2G Running extremely rich and dead time/global fuel don’t seem to affect AFR

406_Talon · Aug 23, 2020

Hello everyone, hoping for some help here... so I had to tear the car down to fix a front main seal leak, it was running great before this, just saw some oil on the timing belt and bottom of the case. Anyway, I got it back together, and I was in a hurry, and I had the oil pump out of phase and started the car. It ran weird and I immediately realized what I had done. (I’ve done the timing on DSMs several times and I’ve never had that happen, just using the gravity method on the pump gear... guess that’s what hurrying gets ya LOL

) I got it back together correctly and started it, and first it didn’t even want to run, but if I pedal it for a bit it idles. It idles at like 11 to 12 to one on my AEM gauge and in link, and the trims just run away negative. It gets to stft -16.8 and stays there. It sounds like it has a blower. The O2 sensor does respond if I rev it, it will read lean after revving when there is no fuel. But it does not seem to be working like normal, ie, switching around stoich voltage. I threw a bunch of dead time at it and pulled out global but it didn’t seem to care. Is my Wideband bad? What could’ve happened?
car is a stock engine 2g 7bolt w fmic, 16g, fix 750s and link v3
Things I have done/checked:
Boost leak test:
Tested to 30 psi post turbo, leaks like 1 psi a minutedown to 20ish, shaft seals (new) and hoses all seam good. Stays above 20psi for a long time. turbo seals leak a little when I test on the turbo. (Faint oilbubbling)
Compression test:
155 across the board on my crappy tester. Same as before I had the issue. The car ran great at these readings.
verified spark on all 4 plugs
Fuel pump is priming and regulator says 42.5, no change.
Cleaned all electrical connectors and crank pos sensor with electronic parts cleaner
I’ll post a log shortly

406_Talon · Aug 23, 2020

Ok, here are logs. The first is from before, the second I just captured, and I managed to get the o2 sensor to respond! By cutting my deadtime all the way to 100, and cranking global global from 38.7 to 44, I was able to get my trims back in line. but now I'm way off from where the calculator thinks I should be. So now my question is what could have caused this to drift so much? I am at a loss here. I am really worried I bent one of my new valves or something... My idle airflow per rev is crazy high too, and I only see -8 in/hg on my boost gauge at idle... Any suggestions would be appreciated. Could the voltage scaling of the o2 sensor be off?I can't tell whether I can trust the gauge and I am thinking about ordering an LC2. Or does this seem like an airflow problem? I previously had to lower my idle cells in my speed density table to 48.5 to get the car to idle, is that too low? Could I have bent valves and not see it on a compression test? Please help!

AWD-Tony · Aug 24, 2020

I don't see anything that stands out in the log besides fuel trims. The oil pump gear being out of phase won't damage anything as long as the other marks were lined up, and If you had bent valves, your compression numbers would tell you.

motomattx · Aug 24, 2020

What did you have off of the car when it was apart?

406_Talon · Aug 25, 2020

The only thing I see that scares me in the logs is my vacuum being 8-10 where it used to be @17. I had the front case cover off, the timing belt, pulleys, etc. but nothing related to the intake. I’m picking up a leak down tester today and I’ll post results. I’ll post a log from before when the car was running right when I have my laptop after work.

406_Talon · Aug 25, 2020

One thought- could my FPR be failing and allowing too much fuel pressure in the rail? I may have to test that...

motomattx · Aug 25, 2020

Im going to suggest checking that cam timing again, things point to that from here, maybe its good but thats where the clues are pointing.

406_Talon · Aug 27, 2020

Hey guys sorry I took a while to update, I have been busy drinking to salve the pain. I threw a leak down tester on it, cyl 1- totally good. Like 0 leakage. Cyl 4? All of its air comes right out the hole in cyl 3. It holds 0 pressure. I didn’t even test 2 and 3. So...hooray for my valves but RIP my 1000 mile head gasket that saw 15 lbs of boost. I thought I smelled coolant. I was so careful, I checked the block for square sooo carefully, even ordered a machinist square for that. I did reuse my head studs though. I guess I’m pulling it out and rebuilding. 2020 f***ing sucks.

