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ECT Sensor
Topic Started: Apr 13 2018, 02:18 PM (368 Views)
OGrilla
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Hey, there, everyone! It's been a while since I posted here, but I've been lurking as a guest in the meantime.

As a refresher, I'm driving a 1995 Geo Metro LSI hatchback with a 993cm^3, 3 cylinder engine.

I just got done replacing the water pump, timing belt and timing belt cover. I replaced my oil and coolant, of course.

A few months ago I replaced the radiator and the ECT sensor. Had to replace an O-ring going into the block behind the water pump, as well.

Started noticing an oil leak about 2 months ago and as I was getting home from a short trip, the car made funny noises and quit on me. I parked it on the side of the Interstate and couldn't get it to restart.

Replaced the camshaft sprocket seal and the valve cover gasket.

When I went to start the vehicle after buttoning everything down, it wouldn't fire up. It does repeatedly and (to my ears) cleanly spin, but it's just not starting up.

I'm getting enough juice from the battery (12.59V) and I've cleaned up the cable terminals as well as 3 ground connections.

Checked all my fuses (none of the relays...) and decided while I was down there to put a spare in the diagnostic slot and it flashed 1-5 for ECT sensor malfunction.

I got my meter in there and it seems to have only 2.38 Ohms resistance when it should have 10.9-43+ according to the chart in the manual.

As I said, I've recently replaced this thing and I know someone's gonna ask about receipts and warranties... Kind of not on my radar right now as I need this thing running to get on the road ASAP.

I can replace the ECT sensor and cross my fingers that the other one was a dud, but I'm wondering if:

A.) the malfunctioning sensor would keep the car from starting

and

B.) is there something going on that might cause the new sensor to malfunction?

Thank you for taking the time to read and answer.
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Crvett69


i would clear the code by unhooking battery for about 5 minutes then hook everything up and crank it to see if it comes back. might also want to run a compression test and try some starting fluid
Edited by Crvett69, Apr 13 2018, 03:35 PM.
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Metromightymouse
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Powdercoat Wizard

And confirm you have spark.
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suzukitom
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Tom

Check if ECT sensor wire short to ground somewhere.

Woodie posted a ECT resistance vs. temperature chart here:
http://geometroforum.com/single/?p=672829&t=4871595

If the ECT sensor signal to the PCM sends an input that indicates it is either very cold or very hot, it will alter fuel injection in such a way that could make it hard to start for your actual ambient temperature conditions.
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ptcapboy


a thought that comes to my mind is to check your timing marks-when the two of them are where they are supposed to be pull away your distributer cap and see if the rotor end is pointing towards the #1 spark plug wire tower-
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freegeo
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As ithers have stated, naje sure you are getting fuel from the injector and spark to the plugs.
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OGrilla
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Crvett69
Apr 13 2018, 02:33 PM
i would clear the code by unhooking battery for about 5 minutes then hook everything up and crank it to see if it comes back. might also want to run a compression test and try some starting fluid


I've been disconnecting and reconnecting the battery throughout the repair and troubleshooting to no avail.

We checked compression and it would appear to be fine.

Metromightymouse
Apr 13 2018, 02:51 PM
And confirm you have spark.


Tested sparks on all 3 plugs and they're fine.

suzukitom
Apr 13 2018, 03:53 PM
Check if ECT sensor wire short to ground somewhere.

Woodie posted a ECT resistance vs. temperature chart here:
http://geometroforum.com/single/?p=672829&t=4871595

If the ECT sensor signal to the PCM sends an input that indicates it is either very cold or very hot, it will alter fuel injection in such a way that could make it hard to start for your actual ambient temperature conditions.


Woodie didn't distinguish between 14 and 15 when he mentioned that one meant -40 and the other meant 400. According to the resistance chart (if I'm reading it correctly), the reading is a little under 70 degrees F, which is coincidentally what the ambient temperature is in the garage.

I'm not sure if it's sending a bad signal, but I have noticed that my temperature gauge on the dash hasn't risen in months...

Perhaps the wire is shorted to ground as referenced in that thread.

ptcapboy
Apr 13 2018, 04:01 PM
a thought that comes to my mind is to check your timing marks-when the two of them are where they are supposed to be pull away your distributer cap and see if the rotor end is pointing towards the #1 spark plug wire tower-


I didn't check to see if it was aligned under the distributor cap.... Thank you for that.

freegeo
Apr 13 2018, 04:15 PM
As ithers have stated, naje sure you are getting fuel from the injector and spark to the plugs.


I haven't checked to see if there's fuel coming from the injector, but there is spark at the plugs.
Edited by OGrilla, Apr 13 2018, 04:56 PM.
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freegeo
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Your 95 uses a separate sensor for the coolant gauge.

Check to see if you are getting fuel when it is cranking over. If you are, try and hold the throttle opan while cranking it over to see if it will start.
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OGrilla
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We lined up the crank and cam and opened the distributor to find it in good position. Cleaned all the contacts inside the distributor cap.

Fooled around with the housing for the distributor and then with the idle adjusting screw.

Finally managed to get it running and idling smoothly.

The temperature gauge still doesn't work, but I'm going to have to work on that another time.
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MR1 Kingsbury
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Exp. builder/rebuilder

Did you adjust the "do not disturb" throttle stop screw? It isn't idle adjust.... Idle is adjusted by the pcm with ISC and TPS positioned properly. The idle stop screw used to have a plastic cover preventing tampering.
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OGrilla
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This is what we used as reference.

http://geometroforum.com/topic/8113309/1/
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OGrilla
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The temperature gauge works. I don't know why it decided to now.

I made a 560 mile trip today. Seemed to running a little rough when we finally made it, but every stop I checked out the oil, coolant and had a good look at everything I was worried about.
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OGrilla
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Seems like my PCV is worn out, possibly effecting the TPS which is on the same circuit as the ECT. Does this make sense?
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Dystopiate666
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Is there oil coming out of the pcv? unless it is blasting oil onto the TPS, I cant see the pcv affecting it.....and if its blasting oil out the pcv......
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freegeo
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OGrilla
Apr 15 2018, 05:14 PM
Seems like my PCV is worn out, possibly effecting the TPS which is on the same circuit as the ECT. Does this make sense?
The PCV has nothing to do with the TPS or ECT.

The TPS and ECT does share a ground and 5 volt reference.
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