poormxdad

I'm trying to get her home. It has died fiVE times in 50 miles. If I turn the key with the laptop connected and TS says Off Line, what could it be?

poormxdad

On the side of the road again. TS was logging. When the car died, TS showed Off Line.

I replaced the battery this morning. No help.

poormxdad

Stopped on the side of the Colonial Parkway waiting for a flatbed.

Whatever is going on the interval between cut outs is getting shorter and shorter. I threw in the towel.

There's no pattern as to why, but I did look at the last log I took before dealing with the roadside assistance folks. Battery voltage suddenly went to 9.5.

poormxdad

Gentlemen,

Here's a short log but other logs are similar.

At 397.066s Alternator Target Voltage goes to 0. One more click of the Right Arrow key and the time jumps to 506.090s. I assume the missing interval is coasting to a stop with the key on, engine off, MS Off Line. Then it takes another second or so for the log to show the minimum Battery Voltage, in this case 9.8V. Alternator Target Voltage doesn't start to go up till 508.978s. I assume I am attempting to start the car and the MS is on line. Looking back at the log in Post #19, the same thing happened. Alternator Target Voltage goes to 0, then some time is missing before the log showed the Min Battery Voltage. And that was with a different battery. What would cause TS or the PNP Pro to make the Alternator Target Voltage 0? Or, is the MS going offline and that Alternator Target Voltage of 0 just one of the last things recorded?

Since I actually had the laptop hooked up, I did notice a few other things. After she would die, sometimes I would turn the key to restart and nothing. TS indicated Off Line. Sometimes after she died, I would turn the key on and I would only hear part of the normal fuel pump prime cycle. Maybe half. It would stop, and TS indicated Off Line. But if I turned the key, got the full prime cycle, and TS indicated Connected, she started normally every time. I've also attached a few Composite Logs I took when trying to restart the car. I do not know if they captured anything.

My next event is supposed to be this coming Thursday. Any words of wit would be greatly appreciated.

sixshooter

iTrader: (12)

I just went through some strange electrical things a few weeks ago that included strange voltage changes. Removing the main battery ground from the ppf just forward of the diff (that's where the big black cable goes and ends) and scuffing all of the surfaces with sand paper and reassembling solved my problem. Your condition could be caused by poor connectivity or a loose wire or any number of things. I know I should have started with removing and cleaning all of the connections for the major power and ground wires initially. I assumed they were good. In your case it certainly can't hurt anything.

aidandj

iTrader: (5)

It's a loose ground somewhere I bet. Check your battery terminals and all engine grounds.

poormxdad

I've checked every one, even the one on the PPF. They all seem fine. There has to be something related to the fact that the Off Lines happened at shorter and shorter intervals. In other words, for some reason it's getting worse. There was no pattern to speed, revs, bumpy road surfaces, or even me moving my feet around under where the MegaSquirt lives for shifting, or having the cruise control on. I even thought that it would get better as the temp dropped in the evening, but it didn't. With the car running, I grabbed and jossled every wire I could find--cam and crank sensors, O2, harness going into the MS, even the fan. I could not get her to die. I'm out of ideas.

aceswerling

Out of curiosity, how hot is your main relay when the engine quits? Could the relay be failing due to extra load/heat? Would that explain the voltage blip you're seeing?

SpartanSV

Main relay is my bet as well. Could be heating up and increasing resistance. Easy to check with a jumper wire. Also explains why voltage at the ecu is that low without cranking issues.

EDIT:
Unless by nothing you meant no crank. Then the relay isn't the issue.

Still could be if power for the ignition switch goes through the main relay. I don't have a diagram handy.

poormxdad

Put in a new main relay. No change.

What next?

aceswerling

Was the main relay hot when the engine died?

poormxdad

I did not check that. Dammit. If it were, what would that mean?

aceswerling

If it's hot then the relay is getting overloaded.

I'm troubleshooting a similar problem to yours on my NA and I'm focusing on the main relay. I've found that my car will run great for a while and suddenly die when the engine gets heatsoaked. I've also got lean AFRs on restart that I've never been able to figure out.

