What’s the converter? Stock or did you upgrade it?
71 Duster 360 turbo build
- Thread starter turbovan
- Start date
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Thanks for the info. I just picked up an FTI 4500 stall so it looks like that just might work for me.
Car is now tuned at full throttle…until about 5200rpm where it looses sync and shuts off. This is a new issue, and I’m guessing I need to increase the crank sensor air gap. The sensor wiring is shielded except(except at a 12 pin connector) so I don’t believe that’s the problem.
I did get the intake built and installed so I’m glad to have cold air and a filter. It’s just a 4” elbow into a 4”->5” adapter. The filter fits very snugly between the front portion of the outer fender(headlight cup), and the turbo discharge piping. Also added a turbo blanket to protect the now peeling paint close to the turbine housing.
I did get the intake built and installed so I’m glad to have cold air and a filter. It’s just a 4” elbow into a 4”->5” adapter. The filter fits very snugly between the front portion of the outer fender(headlight cup), and the turbo discharge piping. Also added a turbo blanket to protect the now peeling paint close to the turbine housing.
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That might be a little on the loose end, but hopefully it couples well before redline once boost is involved. You’re going to have excellent boost response I’d say!
Matts440
Well-Known Member
What's your gap now? I know my old sensor had to be way too close for comfort, felt like a fingernail thickness on the gap.
The sensor calls for .059” air gap. I had it at .04 and it wouldn’t hardly idle. Now it’s at .06”. Maybe the answer is somewhere in the middle, but I haven’t spent much time troubleshooting it yet. Just reading/researching
Matts440
Well-Known Member
Id go as close as you can.
Agree on what Matt said. Get it close as you can and make sure the leads aren’t running parallel to any other high voltage runs like a coil wire, alternator wire or similar. I had similar behavior with the Fitech at high RPM that I solved once I moved the timing wire away from the coil wire.
Matts440
Well-Known Member
What's the mounting bracket lool like? Is that steady?
FYI I did have several clean pulls to 6k with this setup on the last engine. I’ve also taken at least one very solid 5500+(too rich) pull on this engine before the sensor went out. So I am focusing on sensor air gap and loose grounds at this point.
Sensor mount is very solid right between two bolts on a 1/8 steel bracket. However, it it IS inches from the alternator. Not optimal but again it was working fine until suddenly, and without any changes, it started having sync issues.
The alternator mounts through that gap between the two brackets.
Sensor mount is very solid right between two bolts on a 1/8 steel bracket. However, it it IS inches from the alternator. Not optimal but again it was working fine until suddenly, and without any changes, it started having sync issues.
The alternator mounts through that gap between the two brackets.
Matts440
Well-Known Member
Okay, just checking cause I known the one I had was only held by one bolt, so had to change that. I had the same issue on the dyno before and had to move the crank sensor closer for the higher rpms and it cleaned it up a lot.
Hall effect
TT5.9mag
Two atmospheres are better than one
Yes it does. I actually got the design from Subcom so it’s the same specs as his, and cut from 1/8 cold rolled steel. Again, it was running fine to upper rpm’s…until it wasn’t.
I think it would be wise for me to move the sensor further from the alternator, but that’s where it has to live for now.
I think it would be wise for me to move the sensor further from the alternator, but that’s where it has to live for now.
TT5.9mag
Two atmospheres are better than one
Hall effect sensors do not have the same noise problems as VR sensors so it’s doubtful that it’s an interference problem although you shouldn’t rule it out. And the alternator is a big source of noise. I’d be seriously considering looking at sensor mounting, wheel distortion, and crank thrust issues as all possible culprits as well.
racerjoe
Well-Known Member
I run the red cherry sensor as well. I had a similar setup as you with the trigger wheel welded to the steel pulley. I originally had just a few tack welds holding it on because I didn't want to add too much unbalanced weight to the pulley. One day I developed a high RPM sync loss on my MS3. Initially, I thought I was hitting the rev limiter until it got worse and started happening more frequently and at lower RPM. I soon figured out that a tack weld on my trigger wheel had cracked. I guess the wheel would start floating at high RPM. I fixed the one cracked weld and it happened again. This time I completely welded the trigger all the way around. It never happened again. I'd check your welds and your runout on the wheel. You also mention above that you had the air gap at .059". That's a lot. Also shown above is the spec sheet that says 5mm max, which is .0196". I've since redone my setup with a serpentine pulley. I believe I ended up around .026" and it's been running great. Spins to 6800 no problem.
Been busy settling into a new house, but I ran it to 6k on the street yesterday without any sync loss events.
My first attempt was using a copper tinned shielding sleeve(grounded) to help insulate the sensor wiring from the nearby alternator. That didn’t help. Next I dug into the harness and changed my crank pickup sensor from 5v ref to a 12v power source. That helped a little, but still losing sync. Finally, I dropped the sensor gap from 1.15mm to .80mm(.031”) and that seems to have done the trick. Still need to drive it a little, but I’m hopeful. I may drop the gap even more as suggested. If this doesn’t work out I’ll build a new crank sensor bracket away from the alternator. If I have to dig into the harness much more it’s going to turn into a complete re-wire and real megasquirt ECU.
My first attempt was using a copper tinned shielding sleeve(grounded) to help insulate the sensor wiring from the nearby alternator. That didn’t help. Next I dug into the harness and changed my crank pickup sensor from 5v ref to a 12v power source. That helped a little, but still losing sync. Finally, I dropped the sensor gap from 1.15mm to .80mm(.031”) and that seems to have done the trick. Still need to drive it a little, but I’m hopeful. I may drop the gap even more as suggested. If this doesn’t work out I’ll build a new crank sensor bracket away from the alternator. If I have to dig into the harness much more it’s going to turn into a complete re-wire and real megasquirt ECU.
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It would be cool to develop a bracket that has a fine lead screw and lock down adjustment.
Well I have fuel dialed in and boost up to 10psi. Added some timing back in dropping from 38 to 22° at 10-12psi and the duster was making some steam. Then I did a short pull in 2nd gear and something seems to have let go. When I let off I heard some kind of loud mechanical whirling noise “spooling down”. I thought, and hoped, the turbo had gone out but it seems to be fine. The car still runs and drives pretty strong, but seems a bit lazy getting into boost. I’m thinking I better pull and inspect the trans because I have no idea what that sound was. Looking at my logs the converter is flashing to 5k rpm when under boost so I’ll need to have that tightened up while it’s out.
Earlier in the drive I hit overboost in 1st gear about 3 times in a row pretty hard, and am wondering if that could have hurt the sprag. It will be time for a billet front drum if I decide to open it up. I was really hoping to make it to the strip soon.
Earlier in the drive I hit overboost in 1st gear about 3 times in a row pretty hard, and am wondering if that could have hurt the sprag. It will be time for a billet front drum if I decide to open it up. I was really hoping to make it to the strip soon.
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