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🔧 Technical Turbo LS4 with 4T80-E build.
- Thread starter Trinten
- Start date
More miles and more tuning today!
All in, we probably got around 75 miles in today. It's tough to say... since my trip and odometer aren't hooked up yet. lol.
It's challenging to tune with the Fuelabs Prodigy fuel pump and adaptive Fuel pressure Regulator. We had some odd pockets, especially around idle, that we had to make a little rich because when we first stepped on the gas (lightly) to get rolling from a stop, the fuel pump wouldn't quite spin up fast enough, and the engine would lean out and die.
We also had some odd flat spots and stumbles. We aren't sure if it's from the tune... or from the fact that the fuel pump "kinda-died" on our last trip. What do I mean by that? Well, it still makes noise, but it's making a very strange noise, and the car won't start. Has plenty of fuel. We towed it back to Mike's and in a few weeks we'll check the pre-pump filter and post-pump filter, and then do a flow check with the pump by itself.
Fuelabs has a "lifetime warranty", and they shouldn't say my pump died from "wear and tear" (one of their exclusions), it has less than 150 miles on it! So if it is the pump, it'll be going back on an RMA.
In the meantime, here is a really short video of the car going down the street. We didn't do anything obnoxious, it is a residential area. Mike said he would find his go-pro and charge it for next time.
All in, we probably got around 75 miles in today. It's tough to say... since my trip and odometer aren't hooked up yet. lol.
It's challenging to tune with the Fuelabs Prodigy fuel pump and adaptive Fuel pressure Regulator. We had some odd pockets, especially around idle, that we had to make a little rich because when we first stepped on the gas (lightly) to get rolling from a stop, the fuel pump wouldn't quite spin up fast enough, and the engine would lean out and die.
We also had some odd flat spots and stumbles. We aren't sure if it's from the tune... or from the fact that the fuel pump "kinda-died" on our last trip. What do I mean by that? Well, it still makes noise, but it's making a very strange noise, and the car won't start. Has plenty of fuel. We towed it back to Mike's and in a few weeks we'll check the pre-pump filter and post-pump filter, and then do a flow check with the pump by itself.
Fuelabs has a "lifetime warranty", and they shouldn't say my pump died from "wear and tear" (one of their exclusions), it has less than 150 miles on it! So if it is the pump, it'll be going back on an RMA.
In the meantime, here is a really short video of the car going down the street. We didn't do anything obnoxious, it is a residential area. Mike said he would find his go-pro and charge it for next time.
Good news, after doing some reading and talking to Fuelab, we've identified the likely problem. The tank Mike built is non-vented. The cap I picked up was... non-vented. Apparently these systems do not like being in a pressurized environment. We put a vented cap on there, and drove it around today for another couple of hours to do tuning. Only on rare occasions when we would come to a stop would I hear the pump get a little louder for a moment, then quiet back down. I'm guessing this was as the pump was slowing, pressure causing an issue, and it must be right around the tipping point of the gas caps venting spring.
When we stopped for gas, there was still a small hiss when I took the cap off, but nothing like last weekend. When my gas gauges reads at 1/8 a tank, I've still got about 5 gallons of fuel in the tank. I don't even plan on running it down to "E", but at least now I have an idea of where that is, and once I can start tracking mileage and figure out my MPG, I can do the math. In the meantime, I have a metal jerry-can that holds 5 gallons that will be going with me on long trips, just in case.
Mike charged his go-pro and recorded a variety of videos. The GoPro on the sunroof, driving over it, panning the engine, drive-bys, etc. He's going to put together a short montage video. I asked him if I could have the full videos so I could post up some of the others in their entirety if I really liked them.
The engine tune is now really solid for cruising and highway. Cold (and semi-warm) starts are still a little tough. This car will idle smoothly and stay running just fine at 950 RPM... after it's warm. Until then, it's picky and will fall on it's face if you're not giving it a good dose of throttle.
