continus flat spot no rpm rise after starting

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yellow90

yellow90

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in a new pickle
hi guys wondering if any of you can shed some light on a problem I have

shes a 2004 TD5 defender with 124566 miles on the clock
after initial start up it starts perfect but is totally flat for 5-10 seconds RPM refuses to rise at all then suddenly pics up very quick and is normal after that.
only happens from cold and goes ok the rest of the time but a friends 200tdi discovery can happily keep up with it? it seems slightly sluggish in the higher gears? I have earlier in the week replaced the injector harness and cleaned out ecu and wiring/plug as this caused a different fault
I have done a search but cannot find one with this problem

cheers :)
 
If it will rev straight up in neutral,but not pick up revs when trying to pull away straight after firing up - until 10-15 secs then most likely the maf is dead. The later engine ecu's like yours look for a plausible airflow reading from the maf as soon as the engine gets away from the starter motor.Its not sure what to do if there is no or a very low reading from the maf,after about 12 secs it will stop looking for a maf input and use a default value.This restores normal power output and the car will make progress.
Knowing why it is like this is one thing,your choice to do something about it is another.My DII auto was like this and for a while I was OK with it,then I forgot and got caught halfway across a main road with no power - not good.My car now has a new maf...
 
+1 for that^^^... happened to me too and the MAF was gone, I made several tests after that, the fact is that a good MAF will output from 50-60 at idle to around 600 at full throttle which is a linear grow together with the revs from 0.8 - 1.1V to 5V at max. ... IF the EGR is blanked the MAF lost it's main purpose but it will still disturb the management if it's faulty... now, the trick is that it's signal can be emulated using the TP sensor's track 1 signal instead of it cos this is exactly from around 1V to 5V according to the throttle position, this is doable by splicing into the wire from red plug pin 11 and bridging it to black plug pin 12 and the MAF left unplugged.... then the ECU will get a nice linear growing signal exactly as from a good MAF .... since my last MAF 'died' that's what I did to my car and it's working a treat;)
 
hi guys it does indeed seem that the maf is dead if it only picks up a default position after a certain time , this is driving me mad so will replace that asap if I have more problems then I will splice into the loom as suggested

would this also cause it to be sluggish in daily traffic? it goes well when the turbo first kicks in in the lower gears but seems a bit flat in the higher ones , my mates standard 300tdi disco will pull 60 up a hill near me but my TD5 will only pull 55 ?

cheers for the help !!! :)
 
sierrafery said:
+1 for that^^^... happened to me too and the MAF was gone, I made several tests after that, the fact is that a good MAF will output from 50-60 at idle to around 600 at full throttle which is a linear grow together with the revs from 0.8 - 1.1V to 5V at max. ... IF the EGR is blanked the MAF lost it's main purpose but it will still disturb the management if it's faulty... now, the trick is that it's signal can be emulated using the TP sensor's track 1 signal instead of it cos this is exactly from around 1V to 5V according to the throttle position, this is doable by splicing into the wire from red plug pin 11 and bridging it to black plug pin 12 and the MAF left unplugged.... then the ECU will get a nice linear growing signal exactly as from a good MAF .... since my last MAF 'died' that's what I did to my car and it's working a treat;)
Click to expand...

top man ! have done this mod to mine now and it works perfectly , much more power than before and will rev instantly after start up ! thanks very much for this piece of information its saved me loads of money and hasstle :)

you have much gratitude from me :)
 
i'm glad it's sorted... you saved yourself the money cos you believed me and you was open minded enough to try it;) ... you'll not need a anymore I Say again, as long as the EGR is bypassed, if it's not you better do that too otherwise this mod might mix things up a bit, but just if EGR is on
 
sierrafery said:
i'm glad it's sorted... you saved yourself the money cos you believed me and you was open minded enough to try it;) ... you'll not need a anymore I Say again, as long as the EGR is bypassed, if it's not you better do that too otherwise this mod might mix things up a bit, but just if EGR is on
Click to expand...

to pick your brains slightly more how do you by-pass the EGR and what happens if you don't? ( at the moment I haven't ) I don't think it would be any different to having a malfunctioning maf? although this is a mod I plan to do anyway along with a tune,de-cat, tubular manifold and a disco transfer box , want to fit cruise control too but apparently this dosent work with the disco box although I have no idea why that is?
 
for the EGR search "td5 egr bypass", the web is full... with this mod the EGR MIGHT(not necessarily) redirect more gunk in your inlet than normal that's all... get rid of it ASAP as it's bad for your engine anyway
 
sierrafery said:
for the EGR search "td5 egr bypass", the web is full... with this mod the EGR MIGHT(not necessarily) redirect more gunk in your inlet than normal that's all... get rid of it ASAP as it's bad for your engine anyway
Click to expand...

okay cheers , I was planning on getting rid of the EGR anyway as I have the same opionion on that , I have seen too much damage to engines caused by the EGR system while being in the trade
 
sierrafery said:
+1 for that^^^... happened to me too and the MAF was gone, I made several tests after that, the fact is that a good MAF will output from 50-60 at idle to around 600 at full throttle which is a linear grow together with the revs from 0.8 - 1.1V to 5V at max. ... IF the EGR is blanked the MAF lost it's main purpose but it will still disturb the management if it's faulty... now, the trick is that it's signal can be emulated using the TP sensor's track 1 signal instead of it cos this is exactly from around 1V to 5V according to the throttle position, this is doable by splicing into the wire from red plug pin 11 and bridging it to black plug pin 12 and the MAF left unplugged.... then the ECU will get a nice linear growing signal exactly as from a good MAF .... since my last MAF 'died' that's what I did to my car and it's working a treat;)
Click to expand...
Just done this mod to my Defender after my second OEM MAF died. Works a treat. No more wasting money on MAF sensors. Yippee!!!
 
well done.... i hope you dont have EGR do you...cos that's the only risk of this mod to mix up the EGR a bit that's all...so if you have EGR get rid of it and you'll have a smoothly accelerating Td5 then;)
 
Shifty1962 said:
Just done this mod to my Defender after my second OEM MAF died. Works a treat. No more wasting money on MAF sensors. Yippee!!!
Click to expand...

dont you by any chance have an EGT gauge fitted...cos i have some recent feedback that the EGT will rise with this mod... i've just ordered one to make sure
 
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