Yes. If for some reason the filament didn't blow, it could be the cause of your drain. If the replacement blows, then you'll have narrowed down where your ground fault may be.

 

I think if it were me, I'd start with a fresh new battery. Discharged/recharged batteries with a bad cell can cause a car to act all kinds of fool with literally no pattern at all.

 

My 1990 Miata's dark current spec is <= 20 mA. It actually uses about 11 mA. I think that current just keeps the ECU (PCME) stored memory active. [Edit: My 1994 RX-7 FWM also says its battery's maximum dark current allowed is 20 mA (page G-5).]

 

Thanks bill, I noticed that spec this morning.

Since I think that my shorting accident occurred by bumping against the alternator housing, I suspect I may have blown a diode or something in the alternator. The wonderful thing is I have a spare alternator in the garage.

I also think the battery is pretty drained, probably a loser. So I'll find my Sears receipt and get it swapped, or at least steal the battery out of my Maxima for testing. Finally, the fuse that looks a little dark is the 30A EGI fuse in the box by the B+ terminal. I switched it with the 30A fuse for the headlight retractors until I get a replacement.

Blown alternator and half-dead battery, in combination with the crossed vacuum lines, makes for a good theory. I'll post my results.

Dave

 

OK, today the battery was at 6.5V. Nowhere near acceptable, but enough to turn the ignition on and check for abnormal drain. I switched the toasty looking 30A fuse with a good looking one (that feeds the headlight retractors - I figure that's a safe swap for now).

With ignition on, and alternator connected, my ammeter said .45A drain. AC, interior lights, stereo, etc all turned off. Hm, I don't know of any spec that says what it should be, but that doesn't look good. Disconnected the alternator - igntion on again, still says .45A drain. Dark current still near zero.

I also checked the resistance of the alternator field - 29kOhm between one side and ground, 69kOhm on the other, and 98kOhm between the two. Nearly the same numbers on the known good alternator.

I'm going to get a new battery now, but I fear .45A drain is still excessive. Now I guess I need to connect a good battery and start pulling fuses in succession to start narrowing down the short. Would the ignition itself be a likely candidate?

Dave

 

Check the voltages on the TPS. If you knocked it out of alignment far enough, it won't hold idle. It'll do exactly what you said is happening.

 

Well I have the UIM, rats nest, and fuel rail pulled at the moment. So checking the TPS is going to have to wait.

Right now I need to figure out what's causing the 1/2A current draw with the ignition on. (no cranking of course). If it's in the main wiring harness I need to find it before it's buried under rats nest again. It blew the 10A fuse in my ammeter, so I guess I'm kinda stuck until tomorrow morning.

Dave

 

I finally had some time back in the USA and got some quality time under the hood.

1) I didn't have a major electrical problem as I suspected - actually my quick charger took a dump. This is why my battery died - the charger was putting out 6.5v and presumably a night of that would kill any battery. I now have a new battery.

2) The vacuum lines were reinstalled, and I really think I have nothing crossed.

3) I noticed the lower leading plug wire didn't seat well on the coil - maybe this was happening all along. Now I used a pliers to seat it well.

4) I installed fresh plugs, primed the fuel lines, and deflooded the engine.

5) The gas is 4.5 months old, but the fuel pump is delivering and hold pressure fine. The injectors passed a leak test and spit fuel whenever voltage is applied to them. (I know that's a crude test for injectors as finicky as these, but anyway)

----------------------

The car will not start now. I get solid cranking, no CEL, and spark on the leadings. (Didn't check the trailing). Did an unflood, and saw nothing spray out. I sprayed some carb cleaner in the boost gauge port of the UIM, but it still didn't start.

So that leaves...nothing!?! I found a little oily fuel on the leadings, which I cleaned off. I get spark, it looks a little yellow but I chalked that up to it being in broad daylight. The leading coil tests at 13.3kOhm, and the leads are 2.5kOhm each, and 18.0kOhm across both leads when connected to the coil. I've tried cranking with no throttle and wide open. I don't have a spare leading coil to swap with. Can I test for weak spark using my multimeter?

Any suggestions? I'm headed out to try starting it again.

Dave

 

damn, my condolences on this shiz man. who-da-thunk that forgetting to connect a hose could lead to all this.

 

Yeah, it is a pretty strange trip. It's mostly a pain b/c I don't have it in my garage. I can't count how many times I've removed the plugs, but on the bright side I could probably do it blindfolded and underwater now.

I also ran another test where I hooked up the fuel pressure gauge during cranking (to be sure the FP relay activates the pump correctly), and I got 38psi. So that means I have fuel going into the rail, I have spark, and I presumably have air. Still no ECU codes.

Well, I'm reading in the FSM on checking the voltage going to the ECU for the crank sensors and MAP. I was monkeying around near the crank sensors and crank harness (had the vac chamber removed), so perhaps the problem lies there.

Dave

 

1. Did you replace the alternator yet? Your alternator theory makes sense to me.


2. Have you checked the current drain since replacing the battery? The change in battery voltage (from 6V --> 12V) will cause the current draw to change also.


3. Another thing you might look into is the ignition switch on the steering column. If I recall correctly, a bad ignition switch can cause all kinds of havoc. Your short could have affected this.

-s-

 

1) Alternator is replaced. No perceivable difference between them.
2) Current drain on ignition:off is 14mA (<25mA)
3) Haven't looked into it.