The transmission tune still needs a lot of work. Finding when 4th should come in, when the TC should lock up, etc. Right now there are still some pockets with 3rd where the RPM is too low and the car will shudder. So turning all of those shift points is going to take a lot more driving.
Here's our immediate checklist:
-Finish modifying the AC hoses (Again).
-Replace the orifice tube and pull vacuum on the AC system to make sure it holds.
-Put the intercooler reservoir back in (AC stuff needs to be first. The reservoir makes it impossible to get to).
-Get the water pump for the intercooler mounted and wired
-Route hoses for the intercooler.
-Clean up more of the wires under the hood, modifying the electronics mounting to hold the PCS TCU.
-Put in the Rodney Dickman door hinge pins (I hope I can find them...)
-Work on the TCU tune.
-Proper alignment (alignment in a bag got us close, but there's still some fine tuning to do)
Once that stuff is done, Mike wants me to start driving the car home and out there to work on (it's about 70 miles each way). If I'm going to drive this to Carlisle, it needs some dedicated highway time to make sure it's going to behave, and happen in circumstances where Mike can roll out with his trailer if something goes wrong. Three months is less time than most people think on something like this.
When we stopped for gas, there was still a small hiss when I took the cap off, but nothing like last weekend. When my gas gauges reads at 1/8 a tank, I've still got about 5 gallons of fuel in the tank. I don't even plan on running it down to "E", but at least now I have an idea of where that is, and once I can start tracking mileage and figure out my MPG, I can do the math. In the meantime, I have a metal jerry-can that holds 5 gallons that will be going with me on long trips, just in case.
Mike charged his go-pro and recorded a variety of videos. The GoPro on the sunroof, driving over it, panning the engine, drive-bys, etc. He's going to put together a short montage video. I asked him if I could have the full videos so I could post up some of the others in their entirety if I really liked them.
The engine tune is now really solid for cruising and highway. Cold (and semi-warm) starts are still a little tough. This car will idle smoothly and stay running just fine at 950 RPM... after it's warm. Until then, it's picky and will fall on it's face if you're not giving it a good dose of throttle.
The transmission tune still needs a lot of work. Finding when 4th should come in, when the TC should lock up, etc. Right now there are still some pockets with 3rd where the RPM is too low and the car will shudder. So turning all of those shift points is going to take a lot more driving.
Here's our immediate checklist:
-Finish modifying the AC hoses (Again).
-Replace the orifice tube and pull vacuum on the AC system to make sure it holds.
-Put the intercooler reservoir back in (AC stuff needs to be first. The reservoir makes it impossible to get to).
-Get the water pump for the intercooler mounted and wired
-Route hoses for the intercooler.
-Clean up more of the wires under the hood, modifying the electronics mounting to hold the PCS TCU.
-Put in the Rodney Dickman door hinge pins (I hope I can find them...)
-Work on the TCU tune.
-Proper alignment (alignment in a bag got us close, but there's still some fine tuning to do)
Once that stuff is done, Mike wants me to start driving the car home and out there to work on (it's about 70 miles each way). If I'm going to drive this to Carlisle, it needs some dedicated highway time to make sure it's going to behave, and happen in circumstances where Mike can roll out with his trailer if something goes wrong. Three months is less time than most people think on something like this.
Another productive weekend of tuning the engine and the transmission. The transmission tune has been a little challenging because of the torque converter and camshaft (for different reasons). Mike says because it's a little 'loose', that we need higher RPM to keep some of the chugging down (it would shift into third, then we'd feel this odd shake that Mike thought was the TCC locking up in error, it wasn't). Changing the shift points has alleviated most of those issues. Downside is 4th gear won't come on till about 65 (for now), and the TCC won't kick in till about 70. If we still get shuddering with the TCC, he'll just leave it turned off for now, until we can send in the torque converter to get it adjusted. This also means my MPG is going to suuuuuuuuck.
