well i'm finally back home

I did get the bushings in the car a while back and did a four wheel alignment and the car drives and tracks sooo much better now.

here is how the old bushings looked like :




and this is how it looks after they were installed :



and i guess this explains why the car was all over the place :



i also swapped out all the valve seals to see if it would help with slight smoke i get every now and then.

and since the last time i dynoed the car there has been two issues that have been giving me a hard time; the first one is an issue with the boost reading of this thing; on the dyno it made something around 18 psi on the wastegate actuators it had on it ,,, which did not make sense at the time but i was happy so i didn't care

after a while the car stopped making the 18 psi like on the dyno and now would not go past 8 psi . i tried adding preload tot he waste gate actuators to try to eek out a few more psi but no luck. so i assumed there was something wrong with the actuators before and then they got to work properly later since they were rated to 8 psi. i did check all the wastegate lines and everything was in order. so got a new pair of wastegate actuators that are the 17-18 psi version and just installed them to see if they fix the boost issue .


the other issue i was getting was a missfire under WOT after 4500 rpm where the car would buck violently under WOT . i tried swapping plugs from TR8 to TR6 , swapped plug wires , and coils with new ones but with no luck.

so i took the car out this weekend to a local race spot , and did a few passes to see if i fixed anything ,,, and oddly the bost is still at 8 psi ( and since i did nothing to the missfire it was still there )

the logs show that the boost hits 8 psi and flattens out , and you can see the AFR spikes when the missfires happen . the fuel pressure is rising with boost and holding steady for the most part.

i'm not really sure why this is happening , but i think there might be one of two possible reasons ; the first being that the air filters are restricting the air going into the turbos , and the other is that the BOV's i'm using are opening under boost .

as for the misfire ,,,,, i'm still scratching my head ,,, i'll try a new set of coils to see if that helps . i'll aso see if i can clean the filters to see if it makes any difference , or maybe run the car without them or install a better set.


other than that , i'm taking the car to have the AC carged so i can have a nice cold AC ( just in time for winter )

 

What coils are you using, what plug gap, what ecu, what dwell time etc ?

What are fuel mixtures like just prior to the misfire and do injector pulse widths change dramatically at this time or stay sensible ?

Widebands will not report accurately during misfire events so that is fairly normal.

 

nasty build

 

Not sure what to tell you on the missfire. Are you able to track it to an individual cylinder?

As far as the valve stem seals, my bro fought with like 3-4 different sets on his vette before he finally found one that sealed well. He'd use anywhere from a quart every few months to every few weeks depending on the set installed, blowing smoke everywhere. PM me if you need a part number, can find out what they used.

 

dualdj1 thanks for the offer and if its no trouble to you i would like to have them.

silent assasin , thanks .

stevie , the coils are the old style ls1 coils i think . i had them since the beggining of time

as for the mixture its ok at 11.7-11.9 just prior to the misfire , and right after the miss happens it shoots up to 23-24:1 , the pulse width soon follows the afr to try to correct the lean spike then settles back down . fuel pressure acts weird sometimes after a few of the misses and not all of them; the pressure dips about 10 psi after the missfire ,,, i thought that was because of the back fire lowering the boost and thus the signal the regulator is seeing , but boost never drops....

so from the above i can assume that the car is not back firing through the exhaust and not the intake , and it doesn't do it becaue of fuel pressure drop ( the drop in pressure happens after the miss) . so this leaves me with the ignition as a culprit.

i'll try to swap coils first , check the plugs again to see if there is anything to see , and maybe try to move the main harness around to see if it it could be some electric noise.

here is a capture of log :





i also have to adjust the new wastegate actuators ,,, apparently i installed them with zero preload on them which might be the cause of the missing boost

 

If you're open loop, then the ecu should not be trying to correct anything.

If injector PW's are changing, something either MAP or MAF signal is causing it to change.

What ecu are you using ?

And the rpm trace is looking a bit odd during the problem too. Is the cram/cam signal good ?

 

the holley ecu is set up for closed loop so it does the fuel learning by itself, so technically I have it setup to fix any fueling issues that might pop up like a drop in fuel pressure or a spike in boost.

as for the maf ,,, ain't got none but the map has been re located to the port just behind the throttle body on the driver side of the car. this might cause the issue , but the boost reading and map numbers are steady during the events , which rules out the map getting a faulty signal.
( I did have that happen on my friend's car where the map was located just under the throttle body flange on a holley hi rise intake, and I guess it was seeing some turbulence under WOT which was showing in the log,,, we cured that by inserting a long rubber hose connected to the map so it reads from a cleaned area inside the plenum).

the rpm trace is like that because that is how bad the miss is . the cam and crank signals seem to be perfect. I should run an internal log of the specific signals to see if there is anything funny going on with these.

 

It's always bad to give closed loop a huge reign of control, as in cases like this it will actually make problems worse than they might actually be.

Turn closed loop off and see how things behave, but yes I would be ensuring cam/crank signals are good first.

What plug gap ? I doubt it is spark blowout, but it couldnt be ruled out

 

^^ I was going to say same. Also, a randomly developed ecu gremlin can't be ruled out either. I've gotten those where the ecu will crap out but only in one little circuit and/or component where it becomes unable to perform within certain parameters. Mostly oem brains but a few aftermarket as well

 

been messing around tring to figure out why the car was missing at the top end,, well i did a system log and did a few WOT pulls to see if i can see anything ,,,, and i think i found something. during the misfire both cam and crank signals go flat ,, which rules out the reluctor as an issue ( if it was i would still see the cam signal when the crank signal would drop off.)







so this leads me to believe that i have an electrical issue somehwere along the cam and crank wires to the pcm ,,,, so next step is the wiring diagrams

 

Test to ensure the sensors have power when these events occur.

 

Hmm now that's really weird. But now more than ever I'm definitely voting for some kind of software gremlin. Two separate sensors dropping out at the exact same moment is just too coincidental to be anything mechanical or wiring.

 

Except when they're powered from the same supply source.

I would highly doubt it's software related, but it would be wiring, interference, whatever. Power is easy to test.

 

they both share the ground, shield and positive wires according to the holley diagram.

 

I'm still reading through the thread but for all you guys that have done this conversion what's an LS 911 like compared to your typical fbody, vette or any other high powered front engine rwd car for that matter? With a stock 6000rpm LS1 redline I think max speed in 1st is like 33mph... Is that annoying or Awesome!? I feel like with the weight above the rear wheels traction isn't as much of an issue anymore with the shorter gearing.

 

I think it would be best to choose a car/box that has the tallest gears you can find

I would think short gearing like that would be pretty bad, unless it was a very standard engine not making much power

 

It may have weight but it also has no LSD and the factory units aren't so hot. Wavetrack and Guard make them for the G50TT trans and possibly for others. My 996tt has the 6 in it and just under 600ft lbs, if it's not got the front wheels hooked up it's a handful. Torque in these has got to be awesome!

 

Fantastic build. Would you be able to tell me who supplied your LS-Gearbox adaptor plate please.

It looks a lot thinner than the Kennedy ones, which will help with both weight distribution and clearance.

 

Renegade do kits ?

 

the transmission adapter is from kennedy engineering (www.kennedyenginc.com)

the rest of the stuff I made .

you might be confusing my adapter ( the turbo 6 speed to LS engine made by kennedy) with the renegade one which adapts the regular 6 speed ( not turbo transmission to the LS . theirs needs to be thicker cause of the starter ; the turbo transmission has the starter attached to it instead of the block, while the regular transmission has no such provision (starter mounts on the block).