I ended up not having the time to do the vacuum hose replacement yesterday, but another propane test showed up nothing. I'll be replacing the hoses and testing them blocked off anyway.

I replaced the coil with another one, and that improved things slightly. The engine still seems to misfire on cylinders 1 & 3, so I'm starting to think cam angle sensor, or power transistor. I'd hear the odd 'sizzle' from down around between the intake and head. It was still there, still intermittent. I had my wife pump the brakes repeatedly to see if the loss of vacuum would affect the engine. It did, but due to vacuum leaking from the hose like I thought. The 'sizzle' sound came and stayed, and it sounded like it was coming directly from the #3 injector. Weeirrd...

I also figure that I have a worn/broken valve spring somewhere, which could be causing a valve to stick and a screaming sound which is probably coming from one of my exhaust cam journals and causing a leaking exhaust cam seal. None of these stay around long enough to properly diagnose.

Any ideas, rather than sell the car? It runs better, but now totally stalls all the time at intersections when I drop to idle. It ran better with the MAS totally unplugged, albeit rougher...

I also checked my grounds, and they seem to be grounded.

Damn, all the 'easy' options are going away...

I had a prolbem with the #1 & #4 cylinder not firing.

The problem was the transistor connector.
There was some corrosion on one of the pins.

BTW the engine light came on when i had that problem.
hope this helps.

Did you ever hook up a datalogger and see maybe you can find something not sensing right?..

Er...how do I come by a datalogger? (:

Damn. I did another compression test before I came to school today. Where I was getting 160's-170's a few weeks ago, I'm only seeing 145-165 now. The plugs looked fine, although #4 had a really rusty look to it, and slightly more 'burning' around the ceramic base than the other plugs, which got progressively 'better' heading towards #4.

And yes, the timing marks ARE set right. ):

Okay, get this. I did another compression test on Saturday. First of all, 2 of the spark plugs were BLACK where they were all rusty-coloured before. Now, compression is 170-180! WTF? How can it *change*, all things being equal?!? (And no, the tests were identical)

Anyway, I swapped TB's again to solve my stalling at idle problem, and it seems to work for now, so my ISC may have been bad, even though it tested fine. I also taped up my Magnecor wire boots as they were arcing through the boots as well. Swapped cam angle sensors, no change. Swapped power transistor, no change. Damn! This was pretty much all that I'd figured. However, the snapping and popping sounds that were only intermittent before were much more audible now. My wiring harness looks like it's been 'worked on' before now that I look at it closely. May be a break in the wire, or the ECU itself. My idle was still surging when cold, but would set itself at different levels when warm. (1500 one time, 2200 the next, etc.) I may have set the BISS wrong, though...

I was just doing some searches a few minutes ago and I got tons of posts by you. Looks like you've seen EVERY problem possible with your car .....and I thought I had things bad.

Your compression readings look a lot like mine now, without the wide differential though.

Is it possible high compression is a byproduct of a fresh rebuild?

Hey Troy teach me how to increase compression ) Mine is going too low.. I m getting really confused after seeing my friend's turbo engine with 180 compression.. now you, and the other guy.. what's up with talons??..
Troy, did you try a different ECU?

Chris,

To increase compression you change your pistons.

Jeff Mitchell

Gary, don't even get me started. Some people learn because they want to. I did it because I *had* to... ):

That's the way I did it, Chris. 2G pistons and racing rings, which should give 180psi or a bit more as 'factory new' spec. Why some other 1G's are seeing spikes, I don't know, but they shouldn't be. If your compression is around 145-150, I wouldn't worry. When I decided to rebuild my engine, it was at 60-60-90-120... and it still ran well. (:

Hey Troy....

A while back I posted about my high cold idle and you asked me what my vacuum reading was. Well today I finally put a gauge on it and it's 19.5 hg at idle. Sounds like a big part of your problem may be due to your massive vacuum leak. However, the cold idle issue might be a separate problem. (just what you wanted to hear huh?)

On a side note.....I used the same compression gauge on a friends awd tsi and ended up with abnormally high compression readings as well. Very similar to my readings so I'm guessing maybe my gauge is bad.

Did you use the same gauge on yours the second time around?

That's actually what I expected to hear, Gary. (: As for the gauge, I tested mine on a number of different TSi's and got vastly different readings (correct) for each. (With those low readings on my old engine, I hoped that it was the gauge. No dice. (: ) But those Equus cheap gauges are prone to be off, so test it against a known 'good' gauge and you should be able to get a replacement, or a slightly better one.

Well, played around a bit more with the car yesterday. Did the MCCC PCV cleaning. Lots of smoke. No effect. Hooked up a good battery in parallel with mine. No effect. Did find out I have a small leak from the driver's side of my turbo gasket, and around the O2 housing gasket. Unplugged some of the smaller vacuum lines without plugging them back up. Didn't really change my vacuum readings by much. Disconnected and plugged the PCV valve and intake hose. No effect. Put the new O2 sensor in to test. Tested good. Shook my head. Put the 'bad' O2 sensor back in. Tested good of course. So I ended up playing with that for a bit. Readings are sketchy after the thing heats up, but I still get *some* readings...

