High RPM shifting problems are more likely hydraulics than the clutch itself. After all, if the hydraulics are fully extended, then there would have to be something pretty crazy going on with the clutch in order for it NOT to fully disengage.
However, a properly working clutch might not disengage if the hydraulics aren't working correctly.
One thing I've seen happen is that excess grease on the TOB sleeve in the transmission can collect clutch dust and turn to mud/gum/gunk over time. Normal motion of the clutch fingers can push the TOB away from the fingers, but the return spring inside the slave cylinder can't overcome the stickiness of the clutch dust loaded grease, so the TOB sits a little bit away from the fingers. This increases dead space in the clutch pedal travel, with the result that even when the pedal is all the way down, the clutch is not fully disengaged.
This problem was fairly easy to spot. Pressing the clutch in, while in first gear, rev it up to 5-6K. The car would jump/lurch a bit. It even had a bit of a thump/thud as it would grab just a bit. I couldn't find any way to blame hydraulics there.
The idea of the clutch doing something pretty crazy isn't crazy at all when you think about it. When you press the clutch, the diaphragm flattens out a bit, which takes pressure off of the pressure plate. The only thing that causes the pressure plate to retract WITH the diaphragm's movement, is the three spring straps. If there is any kind of imbalance in the pressure plate itself, it could wobble against the diaphram, and could rub the clutch disk as a result, causing a little bit of drag. So if I help the pressure plate stay seated against the diaphragm, it should increase the RPM point where an imbalance will cause the pressure plate to wobble. At least that's what I think is happening.
I can't really fix or detect an imbalance unfortunately. I can't guarantee that the pressure plate itself is centered. I can only be sure that the pressure plate cover is centered and the unit as a whole is balanced.
Perhaps, I could mod or change the rivets to have a peg that pokes through the spring, that would be fling proof. I might do that actually...
Just a quick one of the engine before its put on the cradle, which will likely happen later this week I think.
Incidentally, today I found something peculiar that explained why this engine was so noisy all those years ago. Heres the noise:
And heres the cause:
I scavenged a new tensioner off of the engine block that was in the car earlier. I was looking around for something the other day, and this caught my eye. Glad I have an answer now! That was a long time ago.
I took both suggestions for the clutch that I felt were appropriate. I cut the rivets and pressed them out.
I made some new rivets with a shallow peg on the back to hold the springs in place.
While I had the pressure plate apart, I took the spring straps and bent them a bit more, made them more "Z" shaped then they were.
Hopefully, all this added pressure plate retention force will cure the high RPM clutch disengagement issues.
I had an idea, I took an old 3.4 DOHC crankshaft, and cut the rear flange off of it. It was a ton of work to cut the bugger off! I wanted to make a nice, very accurate flange for machining flywheels. It also occurred to me that with a couple of small, high precision bearings, It would make an excellent balancing arbor as well.
With 1/4" ID shielded bearings, I washed out the grease with WD-40 to cause the bearings to be as low resistance as possible. I then balanced the arbor. You can see the holes I drilled into the face to balance it. It is extremely sensitive.
I balanced the flywheel first, had to do a little bit of drilling to get it nailed down. When I was finished, the flywheel was well enough balanced to stay in whatever position I rotated it to. Then, I bolted on the pressure plate, and balanced that too. I actually put the arbor on backwards so that the bearings were centered within the mass. I had to do quite a lot of drilling to do on the pressure plate to get that balanced. But, when I flipped the arbor back into the lathe chuck and ran the lathe at full speed with the flywheel and pressure plate mounted. There was absolutely zero vibration. Very comforting to see that.
All being well and good, I went ahead and mounted the flywheel, torqued the ARP fasteners to 70 ft-lbs using Loctite on the threads, and ARP lube under the heads. But, once it was torqued the bolts, I washed off all of the ARP lube. I don't want to contaminate the clutch disc.
Then of course, the engine and transmission got mated, and landed, and I'm currently dressing the engine. I can't wait!
Been a while with no updates, so here's the run down behind what I've been up to.
