Did your MAS come unplugged?

Massive Boost leak?
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Had that CEL code pulled yet?

Usually that gives you a good direction to go too.

Pulled the ECU/TCU and looked for Acid/Corrosion/CAPS leaks?

More info?

Sounds a bit like what happened to me when my battery terminals got all corroded up. I was having the same symptoms you are. The day before I had accidently dropped my ratchet right onto the positive battery terminal and it hit the metal on the car. Sparks everywhere. I had to jump the car, seemed okay. Later that day though the car would start but do exactly what you described. Clicking sound and all. Ends up that the terminals and the connectors had somehow gotten a bit dirty and corroded. I scraped off the grime on the connectors and on the battery terminals. Plugged it all back in and everything now works, haven't had any problems.

So, have you looked at your terminals and the connection points? They may be dirty and basically the car isn't getting enough power so it freaks out.

gsxtacy said:

Pulled the ECU/TCU and looked for Acid/Corrosion/CAPS leaks?

Click to expand...

Definitely do that. Luckily I've never had to deal with it but I've read countless times about the infamous clicking noise under the dash that accompanies an ECU going bad usually due to the caps leaking.

We really need a big sticky like they have on the GVR4 forum telling new 1G members to check and replace their capacitors when they first get their cars.

Every single 1G ECU either has capacitor leakage, had it, or will have it unless they are replaced. It's just a matter of time.

So it you pull your ECU than the capacitors are still original, change them ASAP before you wind up repairing/replacing the ECU.

Steve

Thanks guys for the info!
Gsxtacy, stated below I don't quite know how to pull a cel, in my 94 n/a my dad and I read the ac signals coming off some plug under the steering wheel and compared it to a manual he had. But I don't remember where he plugged it in and also if it's the same as my 94.
If I pull my ECU, won't that clear my CEL?
Also, I did do that modification to my headlights that ArcticTsi did to his, "sleepy eye". I thought perhaps the rain had ruined my MAS or I got water in my head, but the head was bone dry, and unplugging the MAS and checking it for any kind of damage resulted in nothing being found. Not to mention when I fired the injectors a couple of times manually the car started for a split second.
To answer your questions, I've replaced the terminals a while ago and they are extremely clean and working fine, I've got spark to the plugs so I don't think that is an issue.
I worried that it might be bad caps in the ECU, just wanted to get everyone elses opinion before I tried anything.
Can you get new caps at radio shack or what kinda caps we talking about here?
Not to be a newb but i'm not familiar with pulling the CEL code, also the cel isn't on all the time, does it stay in some sort of memory?
Thanks, I'll update when I pull the ECU. Good thing I have half a degree in Electrical Engineering

One other quick question so I don't have to stop my productiveness, if it's not the ECU caps, what do I look at next?

Thanks.

Ok I removed the ecu and it's caps are fine, I forgot to mention, (sorry), that the ecu had been replace one month prior to me purchasing it from the last buyer, I have the receipt as well.
So should I check the coil pack now?

Thanks!

Check the alternator, you can pull it and bring it to Advance and check to see if it's still working properly. If it gets too much heat or p/s leaks on it, then it will go bad. After mine was starting to go bad, I replaced it, and noticed a smoother idle.

&nbsp;&nbsp;&nbsp;&nbsp;I could definitely check the alternator and may end up doing that as well, had a used one bought from DSMTuners classifieds that was reported good with only about 60k on it. I don't think that's the issue at this point though since the battery is charged fully and the car won't start, I don't think that would keep the car from running at least momentarily.<BR />
&nbsp;&nbsp;&nbsp;&nbsp;With full charge, a car will run awhile, and I know this because that was an issue I had already had with this car and I drove for quite some time before the battery ran out But it was okay because I knew the alternator was bad haha. I did find out something interesting but still haven't fixed the car.<br />
&nbsp;&nbsp;&nbsp;&nbsp;I pulled the ecu like said earlier and caps were fine so while the ecu was out I used a multimeter to test the power and grounds to the ecu.<BR />
&nbsp;&nbsp;&nbsp;&nbsp;<a href="http://tsipage.brianinside.com/91tsi_pinoutdiag.html" target="_BLANK">Here</a> is the wiring diagram, I found this on http://dmtalon.v8eaters.com/ecu_harness.html but now the site is down I think so I just put it on my server. Anyways I testing for power on pins 102, 107 and got 0v coming in, not good. Then when I testing pin 103 I picked up 12v or close to, (like 11.75v but whatever).<BR />
&nbsp;&nbsp;&nbsp;&nbsp;So does anyone know where a relay or fuse is for the ecu? There is a denso relay I have that's close to the coil pack to the left of it I believe in the engine bay, could this be the relay?<BR />
&nbsp;&nbsp;&nbsp;&nbsp;If it's not does anyone have a picture of it or know where it is? I want to drive my baby

Thanks guys! (gals too if they comment ) I also appreciate all the help recieved thus far, hopefully I can figure this out so others who are definitely having the same issue can benefit from my work!

