Erratic tick over

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E

Edgie

New Member
Posts
34
Location
Somerset
Sometimes it ticks over just fine, then for no reason it virtually cuts out, then revs up then virtually cuts out etc etc etc..... what can it be?

3.9Efi RRC... :confused:
 
and you might aswell clean out every bleedin' breather choob and air pipe you can get your hands on whilst youre there, cos theyre probably all full of gunk.

just be careful in case some of them have gone brittle.
 
Might also be the maf as when cold it runs on a factory mix (rich) and when warn it get signals to the ECU to tell how much fuel it needs so if all are working other than 1 (maf) it will get mixed messages and cause this problem test the maf with a multimeter before buying one as they ain't cheap. Could also be as simple as base idle screw needs a lil tweak
 
Check the resistance between the MAF should be 0.2v with just ign I think but there is a thread on here that goes into detail.
 
lets start simple too much info
1 clean all the pipes and the throttle housing.
2 go and buy a gen coolant ijection temp sensor
3 disconnect the battery replace the sensor leave battery off for half hour
4 refit battery and start car ensure no electrical load is on and the air con is off
5 once upto temp connect a seperate tacho dont use the car one it is not accurate engough
6 clamp the hose to the stepper motor housing and the idle will fall if it stall's release the clamp and turn the idle screw on top of the throttle housing anti clock restart and retighten the clamp the base idle setting is 520+/-20rpm once set relase the clamp the revs should rise then fall and idle returns to 720 +/- 50 rpm if it does not raise and fall then the stepper motor is faulty replace and reset. ONCE SET DO NOT ADJUST THE SCREW!!!!!!!!
7 if the idle will not set with the clamp fitted then you have an air leak issue! seal and redo
8 if you find the idle surging remove and clean the afm conections
9 at idle the air flow meter with a poor connection will damage idle and the lambdas don't effect the idle at all
 
Last edited:
vougese39 said:
lets start simple too much info
1 clean all the pipes and the throttle housing.
2 go and buy a gen coolant ijection temp sensor
3 disconnect the battery replace the sensor leave battery off for half hour
4 refit battery and start car ensure no electrical load is on and the air con is off
5 once upto temp connect a seperate tacho dont use the car one it is not accurate engough
6 clamp the hose to the stepper motor housing and the idle will fall if it stall's release the clamp and turn the idle screw on top of the throttle housing anti clock restart and retighten the clamp the base idle setting is 520+/-20rpm once set relase the clamp the revs should rise then fall and idle returns to 720 +/- 50 rpm if it does not raise and fall then the stepper motor is faulty replace and reset. ONCE SET DO NOT ADJUST THE SCREW!!!!!!!!
7 if the idle will not set with the clamp fitted then you have an air leak issue! seal and redo
8 if you find the idle surging remove and clean the afm conections
9 at idle the air flow meter with a poor connection will damage idle and the lambdas don't effect the idle at all
Click to expand...
All good info except for the last bit - inactive oxy sensors will make the engine run rich,the ecu will struggle to hold its target speed.
 
eightinavee said:
All good info except for the last bit - inactive oxy sensors will make the engine run rich,the ecu will struggle to hold its target speed.
Click to expand...
yes the above is correct on the latter engines not the 14cux system

but when cold the lambda are not used as the engine is open loop on emission

ran ran fine for 2 days with a duff lambda never over fueled
 
vougese39 said:
yes the above is correct on the latter engines not the 14cux system

but when cold the lambda are not used as the engine is open loop on emission

ran ran fine for 2 days with a duff lambda never over fueled
Click to expand...
Stuart you need to look again,even 14 CUX will be running off it oxy sensors at idle less than a minute after start up from cold - try scoping them you will see what I mean.
 
so why is it a have a friend at jlr and they do the mapping and sensor design and dont use them?
as i have 14cux tester gen dealer kit, testbook, ids and sdd covers all bases and i have never diagnosyed wrong yet it is not a case of being serious it is a case of justifing cost as testbook has one i have never needed to use it yet and when at land rover, peugeot,citroen,rover,subaru,isuzu never need or was shown we needed to use one either very odd it is only the idy's that need this tool not the dealer i have worked at previously.
 
Last edited:
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