freelander 1.8 over fueling

[wyldecyote]

Hi all, new to the forum so please be patient with me... really sorry for the long post but am trying to give you the history of whats been going on... recently purchased a 2000 on w reg 1.8 freelander with blown head gasket. Wanted one for ages and this one came up so thought i would bite the bullet and go for it.
Had my local trusted garage fit the modified multilayer head gasket/shim,stem seals,modified green inlet manifold gasket and modified studs, head skim, new modified oil ladder, new modified expansion tank and cap, new modified thermostat assembly with pipes for radiator (old thermostat removed and blank fitted), new waterpump, new cab belt/tensioner, new alternator belt, new coil, new rotor arm, new leads, new dizzy cap, new battery... dont think ive left anything out?! so thats the history of whats been recently done.

But..... now it seems i have a over fueling problem? starts perfect from cold and warms up fine, and also starts perfectly from hot. heater blows hot air, no mis fires etc. when you dab the throttle it takes upto 15 secs to drop back to tickover(which is a bit wierd), very strong smell of fumes from exhaust when hot but not when cold... and small amounts of white smoke from exhaust when warm. I have left the engine running for 2 hours and does not go above half way on temp gauge and radiator fan kicks in and out as it should with a nice hot rad and coolant does not drop at all so good coolant flow.
The idle control valve is fine as the engine revs gradually fall as the engine warms up, and adjusts the tickover when you put load on the engine like lights and heated screen. this would also indicate the ecu is reading the temp sensor ok as it knows the engine is warming up and reducing tickover as it warm up.

I have now replaced the coolant temp sensor (brown one for ecu) and read the resistance on it when its hot which is 400ohms = approx 85 deg c which is correct. I have also replaced the lambda (o2) sensor in the exhaust manifold, i have checked the voltage output on the lambda as it warm up and when warm, you can see the volts rise from .2 to .9 over a few mins as the engine warms up. from research .9v is very rich. i have checked the voltage at the ecu and also reads .9v so no break in the wires from sensor to probe, and have done the same for the temp sensor at the ecu (400 ohms) so i have no breaks in any wires. So it seems the ecu is being told the engine is warm, the exhaust gas is rich but isnt doing anything about it! i.e. leaning the mixture (reducing the injector pulse open times)....
Two things i dont quite understand 1) i cant find a inlet air temp sensor anywhere? and 2)does the throttle position sensor also control the amount of fuel injected or is that just for the hill descent etc? (as when you unplug it the hill descent and t/c lights come on!)
i am now confused as to whats going on.... and having spent quite a lot of money am starting to get a bit dis-heartened now :confused2:

any help please! thankyou...

 

[wyldecyote]

ooops left out its had new platinum spark plugs and a new catalytic convertor too...

 

[50cc]

Strange problem, how do the spark plugs look when you take them out?

 

[wyldecyote]

Hi 50cc, thanks for your reply.... all 4 of them are quite sooty after only a few hours use, and all have the same shade of black so looks like the injectors etc are ok or would have expected one to be wet or a different colour...

 

[DM68]

Have you tried adjusting the throttle cable to see if it makes a difference and since the head has been done did your mechanic re-route the throttle cable correctly because if its taking that long to drop to idle it might be getting snagged also is the fuel relatively fresh and not old fuel depending on what was in the tank when the head went on it

 

[wyldecyote]

i double checked the throttle cable and is returning to the stop position on the throttle body so its not that (worth a try though...) and the fuel is new as i filled it up from empty with 30ltrs few days ago. starting to wonder if its something to do with the tps (throttle position sensor) as when you disconnect it and use the throttle to bring the revs up to 2000rpm then let go, the throttle returns to the closed (stop position and flap closed) but the revs stay at 2000rpm! i understand the sensor is just a variable resistor thats supplied with 5 volts from the ecu and produces a output voltage in direct relation to the throttle position but does anyone know what the voltages are at various throttle positions or what the resistance should be? also from some further research spme people suggest the tps also adjusts the timing and fuel mixture in relation to the throttle position (which would kind of make sense) but can anyone confirm this? and thanks to everyone thats replied with ideas so far...

 

[Northern Irelander]

The TPS potentiometer range is 0 - 5 V

Yes injectors and fueling are related to TPS.

When you read this on Sunday morning, go out and perform one of Rover/MG best kept secrets. They would have charged you heaps of money for the privilage.

Turn ignition to position II

With ignition lights on, press throttle pedal to the floor and then fully up again 5 times in succession.

Switch key to position to 0 again.

Start after a minute and watch the k-series purr (750rpm when warm)

The MEMS 1.9 system on the dizzy cap engine can not be remapped, it's an aftermarket refit for that, very expensive for little power gain.

MEMS 3 can be remapped

 

[Darmain]

Nice one NI, hope he gets the message in time.