At the tail end of May, I had mated the engine and transmission and began dressing the motor Some things that I had to tackle while prepping the assembly: I created a bunch of new heat shields for the crossover, as to not radiate heat near the air filter and Coolant temperature sensor. I insulated the coolant temperature sensor itself considerably more I modified and installed a 180 degree thermostat to cool things down a bit. I created an intake air filter shroud/housing out of a flour/sugar can, and wrapped it with sticky backed fiberglass reflective heat blanket. I'm hoping this will greatly reduce the temperatures that the intake filter is pulling in. I built a heat shield to go between the intercooler and the muffler.
By the 16th of June I had all the hardware checked and the cradle assembly ready to be installed.
It took two weeks to get a moment to roll out the assembly to the car and install it. And another two to find the time to plug everything in, and fill the coolant systems.
Having a kid, and an opposing schedule to my wife, and oppressively hot 105+ degree days makes it very difficult to find the time to work on the car. But, on the occasion I can't sleep, so I go outside and get a bunch of work done.
Finally, yesterday I did my once over. I charged the battery, and cranked the engine without fuel till I had oil pressure. Then I turned the ignition to prime the pump 5 times, till I could hear that the fuel system was filled. Then I cranked it and it started up immediately. Like as if it were driven yesterday. Very un-ceremonious.
I'm working on fitting the new air box into the very cramped engine bay, lots of trimming going on with it. I've also decided to cut up my boost tubes, and weld in some V-band joints. I'm waiting for those to show up. I've had some serviceability issues in my engine bay, like the air filter not being removable if the boost tubes were in place. The boost tubes were damn near impossible to remove because the intercooler ports are pretty tough to get to. So, I'll make the boost tubes come apart easily to free up the air filter area. Especially now that there is an intake housing in that area.
So, to recap. In this rebuild of the engine I... Changed back over to my old used block Replaced the crankshaft with a Forged 3900 crank put a 7X reluctor on that crank Modified the heck out of 4.3L Forged H Beam rods (narrowed, flipped, re-tanged) Got custom forged pistons, lowered the compression ratio from 9.5 to 9.0 New moly rings New bearings with improved lubrication channels Balanced the rotating assembly modified the flywheel and pressure plate for better disengagement made heat shields for the crossover, Coolant temperature sensor, air filter and intercooler upped the wastegate spring from .5 bar (7.25 PSI) to .7 bar (10.15 PSI) welded indexing tubes into the V-band splits on the exhaust
Whenever I have spare time and its too hot outside I've been working on recoding $8F for 3 bar operation. It's been difficult to say the least. But I think I am just about done with it. I just have to test my work, and fix whatever doesn't work.
But, I am really pumped about how well it's running. This means a lot of things went right. Especially the stuff with the 7X reluctor.
I wrapped up a bunch of little details, put the wheels, rear bumper, wheel well liners and tail lights on.
I added the three V-band sets to the boost tubes then installed all the goods.
Then I put the car on the ground, and took it out for a spin. Everything seems to be in order.
I forgot just how fast this car is, either that or it got faster. The boost was on waste gate spring setting, so probably 10 or 11 PSI. I wasn't logging the short lap I took.
All that being good, I decided to try out my 3 bar program with the 3 bar sensor. It started and stalled, was difficult to keep running. That's actually pretty good, I was expecting the first attempt to have some small code error that would have crashed the microprocessor, but it didn't. So now I'm working on code debugging, ported all the MAP ram variables to the ALDL, and configured Tunerpro to spit them out into a graph. Fairly straight forward. We'll see how that goes.
Maybe for the time being I'll just stick to 2 bar it runs perfectly with it. I have to get the car back through emissions as it was due a little after the last engine let go so in the short term its best.
Main bearings are Sealed Power 7242MA STD. Which are for a 3100. Rod bearings are Sealed power 1020CP STD which are stock for a newish 4.3L same as the rods I'm using.
I started doing my 3 bar code debugging today and found that I didn't put the 3 bar patch on the code yet when I put the 3 bar sensor in. So it was running poorly for that reason. I patched the code, then did another debug run. Much to my surprise, it started right up and surged a couple of times before settling down to a nice idle. Throttle response was trash, but it ran pretty well otherwise.
