t2d2

iTrader: (8)

1998 SC400.

I've had three batteries die recently on the various cars, at least two of them during cold spells. The AGM in the '98 was one of them, although it seemed okay after a couple hours on the balance charger. After a week or two of working fine, it fell on its face again after not being driven for a few days. It started but didn't quite stay running, then would crank very weak but not start after that.

So, I put it back on the balance charger and went to drive it two days later, only to have it crank but not start. I didn't check the CCA's on the battery, but I figured it must be toast so I jumped in the '95 and put off worrying about it until later... One odd thing I noticed when I got out of the '98 was very white smoke coming from the left tail pipe.

Today, I swapped the new battery from the '95 (one of the recent cold weather deaths) over to the '98, assuming that would solve the problem. Nope. Still just cranks but no start. My heart instantly sunk at the thought of 1UZ starter problems. It went from starting strong, to starting just the once briefly, to not starting at all. I would expect starter issues to be a gradual decline, unless maybe some wiring failed.

I'm thinking (and hoping!) fueling might be a more likely culprit. I haven't filled up recently, but it could be something was already in the tank or the fuel filter was close to clogging up. Any suggestions of what troubleshooting to prioritize, given the symptoms?

t2d2

iTrader: (8)

To make matters more confusing, I put the '98 battery on the analyzer just now and it read 11.85V, but no CCA's registering, so I hooked up the balance charger again and it instantly read as full and turned off. So, I put it in the '95 and it wouldn't crank at all.

So, that battery is definitely a problem. But, putting the good battery in the '98 didn't help, so a second problem seems to have sprung up simultaneously.

t2d2

iTrader: (8)

No obd2 codes stored, and all engine bay fuses look good.

BiGEZ

iTrader: (24)

If it cranks I think it is not your starter and some other problem like fuel or ignition. Spray some starter fluid in the intake and see if it starts to eliminate the fuel problem.
I would get a new battery just to be sure.
This cold weather just wrecks havoc on these cars.

t2d2

iTrader: (8)

Thanks for the reply. I didn't have time to work on it any further today. Starter fluid is on my list of things to try...something I always forget to purchase.

The battery is brand new and in good health. The NAPA battery in the '95 was one of the recent demises, but it was only a year and a half old. NAPA couldn't recover it, so they gave me a ~80% exchange credit on a new one. It was only in the '95 for a couple weeks before I put it in the '98 this week to troubleshoot.

I think I have a spare fuel filter in the new parts bin, and spark plugs have been on the to-do list, so if it turns out to be something simple like that, that would be fantastic. I think I'll also put a disconnect on the negative terminal and see if there's a parasitic monster lurking. I've been a bit suspicious of the Double DIN w/ nav and security LED...

t2d2

iTrader: (8)

I picked up some starter fluid today and tried it out after topping off the other non-dead battery (swapped the new one back to the '95 so it would be driveable), and no go...literally. I sprayed it into the intake box with the air filter removed, not sure if that matters. Some people recommend spraying it directly into the filter, but that didn't seem right to me. Is it worth removing the intake and spraying it directly into the plenum?

Spark is probably my next thing to check; will have to get a helper for that, unless there's some way on these cars to hook up a remote switch to turn it over from the engine bay? I think the starter solenoid is connected to the starter, so probably not.

BiGEZ

iTrader: (24)

The best place to inject the starter fluid is the port on top of the throttle body. There should be a capped vacuum port there, spray the starter fluid in there. Just leave the intake piping and sensor installed as it should be.
Have a look at the starter relay and replace it too.
Worse case is your starter in on its way out.

t2d2

iTrader: (8)

Well, I think I solved it. I do see the capped port you mentioned on the TB, but I didn't have to use any more starting fluid. I swapped in a spare starter relay (no visual issues with the old one) and got the car to start, although I had to give it gas a few times to keep it from stalling, and then had to keep it at ~1300 RPM or it felt like it would fall on its face. It did finally stay running on its own, but the idle felt low and rough, and revving it lightly had a similarly unsettled feel.

I was going to pull coils (COPs) and plugs today, but it started raining just as I got my tools out, so I figured I'd move on to jumping the Fp and +b terminals to see if it's a fuel pump ecu issue. To my surprise, there's no Fp terminal... Did they do away with that on the VVTi models, being a return-less fuel system? The slot is there in the diagnostics box, but there's no terminal in it to jumper.

So, I looked over vacuum lines again, not expecting to find anything crumbly as I already replaced most of them with silicone. However, I noticed the pinch clamp wasn't holding the hose snug on top of the intake plenum, so I replaced that with a screw clamp. Fingers crossed...fired up and felt like normal!

The best I can figure, it was a perfect storm of dying battery, loose vacuum hose, bad starter relay, and maybe bad gas.

I think I'll change out the fuel filter, just to be safe. After my first experience doing so, I know not to trust the SC fuel gauge that notoriously reads low... I'll be siphoning the tank to bone dry! I might as well bump the spark plugs up the to-do list. Any preferences between platinum, double platinum, and iridium on the VVTi engine? I couldn't find many recommendations one way or the other, and the owner's manual doesn't appear to specify anything.

