p38 keeps changing down gear

i there, i have a problem with my 1995 p38 range.

it all started when i pickd the car up and developed a mis fire on the way home, this in turn knocked one of my cats out.

so i preceeded to fix the mis fire problem in which i fitted a set of leads and plugs and a new ignition pack, problem solved.

i then replaced my catalytic convertors, and whilst i was there i fitted 2 new lambda's and mine were duff after i tested them

then upon the test drive i noticed a flat spot between 2-3k revs which i couldnt excellerate through but when it cleared the vehicle took off like a rocket.

so took off the idle control valve and cleaned it, also the MAF and cleaned it with some MAF cleaner i had bought. i also found that one of the wires from the maf to the ecu was loose in the ecu holder, so i changed the pin and made it all good.

so i took it out on a drive and a new problem has arisen, now not only does it have a flatspot but it seems to hold the car in gear longer and when the car changes into second with very little throttle it keeps 'kicking down' even though i havent moved my foot on the accelerator

so i did some research and found quite a few ppl had the same problems with the mass air flow sensor MAF. so i proceeded to change this with a second hand but genuine one, and the problem is still there.

it keeps dropping down a gear even with the slightest throttle

anyone have any thoughts, i was thinking maybe the tps switch, but would like some other people opinions

I have no real idea about the petrol P38's as far as the engine stuff goes BUT when you change the MAF don't you need to reset the adaptive values??

Have you had the vehicle on a diagnostic machine at all??

-Wills

i have my own generic obd II reader, and its displaying 0 faults, everything else is working ie lambda etc

p38 beasties eh.....sell it.

its nearly at that stage...

No fault codes does not mean alot,live data will help here,but you need to understand what data is bad.A reset of its adaptive values will probably help if the original MAF was dying.A secondhand one if its working OK will be better than a cheapo from E-Bay,but without checking its output via live data you wont know.
The Gems is a reliable and clever system even by todays standards,but it does need a good level of understanding if it faults.

ok thanks for that,a litle bit more info on this, it only seems to do it at 1/3rd of throttle, and its as if the car is confused as to when it should kick down and when to change gear, which is what ive readin the past as regard to MAF faults?? correct me if im wrong?

also how would i go about getting the adaptive values reset?

how about if i take some live data reading and post on here? would that help?

is there 2 kick down stages on the rangie? as i can boot it through the floor and have no probs butjus a lil throttle (what id call kick down stage 1) and it mis behaves like a bugger

had my range on a computer an its saying it has a miss fire

do you think new plugs, leads will solve this...?

im feeling no mis fire though, one mechanic said it maybe to do with the lpg...?

i hate fault they unease me!

how easy are the lambda sensors to change? any online guides?

just noticed this morn that my original maf was a lucas item, and the replacement is a sagem unit, but both are the 20am type, should this matter

Doubt it as if it catches fire walk away...............

i may help it on its way, well im gonna bite the bullet and have it diagnosed via testbook to get to the bottom of this problem
!

i had diagnosed and it came up with faulty tps switch and fuel temp switch

so i changed them and still doing it, im now thinking possibly the replacement maf was faulty or ecu problem

anyone got any more suggestions before i report it stolen? :lol:

wack a set of carbs on it and a manual box......................Job done.

mine is a ****in toooooooool like that esp on gas

no electra****erie for me/...............do it:amen:

214_si said:

i had diagnosed and it came up with faulty tps switch and fuel temp switch

so i changed them and still doing it, im now thinking possibly the replacement maf was faulty or ecu problem

Click to expand...

Unlikely to be the ECU,can you get any live data from the MAF ?

i most certainly can tomorrow matey, am barking up the right tree here with the maf???

the guys at dakar 4x4 (who ive been dealing with a lot) are being stars tomoz, they have a brand new in the box genuine land rover maf, they are gonna fit it to my rangie and let me take it for a drive,and also reset the adaptive values.

if this cures it then they will try and source a good second hand one for me as they said the OE one will cost me an arm and a leg,

must say these guys are very helpful,!

when i mentioned the ecu i was on about the automatic gearbox ecu's under the passenger seat??

cheers for the help here matey, u dont know how much of a relef it is just to discuss the problem with someone, i am really losing my patience now with it! i knew rangies wernt the most reliable but this one has taken the biscuit!

well, bit of an update.

have changed absolutley everything now apart from the ecu's, so im thinking there is a problemwith one f these

gonna start with gearbox ecu, coz its the cheapest, then the engine ecu before finally the becm

GLAD THAT IM NOT ALONE WITH THIS PROBLEM!!
seriously though ..mines is doing exactly the same and its drivin me nuts!!
was driving brilliant before, just was a little rough on idle ..usually cut out.. so like you i replaced the iac valve ..and hey presto!! all the gearcganging problems began ..wouldnt change up til she hit 5000 revs ..she was fkn flyin!!!
i dissconnected the tp sensor and now she changes at a more sensible point of 2500 revs..but like yours it changes down with the tiniest of movement on the pedal..i can BOOT IT and it responds brilliantly but changing up and down and up etc...etc
please let me know if you get yours solved and help me get her back to how she should be..if i get mine cured i will let you know.
living in hope COOL TRUCKER

i most certainly will matey, im currently having the ecu's changed, may have to go down the root of an adaptive value reset or new gearbox if this doesnt cure it

im wondering if we have been supplied the wrong IAC valves? anyone know if the are diffrent between the later and earlier engines

what year is your vehicle