Author Topic: 1Z TDI horrible idle (Read 6684 times)

MikkiJayne · « **on:** November 26, 2007, 12:52:01 pm »

Hi everyone,

I've just put a 1Z TDI in my Corrado and amongst other niggles it has a really really horrible idle. It sits steady at ~850rpm, but shudders so badly it makes the whole car vibrate :x

If I give it a little throttle it smooths out at 1000rpm to a much more acceptable level. It starts fine, warm or cold although it struggles to warm up above 70C/160F. The one time I did get it to 90/190 sitting in traffic it made no difference to the idle.

I don't think there is any air in the lines, as it has a lift pump, and I can't see any bubbles.

Does the TDI ECU learn the characteristics of the engine? Poking around in Vag-com I've found some individual cylinder settings which are apparently random. Is something the ECU will work out, or is this entered manually? I'm not using the original ECU for the engine, and wondering if this is whats causing the problem?
If it's a manual job how do I go about setting them?

This is really spoiling my TDI experience and I want to get it sorted out, so any suggestions are welcome

Tia, Mikki x

jtanguay · « **Reply #1 on:** November 26, 2007, 05:11:28 pm »

how are the motor mounts? i don't think the original corrado motor mounts can handle the diesel vibrations??? my old 1.6 vibrated the dash so bad at idle... :lol: thought it was going to vibrate itself to death!

have you done any compression checks? injectors good? could be the ECU, but probably not. the computer adjusts the timing to give a smoother and quieter idle. the mechanical TDI's are often much louder.

my best guess is injectors. spray pattern or opening pressure. either that or there is a sensor giving false reading so the ECU can't do its job properly.

MikkiJayne · « **Reply #2 on:** November 27, 2007, 03:20:59 am »

Motor mounts aren't great. I have a new hydraulic tranny mount, mk3 type rear engine mount and original front mount. Looking at the aftermarket parts listings the front mount on the mk2 16V is the same as the TD, but the mk3 TDI diesel mount is different. They're not too expensive so I may replace them if I can't solve it any other way.

The ECU isn't coming up with any codes so I'm assuming all the sensors are ok. I haven't got a diesel compression tester, but there's no way I'm taking this one apart after the last one!

I don't think it ran so rough in the donor, so maybe the ecu needs more time to adjust to the engine? I've done about 100 miles in it so far and it drives really nicely - smooth under power and pulls very well.

I had a look on TDIclub last night and may try lifting the idle to 950 as it seems a bit low at 840. Maybe also fiddle with the IQ and try the hammer mod :wink:

Possibly some fuel system cleaner would help?

jtanguay · « **Reply #3 on:** November 27, 2007, 09:46:31 am »

never hurts to try a good fuel cleaner.

Slave2School · « **Reply #4 on:** November 27, 2007, 11:57:06 am »

What is the injector balance like? If the numbers are way off cylinder to cylinder maybe you injectos/nozzles are gummed up form sitting and need cleaned or replaced.

mk2tdi · « **Reply #5 on:** November 27, 2007, 02:16:58 pm »

Quote from: "MikkiJayne"

Motor mounts aren't great. I have a new hydraulic tranny mount, mk3 type rear engine mount and original front mount. Looking at the aftermarket parts listings the front mount on the mk2 16V is the same as the TD, but the mk3 TDI diesel mount is different. They're not too expensive so I may replace them if I can't solve it any other way.

The ECU isn't coming up with any codes so I'm assuming all the sensors are ok. I haven't got a diesel compression tester, but there's no way I'm taking this one apart after the last one!

I don't think it ran so rough in the donor, so maybe the ecu needs more time to adjust to the engine? I've done about 100 miles in it so far and it drives really nicely - smooth under power and pulls very well.

I had a look on TDIclub last night and may try lifting the idle to 950 as it seems a bit low at 840. Maybe also fiddle with the IQ and try the hammer mod :wink:

Possibly some fuel system cleaner would help?

how do you change the idle? and what is the hammer mod? i like what youve done with the raddo

MikkiJayne · « **Reply #6 on:** November 27, 2007, 02:42:57 pm »

Changing the idle is done with Vag-com. I tried it earlier and it made it much much better, but I have to activate the software before I can save the changes :x I don't mind that, but I've run out of money! :cry:

The hammer mod is basically loosening three torx screws on the top of the injection pump and hitting it sideways with a hammer :shock: This changes the calibration of the pump by moving the fuel quantity thingy I think. Have a search for it on TDIclub.com - there are many many threads on it showing exactly how to do it

Mikki x

mk2tdi · « **Reply #7 on:** November 27, 2007, 03:20:12 pm »

cool ill have to have a play woth vagcom then! shame your not closer mines registered, i understand what you mean about the hammer mod now seems to risky to me

lord_verminaard · « **Reply #8 on:** November 28, 2007, 08:41:12 am »

IIRC the factory idle of a TDI should be around 960 rpms. They tend to shake like crazy at anything lower than that.

Brendan

MikkiJayne · « **Reply #9 on:** November 28, 2007, 08:49:00 am »

Well is was 840 :? I've set it to 925 now and it's much better but still rattles the car. I didn't get to check the injector numbers cos the laptop went flat. I'll do that later and post the numbers up.

Mikki x