More test results, getting scared now!

lendaddy · 07-10-2003, 05:25 AM

I pulled the injectors last night and put them in glasses. All exibited good atomization (these were ultrasonically cleaned a year ago) and the volume was very similar on all of them. I watched the spray at different sensor plate positions and all remained well. I think I can rule out the fuel system all together.

I also put in the new MSD 6AL box (seemed to make a noticable difference, but still stumbled under load) with new blaster coil, new plugs (3rd time), new cap and rotor. Now I am afraid that I do indeed have a burnt valve or piston. I am building my leakdown tester today and we shall see but I have that sinking feeling in my gut about it. Other than that I have not changed my 1 year old Magnacores as I cant imagine thats it but who knows.

My first child id due in December and my wife just lost her job since we could not relocate with her company to Cali so this is not a good time to be spending dough. Someone tell me it could still be something simple!

Jim Richards · 07-10-2003, 05:37 AM

I hope your leakdown passes, then try the magnacores. Or try the magnacores first if you have someone nearby that'll swap them with you.

724doorE · 07-10-2003, 05:53 AM

Stumble under load, I seem to recall you going round and round with your distributor last year, so I hope its not that, but wouldn't lack of proper advance at rpm under power cause a stumble?

lendaddy · 07-10-2003, 06:01 AM

Yea, I did have dizzy issues but I bought a brand new one from Andial late last year. I did not check for "proper" advance(I don't want to rev it to 4k in it's current condition) but with a timing light it certainly does advance smoothly. I also checked for vacuum leaks with carb cleaner and found nothing.

724doorE · 07-10-2003, 06:06 AM

Dumb question, did you cleanand regap the plugs after installing the msd?

724doorE · 07-10-2003, 06:07 AM

And use the correct msd coil. MSD likes in the neighborhood of .050" gap.

Mr Beau · 07-10-2003, 06:10 AM

Make sure all plugs are new, and try to borrow someone else's plug wires. Magenecores do not have the best reputation in some circles. Have you hooked-up a timing light?

lendaddy · 07-10-2003, 06:11 AM

Yep, brand new plugs with new blaster coil, gapped to .035". You can't get as aggressive with the gap on a turbo as under boost pressure it is more difficult to produce a spark. I tried .045" last year and fouled one within 50 miles.

lendaddy · 07-10-2003, 06:22 AM

Yep I hooked up a timing light to every wire and I get good consistant strobe. Plugs are new. With the idle off slightly I get just less than my 7 degrees required retard at 950 rpms but I figure that could be a funtion of the poor running. I would say its's at 4-5 degrees. I let it warm up more the other day and it idled better but still missed under load. (the timing got closer to 7 degrees retard when warm as well). I would like to believe it is a vacuum leak but I cannot find anything!

724doorE · 07-10-2003, 06:27 AM

Could you have a bad fuel pump, maybe that is causing you missing at power. Maybe your airbox has a crack in it? I don't know beans about cis though....

RoninLB · 07-10-2003, 06:27 AM

Quote:

Originally posted by lendaddy

I also checked for vacuum leaks with carb cleaner and found nothing.

lendaddy · 07-10-2003, 06:37 AM

As far as the fuel pumps go I don't think I have a problem there. I checked the flow rate and was actually higher than spec by a little. I checked system pressure and got 87 psi, right on spec. I checked the injectors into bottles and all looked the same and atomized nicely, volume was close but I had a little air in some from disconnecting them which takes a couple seconds to work out.

I am curious about the leak detector, how much and where can I get one? Thanks

RoninLB · 07-10-2003, 06:45 AM

Quote:

Originally posted by lendaddy

I am curious about the leak detector, how much and where can I get one? Thanks

I suggest you ask around for a mechanic who has one.. or ask the Snap-On man.. then drive over..I think another distributor, like OTC, may have them for about $100 .................Ron

Superman · 07-10-2003, 07:13 AM

lendaddy, you're doing the right thing by conducting these tests now. I'd agree that it looks as if your fuel and ignition systems are working properly. Further tests are in order and perhaps you will find that there is a mechanical problem with your combustion chamber(s), like a bent valve. Maybe, maybe not. Testing will tell, eventually.

It sounds like you're worried, so let me just make a comment about what a 'worst case scenario' would look like. If you can use a compression and leakdown tester, then you can rebuild a motor. For the cost of a new valve and a fistful of gaskets, you can be back on the road. I'm saying that, in a budget overhaul, you can probably be in and out for just a few hundred dollars.

Perhaps I should not have talked this way. I think your testing should continue. But if you're imagining gloom and doom, I wanted to sprinkle a little reality on your pessimism. A valve is perhaps $50. Gaskets, cam housing sealer, etc., will be another $100-$150.

lendaddy · 07-10-2003, 07:30 AM

Thanks Sup, but I don't know if that actuall the worst case scenerio. A holed piston or burnt crown would lick monkey spider!

Jdub · 07-10-2003, 07:37 AM

Here is a guess: have you bench-tested your battery? Is there any possibility that you have a cracked plate or otherwise?

Again, a total guess and I do hope that whatever you find can be fixed speedily.

Best of luck!
John

lendaddy · 07-10-2003, 07:43 AM

What gets me the most about this is the way it occured. I came home from the local pub the night before, I had had a few so I took it real easy to avoid being pulled over (please no MAD responses, I was not drunk, it just isn't worth the risk). No symptoms were noticed that night.
The next morning I started her up as usual and proceeded out of the driveway. I have to go up a hill right away and it is very common for her to stumble a little going up this hill while she is cold, which she did that day. Got to the top of the hill and she smoothed out as usual and away I went. Got two streets from work and she started stumbling on load. Thats it, I never even got on boost on the way to work, maybe a little but essentually nothing. I thought I just loaded her up with my two grandma trips and just needed new plugs, but here I am.

lendaddy · 07-10-2003, 07:46 AM

I have not checked voltage, but it is worth a try. Thanks

Tom Perso · 07-10-2003, 07:54 AM

You know, you can use a propane torch as a leak tester, just crack the valve open and run it near the possible areas and see if she starts to run a shade better. If you've got a torch, it might be worth a try.

Jenison, eh? I am going to be up in Grand Rapids this weekend (my fiancee's parents live in GR, Plainfield & 5 Mile), if you need a hand, I might be able to help.

I don't have a lot of 930 experience, but I've turned wrenches on my friend's 911S and I have built almost everything on my 63 Bug (type 4 power, I browse thru the 914 forum and then here to drool).

Later,
Tom

lendaddy · 07-10-2003, 07:56 AM

Another bit of information is that all of the primaries get hot so it is not a totally dead cylinder. Does that say anything to anyone?