THE PROCESS OF ELIMINATION - ADVICE PLEASE GUYS

[blackapache]

Hi all firstly thanks to those who helped me do the first full service on the deefer, advice was much appreciated.

Anyways Ive had a surging throttle for some time now - since i got the car really. Its part of the reason i started servicing despite having been told itd just had a service before i picked it up.
It has some decent lag off the mark, but starts first time every time like clockwork idles perfectly and when its on boost its fine too i really notice the surging when im just using enough throttle to maintain speed its quite jerky throttle response - and its present in all gears high and low. from 10km/h to 110km/h

Ive devoured everything i could find on the forum about the subject.

Today i found a delaminting turbo hose and oil in the harness, ive since started the tedious job of cleaning the main harness and also ordered a new injector harness, even after cleaning plugs at both ends with contact cleaner it still seems to run the same.

I have deleted the EGR cleaned the MAF, changed the fuel filter, gearbox oils, transfer case oils even diff oils, It doesnt seem to be behaving like a faulty TPS as its not dependant on throttle position/pedal position but rather engine revs/ maintaining revs and its the same for high and low gear. Ive adjusted the turbo waste gate, but should i be able to manually move the arm? this gave some improvement but it made the revs stay on for a bit longer after easing off the pedal which was a weird sensation, like the car was driving itself.

I also found some oil leaking behind the turbo vane down onto the engine mount.. quite a bit actually though it looked like a few years of accumulation. So im wondering if the turbo is the problem though as i said its fine under boost, ive cleaned everything and will monitor any leaks over the next few weeks.

Im hoping as i get a new injector harness installed this will ease the woes? my only other thought is it may be the MAP is faulty?

can anyone tell me will the car run with the MAP disconnected? does it have a default setting like it does for the MAF so i can test it out or do i need a working example?

in short im thinking either the wastegate the harness or the MAP are my issues, maybe the fuel pump?

any other suggestions would be well listened too. cheers

[Jazzman]

I've just posted a very similar fault in the Discovery 2 section. My TD5 has a hunting throttle as well. I'll bet whatever is faulty we have the same fault. I've heard the MAP sensor needs cleaning sometimes, maybe this is the fault symptom.

[sierrafery]

Unfortunately this kind of fault is very hard to be diagnosed without tester and the process of elimination can be expensive and irrelevant some times

for example you can unplug the MAP but being double purpose MAP/IAT sensor both values(the manifold pressure and the inlet air temp) will go on default and the engine's performance will be seriously reduced... so at such reduced preformance maybe the initial symptom dissapears too but exactly due to the reduced performance not cos the fault was eliminated so you might replace the MAP/IAT sensor in vain

if there was oil in the red plug and the injector loom was replaced the oil will keep coming from the harness and needs cleaning untill it dries out cos the oil can act like an insulator and mix up some inputs, in this case the crank sensor inputs are very important too and the input is in the red plug, give electric contact spray in both ECM plugs and in the TPS plug too

there are many other issues which can cause such symptoms which are almost impossible to reveal without tester

[blackapache]

Unfortunately this kind of fault is very hard to be diagnosed without tester and the process of elimination can be expensive and irrelevant some times

for example you can unplug the MAP but being double purpose MAP/IAT sensor both values(the manifold pressure and the inlet air temp) will go on default and the engine's performance will be seriously reduced... so at such reduced preformance maybe the initial symptom dissapears too but exactly due to the reduced performance not cos the fault was eliminated so you might replace the MAP/IAT sensor in vain

if there was oil in the red plug and the injector loom was replaced the oil will keep coming from the harness and needs cleaning untill it dries out cos the oil can act like an insulator and mix up some inputs, in this case the crank sensor inputs are very important too and the input is in the red plug, give electric contact spray in both ECM plugs and in the TPS plug too

there are many other issues which can cause such symptoms which are almost impossible to reveal without tester

time to buy a nanocom then..;)

[blackapache]

I've just posted a very similar fault in the Discovery 2 section. My TD5 has a hunting throttle as well. I'll bet whatever is faulty we have the same fault. I've heard the MAP sensor needs cleaning sometimes, maybe this is the fault symptom.

im gonna work through them all methodically, i have a new cooler and ECU coming for upgrades so id like to sort this out before i go adding more horses as it seems it often makes the surging worse.

ill stick with it and let you know how i get on as we progress. If i find my fault it may help lead you to yours perhaps or at least give you some things to rule out.

[Leyland1980]

What about a problem with the throttle itself? the accelerator pedal just moves a potentiometer which are known to fail not sure if the would deliver the symptoms you describe but its worth checking.

[blackapache]

What about a problem with the throttle itself? the accelerator pedal just moves a potentiometer which are known to fail not sure if the would deliver the symptoms you describe but its worth checking.