Engine tuning for driveability is pretty much done. We gradually raised the RPM cutoff, and upped the boost a tiny bit (capped at 7psi right now). Startups are still an issue, but we noticed something odd when we were tuning for that. When starting it, I had to give it a little gas (RPM up to around 1800) for it to stay running. The FAST was reading 0-1% for the TPS! That's not right...
Here's where it gets stranger, after about 30 seconds I slowly let up off the pedal... as I do, the TPS reading creeps up! No pedal, FAST things the TPS is at 2-3%. When driving it, TPS seems to read correctly!! So this is what I think right now.
I know we replaced the IAC. I thought we had replaced the TPS as well once already because the original one wasn't sending a signal to FAST at all. So next weekend we're going to ohm out the TPS wires. If they're all good, I'll buy a FAST TPS to see if that solves that oddity.
We also did some testing and tuning with the brake proportioning valve. After that was done, Mike did a brake launches in a deserted parking lot. He was surprised when the rear tires broke loose and did a burnout, given we have those z06 wheels and Nitto 555 tires on there, and all the weight sitting over the axles. So he's curious to see how tough it'll be to get it to hook and launch well at the track as we turn the boost up. I might have to get a set of slicks sooner than expected. He tried explaining to me that most of your 1/4 mile or 1/8 mile time is made in the first 60'. If you don't do well in that space, it's hard to make up for it.
I also have a few videos I need to get off my phone so I can post them. This isn't the montage that Mike was working on, that isn't done yet. Just stuff I recorded while in the passenger seat.
Engine tuning for driveability is pretty much done. We gradually raised the RPM cutoff, and upped the boost a tiny bit (capped at 7psi right now). Startups are still an issue, but we noticed something odd when we were tuning for that. When starting it, I had to give it a little gas (RPM up to around 1800) for it to stay running. The FAST was reading 0-1% for the TPS! That's not right...
Here's where it gets stranger, after about 30 seconds I slowly let up off the pedal... as I do, the TPS reading creeps up! No pedal, FAST things the TPS is at 2-3%. When driving it, TPS seems to read correctly!! So this is what I think right now.
I know we replaced the IAC. I thought we had replaced the TPS as well once already because the original one wasn't sending a signal to FAST at all. So next weekend we're going to ohm out the TPS wires. If they're all good, I'll buy a FAST TPS to see if that solves that oddity.
We also did some testing and tuning with the brake proportioning valve. After that was done, Mike did a brake launches in a deserted parking lot. He was surprised when the rear tires broke loose and did a burnout, given we have those z06 wheels and Nitto 555 tires on there, and all the weight sitting over the axles. So he's curious to see how tough it'll be to get it to hook and launch well at the track as we turn the boost up. I might have to get a set of slicks sooner than expected. He tried explaining to me that most of your 1/4 mile or 1/8 mile time is made in the first 60'. If you don't do well in that space, it's hard to make up for it.
I also have a few videos I need to get off my phone so I can post them. This isn't the montage that Mike was working on, that isn't done yet. Just stuff I recorded while in the passenger seat.
The stock Fiero's were surprisingly heavy (it was one of the things Car and Driver whined about when they reviewed the Fiero against the Toyota MR2 back in the 80s). It's because the Fiero spaceframe is like 180+ steel parts all welded together. So the OEM curb weight was around 2800.
With the LS4 and the 4T80, even with losing some weight from putting in the chromemoly cradle, I imagine we're still tipping 3k lbs. I need to find a place with a vehicle scale that I can use. I don't know what the current power is, and I don't want put out a guess that people take out of context or gets telephone-gamed.
When I get back from Carlisle we will be taking it to a dyno, so I will post numbers when I have paper in hand. Hopefully we don't blow anything up. But hey... that's why I have a spare transmission! lol
With the LS4 and the 4T80, even with losing some weight from putting in the chromemoly cradle, I imagine we're still tipping 3k lbs. I need to find a place with a vehicle scale that I can use. I don't know what the current power is, and I don't want put out a guess that people take out of context or gets telephone-gamed.