0.1-0.2 while warming up. Steady, no bouncing.
Spikes to 0.8-0.9x when reved.
After awhile, idle shows 0.0xxx. No bouncing. Spike to 0.9 then right back to 0.0xxx VERY quickly...

These readings tell me that I'm running so lean my motor should be exploding... Argh. Maybe I'll try installing the new sensor for
a bit longer of a test.

I played with it some more. Got the O2 sensor working a bit better. With the same plugs I used with the MCCC I was seeing 0.88 to 0.90 or so during WOT, but it didn't seem to bounce as much it should during cruise. Also, during decel, I was seeing negative voltage...

not that they are supposed to, but I've had my O2 sensor throw me some negative voltage readings too, Troy. I heard something about it being a ground loop issue when the grounding point of the meter is in a 'less than ideal' location from the ECU. I wouldn't worry about that situation too much.. your other one(s)are turning out to be quite a PITA, eh? good luck (I'm out of ideas)

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93 Talon Tsi AWD
out of the bubble and ready to rock!
my website

It wouldn't be so bad if people could give me answers other than the ones I give people. (: Usually fixing one thing solves the problem for most people. This one has been a concatenation of several...

But I think I may have discovered the ultimate cause. I removed my intake manifold yesterday and found that the damage to the gasket around cylinder #1 was worse than I'd thought. There were a few 'tunnels' made through the edges until it looks like one side was blown out a little. Hopefully the new gasket will fix the problem and everything will be hunky-dory again.

I finally got the new intake manifold gasket on.

Idle is now at 18-20in/hg, rock-solid at 1000rpm and dropping to 750rpm. This isn't even affected by my fans coming on (open K&N and 2 fans). Cold idle surge is history. Power is back, and turbo boost holds at 12psi max (by my gauge). I think I may have some other small leaks in the system, though. The timing is still well-advanced, and I haven't readjusted the BISS yet, so I think things have gone well.

The car now idles like a 4-cyl (doesn't sound like it 'lopes' anymore, damn (: ), and the exhaust pressure has dropped a bit. It's quiet and smooth with no noises or misses.

Nice long 250km drive yesterday (took her to 200k kms) in hot weather and it felt nice. Driving 'normally' gave me 200kms or so on 1/4 of a tank.

So everything is hunky-dory. Now I can rest my mind for a bit and then turn my attention to fixing up some other small things, then the suspension... Whew!

Congrats. Now I know why you have nearly 5000 posts. 11 on one thread I got so frustrated with my myriad of problems that I went out and bought a different complete motor, tranny and transfer case and all the sensors that go with them. Ported the sh!t out of everything, did all the cheap free mods, and I'm happier than a pig in sh!t. Car runs great now, but I too have several other things I should be concentrating on now. Suspension is first on the list for me too. Glad your frustration is over. I would have given up long ago.

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1990 Eagle Talon TSi AWD
My car is slow.
mzeppier@apotex.com

Good deal Troy! Glad to hear you finally got it running properly Must be a strange feeling, huh?

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91 Talon TSI FWD

Troy, everything has finally paid off! Glad to hear you've solved it. I bet you feel good.
Now, since I have the same problem as you, I have to worry about getting *my* intake manifold gasket replaced.

'bout f%&*$#g time.

You wait until I get it 'running', Adrian. (:

That's what people with money do, Mike. (: I didn't have that option, and like Marty says, it's been coming up a LOT lately. I knew that the 'engine' was good, and just wanted to track down the real problem.

Gary, let's just say that I was *scared* to actually take it over 5psi for the first 1/2 of the day... I know it won't last. (:

Troy, congrats.

How did you find the leak (or leaks )in the intake?
did you just compressed air?
If so were there any other leaks?
and what was your O2 reading before you fixed it?

When i checked my intake system there were leaks everywhere
Now i'm trying to knock them off one by one.

It's going to be awhile before i fix them all.

I was wondering how much air needs to leak out before the car starts the bog.

It was a bunch of problems, Tony, including my O2 sensor not working. It decided to fix itself later on, though. (: Readings were around .86-.90 at WOT, but remember that only one cylinder would have been majorly affected by this. I don't usually drive hard enough to have to worry about detonation, though. Now that it's fixed, I have to change my plugs and retest the O2's again.

I have a tester at the moment, but I never got a chance to use it. I couldn't detect any leaks other than one small one around ths intake manifold gasket (that we sealed, or so we thought) with propane gas. After everything else was eliminated, it was the only thing left...

I could just barely hear a leak after a hard run probably blew out the rest of the gasket on the one cylinder. Let's just say that comparatively, unplugging a few vacuum lines had no effect at all. You have to be losing a lot of air to affect the idle like that, but not so much that it can't run (disconnect PCV hose or something).

Now I get to pressure test the system and hunt down the small leaks, and I'm sure there's quite a few. (:

Troy, glad to hear you finally found the problem, after your 2 months of pure furstration I bet you enjoy driving your car again.



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91 Eagle Talon TSi AWD 13.98 @ 100.24mph
Chirped Neutral.....oh wait that was my timing belt breaking.
My Attempt at a website