There is a troubleshooting diagram in FSM G-6 that I'm going through, and so far I went through it 1, 2, 3, 10. I'm still evaluating 10. If there is bad wiring between the PCME and CkPS's, that would explain the whole episode, and why it was hard to diagnose. I suspect that is the case, since from the ECU connector I could get no continuity b/t terminals 4E, 4H, and 4G (ref. page F-26 and F-27, step 6).

Dave

 

Using a spare cut-up harness in clear light to refine my technique, (mostly how to poke the mulitmeter leads into the harness connector), I got some valid readings tonight.

The CASs both read with in-spec values for resistance. As do the fuel injectors, but I'm still doing readings on them to be sure if that circuit isn't shorted. Grrr. Now to figure out if the injectors are getting signal during cranking, and if so, that they fire. Also, I need to verify the MAP is reading correctly. And yet through all of this, I get no ECU codes.

Now that the gas in the tank is 4 months old, could this be my problem? Much as I'd like to use it in my other car, it's nearly a full tank and that would be a mess to drain while in a parking space.

Dave

 

4 month old gas would be no problem at all. I've started cars with 4 *year* old gas that ran fine...as long as there is no rust in the tank.

 

Just to second this, I have another car that only gets driven a few miles a year and the gas in that tank is much older. I can't believe that would be any problem.

 

Well since I have spark and I have fuel running in the rail, that leaves the injectors not firing as the only cause for a no-start. Whenever I run the unflood procedure, I get no fuel spray out the leadings. The plugs aren't quite dry, but they certainly aren't dripping wet. I think they just have a little MMO on them.

That leaves 3 possibilities I see now:

1) Injectors not working right: possible, although they shoot fuel when I applied 9V.

2) Injectors not receiving signal: possible, if the harness is shorted somewhere. I'm still studying the diagrams to verify the circuit and how to isolate any short.

3) Injectors not being sent signal: possible, if the ECU is shot or a critical sensor isn't working right. However, the ECU posts no codes. Must the engine actually be started to post a code?

Dave

 

Is there a way to test the TPS? I'd look at whatever got sprayed with coolant first.
Then I'd replace the injectors.

 

I second that highly.

The TPS wires bend around there quite tightly. If they are baked, it is possible you lost one or cracked one messing around. The result would be what you originally described. It is easy to check. Use a voltmeter and get a stickpin to slide into the back of the connector along side the wires as a probe.

 

Also, I had the same problem with the vac line you described. Did the same thing....

 

Just a note that helps explain why I have been stumbling around:

In the FSM, there are two no-start troublshooting procedures: the list in the chart on F-179 and F-180, and the list on G-6.

As well, when you dig into section F, sensors like the TPS and CAS have multiple troubleshooting lists as well. Offhand, I find some sensor tests following the ECU trouble codes (F-18 to F-75) and the PCME troubleshooting (F-150 to F-165).

I have plenty left to check, by the end of tonight I should be done checking all the wiring and sensors.

Dave

 

sidenote: Section F is pretty hefty isn't it? I had to work comp time just to print it out at work on a slowass HP 3si.
Good luck.

 

It's not only hefty, it's severely disjointed. Well, it's better to have the extra info than not have it at all, as far as I'm concerned.

I have the full print copy, but whenever I tackle somethign specific like this I print the pages for my issue on the printer so I can scribble all over it and not lug the book all around the car.

Dave

 

Update:

Last night I was running the TPS tests with the Ignition On (found that the narrow range voltage was a little high - 1.33v where the spec is 0.75 to 1.25v), and in that process it stopped getting power to the sensor. The battery, which was at 12.6v when I started, had dropped to 12.4v. That's when I noticed a very faint humming/buzzing sound coming from under the UIM or engine block. I could feel it when I put my hand on the UIM. I couldn't pinpoint the source, and decided to stop since the battery ahd gotten down to 12.3v. (I'm working across the street from my garage, so I'm working on battery power alone).

What could that humming sound be? Is that normal? (my fuel pump isn't jumpered at the moment - everything is connected as normal)

So again, it seems strange that a brand new Sears DieHard battery would lose .5v in about 5 min of Ignition: On. I'm going to buy a new trickle charger today (mine must have gone bad and killed the last battery, since last week I noticed my charger only outputs 6.5v) and freshen up the battery. The dark current is only 15mA.

I will try to pinpoint the humming sound, and search the FSM for all wires that carry power when the Ignition is on. Maybe I can figure out which one it is. I'll also pull the plugs and do a quick unflood, in case it was an injector dumping fuel.

Dave

 

The spec on the TPS is pretty critical. Shoot for the middle of the tolerance. I suspect there is also something else amiss though.

 

Well once I get the battery recharged, and confirm that I have the TPS adjusted to the middle of the range, I'll surely try and start it up. If it runs, that would be a nice accomplishment since I could at least move the car around and into my garage.

But I would like to know if it's normal to see battery voltage to drop measurably in 5 min of the ignition in the On position, without any accessories or lights on. Maybe it is, and the combination of running these tests with ignition on and cranking the engine to unflood it is simply abusive to the battery.

But I think I've logged less than 2 min. of total cranking and less than 10min of Ig:On with this new battery, and it's gone from 12.8v to 12.3v.

Dave