Bypass key transponder aerial?

[ben19td]

Hi all, just joined this forum, hoping for some advice with a problem I'm struggling with.

My car is a 1998 1.9TD (XUD) it's done 82000 miles, I'm only the 3rd owner and it has a full service history. As soon as I got the car I changed oil, coolant, all filters, glow plugs. It runs and drives beautifully.

The problem lies with starting, 8 out of 10 times it starts immediately, but sometimes the engine will crank forever and it won't start. Normally, turning it off, waiting a few seconds and then trying again will get it started, but every now and then it can take 5 minutes of repeatedly trying to get it going.

I've been reading as many threads as I can find and will be replacing the crank sensor and cleaning the pins on the ECU, but I had another thought about the aerial that receives the signal from the transponder in the keys. If the key / aerial is the problem, would it be possible for me to remove the aerial and as there are two wires coming out of it could I just hard wire the connection so the ECU thinks the aerial is permanently positive?

Any advice would be very welcome, I can live with it as it is but I would like my wife to be able to use the car too and I don't want to put her in a car that has problems starting.

Cheers guys

Ben

[markw]

The aerial isn't supplied with 12v! It's data to and from the ecu...it's recognising the chip in the key after all.
Those aerial assemblies are quick and easy to swap out...it's about the only thing on the immobilising side of things that can be. Get a used one from a scrappy or a new one...they're not too expensive I believe.
A quick look on Servicebox shows about £23.

[steve_earwig]

Just to expand on that, inside the key is a transponder chip (like the one they inject into dogs), every time you put the key in and try to start the car it interrogates the chip (via the aerial) to check it's the right key, so disconnecting/shorting the aerial will ensure that the car doesn't start at all

Just on the off chance: my D8 came with 3 keys, I had no idea about transponder chips because I'd never had a car that recent, I carried 2 keys with me (one separate, one with my door key) and it took me a while to figure out the reason it wouldn't start occasionally was because one key didn't have the chip in it

[markw]

Does that mean if a suitably chipped doggie wanders past my car, it'll start?

[steve_earwig]

Nah, it'd have to be wrapped around the steering column

[ben19td]

Thanks for the advice, I'll grab an aerial off ebay, can I just fit the new one myself or does it need to be paired to the ECU?

Cheers

Ben

[steve_earwig]

As far as I know it's just a coil of wire

[gumby6371]

I could well be (and probably am) completely wrong here but I didn't think they had transponder keys?
I thought the uber reliable and easily bypassed imobiliser keypad handled that bit on D8's?

If you're having problems starting from cold you might want to look at plugs or air in the fuel system first.

[gumby6371]

Just read your first post properly and you given her a full service, if you get lots of white smoke when she finally fires I'd be looking at removing air from your fuel lines.
2 minute job and could solve your problems.

[jonsowman]

I could well be (and probably am) completely wrong here but I didn't think they had transponder keys?
I thought the uber reliable and easily bypassed imobiliser keypad handled that bit on D8's?

Only the very early D8s (1996-97) had keypads, later ones (97-end) had transponder keys

[gumby6371]

That explains it, both of my D8's were P plates

[ben19td]

Thanks guys, will look into the fuel lines on Saturday and will swap out aerial and crank sensor too.
Will let you know how it goes.