Air con affecting performance when turned on, on 1999 disco 2 td5

[D2Drover]

Hi y'all
I am having a dilemma every time i switch the air con on, on my 1999 disco 2 TD5 manual, as it reduces the throttle response quite considerably. It's fine with it off but still not performing at it's optimum. I swapped vehicles with a friend and followed him and noticed a dirty black puff of smoke at the beginning of the take off, more than the usual I see coming from other td5's where their's is black but then it cleared as it pulled away and stayed clean.
It's had a recent service by a Land Rover mechanic and he cleaned sensors and cleared codes but is stumped by it's performance, as it does not have the turbo umph it should have. It's there but it runs out of steam with a top speed of 139 kph. It is dangerous to attempt to pass cars even at 90 kph.

2 things have sparked my interest, first is. The AAP sensor and the second is the clutch pedal switch, I can not find anyone mentioning any problems with the AAP sensor but at the Land Rover dealer, it is mentioned as an air con sensor also but I have guessed that that may be because that it sensors the condition of the air pressure.
The clutch switch is mentioned in the wiring diagram in connection with the air con but not directly and I can not seem to follow it's existence. The only other connection that appears is with the air conditioning clutch itself but I do not know it's full purpose, apart from engaging the compressor. But all this goes through the ECU, so I do not know what happens after that.

Any suggestions on this matter would be greatly received
Thanks in advance

D2D

[bullfrog]

Hi D2D,
I see this problem is quite isolated judging by the lack of response, however I have the same model Disco with the same symptons and would be interested to here if you've sorted it. I've always been sus of the ECU, having ruled out the obvious possible culprits. Re-occuring faults relating to EGR, ie: 07-07 vac mod short circuit, 09-06 EGR inlet throttle open load, 09-07 EGR vac mod open load and 13-06 EGR inlet throttle short circuit could have a bit to do with it. I guess a blanking kit would eliminate these. There are no other codes present. I'd be interested to here if there are any similarities with your car.

[OffTrack]

Just a comment on the first post. The aircon does not use the aap sensor. There is a dedicated temp sensor located behind the grille. From memory it is mounted on the passenger side fan support strut.

Judging by the first posters comments his issue has nothing to do with the air con. Black smoke tends to indicate lack of airflow into the cylinders. The primary cause is collapsed turbo hoses. I've seen people mention blocked air box intake and clogged filters as causes.

I'd also recommend finding a mechanic who has a bit of a clue about TD5s.

Cheers
Paul

[OffTrack]

Hi D2D,
I see this problem is quite isolated judging by the lack of response, however I have the same model Disco with the same symptons and would be interested to here if you've sorted it. I've always been sus of the ECU, having ruled out the obvious possible culprits. Re-occuring faults relating to EGR, ie: 07-07 vac mod short circuit, 09-06 EGR inlet throttle open load, 09-07 EGR vac mod open load and 13-06 EGR inlet throttle short circuit could have a bit to do with it. I guess a blanking kit would eliminate these. There are no other codes present. I'd be interested to here if there are any similarities with your car.

The faults you've listed are indicative of wiring damage to the EGR modulator harness. It's only a short run of wiring from the drivers side inner guard to the ECU so is simple to check.

That said faults like this will disable EGR operation, so won't be directly causing power loss.

It is probably worth pulling the EGR valve off and giving it a clean, and making sure the valve isn't stuck just to eliminate it as a suspect.

Cheers
Paul

[bullfrog]

Thanks for the heads up on the wiring issue, I'll be chrcking the EGR lume next available chance. I've had the EGR valve apart recently and after a good clean up and a bit of a look, everything seemed ok. So we're still in the dark with the a/c related lack of power D2D, but on your advice OffTrack I'll make a couple of well directed phone calls.

[D2Drover]

Hi guys,
Well, I have good news. When I first bought my disco, I read all of the threads I could on this forum and instructed the dealer to clean the injection harness and a few other things. When I looked at it, it appeared clean. I kept reading all I could, downloading all relevant materials and bought a Haines book, and asked my land rover mechanic to service the fuel regulator. He found the fuel filter in the regulator almost unrecognisable and took a photo to show me. While he was doing that, I cleaned the connector plugs on the ECU, with mass air cleaning spray, which were totally oiled up and hey presto, going like a charm and getting full revs. Can not wait to chip it.

I hope this helps some of you whom may be having the same problemo.

I am also having a problem with an oil leak coming from the back of the head on my TD5, when I reach my hand in, it feels like the cam seal is the culprit and am trying to devise a way of replacing it with out taking the head off, which has been quoted at $1500.00. If anyone has any suggestion, it will be greatly received.

Thanks

D2D

[D2Drover]

Thank you so much for your help Offtrack, the sensor behind the grille had a bad connection and the fan next to it would not kick in and made the air-conditioner operate under high pressure constantly.

Cheers
D2D

[D2Drover]

BTW Paul of Offtrack, I took your advise also and replaced the turbo hoses, all is good thanks mate. It did find a good and reliable Landy mechanic too, as he was schooled at the Land Rover college in England.

This forum is awesome, thanks to one and all, especially ALRO for making it possible.

D2D

[bell1975]

I am also having a problem with an oil leak coming from the back of the head on my TD5, when I reach my hand in, it feels like the cam seal is the culprit and am trying to devise a way of replacing it with out taking the head off, which has been quoted at $1500.00. If anyone has any suggestion, it will be greatly received.

Thanks

D2D

It might well be the camshaft seal. You could prise it out and reseal with suitable sealant and see if it cures it. It's not the most fun part of the engine to be doing anything with really.

But the (potential) joy of stopping a leak will be worth the skinned knuckles and swearing that your neighbours might hear from over the fence....