The debug was important, It showed me that the re-calculated value used for processing the fuel control was bang on, as was most of the other 3 bar variables.
What wasn't doing so hot was all the 1 bar values. I need to work on those. They were all zeroed out, so some math is completely failing. I also found that the 3 bar value that it uses for timing and boost multiplier was calculating correctly, but the value wasn't getting off the floor (zero) when idling. The 2 bar debug revealed that it is off the floor when idling, so I'll have to fudge the math on that value to make it read similarly to how it did when running the 2 bar and adjust the tables that reference it accordingly.
Easy fix for the 1 bar stuff. I didn't see any errors in the code, so I changed it over to addition instead of multiplication on the math to make 1 bar variables. That fixed that issue. Then I tested it in the car, and It drives just fine now on the 3 bar sensor and code. Still having a little problem with Baro calcs... but I'm sure I will get that straightened out too. I did peak boost at 20 PSI... heh, it's really pretty intense at that boost level. The code Is limited to 22-23 PSI by several mechanisms. So I will likely not go above 20-21 PSI. The sensor and the computer can handle more, but it would require a heavier rework of the code.
This 3 bar code Is ironing out just beautifully
[This message has been edited by Fierobsessed (edited 07-27-2015).]
Got my car through its second emissions test, and it passed
Anyway, I've been really scratching my head about my coolant temperature lately.
Ever since I turbocharged the 3.4 DOHC, the engine has a really hard time maintaining temperature. My temperature profile always looks like this:
Starts out cold, slowly builds up till it hits 182 degrees. My thermostat is a 180 degree, so thats expected. I get on the highway and it slowly creeps up to right about 208. Approximately 20-25 minutes into the drive, the temperature then starts to slowly increase into the 220's and 230's. It gets to where its almost touching red on the gage. I checked it out with an IR thermal gun, and it said my engine outlet pipe (under the car) was 217, and the upper radiator hose was 220. So, it's running hot for sure, not overheating badly, but getting up there. My fan is working just fine too.
I've always been concerned that the CTS is being cooked by the turbo crossover pipe. Its very close to it, but also well insulated. So I got another CTS and put it in a brass T, and inserted it in-line in the water feed to the turbo and connected the CTS wire to it. This small loop bypasses the thermostat, and recirculates back into the water pump so its temperature is pretty accurate. I still found it getting into the 220's today. My fan setting is 192 and the thermostat is 180, so I should never see any temperatures above 200 if the system is working correctly, or within its capacity.
My curiosity or fear, is that my intercooler FMHE may be causing the radiator airflow to be weak. I ran this radiator when I was still NA, and never had any issues with its ability to keep the engines temperature right where it is supposed to be. But I also wonder if it could be the water pump. I'm trying to remember which water pump I put in the car, since I haven't changed it out in a long timeI want to say its the one from either the crate engine, or just a cheap replacement from autozone.
Perhaps I'll just pull the FMHE and see what happens.
Those are the only two things that I can see causing this issue. As always If anyone has suggestions or any other ideas I'm all ears.
If its 220 going into the radiator, I would measure the temp coming out of the radiator too. If its much cooler, then it could be a flow issue (water pump), if its still hot, then it could be an air flow issue across the radiator.
I did measure inlet and outlet temperatures at the radiator and wasn't quite sure what to make of it. There was some temperature drop, but only a few 8-10? degrees. This could mean high water flow or an ineffective radiator. Or, it's normal? I don't have anything to compare it to. I'm sure I'm going to have to pull the heat exchanger. It would suck if its the problem, but it probably is.
The water temp doesn't actually drop much going through the radiator... a handful of degrees is normal. Yeah, pull the heat exchanger. It's likely the culprit if all of your radiator airflow is otherwise stock. Do you still have a stock radiator or do you have an upgrade?
Stock replacement V6 radiator. This car has had this same engine in it for 8 years or so and didn't have overheating issues till I turboed it. So I'm fairly certain its not a radiator quality issue. Ill let you guys know how it goes.
