cheap car racing

[MostMint]

Only one pass, 3rd shift not too good, 1/8 mile was 10.66 so not a good number.

[MostMint]

Weighed the car this morning, and to my surprise it came in at 2136 with a full tank of gas. Need to do some digging to figure out how it was weighed last time at 2210.

Also been playing with the tune some - lots at the track day on 10/16 but also the regular driving and operating ranges. I like the idea of demonstrating our car can start cold and warm up well, with minimal fuel consumption, and the cruise mode stuff is relevant to save fuel during full course yellow not to mention back and forth to the track

[MostMint]

Yes we have enough trophies to warrant a trophy case

[TireSmoker]

That looks great!! Gwen says she likes it too

-Dave

[MostMint]

Many things happening in Mostmint garage. Finally the race car gets some love.

Removed the stock engine wiring harness. We've done 68 hours of racing with the Megasquirt it has proven itself. We'll get a spare Megasuirt set up for the next race

Took the unaltered fuel lines from the recently parted out car and installed them into this car.

Corrected a couple exhaust issues. 1) got some Walker steel band clamps and the cheaper stainless clamps were allowing the pipe to rotate and the tail pipe would hang down. 2) we replaced a broken top engine mount last year and it raised the engine which caused our exhaust to hit the subframe. This was discovered testing the day before the 24. So I altered the downpipe to put the exhaust a bit lower and I think we're good to go.

Also started on a transmission. I have enough parts to make one - so today I got to work preparing the case that lost a bearing at the end of the VIR race. Kurt had welded it shut but there was a lot of cleanup needed to install replacement bearing.

[MostMint]

With no races in 2020 there was not much action after the track day in 2020. That day the car performed well.

This year we took the car to track day again, with very little prep work. Did make some adjustments to the tune as it was not idling right. Test drive left me thinking it was a bit down on power, but we still went.

We ran maybe three hours at the track day. Colin did not make over 101 on the back straight, and with 1:22 lap times I don't think the problem was the driving. Also loading it on the trailer uncovered some knocking.

Compression check found all the cylinders in good shape - over 180 psi. Oil and filter check found a fine sheen of metal in the oil and bits of metal in the filter. Engine of course had to come out. Tear down uncovered all the bearings in good shape. Further tear down located the source of the metal. The pistons in cylinders 3 and 4 both had cracks in the skirts and little bits of metal were breaking off the bottom edge of the skirts. By my records these had about 85 hours of track day use. They are Speedpro hyperteuctic. The rings were just seating into the bores. I went to get another set and they are discontinued - found a new set on eBay.

Reassembled the engine with same bearings and rings. Got help from Fred32v, Tiresmoker on the remove and install processes.

Draining the transmission I noticed a high amount of metal in the oil. This trans had only done two track days. With it sitting on the floor I chose to disassemble and inspect. Found everything to be in good order - I can only assume the parts that were in the blown up case had lots of shavings left over so I cleaned what I could see off the case and put it back together.

This year the fire suppression system, window net, seat belts are all expired. Fire suppression no longer meets the rules so we need a new one. Fred32v has been over helping on the race prep and took on this task. He also took on the window net replacement.

Today we were planning to replace the LF spring since the car rides a bit lower on the LF than the RF. During this disassembly Tiresmoker noticed the strut has lost almost all of its firmness, and it appears to no longer be gas charged. We put these on in 2012 after our second race. Replacements will be here on Thursday.

Also there were a couple holes in the floor in the back, and Kurt stopped by to fabricate patch panels and weld them in.

[MostMint]

Post race there have been several things done on the car:

* replace the flexpipe in the exhaust - it failed during the race. It had been replaced in 2014 after the race so now we have a maintenance interval
* fabricate a gusset for the top dash bar to address an unwritten rule. that rule is if the bar has a bend in it that is inadequate strength
* replace the front rotors
* brake ducts had gotten separated from the front bumper cover and the passenger side duct got crushed. Repaired the right side and reconnected both.
* front tow hook took some damage in the same incident that separated the ducts, so we took the opportunity to make a new hook - from non-threaded material this time
* water replaced with radiator fluid for winter
* we have a stack of fairly worn out tires but two tires and two rims were deemed not useable after the race. The rim that got tacoed is a souvenir for Rachel the rest are trashed
* change out the spark plugs - we were down on power just a bit and plugs are cheap
* added a resonator to the exhaust in attempt to quiet it down a little
* there is a hole in the floor where the ebrake cable goes on the passeneger side - fabricated a piece to replace out the rusted part. Kurt welded it in and I followed that up with fire resistant caulk to fill the remaining gaps
* change the transmission fluid - regular post race maintenance

During the race we had an issue with our Megasquirt that cost us some time. I am about 90% sure it is having intermittent problems, so the car is out to Tiresmoker's to get the upgrade.

[MostMint]

Dave successfully replaced our MS2 chip with an MS3 chip, and roughed in a tune so it could be driven.

It didn't start that great thought so I planned to adjust the tune accordingly. I transferred a bunch of settings from the old tune to the new one. The MS3 has more features and so the old one won't just "import". In my efforts to change things I overdid it a bit and changed one of the ignition settings which only made the cold starting problem worse. The thing was flooding out and backfiring in the intake and exhaust - due to wasted spark configuration troubleshooting whether timing was too far advanced or retarded was not possible.

I decided to get back to basics, so I set up a temporary timing marker and brought out the timing light. I also cut power to the fuel pump and just focused on cold cranking timing. This helped me clear up the incorrect settings I had made. However the timing was at 0 when it was cranking which is just not right. There was some inconsistency in the behavior which was also confusing and quite frustrating.

