AAP sensor and rough idle

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northernbobber

Active Member
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165
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Funny how the circle closes. The first post i posted here started somehow the same as this. When engine is cold (now as we are hitting 5deg celcius it's even worse) my idle is rough/jerking/trying to find the idle. Something like when you cost into traffic lights and it does the search for idle routine, but its constant. When the engine gets properly warm it disappears pretty much all together. NOW, when I disconnect the AAP sensor. the engine finds the idle even as cold. I have replace the AAP sensor with a new one, but the issue remains. Since my first post I have replaced most everything like fuel pump, injectors, crank sensor etc. etc. Car pulls strong and nice and when I just give it a little higher rpm from idle the problem disappears.

I have an idea wha the AAP is doing and have a pretty good idea of the engine in general. But this I cannot erap my head around why this sensor will not work and what all it is connected to beyond MAP and turbo.

I have also deleted the EGR and the complete cooling system for it. No difference before or after. I have also removed due to this the vacuum hose that runs from the air filter box from just below the sensor and plugged it. Didn't make any difference plugged or unplugged. Should I have some vacuum in the hose?

DEFENDER 2002 TD5 110 HCPU
 
Yeah, I have been thinking about that too and that is actually next on my list to replace. It's just that Im confused why unplugging AAP sensor solves it pretty much?
 
To figure that out a live data log with nanocom is necessary...it seems that the default map for AAP open circuit is more stabile in those moments
 
Insert SD card in the slot, go to inputs fuelling and at the bottom of the page there is an icon with a disk prompt on that and follow the steps, after it says the recording started go for a ride then download the data from the card into computer
 
Ok, I got a .CSV file, since i have only mac I can open it but not get anything smart out of it. Do you think I could send it to you and maybe you can make some sense out of it?

I ran the morning with AAP unplugged, and it does also get the rough idle but way less than with plugged. Also it reaches the smooth spot much earlier. With AAP plugged I need to get the engine really warm to get it smooth, then it runs fine.
 
The only thing it shows is the injector codings. Have to do a new run. It seems like the issue is getting worse. Maybe due to colder weather but even though I run the engine real warm its hard to find the idle. The injectors are compensating a lot during the rough idle. But sporadically over all injectors up to +-20. But I have just replaced them with reconditioned ones and when I just lay my foot gently on the throttle to pick up the revs to a just a little higher idle maybe 900rpm or so. The compensations drop back to +-1 or 2. The car runs so nice when driving so i dont think its the injectors.

PS. My wipers goes on by themselves and makes one roatation maybe once or twice times per week. Could there be an electrical issue causing both of these issues? or should I just replace the wiper relay for this one?
 
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One more idea... could the rough idle be due to a faulty temp sensor? I havn't replaced that one. I seem to get normal readings to the gauge but could it still give the ECU wrong readings?
 
northernbobber said:
I seem to get normal readings to the gauge but could it still give the ECU wrong readings?
Click to expand...
At what gauge? cos the factory fitted one goes to the middle at 70*C and stays there untill 119, can be more things, download some app for pennies from the mac app store or learn somehow to convert that .csv fie into .xlsx onine to be able to show me the readings then i'll help you as i can... or if you want to go on luck replace the fuel pump cos bad injector balance without fault codes means low fiuel pressure... or leaking copper washers but i dont like to guess as long as a nanocom is availabe
 
I converted the file to .xlsx but it only showed the injector codes, I'll make a new run and see if I did something wrong. My fuel pump gave up befor so I have replaced that a few months ago with a VDO. Went thru the regulator also. I have a new filter housing waiting to be installed but all lines are cleaned and gone thru. I'll get back when I have a new file.
 
Ok, now I think I got it done. The page just doesn't let me upload an excel file so I zipped it.
 

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Is the injector loom genuine LR? , if not i'd fit a new genuine one and concentrate to set well the rocker clearances as first step cos otherwise the readings are OK, eventually replace the washers and seals
 
Thanks, the injector loom is new but not genuine (i have the paddocks 27bps version i think), is there a big difference? so i could try that first. So you also think the values was all ok except during idle? The washers and seals are newly replaced as I replaced the injectors. But I could ofcourse there can be bad washers. The thing is that I had the same issue before I replaced the loom, injectors, fuel pump and been thru a few set of washers and seals as i was playing around to find a faulty injector. I set the rockers to one turn out from seated, that should be right? I will double check them. Do you think there could be any possibility either cooling temp sensor or throttle position sensor could have something to do with this? Anyway I'll get hold of an genuine injector loome and try that.
 
The coolant temp sensor readings are OK the fuel temp input is a bit suspect cos the difference between the ECT and FT should be between 10-20 max with warm engine and your's it's bigger also at first start in the morning the ECT and FT should be similar cos the fuel and the coolant are both at the same temperature and on your's is also a difference...is the MAP sensor clean? cos the IAT reading seems a bit low on a second look
 
I cleaned the MAP just the other day just in case as I did when I did the EGR bypass and it had stayed clean and nice. That ride was done with the car standing just a few hours, so both fuel and coolant probably had some temperature left at take off. You think I should replace fuel temp sensor? could that cause the rough idle?

PS: I ordered a new LR genuine wiring assy. Lets see if that does the trick.
 
watch the inputs in the morning on cold start after it stood all night, not necessary to record it just write them down immediately after start up the ECT, FT and IAT should be very close cos everything should be settled at the ambient temperature then... IMO the FT can mix up things cos it's important part of the fuelling strategy
 
Ok, I'll do that, I'll record them just in case too. Is the fuel temperature sensor the same as coolant sensor part number ERR2081? what are the ECT and IAT short for, FT is fuel temp right?
 
Yes, ECT = engine coolant temp, IAT = inlet air temp (part of the MAP/IAT sensor's input) , and yes the temp sensors are the same
 
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