"It doesnt seem to be behaving like a faulty TPS as its not dependant on throttle position/pedal position but rather engine revs/ maintaining revs and its the same for high and low gear."

i wrote this originally, but i haven't ruled out oil in the throttle harness. have a full day tomorrow and some more time this week to do some more fault finding. will report back on what i find guys, seems like there are a few threads on this problem but not too many definitive answers ill try add some results to the data available.

[Jazzman]

im gonna work through them all methodically, i have a new cooler and ECU coming for upgrades so id like to sort this out before i go adding more horses as it seems it often makes the surging worse.

ill stick with it and let you know how i get on as we progress. If i find my fault it may help lead you to yours perhaps or at least give you some things to rule out.



I'd appreciate that. I'll do the same.


Disco W.A mentioned he had a similar fault with a bad earth at the ECU.


http://www.aulro.com/afvb/showthread.php?p=2301308#post2301308

[BilboBoggles]

So one other interesting possiblity.



What year is your Defender? If it's post 2003 it's an EU3 engine. I've heard that if you have to replace and ECU on a Defender, and you use a factory ECU with a EU2 map in an EU3 engine or vice versa it will surge under light throttles.

[blackapache]

So one other interesting possiblity.



What year is your Defender? If it's post 2003 it's an EU3 engine. I've heard that if you have to replace and ECU on a Defender, and you use a factory ECU with a EU2 map in an EU3 engine or vice versa it will surge under light throttles.

that is interesting but im in a 2000 with the old MSB ecu

[blackapache]

I'd appreciate that. I'll do the same.


Disco W.A mentioned he had a similar fault with a bad earth at the ECU.


http://www.aulro.com/afvb/showthread.php?p=2301308#post2301308

ok so here's the deal so far,

i removed the clutch sensor it did SFA so i put it back on, checked the throttle harness near the potentiometer no oil there so that was a good sign, rehecked the ECU found more oil so cleaned it out again, and postioned the ecu on an angle to help any more oil drain out. pulled the rocker cover gasket changed the injector loom, there was oil in the plugs big time and all through the harness, put a new gasket in, used a little threebond gasket sealant as well (stopped the leaks which was nice) and around the plug itself no leaks so far - torqued it up, changes the inter cooler hoses to nice new silicon jobs and chucked the old elbow hose that was delaminating checked all the other connections and fuses, got under the passenger seat, and lo and behold we have a dual battery setup from the PO thankyou sir! it was crusty and horrible in there though so pulled those out cleaned them up and serviced them etc, one wasnt earthed properly either. checked the wastegate again and dialled it down another full turn (havent hit overboost yet) put it all back together and went for a long run into the hills.

Result? its about 80% better, yesterday it didnt seem super great but on my second run this morning the surging is like 80% better than it was, it will drive in second gear and even idle along and up hills in second gear with no throttle and no jumping about like a bipolar grizzly bear like it used to. i still feel very slight surging at 100km/h when im holding speed... its way less than before it almost feels like im driving on a windy day and the wind is intermittently hitting me front on and slowing me down a tiny bit, but its bugger all now.

my guess is adjusting the wastegate and changing the oil ridden harness were the two biggest factors affecting my engine. I have a new NNN ECU coming from Jose shortly at TD5 inside and the new allisport intercooler as well with a boost box so we'll see what difference that makes. also i'll have the chance to put it onto a nanocom thanks to help from the forum guys in my area so it'll be interesting to see what codes have registered.

** INTERESTING SIDE NOTE**

in the course of doing the fault finding an repairs i got fairly tuned into my engine with what was normal and what wasnt, after adjusting the wastegate and cleaning the harness for the first time i noticed my engine was a bit beserk, id put my foot down and it was like it was already chipped, ironically after cleaning the harness again the second time it seemed to disappear and go back to the original state.... weird.

subsequantly adjusting my wastegate has seen little improvement even using full turns. i still havent hit overboost but havent seen any substantial gains either.

overall im about as happy as i can be till i get my new ecu/boost control and cooler. im guessing that a surging engine seems to be the result of a few related circumstances not just one definitive problem with the car itself, which is why its hard to find concrete answers on the subject. for the other guys having the same problem id suggest attacking it from every angle: harness, wastegate, potentiometer clutch sensor, map etc etc that way you know for sure where you stand.. especially for me as i have only had this car for about 2 months so im still learning whats outta the ordinary and whats "normal defender behaviour"

[Jazzman]

Well done mate. Mine was a more simple fix. Replaced the boost modulator, apparently the Defender TD5 does not have one, and my problem was solved. I'm also going to see TD5 Inside shortly for a remap of my ECU. Just need a Nanocom to download the map and load the new one.

[sierrafery]

If you didnt remap it yet better ask for a remap with wide range MAP rather than boost box, IMO that voltage clamp(cos that's what it is) doesnt do any good to your engine cos it only tricks the engine management so the ECU will calculate fueling based on vitiated MAP reading corroborated with real MAF reading(which might top up with greater boost) so the addaptive strategy will be mixed up bad... though if you decide for boost box at least have an EGT gauge fitted to be on the safe side