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        General >> Give/Need advice to/from others >> fuel trims    2.3
        
(Message started by: pedropedro on Aug 1^st, 2011, 8:06am)

Title: fuel trims 2.3
Post by pedropedro on Aug 1^st, 2011, 8:06am

i started a query in obd but this seems best place.........when cold the stft sits fixed at zero and ltft is at +30% .....o2 sensor doesnt switch ,,has been changed.

Think ltft shouldnt be running so hard and suspect sensor sees air/fuel as lean....cant really figure out so need advice...engine is very lumpy when in this mode .eventually o2 sensor starts switching after 10 mins

have trace/log ve but dont know to attach

Title: Re: fuel trims 2.3
Post by scorpio_man on Aug 1^st, 2011, 8:28am

hi there

it sounds like you have an air leak somewhere. i'd check the egr pipework and the exhaust manifold, which might be cracked.

have you had the spark plugs out? what condition are they in?

you need to scan the following...

RPM
MAF
LTFT
BOTH LAMBDA SENSORS
run these for 10 mins at idle (a/c OFF). every minute, blip the throttle to 2k rpm. end this scan.
then do another scan, switching on and off various temp sensors. also check the tps with the engine off (ignition on). should be from 16% to 92% ish.

try not to drive it on the scan.

oh, check the box with auto re-connect under the GATEWAY, PROTOCOL tabs. that way it should continue to scan even if you need to re-start the engine.

save the scans and email them to me (3 parts).

There are three files for every scan, .dat, .txt and .log. As long as these three files are together in a folder, then Vehicle Explorer can play the scan back.

so you will have 2 folders with 3 files in them. save them with the name scan1 and scan2.

http://www.fordscorpio.co.uk/obdfaq.htm

hth

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 1^st, 2011, 10:35am

ok will do ..a tad confused re saving file.....when i save at end of session its just a log file...you can play back and see all data as if its live...how do i save the text and dat files ?

think it is air leak can hear under heatshield around egr a hissing noise ...

Title: Re: fuel trims 2.3
Post by scorpio_man on Aug 1^st, 2011, 11:03am

hi there

when you save the file, all 3 parts get the same name.

ie, scan1.dat, etc. you need to search in the ve program for these 3 files and put copy them in to another folder.

that's what you email to me.

hth

btw, if you can hear a leak around the egr/exhaust manifold area, that would stop your lambda from switching at start up. maybe the gap is closing a bit when heated up.

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 1^st, 2011, 11:39am

ok thanks for that ...YID

"yes it does"

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 1^st, 2011, 7:23pm

just pulled the heatshields off..what a rotten job..anyway one of the rubber tubes from the differential pressure sensor was split and hanging off the egr pipe ....sorted now and the sensor is switching when warm eg within 2-3 mins

a bit confused as thought egr would be closed when idling and it wouldnt have made any difference if that tube was off

putting back the shields a nightmare !!

Title: Re: fuel trims 2.3
Post by Tompion on Aug 1^st, 2011, 7:36pm

Strange, the metal pipes should stick out of the heat shield far enough that you can easily see if the rubber hoses are off, & since there are Differential Pressure codes you’d expect to see one.

P1400 Differential Pressure Feedback Electronic Sensor circuit Low Voltage.
P1401 Differential Pressure Feedback Electronic Sensor circuit High Voltage.
P1403 Differential Pressure Feedback Electronic Sensor Hoses Reversed.
P1405 Differential Pressure Feedback Electronic Sensor circuit Upstream Hose.
P1406 Differential Pressure Feedback Electronic Sensor circuit Downstream Hose.

The hose is between the manifold & the EGR so exhaust will come out & contrary to what you might expect air can go in making the sensor think the mixture is weak.

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 1^st, 2011, 7:47pm

my lack of experience re that part of the car,,,was looking leaks around egr pipework so thats why i removed the heat shields..yes maybe venturi effect and would suck air in as gas went past the tube....but no codes ? definitely much better by factor of x3 not lumpy when idling and sensors switching.....its not perfect but has been neglected (2nd scorp back up )

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 6^th, 2011, 12:26pm

seems as though my fix only brought the lambdas back for first 3-4 mins...its much better but still very lumpy when idling ..scorpioman ive sent log from ve for you to check out....sent email

seems as though after 3-4 mins lamdas stop maybe because its too lean .....

Title: Re: fuel trims 2.3
Post by scorpio_man on Aug 6^th, 2011, 1:17pm

hi there

i'll have a look at your scan over the weekend and let you know if i see anything.

regards

Title: Re: fuel trims 2.3
Post by scorpio_man on Aug 6^th, 2011, 1:44pm

hi there

after a VERY quick look at it, it's a bit of a mess. :-/

check for air/vac leaks and the wiring, as the figures are all over the place.

as i said, i'll have another look at it after i finish work.

might pass your scan around and get a few opinions.

will get back to you.

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 6^th, 2011, 2:55pm

thanks....john

Title: Re: fuel trims 2.3
Post by Tompion on Aug 6^th, 2011, 6:42pm

Hi,

Andrew sent me the scans, it doesn’t look as though the oxygen sensor is doing much at all, you said before you’d changed the lambda was that a new one & do you know it was the correct type?