I'm thinking quarter panel scoops, small radiators and fans are in my near future. I really have got to start thinking about learning bodywork. This car needs it badly anyway
Well, There's my new intercooler, just a piece of pipe. I did connect it to my fill port/radiator cap, and made sure it was topped off with coolant. This way at least it'll radiate with its 25' or so of pipe and hose, and still breathe in and out coolant as a radiator should.
I also reconnected the original CTS, and then I flogged the car some. It seems to be much better. Temperatures were staying around the 1/4 mark, and ventured up to the 3/8 mark, but cooled off easily when the A/C was turned on. I'm thinking it's working fine now, but It was cooler outside and raining. I'll drive it to work tomorrow with the A/C on and see how it holds up.
If all continues to go well, I think a pair of these "Oil coolers" might be my future intercooler.
I am contemplating the location. Quarter panels seem like a possibility.
Another thing I had a chance to really test yesterday was the clutch. I got curious about how my changes to the clutch had improved the disengagement at high RPM. The answer is... Perfectly. I achieved the fastest shift I had ever done in my Fiero on the first try. I spun the tires in first, and kept the turbo spooled more than enough through the shift into second that the tires continued to spin. Needless to say, this made me very happy.
So it looks a lot like this iteration of this engine is doing much better than the first so far. I still have the boost set at a relatively low wastage spring controlled 11 psi. I set the ECM to shoot for 13, but I'm leaving the control solenoid disconnected for the time being till I have a good intercooler back in service.
Go figure, I was wrong about the intercooler. I drove the car to work, it's 109 degrees outside. Just like it did before it seemed to have the temperature under control, and then slowly started to overheat just as I was about to get off the freeway before I got to work.
It seems like removing the FMHE made absolutely no difference. I just had to re-test it on a hot day like today. Also, just my luck, It was low on refrigerant, so.. No A/C for me today. My phone overheated. I think I overheated a bit too. Now, all I can think of, is possibly the water pump, Radiator, or still an airflow problem somehow. But for the life of me I have no idea at the moment which is failing.
I'm questioning now whether or not the stock v6 radiator has enough cooling capacity on a hot day to cool this turbocharged engine, especially with the A/C on.
The turbo does add back pressure to the exhaust, causing the engine to retain more heat. That coupled with the turbo having to work a little at highway load only adds more heat and back pressure to the engine, effectively, I think that the turbo is causing the cooling system to have to cool not just the engine, but the heat that normally would be lost out the exhaust as well.
Does that sound like a reasonable theory?
Perhaps a big aluminum radiator is the answer?
Still confused about this issue, everything seems to be functioning, it just runs hot!
The turbine won't be pulling significant heat out of the exhaust unless it's making significant boost... IE, the exhaust volume/energy won't be high enough to make the turbine a restriction unless the compressor is making boost.
Have you checked all the seal flaps and material around the radiator to eliminate air paths. As you drive above 30 mph, you shouldn't need the fan to even run if the lower air dam and all the flaps around the radiator are properly installed.
Have you pulled the radiator to see if there are a bunch of leaves (or just built up dirt/muck) between it and the AC condenser?
On the topic of restriction I was thinking about the exhaust restriction on more of a function of the narrowing of the exhaust corridor before it impinges on the turbine. I mean, I go from a pair of 2.25" feeds, to one 2.25" inlet at the turbo, which funnels down to about 1.5" (?) before it's exposed to the turbine. It's not an insignificant restriction, but I know it's also plenty sufficient to not be a restriction at idle and low part throttle. Which on the highway may be on the border of being a pretty fair restriction. Even then the turbo may be producing a decent amount of air that is banging up against the mostly closed throttle blade. Perhaps I'm over thinking it too, maybe it's nothing to be concerned with. I know that a bad catalyst provides plenty of back pressure to cause a car to overheat, so that is where I'm getting this line of thought from.
Anyway, about the duct work. I did install the FMHE, and I did have to mangle the two side flaps on the inside of the nose a bit which were already falling apart. They are still in place for the most part. But to be honest, they're not in all that good of shape. I just took a look online at what complete ones are supposed to look like, and am realizing just how much of them is missing, and that it likely is an issue if not THE issue. I'd like to see this car cool as its supposed to before I attempt to reinstall the FMHE. So, I guess I'm either buying new side air dams and fresh rubber for them, or making something more specific to my application. Worth a shot before dropping coin on a radiator that I'm not entirely sure is necessary, and may not fix the problem.