The Distributorless Ignition System (DIS) is capable of controlling the timing on its own, as well as taking a signal from the ECU and using that. I ultimately cut the signal wire to see if the DIS would behave and it was still putting the timing a 0 while cranking. With some analysis I was able to ascertain the problem here. In 1993 Saturn decided to move the notch in the crank back 10 degrees to improve startup. So if you use a DIS from a 93 or newer with a 92 crank you get 0 degrees advance. Switching to a 92 DIS moved it to about 5 degrees BTDC so at least I knew something was better there.

In this configuration I was able to get the car to start reasonably well with my updated version of the baseline tune from Dave. Still a ways to go til its refined like a factory tune.

So on to the next problem - why was the DIS not getting the signal from the ECU. Well there are two wires going to the DIS from the Megasquirt. One provides instruction on when to fire, the second is a "signal" wire that tells the DIS to use the instructions from the ECU. The signal on that wire is +5v DC, but the wire is only sending +4v DC. When I send +5v DC to the DIS it works just fine off the ECU instruction wire - which I can see with the timing light. Kurt had a device where I could specify what DC voltage I wanted and when I hooked it up to the signal wire the timing changed.

Now the Megasquirt is supposed to send +5v to the TPS and down this signal wire. Last night I was able to confirm that the TPS wire is getting +5v while the DIS signal wire is just below +4v.

I know which pins are outputting these two signals so the next step is to figure out why the DIS signal voltage is low. I'll check the resistance in the wire then try to get the voltage output right at the pin coming out of the Megasquirt. I might need to look in the case. If all else fails I can experiment with splitting the TPS +5v and see if it will work for both, or make my own source of +5v and make it so the car requires the ECU signal at all times. For reasons I do not understand the factory configuration has the car starting with the DIS not using the ECU signal.

With the weather being crappy and so many other excuses these events span out over the last 5 months or so.

[MostMint]

I now have a temporary harness for testing. Should have some test results tomorrow

[MostMint]

Made a lot of progress. We had one wire set up incorrectly. With that sorted out I put the unit back together, bench tested, then put it back in the car.

There is another problem. The signal wire to the DIS from the ECU should be 0 volts until the car runs for 5 seconds then send +5 volts. 0 volts tells the DIS to control the timing and 5 volts tells it to accept the timing from the ECU (how the factory ECU works as well). The problem is that the signal wire is doing the exact opposite. The DIS has a very basic timing advance and while it will run this will not be optimal performance. I've got some digging to do to figure out why this is so.

[MostMint]

I'm now past the problem. Searching Megaquirt forums I found a reference to someone who had a list of problems including this, and someone recommended changing "Spark Output" setting - and this fixed the inverted signal to the DIS. I've done a couple rounds of refining on the tune and the car now starts with just a turn of the key.

Still a ways to go as the RPMs pulse when it's cold, and it's a little sluggish on the throttle. There are some new tables in the tuner software I want to investigate, and I'll double check my settings.

[MostMint]

Getting closer to calling the MS3 conversion complete.

I have a laptop sitting on a card able next to the RF fender with easy access to the remote start switch. When I'm in the garage this is where I do most of the work.

Since last update:
* Discovered the TPS input was not changing, which led me to reconnecting the TPS connector. This helped with the hesitation when using the throttle
* Made some tweaks to the lower left of the Volumetric Efficiency (VE) table (lower RPMs and higher vacuum). The first round of testing had it idling fine until it started warming up and the Warm Up Enrichment (WUE) started adding less fuel and then the idle would start pulsing up and down in a pattern. In the second test I used the throttle to get past this and idle it at normal operating temp, and used the air-fuel ratio as my guide to make final adjustments to the VE table. I am still not certain why the VE table from the MS2 is not correct, but that is for another day to solve.
* The electric fan was kicking on at 170 degrees. Found the settings for that and changed it to come on at 202 and off at 195.
* Used the third session to refine the WUE, confirm fan working properly, and reduce the idle air (effectively turn in the idle air screw) to get the idle down to about 900 RPMs at regular operating temp.

Right now I've got the Air Fuel Ratio auto correction set at 1% just so I can see if it's working, but eventually I will give it more control to make AFR match the targeted values. Optimizing all the settings to keep AFR good without the O2 sensor input helps ensure that if we have problems with the O2 input the engine will still run decent.

Up next are
* getting the timing in the ECU to match what I see on the crank. I think crank timing is about 3 degrees lower than the ECU is showing.
* refining WUE during warm up cycle.

After that I think it's time to put the car back on the ground and take a test drive.

[MostMint]

Went through another engine start/warm up cycle and made several adjustments. It idles really smooth - can still use some refinement - but that part of the process is probably not the most important right now. I made adjustments to align the on the crank timing with what the ECU read as well.

It now needs a test drive just to make sure it runs decent under power and not too rich/lean.

[MostMint]

Action from today:

Fred32v was over for a work session. Before we started I went to start the car and it wouldn't start. I moved around some of the wires near the Megasquirt so I wonder if some connection was lost. The fuel pump seemed to cycle more times than it should. IDK will get to troubleshooting later.

We did some of the post race inspection (from last year's race): compression test showed 175-185 PSI, checked the rear suspension bolts for tight, measured wear on rear brake pads.

Also created a plate on which to mount the Megasquirt - building something sturdier to keep it in place during the rigors of racing, relabeled all the plug wires and coil packs, fixed the low coolant light (it gets power from the fuel injector fuse - which had been removed since we not using those wires anymore).

[MostMint]

Today the mounting plate project for the MS3 is complete. We had some adventure as the welding caught some material in the duct on fire but it was tiny and we just used a syringe to shoot some water in there and put out the flames.

If I had it to do over I would have made the plate bigger and mounted the fuse and relay block on it as well.

Also, the car did start but apparently the MS3 will not accept a negative trigger angle. After I reset that, It was unhappy at colder temps. More experimenting required