The ECU uses two fuses. The MPI fuse mounted on the positive mattery terminal and the "room" fuse #19 in the drivers footwell. The MPI fuse feeds the MPI relay pin 10 mounted to the inside of the passenger side of the center console and is switched via pins 4 & 5 to the ECU pins 102 and 107. The "room" fuse powers pin 103 to provide backup power for the RAM in the ECU and the same for the radio. Pin 103 should have battery voltage on it all the time.
Pin 102 and 107 won't have any power until the ignition is on. Pin 10 on the MPI relay should have battery voltage on it all the time and switch that to pins 4 & 5 when pin 8 is pulled to ground.

If the CEL comes on for five seconds when you turn the ignition on then this is working.

Steve

Steve, thanks so much for your continued support, I have seen your posts on the other threads with my similar issue so I know you have unfortunate experience with this as well

So here's the update, I went out to the car, turned the key to on, (as far as it will go before cranking over begins), and the CEL does not come on. So this to me, (from what I've found and researched/read), that the MPI relay is faulty. I have checked the MPI fuse and it is in good working order, I tested with test light not just visual inspection, (can never be too precise).

Once again, because I wasn't sure if I tested it this way before, I turned key to on and checked for ECU pins 102, 107 for power and no power was found.

So I unplugged the MPI and I see this pinout (I just made this, because I couldn't find one):

<img src="http://tsipage.brianinside.com/images/archives/apr06/mpi_pinout91tsi.jpg" width="500" height="303" alt="91 TSI MPI Pin diagram" />

The pins circled in red are the ones that were receiving 12v. Steve, you mention a MPI pin 10 getting 12v but looking at my MPI relay there are only, physically, 9 pins on it, but there is one spot, (you can see on the diagram I made), a blank is left there where a pin could be. I'm assuming the pin count is 10 including the blank spot?

So from all the tests I did I'll write up a quick list of what I know to be true for anyone not wanting to read through everything.

Problem: car won't start after hearing a "clicking noise" from ecu, mpi, radio area.
Diagnoses: injectors aren't getting fired
Testing:
1) Checked terminals, receiving power from battery and are clean, checked past the terminals and also receiving good power.
2) Pulled the spark plugs out very dry and a little white on the tips which might mean car was running lean recently.
3) Checked for spark from plugs using a screw driver and turning the engine over, was getting good spark.
4) Unloosened bolt on top of fuel filter, turned engine over with a rag covering the filter, fuel gushed out so it's getting fuel.
5) Checked to see if "room" fuse was blown, was not.
6) Checked MPI Fuse at positive battery terminal connector with test light and visual inspection, was in working order as it appeared to be.
7) Used noid light on injector plug and had another person turn over the engine, light never blinked, not getting any grounds sent to it, thus injectors aren't firing fuel.
8) Just to check the injectors themselves I fired them manually and all seemed to be in working order with an audible click, car turned over and fired up for a split second after firing injectors manually a couple of times. (Note: this could harm the injectors so I don't take any responsibility if you fry your injectors while trying this, I had other issues like my clogged fuel filter that I thought since changed could've been sending that clogging crap in my fuel lines straight to fuel rail, so I checked it, not so however).
9) Took out ECU, took apart and examined the capacitors, not blown and no signs of heat or other exploded parts.
10) Turned key to on position, CEL is not coming on for first 4-5 seconds as supposed to, possible MPI malfunction.
11) With key turned on, no CEL, checked ECU pins 102, 107 for 12v, pins are receiving no power. ECU pin 103 (labeled as "POWER SUPPLY FOR BACKUP") is getting 12v power.
12) Unplugged MPI from under center console on the passengers side and checked what was believed to be pin 10 for power, was receiving 12v.