When the engine dies on my car, the relay will be hot and the engine won't start until I swap it out for a cooler one. The cooler relay will allow the car to run for a little while but that interval will be shorter the hotter the engine is. I've taken several steps to alleviate the problem, each of which has helped a bit. The first was to replace bits of wire in the harness leading to the hot pins on the main relay. Flyin Miata turned me on to this by indicating the wires get overheated just like the relay, increasing resistance and making the problem worse. The second was to install relays on current-drawing accessories like the fuel pump and radiator fan. This offloaded current going through the main relay, lowering heat and making things more reliable.

I'm still having a bit of trouble though. My current theory is a loose connection on my CAS (which you've already looked at) and bad grounds. I noticed that the ground strap on the driver's side from the engine to the chassis is frayed. That led me to theorize that the positive side of these circuits could be getting plenty of power but the negative side wasn't able to return power properly. This would increase resistance, cause heat to increase, and blow the main relay. I recently installed an additional ground strap from the valve cover gasket to the chassis with the hope this will improve things. Does any of this sound familiar to your car?

I haven't been able to fully test this because I'm waiting for parts for another project and my car isn't running this week. I'm hopeful to have it going by the weekend, at which point I'll determine if I've fixed anything.

poormxdad

This is a relatively new problem for me. I thought I had it conquered with the new cam position sensor and the sensor pigtail. When it happened Saturday morning, CLT was below 187 and MAT was about 100. The car was not hot.

It wasn't doing this a couple of months ago. It sounds like you're saying we have deteriorating hardware. If so, wouldn't the fix just be new wiring to the main relay and a new main relay?

aceswerling

I'm saying that we have similar symptoms but there may be different causes. I'm sharing my experience to see if anything resonates.

I've observed more problems when my engine is heat soaked, but like you, it doesn't have to be the case. If there are electrical issues causing the main relay to fail then it could happen even if the engine is relatively cool.

Regardless, it's reasonable to guess the engine dying like this is caused by some electrical connection breaking. It's a matter of figuring out which connection that is, which is probably easier said than done. I've seen that my main relay cuts out (breaks the electrical connection) sometimes and I'm suggesting that could be happening for you too. You'd know for sure if your relay is hot when the engine dies. If not, then we need to keep looking.

poormxdad

Roger that.

I had planned to drive her around after work, keeping close to the house but it's raining like hell now. I doubt I'll get to it tonight. If it's not hot from an overload, what else could it be?

It's funny. It's been a perfect storm... my sh!tbox '90 daily driver needed a right rear caliper. I ordered one from Rock and some pads, and brought the car into the garage about three weeks ago. I found the left caliper leaked when I backed out the adjuster. Ordered that. Then I found the reman Rock sent was bad. Reordered. I noticed all my front end dust boots were bad. I did tie rod ends, lower ball joints, and upper ball joint boots. And then I saw water under the engine. She needed a water pump. The water pump/timing belt kit didn't come with the correct SNC crank seal. Sourced one from O'Reilly's. It folded over while trying to seat it. I had to pick up one the next day across the water in Norfolk. I pushed it ALL THE WAY IN with my thumbs. I needed to source another one. She is STILL taking up the garage, and my track car is out in the rain, down for the count.

Will idling in the driveway reveal an electrical overload?

poormxdad

She died three times in the driveway with the hood up. I could hold the main relay between my fingers each time and it was warm but not near uncomfortable.

I was able to grab and shake the fuel injector wire bundle near where the three connectors come out, and make her die twice. But I shook it a few times and nothing happened.

Battery voltage running was 13.63. I thought it would be higher.

aceswerling

OK, so the relay isn't the problem then.

It seems reasonable to chase down the bit of the wiring harness that's making the engine die. There's a good chance you've got a loose connection somewhere. Have you cut any of the wires? Maybe check those connections?

poormxdad

I spliced in a new cam position sensor pigtail a few days ago, but after I started having this problem. The only other thing would be the extension for the coolant temp sensor required by the reroute. I did that three plus years ago. Maybe the injector harness is just old and tired, like me.

aceswerling

I'm sure there are much more qualified folks than I to comment on the wiring harness. Perhaps others can suggest the best way to figure that out.