You could try disconnecting it. I’ve just tried mine with the oxygen sensor disconnected and it ran and drove just fine – I couldn’t tell any difference it revved to the red line without problem although I expect there would be a hit to the wallet as far as fuel goes – definitely not limp mode. Surprisingly the only code was P0135 oxygen heater circuit. I’d not long come home so the engine was good and hot 205-210 ECT.

I noticed with the oxygen sensor disconnected the short term fuel trim stayed firmly at 3.1 but with it reconnected this constantly varied between .8 & 3.9

My ltft is about 10 and drops when I rev it, but you can’t really make any comparisons as I have fairly new injectors.

With ignition on engine off does your TPS figure rise & drop smoothly throughout the throttle range as I noticed it sometimes dropped to 15.7 around the time you blipped the throttle.

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 6^th, 2011, 10:19pm

Hi..yes was a new ford lambda...i will try disconnecting tomorrow but wouldnt that be the same as if it werent working ? in other words if mine were caput what difference would there be?...there is a code p0171 i think lean fuel mix which when cleared recurs

yes mine stays at 3.1 fixed doesnt move so maybe its the sensor...ive another so could try replacing..the tps seemd smooth when i looked at it earlier will double check......tks for the interest

Title: Re: fuel trims 2.3
Post by Tompion on Aug 6^th, 2011, 11:53pm

The engine management relies on the sensors giving the correct information, small discrepancies it can cope with but if a sensor is completely wrong then it manages better without it, it’ll just use a default setting. Like I say I couldn’t tell any difference with it disconnected, indeed I’ve found with most of the sensors disconnecting them has little effect on the running of the engine – but the emissions will probably be high.

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 7^th, 2011, 10:48am

any ideas why it runs smoothly during first 3-4 mins whilst lambdas working ? also why would they stop working? just dont think the lamda is faulty as it did this a year ago and had lambda changed made no difference ...

Title: Re: fuel trims 2.3
Post by scorpio_man on Aug 7^th, 2011, 10:52am

hi there

if you look at the scan, pic 03 is showing you if the car is in open loop or closed loop. most of the time it is going in to error mode (open loop). that means it's using default values, not 'live' reading from the lambda.

so at this time, we will say the lambda is working, but can't switch because of the fuelling.

what could be causing this.....
1. air leak (my number 1 choice)
2. faulty fuel regulator
3. wiring issue

i'd say you need to check everything from the beginning.

using WD40 with the straw, start spraying around both manifold and egr pipe work with the engine running. if it changes note, you've found a leak.

next check all vac pipes, including the one for the brakes.

check the spark plugs.

check all wiring.

iirc, you said 1 of the rubber pipes was off on the egr? blocked cat/exhaust?
try un screwing the lambda (leave it plugged in) and drive the car around the block to see if it's any better. mind this will be only a little better if the exhaust is blocked.

see how you get on with this.

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 7^th, 2011, 10:59am

hi...what do you mean pic 03? i can say i think can hear an air noise around egr area..i did spray that area yesterday with wd 40 no change in engine noise

the pipe was split and hanging off dont think pressure caused that but may be wrong

Title: Re: fuel trims 2.3
Post by scorpio_man on Aug 7^th, 2011, 2:51pm

hi there

pic 3 is the 3rd one down on the data tab.

fix the air leak, will imo, cure most of your running issues.

the usual place for the leak is where the side pipe joins the valve (mushroom).

hth

Title: Re: fuel trims 2.3
Post by lleewar on Aug 7^th, 2011, 6:21pm

John, the pipes on my egr blew off and split, probably under pressure. Put them back on and they blew off again. Indications pointed to the exhaust being blocked and after good advice took off the cat. The honeycomb had dropped 11/2 inches. Different car afterwards ;D Replaced the tubing with strong fuel line piping and have stayed on since. Lee

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 7^th, 2011, 6:52pm

that makes sense re blocked cat .

the connections to the egr valve are all sound..one clue, maybe a red herring; there is water coming out of exhaust pipe not much, steam really...had head reworked a year ago..wonder if water is getting into the fuel mix ? header tank needs a pint every 1000 miles

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 14^th, 2011, 4:57pm

there has to be some connection here...starts up runs smooth as a whistle for 5 mins then goes into limp mode once warm engines lumpy shakes ...any ideas there has to some connection that i am overlooking

Title: Re: fuel trims 2.3
Post by Mike H on Aug 15^th, 2011, 1:58pm

Too rich? PCM thinks engine is still cold?

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 15^th, 2011, 2:41pm

sensors sending back right temp to ecu eg 196f ..fuel trims are high and lambda doesnt switch code on obd is 0171 lean...just odd that it runs so smoothly for first 5 mins

Title: Re: fuel trims 2.3
Post by Mike H on Aug 16^th, 2011, 1:56pm

I think a big clue here is "header tank needs a pint every 1000 miles" and "water out of exhaust", does suggest coolant is leaking into a cylinder or intake somewhere (?)

Title: Re: fuel trims 2.3
Post by pedropedro on Aug 16^th, 2011, 2:23pm

yes but ive fixed that now...put some K-seal in tank totally stopped the leak .......