BiGEZ

iTrader: (24)

Glad you got it figured out and running. I had the intermittent no start on my 99 SC400 which leads me to believe my starter is on it way out. I replaced the starter relay and it has been behaving itself like normal . I know I am on borrowed time with the starter.
I recently replaced my spark plugs with Denso SK20R11 long life Iridium and the fuel filter.
I have not used the double platinum plugs so not sure about those.

t2d2

iTrader: (8)

Thanks for the spark plug recommendation. There's hardly any difference between the iridiums and double/triple platinums, so I might as well go with what works for you. I figure Denso and NGK are always a safe bet.

The thoughts of a 1UZ starter going out will make anyone pucker up... If I ever have to tackle that, I plan to try the recently popular approach of just doing the contacts, requiring much less disassembly than getting the whole starter out.

With the starter relay fixing your problem, I wouldn't think there's any reason to fear your starter being the issue? Unless a dying starter can kill a starter relay?

Another odd thing with my situation, the head unit lost all its memory settings, as if a hard reset had been done. Even when the battery went flat, interior lights still worked. Whatever happened, seems to have temporarily zapped the electrical system with no permanent damage. I'll be keeping an eye out for related oddities, but it's driving perfectly now.

Ali SC3

iTrader: (10)

if the engine is cranking then that means the starter is working fine. when the starter goes out it will make a loud click when you turn the key and the engine wont crank over.
At first this will happen intermittently, and eventually it will happen every time.
the starter relay just powers the starter, so if the engine is cranking over then that means the relay is giving it power, I think it was just chance that the starter was behaving after replacing the relay.

It was most likely the combination of the weak battery and the loose hose. when the battery is that low or dead the ecu might not even be on but the starter will still crank some.
If the battery is low but the ecu is still on, it will inject the startup fuel (its cold so it sprays more fuel), and without enough spark energy (low battery) or an air leak, it won't combust properly and you basically flood the motor.

if you crank it over and it does not start, after replacing/charging/jumping the battery push the gas pedal all the way to the ground and crank it for like 5-10 seconds, this will help clear out the extra gas.
Then get off the pedal and try and start normally.

I always use Iridium on these cars, usually NGK but Denso is good too. don't mess around with the platinum plugs, they aren't even close to as good.
The Iridiums have better spark energy and are very difficult to foul, and will give you better luck with cold starts.

also with regards to the memory loss settings, that's a sign of the battery having some bad cells. generally it will hold enough charge to keep the lights and stuff going, and sometimes it will even charge up to proper voltage... but as soon as you load it up like trying to start the car, the bad cells will short out and the voltage drops enough to loose all the settings etc.. the good cells will keep the light load stuff working, like interior lights, but the drop in voltage when its in the shorted state (when you turn the key to crank it) will erase all the memory cause the battery will drop really low.

A good practice in the future is to charge up the battery before you go to start it. Do this when the car has been sitting for a while and its cold outside (like winter).
A battery that is low on charge which happens normally with the cold weather and sitting, can be recharged and the cells will have a good chance of operating like normal depending on battery age.
Now if you were to start that car without recharging the battery, you have a really good chance of damaging the cells, which happens when they drop below 11v or so.. and once you do that they will not hold a charge even if you put it on the battery charger. the battery charger will read that its charged, but as soon as you load it up that bad cell will loose all its charge.

In short good practice to charge up a sitting battery before you load it, cause after you load it up its likely to be toast. thats why alot of poeple use battery tenders in the winter, so the voltage always stays above the level that damages the battery. Also AGM batteries are more sensitive, and I would recommend a battery tender on those batteries or even going back to a regular battery.

t2d2

iTrader: (8)

I never got any clicking, but then I've helped friends with cars that clicked when it was the battery and not the starter, so I've lost faith in that being a reliable diagnostic measure.

The problem with the weak battery theory is, I swapped in the brand new, fully charged battery and the problem persisted. The old battery is back in now and running fine after another session on the balance charger. Whatever happened seems to have created a problem with the battery, rather than stemming from it.

When got it running after swapping starter relays, it did smell strongly of fuel for a few minutes. I figured it had been flooded from failed starting attempts, like you said.

The [aftermarket] head unit is supposed to store backed up settings in case of battery failure. "Audio Control, AV-IN SETUP, Camera, and Audio SETUP settings can be memorized. The memorized settings can be recalled at any time. For example, even when the settings are cleared due to replacement of the battery, the settings can be restored." Everything about what happened is contradictory...

The balance charger generally works well for low voltage batteries that the trickle charger can't recognize as needing attention. My truck battery was nearly dead when I got it and looked like it was destined for being a big door stop, but a couple sessions on the balance charger and it's still cranking strong a year later, even in cold weather and despite infrequent use. It had virtually no output on the battery analyzer and wouldn't respond to the trickle charger.

Iridiums it is!

Ali SC3

iTrader: (10)

I could have described it better, when the starter is going bad its one very loud "thunk" sound and that is it, no cranking, no clicking.
I had written loud click above, but I can see that is confusing cause its just one loud thunk sound, if it repeats its not the starter.
When you turn the key and it repeatedly clicks that is 100% the battery, or a loose/corroded terminal on the battery.

I think when you put the new battery in it was too flooded to start in that weather. but with batteries its kind of a test and guessing game.
the old battery can work if it fully charged, but I wouldn't be surprised if you lost one or more cells. sometimes you get lucky and they are able to get revived.

Some aftermarket headunits will recall after you disconnect the battery, but when the battery voltage dips too low while its powered on you might loose the settings.

that isn't really that important though, at least you got it all solved. the Iridiums are 150% the way to go!