Hybrid Spark plugs

[Maverick H1L]

Well, I found the cause of my blowby problem. It's been going on for months (well, while the engine was running, which is mostly hasn't the past year). Not sure what happened, but there have been 2 holes burned in pistons 1 and 4, and resulting compression is 65 PSI (should be 225 or thereabouts like the other 4). A possibility has been raised that the spark plugs I am running on the 11.4:1 CR are too hot... Stock R44LTSM6. Looking for input on colder plugs. Probably going to be getting another short block as I'm also having issues with the starter mount on this one. And also going with the 3100 head gaskets to bring the CR down a bit.

[fasteddi]

Well, I found the cause of my blowby problem. It's been going on for months (well, while the engine was running, which is mostly hasn't the past year). Not sure what happened, but there have been 2 holes burned in pistons 1 and 4, and resulting compression is 65 PSI (should be 225 or thereabouts like the other 4). A possibility has been raised that the spark plugs I am running on the 11.4:1 CR are too hot... Stock R44LTSM6. Looking for input on colder plugs. Probably going to be getting another short block as I'm also having issues with the starter mount on this one. And also going with the 3100 head gaskets to bring the CR down a bit.

I use ac delco Rt42LTS plugs. IIRC they are stock back in the day on Gns. But Ive ran them since day one of my 3400 heads on the 3.1L block and they seem to work well. 3 years now and counting. Just a FYI autozone doesnt carry them and say they are discontinued. I can only find them at advanced auto or on the internet for some reason. They are the same as a the r42ts that i ran in my turboed all 3.1L build but they are a different length hence the L added to the r42ts. And compared to the stock 3.1L r44ts or 43s... the r42lts are colder by a few points.

[Maverick H1L]

I got the same baloney at AZ as you did when I asked for the R43LTS plugs... Ended up getting NGK platinums instead.

None of that matters now anyways. Powertrain has been yanked. Trans needed to be resealed, keys replaced in 5th and 3-4 synchros (all broken in 3-4 and 5th had one bad one), the shift rails needed to be cleaned and relubed, and the 1-2 shift fork replaced (no wonder why 1st was a PITA and 2nd was only marginally better). Engine is NOT going back in. Between the bad pistons, the MSII issues I've had from first start, and the starter mount debacle from early last year, I've had enough. Got a stock 3.1, 2.8 fuel rail/cold start injection/EGR, and 2.8 harness I'm converting to the 3.1, and that will be in probably next weekend provided the stuff from Summit arrives on time (Monday? Since when does it take more than 24 hours for delivery?) and I can get a good MAF from the guy I bought the engine from. And go and buy a spark plug wire kit since said guy saw fit to cut the coil to dizzy cap wire in HALF along with the throttle cable I specifically told him I needed...

:edit: And no, I won't junk the engine. I'm keeping it in case I want to try again with a FAST EZ-EFI system. And I'm keeping the LC-2 WB in place and rewiring the ECM output for proper NB signal.

[koolcamaro]

So you had the 11.4 CR 3.4/3500 hybrid from what I undestand? What kind of issues did you have with it? Curious as I also did the 3.4/3500 so many years ago with no success. I started of with a 260 comp cam and cranking compression of 240psi on all cylinders. It would run okay for a little while, then all of a sudden start spitting and sputtering violently to the point where it would just shut down. If I waited about 10 minutes, I could drive it back home. At the time, I though it was the small cam so I upgraded to a much larger cam. The cranking compression only dropped down to 230psi, but the engine ran much better. Unfortunately, it still got to a point where it would spit, sputter, and shut down although it would take much longer to get to that point. Finally I just gave up on that engine setup and now I have a 3.4/3500 with 9.0 compression and no problems so far.

The high compression setup i used to have had TR6 spark plugs(maybe i needed colder), 160 thermostat, large cam, and megasquirt II.

Let me know if you had the same engine problems with the high compression 3.4/3500 you used to have as we might be onto something!