 

[wyldecyote]

thanks for your reply, have done exactly as you suggested, ignition position 2 (dash lights on) depress throttle to floor and release 5 times. switch to position 0 wait a min then start. its still doing exactly the same i then tested the tps, 5 volts going in on top pin, ground on bottom pin and varying voltage in relation to throttle position, idle is .65v, smooth voltage right through to full throttle 4.9v with no drop out through the travel of the throttle. so the tps is working fine. my thoughts are now turning to the map (maf equivalent) sensor built into the ecu, when i disconnect the vacuum pipe the mixture turs very lean, .1v on lambda sensor and engine running rough (as you would expect), fumes smell from exhaust dissapears after a min. when vacuum re-connected lambda reports .9v within a second very rich. then i varied the vacuum going to the ecu, the ecu switches from lean to rich with nothing in between, like a switch. correct me if im wrong but shouldnt it gradually increase the mixture with the more vacuum thats applied? also noticed when the vacuum pipe is disconnected and when you apply throttle the mixture instantly switches from lean to rich and the revs stay at whatever revs the engine went to when you applied the throttle and the mixture stays rich, even when throttle is released (would be good for cruise control! lol).... getting more puzzled by the minuite!

 

[wyldecyote]

just for the latest update....have just replaced the inlet air temp sensor and no change, still over fueling....

 

[Darmain]

It is difficult to determine what is going on without knowing exactly what the software in the ECU is doing. However, the Labda sensor is an oxygen sensor, as I understand it the ECU will run the fuelling such that the oxygen content of the exhaust is nearly, but not quite zero. That way it knows that complete combustion is occurring. I would suspect this little beast as you did.

Having just consulted the Haynes manual I notice that there are two Lamda sensors!! Front and rear. Is this true for your car and have you check both???

If the lambda replacement didn't work then either there is a connectivity problem with the ECU (Have you unplugged the thing from the wire loom and plugged it back in) or the signal conditioning or ADC stages are defective, and that means a new ECU.

Also, is the ECU happy? Have you accessed its fault codes? If not it might be worth getting it on diagnostics and find out what its problem is.

Good luck, Dave

 

[Northern Irelander]

You may have a number of issues? a diagnostic will identify some

Reset on the TPS usually does the trick, plastic throttle bodies can warp causing the butterfly valve to stick.

That doesn't explain the overfuelling.

I haven't dabbled with intercepting the signal...........not yet anyway!!

you might want to read the parts to these links:

Browser Warning

http://autospeed.com/cms/A_110625/article.html?popularArticle

MG-Rover.org forum has a modified section, not sure if anyone has tinkered, a good project if you are up for it.

Wouldn't mind seeing any definitive outcomes if you come up with any

Vorsprung Durch Technik!

 

[wyldecyote]

well i have just replaced the engine ecu with an identical unit, and now it does not want to start? re-done the tps calibration, made sure all connectors are clean and no bent pins, dash lights up as it should, fires up for a sec and then dies and wont re-start untill ignition off then back on again, plug the old ecu in and fires up straight away.... the remote keyfob still works fine (central locking etc...)does the new ecu need re-coding? .... more money! and thankyou all for your replies and help so far!

P.S....
from what i understand there is 2 lambda sensors on the engines with coil packs and no distributor (2001 onwards?), but mine is the distributor type engine (earlier one 2000 and before) so only one lambda sensor on this one....

 

[wyldecyote]

sorry last post wasnt that clear.... will fire up for a second then die, can crank it over and over and will not start, turn ignition off then on then will fire up for a second then die etc etc.... like its immoblised?

 

[wyldecyote]

just spoke to a auto electrician and yes you do have to have it re-coded to the vehicle, the main control unit (ccu) talks to the engine ecu, and if the two codes dont match up then it wont start!. so its now booked in for tomorrow for reprogramming.... then i can get back to testing to see if the overfueling problems finally cured! or will have to look into fuel pressure regulators and fuel purge canister valves....

 

[wyldecyote]

just got the freelander back after replacing the ecu and having it re-programmed...guess what..... STILL THE SAME!!!!! have now disconnected the vacuum pipe for the purge valve and blanked off the inlet pipe where it fits, that didnt cure it either.... am now gettin a bit p*ssed off with this vehicle :angry:

 

[wyldecyote]

have just ordered the fuel pressure regulator on the injection rail, and the only thing on the entire system i have not changed yet! (another £52!) so will find out on monday when it arrives if that does anything, if not then i have ran out of things to change and its been a waste of £1400 (not including buying it!) on this thing. why did i ever sell my series 2a and series 3 safari for this thing! ! ! enough to put you off landrovers for life! lol ....... well go back to a trusty series 3 anyway!

 

[eightinavee]

Cancel the order,its not a fuel pressure regulator - its just a damper.When you had the ecu recoded did they go through an adaptive reset ?
When the engine is hot and running at a steady 2000rpm what does the Oxygen sensor show - does it just stay at .9v ?

 

[wyldecyote]

ok will cancel order first thing in morning, not sure if they done an adaptive reset....(what is that exactly?) and yes the lambda reads .9v at 1000rpm/2000rpm/3000rpm, when you blip the throttle it can drop to .1 for a split second but then goes straight back to .9 and sometimes 1v.......

 

[eightinavee]

The adaptive reset makes the ecu learn the characteristics of the engine again,it should be done as a matter of course when a different/new ecu is fitted.Saying that the ecu should be trying hard to shorten the injector pulse width down enough to get the Oxygen sensor to read lean - 0v.
I think that enough has been done to the engine physically to warrant a decent checkout on Testbook - the MAP reading is critical to good closed loop control and resetting the ecu would help prove what is going on.
Mems ecu's can and do fail,I keep a known good unit on the shelf because of this,unless you know the replacement unit you have fitted is good,there could still be doubt there.
On Testbook the live data will show if the ecu is trying to run closed loop - off the Oxygen sensor or Open loop because of a sensor fault.