll loose tons of power and sort of 'bog'. How should I try and fix the problem? Any opinions are appreciated. Thanks!

Tanner

 

D

Disturbed One

New Member

Jun 26, 2005

191

0

0

Oct 25, 2007

#2

• Oct 25, 2007

• #2

I don't know much myself but maybe try adding some kind of octane booster or some higher rated gas to see if there's been a switch with all the additives that are put in the gas??

 

twogts4us

15 Year Member

Apr 1, 2004

4,188

12

79

Dunedin, FL

Oct 25, 2007

#3

• Oct 25, 2007

• #3

I trust you properly gapped the new plugs for your blown application....?
Otherwise, did you fail to re-hook-up a hose or something, allowing additional, un-metered air in?

 

hotstang_46

Member

Apr 11, 2007

481

4

18

Charlotte NC

Oct 25, 2007

#4

• Oct 25, 2007

• #4

I'll preface by saying I'm no mechanic....... but when my car started bogging in upper rpms it was driving me nuts figuring it out....

I ended up replacing the fuel filter, fuel pump filter, and the filter on the canister the fuel pump sits in........ then she cleared right up....


hope that helps!

 

2

2002BLGT

Well-Known Member

Dec 18, 2003

2,945

4

59

Bedford VA

Oct 25, 2007

#5

• Oct 25, 2007

• #5

have you changed the fuel filter?
what plugs did you put in ?
what did you gap them at ?
check engine light ?
I see you have the pro racer package have you done anything different on the tune ?
have you cleaned the MAF ?

lots of variables to go over

 

the98stang

Active Member

Aug 12, 2005

2,408

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47

Clovis, CA

Oct 26, 2007

#6

• Oct 26, 2007

• #6

I'm beginning to think un-metered air is getting in. I'm going to reposition the intake a little. I did mess with the intake when replacing the plugs. My fuel filter is fairly new. I gapped the NGK BR7EF plugs to .033 and torqued them to 13lbs. I do think there is a vac leak though. I just noticed the idle was at 1100 RPMs the other day. But it was weird because it wasn't always at that RPM when I came to a stop. I'll check the connections and report back.

 

Venom_Nitrous

Founding Member

Aug 23, 2002

416

1

0

Spearfish, SD

Oct 26, 2007

#7

• Oct 26, 2007

• #7

did you put the maf back the EXACT same way?

 

the98stang

Active Member

Aug 12, 2005

2,408

0

47

Clovis, CA

Oct 27, 2007

#8

• Oct 27, 2007

• #8

Venom_Nitrous said:

did you put the maf back the EXACT same way?

Click to expand...

I never reclocked the MAF. Anyway, I fixed the problem. When I changed the spark plugs I had to remove the intake, and when I did so, I guess I installed it incorrectly and extra air was escaping causing a vacuum leak. So I made it a more tight fit and she runs great