944T project updates

[Drscottsmith]

Hello all -

Finally back to the car. Some Updates and time to get back to work on this car.

So...since my last threads here is where we are:

1. When I paused working it was due to a small fire! The fuel line at the FPR sprung a leak and must have been ignited by the burning insulation on the O2 sensor wiring that got too close to the turbo inlet feed...no major damage other than scorching the paint on the hood which will now have to be repainted. UGH but could have been much much worse!

2. Had to rewire some things and move the harness around a bit to alleviate concerns. All in all it was a good thing as I believe everything is much better positioned and secured better than in version one

3. Car is back to running now!

3. Still fighting two oil leaks...I finally had a chance to get the car on my buddy David's lift to really figure out what is going on. We pulled the transmission (good because it needed to be cleaned and I added some reinforcement to the trans bracket to reduce the sway) and exhaust so I could see where the rear leak was coming from. Oil pan seal looked good and after the dye we could easily see the Rear Main Seal must have torn or something. Replaced that and no more leak there. The other leak is in the front of the engine. In my other posts related to this - I was looking at the lower balance shaft. Oil drips down right at the corner of the oil pan where it makes the soft 90 degree turn towards the oil pump. We were able to slowly remove the bal shaft carrier to determine that the seal is working great up until it comes out of the shaft housing, so we know that is sealing correctly. No oil out of the front seal. So we are back to the oil pump not seating properly. Pump has been removed and all of my stop gap Yamabond removed/cleaned up so we can really fix the issue. It looks like there is in fact a little area about where the leak was where not enough Locktite 574 was on the sealing surface and this could have been the problem. Will clean these surfaces good and then reassemble. Hopefully this will take care of the leaks.

4. In the spirit of making improvements to the first version of the install (remember I am going to a microsquirt here), I am looking again at the setup of my trigger wheel on the front crank pulley sandwich. Everything works fine in this situation, but I was concerned at the initial lack of oil pressure perhaps from the crank bolt not tightening enough to turn the pump drive gear. I added a washer between the bottom of the PS pulley around the crank to give me an extra 2mm or so of depth to compensate for the depth of the trigger wheel and ensure the convex washer had enough to pull against before the crank bolt bottomed out. My question is do I really need that washer, and is the threaded portion of the inside of the crank actually longer than the threaded part of the bolt such that there is room for it to tighten down enough without the washer? Again - everything works fine, but I am trying to make improvements and the extra washer is just one extra part in there.

So thoughts on this long email - I am glad to just have this project slowly moving forward again.

[Drscottsmith]

Some updates -

1 - NO MORE LEAKS!!! The front oil leak I had was coming from the oil pump mating surface where the block and girdle meet. Made that more flush than it was and used a bead of Loctite 574 instead of the roller method and all is well!

2 - Replaced rear main. Could not find any visible damage to the old one, but put the new one in and all is well there.

3 - Completed rewiring to include moving my new aux fuse and relay panel inside the car above the pass. kick panel. Now out of the elements even though it was a sealed box.

4 - built a new bracket (thanks to my friend woody) for the crank trigger wheel sensor and relocated the trigger wheel itself. Now the wheel is sandwiched between alternator and bal shaft pulleys. much stronger and more stable installation versus version 1 and now the trigger wheel does not have to come off to change PS belt and alt belt. This also fixed the need for a washer to offset the spacing from the trigger wheel depth since it is further back.

Moving on now to the tuning phase!

[Drscottsmith]

Follow up question....

For you 951 guys with a Wideband, did you use the stock location for the Wideband O2 sensor or relocate? I think the stock location is fine but the AEM manual mentioned the distance from the headers on turbo cars as well as the amount of heat generated and I wanted to make sure I did not need to relocate it.

Thanks -

[four0four]

Absolutely relocate! The stock location is in the crossover, and wideband sensors are sensitive to pressure - you can correct for it, but you need to also be tracking crossover pressure to do so.

I think most folks stick it down on the bend before the wastegate tie-in. Here's mine, pre-welding:

fabspeed-wbo2.jpg (2.54 MiB) Viewed 376 times

[Tom]

Agreed -- most people put it where four0four shows above. You also don't really want to give up the factory sensor. It serves a different and worthy function.

[Drscottsmith]

Thanks all!

Tom what am I missing with having 2 sensors with microsquirt?

[Tom]

Thanks all!

Tom what am I missing with having 2 sensors with microsquirt?

Ah, didn't realize you had microsquirt. But I wasn't saying you give something up with 2 sensors -- I meant you'd be giving something up if you ditched the narrowband and only ran the Wideband. I was thinking you'd lose your narrowband's closed-loop AFR control if you just put the Wideband in the factory port, but suppose you could use a simulated narrowband output with some sensors. Still, the factory O2 port is not a good location for a Wideband sensor, so I wouldn't put a Wideband there regardless. Narrowband's are good at exactly one thing: reporting whether your AFR is richer or leaner than 14.7 -- that's what makes them so good at closed-loop control. Wideband report ARF across a broad range of AFRs -- and many can simulate the output of a narrowband, but unless technology has really improved recently (very possible), they are not traditionally as fast or accurate as a narrowband for that particular task. I'd run both, one for closed loop in the original location, and a Wideband where shown above for tuning.

[Drscottsmith]

Gotcha - that makes perfect sense and I learned something new!

Thank you much!

[Drscottsmith]

Ooops - well i can't get the logs to attach?

[Drscottsmith]

Ok - so moved the O2 sensor to the spot where four0four suggested and also picked up a new AEM AFR (I had the good old chineseum version from amazon).

I made two data logs and now need to start reworking my tuning to account for the revised AFR values. Please take a look and see what you would advise. This is a 951 fully rebuilt engine fully stock.

The first log is just a long idle while engine temp comes up. The second is a few sitting still revs to about 4K.

Thanks