Strangest thing when turning off the key - '91 Civic

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D-vid
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Strangest thing when turning off the key - '91 Civic

Post by D-vid »

Okay, so I just registered for this site, because I own a 1991 Honda Civic DX(4 door) with a 1.5L engine.
So, not long ago, I drove my Honda to Las Vegas from Portland, OR because we just moved down here from there.
The car has ran fine, other than rack and pinion, power steering leaks(from R+P), and alignment issues. I fixed it all before leaving, and had no problems on the road. However, when I got into Idaho, the low-grade (regular) gasoline was of octane 85 instead of the usual 87 I am used to seeing. I put in the 85 before I even realized it wasn't 87, and the car seemed to run fine the rest of the way.
This was about 3 weeks ago.

Now, about 2 weeks ago, when I stopped at the gas station to refill my tank on 87, once I turned off my key the engine kept going, but it was sputtering to a stop for about 30 seconds to a minute after fully pulling out my key and everything. Now, it hasn't done this until yesterday I got an oil change and then went to work and once I parked at work, the car did it once again.

I have never heard of this problem, so I am really confused about it. I would like to know what it most likely would be.

Another somewhat related issue is while driving, after 1st gear(my car is auto), it shifts to 2nd and then it seems like I lose a decent amount of power until I reach 3rd gear, and it picks up tremendously. Why would it be like this?

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Re: Strangest thing when turning off the key - '91 Civic

Post by Sandman »

I had that in my old volvo, I got rid of it by using a higher octane fuel.
You could try better fuel see if that helps. I know how it happens, I just don't know how to explain it.
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D-vid
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Re: Strangest thing when turning off the key - '91 Civic

Post by D-vid »

Sandman wrote:I had that in my old volvo, I got rid of it by using a higher octane fuel.
You could try better fuel see if that helps. I know how it happens, I just don't know how to explain it.
Do you think that maybe I could benefit from octane booster and/or even fuel injection cleaner? It's the DPFI, and I hear they're pretty lousy anyways. My thoughts have been with maybe even the fuel filter(if this car even has one?), because if it's pretty clogged, one would assume that would cause the lines to back up accounting for the lack of power and the trying to continue to run after I turn it off(from the lines still pulling the excess gas that took too long to get through the filter). Of course, I am in no way a mechanic.

Would there be anything I could go out and check in my car to kind of diagnose what it COULD be?

I also have no CEL on.


EDIT: I consulted my dad, who knows a decent amount of information about motors(not honda so much though) and he said that it sounds to him as if it's the fuel injectors causing problems, like maybe clogged(which could result from using poor quality and low octane gas). What he told me to try is to take out the injectors and try blowing through them backwards, and see if any gunk comes out, as well as using FI cleaner and higher octane gas from now on.

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Re: Strangest thing when turning off the key - '91 Civic

Post by Sandman »

octane booster could help. Personally I've got no exp. in them since our fuel is different(95 oct or 98oct)
blowing through won't help, since they're going to be closed. They're electronic.

Cleaning your fuel system might help, it probably won't hurt to clean it anyway.
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Re: Strangest thing when turning off the key - '91 Civic

Post by drivinacivic88 »

What you're describing is called dieseling. It's called that because diesel engines are generally the ones that do it.

Basically, you still have fuel going into the engine after the engine is shut off, which causes the engine to run on for a while. Now, fuel alone will not cause this. You also need an ignition point. My guess is that you probably have a leaking injector and a little carbon buildup in your combustion chamber. The carbon gets really hot and ignites the fuel without the need for a spark from the spark plug.

It's just a theory, but it could be what is happening.

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Re: Strangest thing when turning off the key - '91 Civic

Post by D-vid »

drivinacivic88 wrote:What you're describing is called dieseling. It's called that because diesel engines are generally the ones that do it.

Basically, you still have fuel going into the engine after the engine is shut off, which causes the engine to run on for a while. Now, fuel alone will not cause this. You also need
an ignition point. My guess is that you probably have a leaking injector and a little carbon buildup in your combustion chamber. The carbon gets really hot and ignites the fuel without the need for a spark from the spark plug.