Hypothesis: MPI Relay is bad so MPI pin 8 isn't grounded out which turns power to pins 4&5. This would mean that ECU pins 102, 107 aren't getting turned on which means that MAF, CAS, ISC etc will not be turned on as well as injectors not getting fired up.

If there is anything else I can check let me know, I'm going to the pick n' pull here in columbus to get another relay.

Seeing as how the turbo and n/a ECU pinouts are the same for power, ground and backup power I would assume that I could use a MPI relay from a n/a car if that's all pick n' pull had correct?

Thanks again everyone and I hope my above check list clears some things up for people who've been having this issue, it's nothing new really, just a compiled list of things I've found from peoples' posts on this thread and many others on dsmtuners/pinouts etc. Perhaps make this a sticky as it seems to be a common issue for dsmers.

It's 5am but I can't stop thinking about the relay and just had to open it up to see what was up. I took the cover off of it and it looks beautiful inside, very clean and looks almost new. So I've heard "the clicking" and after I saw how these work it explains why I was hearing the clicking. These relays click loud and fast when the power is staticy these will continue to click and click because they are going through the starting cycle.

Anyways, on to the good stuff.... I don't recommend this but I'm crazy and plugged the MPI relay back in, (uncovered), while the ground terminal was disconnected. I made propped it up in a place where nothing was touching it, (normally the case top would do this but of course I don't have that on hah).

Here's the crazy thing, I turned the key and now it has a CEL, but it never turns off. I remember reading somewhere about the CEL never turning off but can't remember what I read, (it's all mixing together ).

I tried to crank it over and still nothing, however I can see the MPI relay working. The first relay switch is slamming together and then when I turn the key the other relay kicks on, now my battery is getting dead because of leaving the interior lights on and all the cranking.

Steve do you have any ideas?

My next thought for a good test, would to be unplug the one ECU plug that has the pins 102, 107 on them and hook them up to a multimeter, with the MPI plugged in and have someone turn the key to see if any voltage jumps across with it uncovered now that I have the CEL?

Thanks everyone,
Brian

Ok another update, I had my friend turn the car over while I checked pins 102, 107 for power, it's getting .4v, which to me means the contact points on the relay could be bad possibly? I'm taking the relay into my electronic bench for testing.

I'll post my finding as usual.

Alright, I'm saddened that no-one has updated with me, but it's okay I've still got enough juice in me to keep going by myself, (just wish my car was the same ).

I have tested the relay and made another diagram explaining the action and a more thorough pin layout:
<img src="http://tsipage.brianinside.com/images/archives/apr06/mpi_actionpin91tsi.jpg" width="500" height="396" alt="MPI Action/pin Diagram" />
(not bad for mspaint eh? )

Anyways, what I did was I found power at the 12v pins marked above and soldered wires to them and plugged them into a breadboard which was getting power from a computer power supply (molex connectors yellow wire supplies 12v). I then had another wire that was ground and started hitting the pins that I thought were ground and sure enough Relay 1 clicked, so I knew that was what was supposed to get grounded when the key was turned. I then found the one pin that is ground for Relay 2. I permantently soldered these grounds to the pins on the MPI because I didn't have any other way to hold them in place.

With both relays clicked, and grounded on both 12v pins I used my multimeter to find the pins 4, 5 that Steve has been talking about and low and behold I found 12v on what I labeled in my Diagram above A1, B1. So now I know the relay is good, which now I need to figure out why .4v was coming to pins 102, 107 when my friend was turning the key while the MPI was plugged in and I had a multimeter hooked up to pins 102, 107.

Here is a picture showing B1 getting 12v once Relay 2 is clicked:
<img src="http://tsipage.brianinside.com/images/archives/apr06/testing pin that goes to ecu.jpg" width="800" height="600" alt="B1 voltage"/>

So what I have happening is when the key is on, no CEL light now again for some reason, Relay 1 on the MPI clicks and I have 0v going to 102, 107. When my friend turns the key and turns the engine over I get 0.4v to 102, 107.

Is this how it's supposed to be Steve, anyone?

Thanks,
Brian

This should be the last update, as I found this issue.

When I pulled the ECU last time every cap looked fine even on the bottom of the board, but after inspecting it again today I see that they have leaked and it's slightly burnt on the bottom of the board below the caps.

So my guess was that the caps weren't leaking much yet but all the starting I've been trying to do while testing the MPI and other things has made them leak more.

Thanks to everyone who has helped.