Severely Delayed Throttle Response - 2000 Disco 2 TD5 Auto

I carried a spare MAP sensor that I sometimes swapped on the side of the road but Ive forgotten what it cost. However I only had the spare because I began replacing sensors because LR wouldn't recognise mine's severely and IMO dangerous delayed throttle response that occurred from new. Eventually I test-swapped the MAF from a traded-in D2 (mine was the 1st D2 sold at the local dealership) and knew it solved the problem the moment I pulled into traffic. In line with this dealer's previous lack of customer support, the dealer wouldn't lend me the good MAF so I had to order and buy a new one which didn't arrive until after I had started my holidays.

Edit: I had the MAF disconnected for 2 years because the lack of throttle response wasn't nearly so bad.

Could you point me to any photos of the MAP sensor? I don't know what to look for and I can't seem to find it.

Thanks :)

David

Take off the engine cover.
Look at intake manifold.
About 150MM behind the join at the front of the manifold where the EGR butterfly is , you should see a black device sitting on the manifold but facing in towards the engine at about say 1-2 oclock, with an electrical connection on the engine side.
There is a photo of it in another post today, but it looks like a black plastic device about 40MM long shaped like 2 triangles facing each other.<>.
Undo the 2 screws, undo the electrical connection by pressing the tag in, take it out and clean it.
Regards Philip A

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Originally Posted by PhilipA

Take off the engine cover.
Look at intake manifold.
About 150MM behind the join at the front of the manifold where the EGR butterfly is , you should see a black device sitting on the manifold but facing in towards the engine at about say 1-2 oclock, with an electrical connection on the engine side.
There is a photo of it in another post today, but it looks like a black plastic device about 40MM long shaped like 2 triangles facing each other.<>.
Undo the 2 screws, undo the electrical connection by pressing the tag in, take it out and clean it.

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Thanks :) I meant to edit my post and say that I'd searched Ebay and found photos of it, but it didn't seem to edit properly. I found it, removed it (truly a 10 minute job as you say) and it was FULL of gunk. So I filled it with CC and about 10kg (ok that's a bit of an exaggeration) of black goop came out (I made an awful mess of our front veranda). Even if it wasn't the main problem (with the throttle), it certainly can't have been helping. I'm rather excited to get it back in and try it out now, see if it helps :D

I have photos:

Gunk...
https://www.aulro.com/afvb/images/im...013/12/987.jpg

...and no gunk! :D
https://www.aulro.com/afvb/images/im...013/12/988.jpg

Thanks for your help, I'll report back with the results later on :D

David

If cleaning the MAP sensor hasn't cured the problem then you may want to clean the inlet air temperature and pressure (IAT) sensor located in the lid of the airbox as it also needs an occasional good squirt of cleaner.

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Originally Posted by Graeme

If cleaning the MAP sensor hasn't cured the problem then you may want to clean the inlet air temperature and pressure (IAT) sensor located in the lid of the airbox as it also needs an occasional good squirt of cleaner.

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Well I took it for a test run and it was acting exactly the same way, which is slightly disappointing, but as there's still a lot of things to try I haven't given up hope :)

Thanks, I'll try that, though I don't know if it'll fix it, because when I took it for the test run, my brother came with me and we drove 'til it was thoroughly warm, pulled over, opened the bonnet and unplugged the MAF sensor. I floored it and it took the same length of time to start revving. We pulled over again and plugged the MAF back in, and unplugged the sensor on the side of the airbox (which I now know to be the IAT sensor), and it was still exactly the same. So we plugged it back in and finished the drive.

Very confusing :confused: Is it possible that it could still be the MAF sensor even though the throttle still waited 2-3 seconds with it unplugged?

You need to check that the MAF is getting 12V power. I'll have a look at the wiring diagram later unless someone beats me to it.

You seem to be working your way through all the possibilities,but,have you considered a voltage issue.
Check your battery/alternator and earth points thoroughly.the weirdest issues can come up from low/fluctuating power including the flashing M&S lights you mentioned.
Just a thought.

Trev.

Check engine bay fuse 2 (15A) to make sure its not blown. It powers the MAF, the EGR solenoid(s) and the wastegate modulator so would not necessarily be detected.

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Originally Posted by Graeme

You need to check that the MAF is getting 12V power.

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That's an idea. Definitely something to check tomorrow. I'll make a list of things to check so I don't forget anything :)

Quote:

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Originally Posted by trev

You seem to be working your way through all the possibilities,but,have you considered a voltage issue.
Check your battery/alternator and earth points thoroughly.the weirdest issues can come up from low/fluctuating power including the flashing M&S lights you mentioned.
Just a thought.

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That was one of the very first things we had checked repeatedly when we first had the issue with the M&S lights. The alternator is definitely working perfectly and the battery is almost brand new. I don't know about the earth points, but it's probably worth checking just in case. You can never be too careful :cool:

Quote:

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Originally Posted by Graeme

Check engine bay fuse 2 (15A) to make sure its not blown. It powers the MAF, the EGR solenoid(s) and the wastegate modulator so would not necessarily be detected.

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Another good suggestion, thanks :D I wish it wasn't quarter to eleven at night so I could go try these things out right now :mad: ;)