[Maverick H1L]

3.1/3100 small port hybrid. With 3.1 RWD pistons, giving 11.44:1 CR. Stock cam. Figured it would be better to get a stock baseline down before trying to break in a cam.

Most of the issues were with the MegaSquirt II ECM I was using.
1. No IAC control. Not automatic, anyways. Manual control was just fine. I figure on a bug in the code somewhere.
2. Knock sense useless. The signal was apparently somehow tied into the TPS and MAP readings. Signal curve matched TPS and MAP readings exactly, making knock retard useless.
3. Metric ton of sensor signal noise.
4. When I would put a setting into the MSII, eventually it would have to be completely rebooted and reflashed with working restore point. For whatever reason, it would lose settings and go nuts after a while.
5. MSIIExtra DID NOT WORK whatsoever. I paid a guy $100 to remote tune the thing. He practically INSISTED I use MSIIExtra even AFTER I flat out told him that, A, I already had a running tune that just needed tweaking, and B, I had already tried Extra and it did NOT work. I still want my money back from the guy. He completely screwed up the ignition curves and didn't do crap with the fueling table, which is where it needed help.
6. Bosch/Ford 22lb fuel injectors would not work properly with MSII. Kept running super rich when hot. GM Multitec injectors from a 350 did NOT have this issue with the same code.
7. Autotune in the Tuner Studio program did not work. Period. Kept trying to tell me the "O2S Out of Range" when it was using a wideband O2S and it knew the AFR and what it was supposed to be. And wouldn't do a thing. With the AFR less than one full point off.
8. The people on the MS forums were as helpful as a horde of zombies. Kept asking the same questions over and over when I would continually bring up the same issues over and over on the same MSII code version and same Tuner Studio version and didn't come up with any useful solutions (actually, NO solutions whatsoever but I digress).

When it ran properly, it ran pretty good. Until whatever happened that burned holes in pistons #1 and 4 giving me 85 PSI compression in both cylinders (should have been 225 PSI). Bad injectors on both? Bad plugs? Bad ignition coil? I don't know. Either way, that engine is sitting on a tire in my garage waiting to be put on the stand and have the piston/con rod assemblies replaced. I bought a set of NGK plugs for it a heat range comparable to Delco R43LTSM6 plugs (because those apparently no longer exist anymore... Along with my R43TSK plugs in the stock 3.1 I have now).

Your problem sounds either ignition or fuel injector related. When I swapped my perfectly good 2.8 harness in my 87 for a 3.1 harness, it would do the exact same thing on the exact same parts that I KNEW were perfectly good on that engine. Which I had driven 400 miles straight, one direction, with no issues whatsoever. Put the 2.8 harness back in and scrapped that 3.1 harness AND the replacement 3.1 harness I bought and had no problems. I even modified that harness to work on the hybrid engine and it worked fine (with the exception of the MSII issues I outlined above).

[koolcamaro]

Wow! Sounds like you had a terrible experience. The only thing I liked about megasquirt was that you could make changes to the car while it was running and datalogging seemed easier. But yeah, didn't care too much for no IAC control, no sequential fuel injection(at the time), no knock control(without having to modify the MS board and buy a different sensor), and a couple other things.

An engine is more prone to detonation with a higher compression. You could have been knocking and didn't even know it, since you didn't have any knock control.

I don't know what my problem was, but I am forever scarred from it lol. I will never run higher that 10.5 compression because of those bad experiences with 11.5 compression.

[Maverick H1L]

Knock control only required one wire physically on the MS board. However, I did buy a $13 expansion board and parts to connect MS directly into my wiring harness without modifications to the harness. Only modifying I did to the harness was to add a wire for a GM MAP sensor and a wire for the knock module running to the MS.

That thing was great until the malfunctions started over and over again. Even down 2 cylinders I could still lay down rubber if I wanted to. I don't think I'll ever find out why the IAC control never worked automatically or just what was up with the knock sense. Especially since a good 2/3 of the time the engine was running overly RICH, according to my wideband.