AWD-Tony · Aug 27, 2020

What hg and did you check head for flatness? Studs can be reused and don’t think they’ll stretch at 15psi unless they were over torqued.

406_Talon · Aug 28, 2020

It was a Topline gasket from a complete engine gasket kit. I knew it wasn’t optimal but I wasn’t resurfacing the block so I was afraid to go MLS. I have been planning to pull the motor and fully build it, but the season was starting and I just thought this would be a good enough bandaid for a few auto x sessions. (I don’t drive the car except for fun or auto X.) I had the head measured and resurfaced at a shop by me. Studs are standard ARP studs but I don’t know how many times they’ve been torqued. I got new bolts and washers, I hit them with 90 # in increments, not sure why it failed. Anyway, L19s and a perma-torque in the mail, cherry picker at the ready. Lesson learned - don’t be cheap :/

AWD-Tony · Aug 28, 2020

My topling hg blew a few months ago also LOL

. But I knew it was temporary since the block had a low spot and pushing 36psi didn’t help.

motomattx · Aug 28, 2020

If you have zero compression its likely the valves and not the gasket, do a compression test before you tear into it, something is wrong with your testing, you cant have 155psi compression across the board and at the same time have 100% leakage on a cylinder.

406_Talon · Aug 29, 2020

Could it be the valves and come out cyl 3? I’ve always been told that a compression test will tell if the valves are good, a leak down tester will tell if the rings and gasket are good. I’ll redo the test in the AM. I have lots of spare time this week and Autox next weekend so I’m gonna pop he head off and throw this spare organic head gasket I have in, I figure worst case scenario I end up back where I’m at. But I will redo both tests first. I could imagine intake slightly open on 4 and fully open on 3 with the throttle plate shut would give me these results.

motomattx · Aug 30, 2020

To do a proper compression test hold the throttle fully open and crank the engine until the gauge quits moving up, thats your compression numbers.

biglady112 · Aug 31, 2020

It sounds like you did the leak down incorrectly. You need to make sure each cylinder is at TDC and all of the valves closed. You cannot test all four holes with the motor in the same position. Unless you take the cams out.

406_Talon · Sep 4, 2020

Ok I finally have some free time for my car, and I was initially doing the leak down wrong. I assumed since 1 and 4 were at tdc simultaneously I could test 4 with 1 in position and 2 and 3 likewise. This time I rotated the engine through the firing order and tested each cyl on tdc compression and it looks like the hg is ok... each cylinder kinda leaks at 10% until I get it to 80 psi or so and then it seems like the ring seats (?) or something and it goes to like 2-5% leak down. I have turned it through twice and tested with nearly identical results. It seems like the hg and valves are good then, correct? Keep in mind it’s a cold motor so it seems like that is pretty good re the leak down. I am retiming the motor again to verify it is correct. My timing tool fits loosely on my aftermarket cams, I think this may have let me get a tooth off somewhere. I almost have it back together and I’ll update.

406_Talon · Sep 4, 2020

Ok I’m an idiot. The timing was off. Pics included. The pics where it’s off are the old ones and the ones where it looks right are the new ones. Worn out little plastic cam gear doodad meant the cams were off a bit. I even had the balance shaft belt off a tooth because I had been trying to kinda split the difference on the slight mismatch on the marks. Thanks motomattx for the timing suggestion. Last question - I was thinking I should test fire the motor with the pulleys and cover off to verify it’s working before I put it all back together, is there any reason not to do that?

jimsgsx · Sep 5, 2020

Everything looks good to me! Make sure that balance shaft belt has enough tension. And torque the bolts properly on the various timing components. I agree, the plastic tool works decent, but still need a wrench on each cam bolt to really get er lined up just perfect. Using binder clips works way better than zipties too. Good job!

1990TSIAWDTALON · Sep 5, 2020

You can start it without covers just make sure NOTHING is in the way. My son did his. It was a PITA to get them on in the car but he did it for the same reason you want to. Made him "feel" better and you will to. Just run it long enuf to check everything then shut it down and double check before reinstalling them.

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2G Running extremely rich and dead time/global fuel don’t seem to affect AFR

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