On air path clogging, I recently had the condensor out of the car when I was working on the A/C. I also made sure that my condensor is in nearly flawless condition. Straightened almost every fin out for the most part. So I'm definitely clean there.
Water pump, I believe, If my memory serves, that I have the cast impeller on my water pump. I got it off my crate engine when my junk yard water pump failed when I first put the 3.4 DOHC in the car. I remember seeing those stamped ones, I don't think I would ever put one of those in a car and feel good about it. The stamped
So, I think I'll do some makeshift mods to my side air dams to see if eliminating the leakage fixes the issue.
FWIW... I took my LS4 car out for a 30 minute spin today. When I got back in the garage, I grabbed the temp gun and measured the chassis coolant tubes right before the radiator hoses. Coming from the engine was 191 degrees, and returning from the radiator was 170. The fan was on, ambient air temp was about 76 degrees, and I am running the 3-core champion radiator with the stock Fiero fan.
Driving around in vegass will help you find out if the cooling system isn't adequate. I had a fluidyne 3 row rad in my mustang and it worked fine until I moved to LV, then during the summer the coolant temps hung around 205*F. Installed a champion 4 row and the temps wouldn't creep above 195*, drove it 600 miles a week. Same issue with the GN, would not drop below 208-210*F cruising around, even with the fan on high.
IMO is good rad and a fan like the Mark VII would keep the engine cool, the original isn't going to cut it.
[This message has been edited by sleevePAPA (edited 08-24-2015).]
I figured making new, and better air dam sides couldn't hurt... Heres what the old ones looked like:
And the new ones, which will also accommodate the intercooler FMHE, if I ever get the temperature situation under control.
Drove it to work yesterday with the new air dam sides, and it didn't make any difference at all. So I had to do what I had to do and bought a new radiator.
I've been fairly confident that the stock V6 radiator could handle this engine's heat output, but short of changing the waterpump, I've investigated every alternative to upgrading the radiator, so now it's time to do just that.
When the gas tank is full, and I am on a rear downward grade (driveway) fuel leaks out of the car.
I jacked up the front end of the car the other day to work on the air dam project, and I could see the fuel dripping out of the back of the tank. I took a look and could not exactly identify the source but it looks to me like the Filler neck vent hose is a bit dry rotted. It was new from the fiero store about 8(?) years ago. That sucks, but I'll have to find a replacement for that too.
I agree! However, I haven't Had any coolant loss, or reservoir overflow issues, and I have no rear filler or cap. I've also made sure that there is no air in the rear half of the system by cracking the fitting at the turbo (highest point in the rear).
The other thing I've been considering is spark advance. I know it can cause the engine to expel more heat, and murder gas mileage and power. Also, I am running with no EGR too, which also adds some to the heat loading. So that is something I will attack too. But for sure, it's now getting a new radiator.
I'm thinking about sending the knock sensor input directly to the data stream to plot it on a RPM vs MAP histrogram to help work on my timing table. Should yield some interesting results.
Interesting development on my drive home tonight, it was a nice 88 degrees outside. The engine stayed cool, reaching the 1/4 mark for the entire drive and staying there as it should. That was sweet confirmation that my issue has been a cooling capacity problem all along.
I did a WOT second gear run to 6500 rpm, and achieved a pretty fast shift into third, mostly to test the clutch and the between shift boost lag. Very little loss of boost on the shift.
Anyway, the temp gauge didn't budge after that little beating. So I'm confident that I've made the right choice to get a new radiator. It's just too hot outside to cool the coolant enough. Especially with the a/c on.
Originally posted by Fierobsessed: I figured making new, and better air dam sides couldn't hurt... Heres what the old ones looked like:
Being able to see that much daylight was allowing a good portion of air to bypass the radiator at highway speeds vs. it being forced through the radiator. Your new side guides likely helped some, but probably wasn't the entire issue, and the larger radiator will provide some additional cooling capacity as well.