When I get back from Carlisle we will be taking it to a dyno, so I will post numbers when I have paper in hand. Hopefully we don't blow anything up. But hey... that's why I have a spare transmission! lol
Another productive weekend!
The new FAST TPS went on, we did the TPS learn sequence, and immediately saw some improvements with cold and warm starts. Hot starts are still a little twitchy, but it's much closer now.
We noticed a behavior Mike called "trailer hitching" at certain RPMs when keeping an even speed. We then did more transmission tuning, and it's running much smoother now. We reconnected the wire for the torque converter lockup, and didn't feel the shuddering we had before, but we didn't get on the highway much today. We also turned up the boost a little more, we're around 8psi now.
Mike is fairly happy with the brakes. He took the car out to an empty spot and tested heavy braking to see how the car would behave - he was worried about the rear end swinging around. He did have to do a little corrective steering, and said he wanted to look into options to increase the braking for the rear. So I'm going to look into brake caliper upgrades the Corvette guys run. Given that I have the S10 brake booster upgrade already, I hope those two things will work out well. And we have the adjustable proportioning valve if the new rear calipers are too much.
We have work to do up front to push more air through the radiator. I have a tendency to think farther ahead and get caught up in my own concerns, so I had bounced my ideas off another respected guy in the Fiero community (FieroGuru, who also worked on my last Fiero). He gave me some ideas. When I brought them up with Mike, he had it a little further down his list since the engine was staying at stable temps right now. I was thinking ahead to what would happen once we have the air-to-water running and A/C. For under the car Mike wants to setup a hinged plate with rubber sides, so if I bottom out on anything, it won't be as likely to get ripped off the car or permanently smashed upwards. The rubber sides will let it 'flap' on the hinge and settle back into it's proper spot.
We also noticed the intake has some resonance, very similar to what my last intake was doing (the whoooshing sound goes away when Mike put his hand on it with a little pressure, same behavior that FieroGuru chased down on my SBC and solved with a clever internal mechanism). So I might see about attaching some kind of bushing to the underside of the decklid so it puts a little pressure on it.
The new FAST TPS went on, we did the TPS learn sequence, and immediately saw some improvements with cold and warm starts. Hot starts are still a little twitchy, but it's much closer now.
We noticed a behavior Mike called "trailer hitching" at certain RPMs when keeping an even speed. We then did more transmission tuning, and it's running much smoother now. We reconnected the wire for the torque converter lockup, and didn't feel the shuddering we had before, but we didn't get on the highway much today. We also turned up the boost a little more, we're around 8psi now.
Mike is fairly happy with the brakes. He took the car out to an empty spot and tested heavy braking to see how the car would behave - he was worried about the rear end swinging around. He did have to do a little corrective steering, and said he wanted to look into options to increase the braking for the rear. So I'm going to look into brake caliper upgrades the Corvette guys run. Given that I have the S10 brake booster upgrade already, I hope those two things will work out well. And we have the adjustable proportioning valve if the new rear calipers are too much.
We have work to do up front to push more air through the radiator. I have a tendency to think farther ahead and get caught up in my own concerns, so I had bounced my ideas off another respected guy in the Fiero community (FieroGuru, who also worked on my last Fiero). He gave me some ideas. When I brought them up with Mike, he had it a little further down his list since the engine was staying at stable temps right now. I was thinking ahead to what would happen once we have the air-to-water running and A/C. For under the car Mike wants to setup a hinged plate with rubber sides, so if I bottom out on anything, it won't be as likely to get ripped off the car or permanently smashed upwards. The rubber sides will let it 'flap' on the hinge and settle back into it's proper spot.
We also noticed the intake has some resonance, very similar to what my last intake was doing (the whoooshing sound goes away when Mike put his hand on it with a little pressure, same behavior that FieroGuru chased down on my SBC and solved with a clever internal mechanism). So I might see about attaching some kind of bushing to the underside of the decklid so it puts a little pressure on it.
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