Need help diagnosing problem
Need help diagnosing problem
history first:
so i messed with the factory adjustment screw on the maf housing and all went to crap from that, but thus far i've managed to get it back close to stock. at the same time i put on my stock intake tubing which had been sitting around for a while, cleaned it as best as i can.
situation:
okae so now when i drive in the city or traffic, the car likes to sputter (a/f jumps ranging 10.1 - 17.9), sometimes it would lunge, vibrate or just die when i get to a stop. All this time i'm thinking what an *** i am for messing with the maf, so i ordered one from aliga. Now in the past couple of days driving around like this, i noticed the problem is more apparent when i do a firm braking stop, i guess you could say it's an intermediate between hard braking and regular braking. In conjunction i also noticed that this problem does not appear when i have the AC on. So i'm stumped, part of me is thinking possible dust got into the IAC from the stock intake tubing, clogging the bearings in there or there is a vacuum leak somewhere along the lines of the brake booster. I can't be sure on any of this so here i am asking for any help from you guys.
TIA
so i messed with the factory adjustment screw on the maf housing and all went to crap from that, but thus far i've managed to get it back close to stock. at the same time i put on my stock intake tubing which had been sitting around for a while, cleaned it as best as i can.
situation:
okae so now when i drive in the city or traffic, the car likes to sputter (a/f jumps ranging 10.1 - 17.9), sometimes it would lunge, vibrate or just die when i get to a stop. All this time i'm thinking what an *** i am for messing with the maf, so i ordered one from aliga. Now in the past couple of days driving around like this, i noticed the problem is more apparent when i do a firm braking stop, i guess you could say it's an intermediate between hard braking and regular braking. In conjunction i also noticed that this problem does not appear when i have the AC on. So i'm stumped, part of me is thinking possible dust got into the IAC from the stock intake tubing, clogging the bearings in there or there is a vacuum leak somewhere along the lines of the brake booster. I can't be sure on any of this so here i am asking for any help from you guys.
TIA
Pole Position
Joined: Nov 2005
Posts: 264
Likes: 0
From: ca
did you reset your ecu when you put the new maf in? you know unplug the battery for a while and let it relearn? mayby what happened before caused the spark plugs to foul out or something, sounds like it needs a tune up kinda
Well if the car stalls or sputters when braking hard it sounds more like the pick-up in your fuel tank. (fuel filter-check)
Stranger things have happened for no apparent reason. Myself and another Mercedes owner have disconnected our batteries only to have the MAF be no good when we plugged the battery back up! (......and that is a $450 WTF?! kinda moment)
Stranger things have happened for no apparent reason. Myself and another Mercedes owner have disconnected our batteries only to have the MAF be no good when we plugged the battery back up! (......and that is a $450 WTF?! kinda moment)
Instructor
Joined: Jun 2001
Posts: 1,135
Likes: 1
From: Seattle
That sounds like a vacum leak to me.
Don't forget that it takes a few driving cycles to re-establish the new settings when screwing around with the MAF. You should only move the screw a very small amount at a time, no more than the thickness of the slot, then drive for a couple days before making any judgements.
Good luck.
Don't forget that it takes a few driving cycles to re-establish the new settings when screwing around with the MAF. You should only move the screw a very small amount at a time, no more than the thickness of the slot, then drive for a couple days before making any judgements.
Good luck.
update:
so i installed the maf i ordered from gazi. engine response is a whole lot better now. but something else happened. now when off-throttle or at a stop, the a/f ratios go to 10.3-10.6, always within that range, and the check engine light comes on. The engine doesn't sputter or anything, it just starts running rich like this now at idle. Once i give it throttle, a/f ratios go back up to the 14s. The car still dies now and then, but i'm guessing it's from the rich condition. Any ideas on why the car can be running rich at idle? also i have changed the fuel filter already, efi fuse was pulled for a good two hours before starting up with the new-ish maf. i'm stumped as to what is causing this rich condition cuz if i don't get this fixed, i think i'm screwed when emission testing comes along in a couple months. car has been driven for 70 miles already, hoping the ecu would work out of it but no luck.