It's just a theory, but it could be what is happening.
My dad and I ordered up new injectors and are gonna take it to a local shop to pay 35 bucks and have them figure out everything that is wrong.

Another problem I am having is while driving after the engine warms up, it accelerates poorly unless I put my foot down harder to make the auto tranny drop a gear and then it picks up from there. I don't have an rpm guage but it usually seems to drop rpm and acceleration around 30-40mph and once above 40 it picks up without much hesitation. I have also noticed that sometimes when I pull my foot off the gas it will take a couple seconds before it stops accelerating.

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Re: Strangest thing when turning off the key - '91 Civic

Post by D-vid »

I have HOPEFULLY solved the high idle, "hunting" idle, and rough idle issues simply by playing with the throttle cable adjustments, I noticed when I had it at a high enough idle it would start going up and down over and over on it's own.

I took it for a test drive, and I feel as if I have some power back, but I don't know if it was just playing with me so we will see when I drive it more and further distances.

As far as the dieseling, I would assume that could be the cause of it as well, as my throttle seemed (when i played with it under the hood) to get stuck at certain adjustments, and would stay at a higher idle than with it fully closed. So that leads me to believe it was idling too high when turning off the car that it caused it to try and stay going? ???

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Re: Strangest thing when turning off the key - '91 Civic

Post by cjohnsontech »

Couple thoughts...

Take some throttle body cleaner and clean up the tension spring on your throttle cable at the intake. That may take care of some of your stuck issues as well with it not closing completely.

If your car is still DPFI, you may have some residual fuel sitting in the chamber that could be getting sucked in while your throttle is still slightly open after turning off your car. Albeit, it shouldn't be firing anymore since the spark plugs shouldn't be getting a signal, but it's worth looking at. So check your injectors while you're already there looking at the throttle body.
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Re: Strangest thing when turning off the key - '91 Civic

Post by D-vid »

cjohnsontech wrote:Couple thoughts...

Take some throttle body cleaner and clean up the tension spring on your throttle cable at the intake. That may take care of some of your stuck issues as well with it not closing completely.

If your car is still DPFI, you may have some residual fuel sitting in the chamber that could be getting sucked in while your throttle is still slightly open after turning off your car. Albeit, it shouldn't be firing anymore since the spark plugs shouldn't be getting a signal, but it's worth looking at. So check your injectors while you're already there looking at the throttle body.
Either way, I will be replacing the injectors in a few days but as of the idle issues, I am still having to keep re-adjusting the throttle cable as I have no gauges or even a tach that I can go by to adjust it to the accurate rpms. Mainly doing it by sound, and it's still not idling properly. :-/

EDIT:
Well, I found out my dad has a timing light with built in tach that you hook to spark plug wire #1.
I used it to measure RPMs and set idle WAYY down from what it was set to. It was at about 1200+ RPMs on idle with the IACV plugged in, and about 1000+ RPMs without it plugged in. Now, I adjusted the idle SCREW, and I shall be playing with it and the throttle cable to set it all to OEM specs. I have the Tune-up chart from HONDA(wit all their engines in 90-92(if anyone needs it I can hook it up), and I set the timing from 10 to 18 deg(as per the chart), and I set the idle down to 700-800RPM (with IACV) as per the chart.

I feel it's running a bit better now, but I need to adjust a few more thing with idle/throttle to make it a bit better, because I notice the RPMs drop down a bit when I stop(in gear) so it's making my car vibrate.

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Re: Strangest thing when turning off the key - '91 Civic

Post by el_jelly »

from http://www.civic4g.com/index.php/forum/ ... =8&t=11423

Problem: Engine diesels (continues to run) after switching off
- Idle speed too high
- Excessive engine operating temp
- Vacuum leaks
- Ignition timing not correctly adjusted
- Carburetor in need of overhaul
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