so i installed the maf i ordered from gazi. engine response is a whole lot better now. but something else happened. now when off-throttle or at a stop, the a/f ratios go to 10.3-10.6, always within that range, and the check engine light comes on. The engine doesn't sputter or anything, it just starts running rich like this now at idle. Once i give it throttle, a/f ratios go back up to the 14s. The car still dies now and then, but i'm guessing it's from the rich condition. Any ideas on why the car can be running rich at idle? also i have changed the fuel filter already, efi fuse was pulled for a good two hours before starting up with the new-ish maf. i'm stumped as to what is causing this rich condition cuz if i don't get this fixed, i think i'm screwed when emission testing comes along in a couple months. car has been driven for 70 miles already, hoping the ecu would work out of it but no luck.
Last edited by LexAnt; Oct 29, 2006 at 11:19 AM.
update:
so i installed the maf i ordered from gazi. engine response is a whole lot better now. but something else happened. now when off-throttle or at a stop, the a/f ratios go to 10.3-10.6, always within that range, and the check engine light comes on. The engine doesn't sputter or anything, it just starts running rich like this now at idle. Once i give it throttle, a/f ratios go back up to the 14s. The car still dies now and then, but i'm guessing it's from the rich condition. Any ideas on why the car can be running rich at idle? also i have changed the fuel filter already, efi fuse was pulled for a good two hours before starting up with the new-ish maf. i'm stumped as to what is causing this rich condition cuz if i don't get this fixed, i think i'm screwed when emission testing comes along in a couple months. car has been driven for 70 miles already, hoping the ecu would work out of it but no luck.
so i installed the maf i ordered from gazi. engine response is a whole lot better now. but something else happened. now when off-throttle or at a stop, the a/f ratios go to 10.3-10.6, always within that range, and the check engine light comes on. The engine doesn't sputter or anything, it just starts running rich like this now at idle. Once i give it throttle, a/f ratios go back up to the 14s. The car still dies now and then, but i'm guessing it's from the rich condition. Any ideas on why the car can be running rich at idle? also i have changed the fuel filter already, efi fuse was pulled for a good two hours before starting up with the new-ish maf. i'm stumped as to what is causing this rich condition cuz if i don't get this fixed, i think i'm screwed when emission testing comes along in a couple months. car has been driven for 70 miles already, hoping the ecu would work out of it but no luck.
Trending Topics
Lexus Test Driver
Joined: Jun 2007
Posts: 1,573
Likes: 1
From: Nashville, TN
I've noticed that my SC sputters/jerks occasionally (rarely), too, rocking violently up and down, where the car acts like it's about to die (before and after I got a tune-up). It hasn't happened in a while (a month or two) but it happened again briefly a few days ago. It may be happening while the car might not be warmed up all the way yet and/or hasn't been driven in a few days (two or three). Other possibilities are the pre-cats (and/or the center cat) could be clogged, etc. or something clogged in the intake, like what is mentioned in the above posts.
ClubLexus Stories
Celebrating Lexus & Toyota from Around the Globe
Top 10 Most Confusing Things Lexus Has Ever Done!
Joe Kucinski
2026 Lexus ES Review: Lexus Re-Embraces Founding Principles
Michael S. Palmer
10 Lexus Bargains That are Cheaper Than a New Toyota RAV4
Joe Kucinski
8 Weirdest Things Lexus Has Ever Built
Verdad Gallardo
10 Lexus Designs That Have Aged Like Fine Wine
Verdad Gallardo
8 Tips for Improving Your Hybrid or Plug-in Hybrid's Efficiency!
Michael S. Palmer
10 Best Lexus Models No One Remembers
Joe Kucinski
TRD Off-Road Premium: Best 2026 4Runner, Except This One Thing
Michael S. Palmer
Top 10 Lexus & Toyotas to Drive Before You Die!
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post
sc101
SC - 1st Gen (1992-2000)
9
Nov 4, 2013 10:21 AM
ISF-88
IS F (2008-2014)
7
Aug 17, 2010 06:36 AM
