POOR fuel economy?
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Author:  meenhaj [ Fri Jul 02, 2010 11:14 pm ]
Post subject:  POOR fuel economy?

I have an 89 swift GTi. The speedo cable needs to be replaced so I'm not sure what the exact miles I'm getting. A few days ago I put in about 4 gallons of gas, drove around here and there, and within the 3rd day it was empty! After a little estimating on how far I drove it seems like I'm barely getting 18 mpg?? I thought these cars, even the GTi, were pretty good on gas. So my question is, what can I look into? I did some basic things like get an oil change change plugs and wires. I'm going to probably replace the O2 sensor within the next couple of days. Just need to figure out what can possibly make the fuel economy drop so low though. Any thoughts are suggestions will be greatly appreciated.

Author:  TFS Jake [ Fri Jul 02, 2010 11:57 pm ]
Post subject:  Re: POOR fuel economy? are you guessing mileage?

Author:  meenhaj [ Sat Jul 03, 2010 9:13 am ]
Post subject:  Re: POOR fuel economy?

TFS Jake wrote: are you guessing mileage?

All thanks to google maps lol. I have inputed the start and end locations of every place I went to ever since I filled the tank, so I managed to get a good estimate of the total distance.

Author:  meenhaj [ Sat Jul 03, 2010 3:15 pm ]
Post subject:  Re: POOR fuel economy?

This is probably going to be a noob question, but can anyone help me locate the oxygen sensor for the 89 swift GTi? I looked everywhere after the headers down but could not find it anywhere.

Author:  Phil N Ed [ Sat Jul 03, 2010 5:37 pm ]
Post subject:  Re: POOR fuel economy?

Only thing sticking out in front of the engine with a wire on it:
Should go in that hole, eh?

Author:  meenhaj [ Sun Jul 04, 2010 12:23 am ]
Post subject:  Re: POOR fuel economy?

Thanks for the picture. I know for a fact nothing was sticking out from around that area, so tomorrow I'll take a look and see if a hole exists there.

Author:  Phil N Ed [ Sun Jul 04, 2010 2:20 am ]
Post subject:  Re: POOR fuel economy?

wheeze here 2 help 8) 8) 8)

Author:  gamefoo21 [ Sun Jul 04, 2010 11:51 am ]
Post subject:  Re: POOR fuel economy?

If there is no wire going there, then you have the reason why your car is getting bad mileage. Without the O2 sensor present, the computer will never go into closed circuit mode, and will run the car very rich.

This is bad because all that extra gas will contaminate your oil, and wash the cylinder walls down, so the piston rings literally are grinding on the walls, and this leads to bad compression in a hurry.

Author:  meenhaj [ Sun Jul 04, 2010 12:08 pm ]
Post subject:  Re: POOR fuel economy?

:( I just checked, theres NO O2 sensor. I tried sliding my hand down the headers to see if there was a hole but I couldn't reach all the way down. It seems like theres no hole though? I can't even find the other end of the harness to the sensor lol. I guess you are right, that is whats causing such bad fuel economy. Waiting for the car to cool down so I can feel around the headers properly to check for holes.

Author:  TFS Jake [ Sun Jul 04, 2010 2:05 pm ]
Post subject:  Re: POOR fuel economy?

Should be noisy without that plugged up.

Author:  Woodie [ Mon Jul 05, 2010 6:44 am ]
Post subject:  Re: POOR fuel economy?

With no speedometer cable you're running in a constant error condition too, the computer wants to see feedback from the speedo.

Author:  meenhaj [ Tue Jul 06, 2010 12:07 am ]
Post subject:  Re: POOR fuel economy?

These replies have been most helpful. I should be getting my speedo cable replacement within the next few days. Ill plug that right in and then see if theres any change. After that is done i'll probably head to the muffler shop and get the header drilled for the oxygen sensor.

Author:  swift13b [ Tue Jul 06, 2010 2:37 am ]
Post subject:  Re: POOR fuel economy?

Woodie wrote:
With no speedometer cable you're running in a constant error condition too, the computer wants to see feedback from the speedo.

the 89 has a vehicle speed sensor?

Author:  meenhaj [ Tue Jul 06, 2010 8:14 am ]
Post subject:  Re: POOR fuel economy?

I believe it doesn't..It's just the speedo cable.

Author:  meenhaj [ Tue Jul 06, 2010 8:37 am ]
Post subject:  Re: POOR fuel economy?

Does anyone have a picture of where the oxygen sensor harness would be located?

Author:  Phil N Ed [ Tue Jul 06, 2010 10:35 am ]
Post subject:  Re: POOR fuel economy?

Normally when Woodie posts something, it doesn't need much clarification, if any. I rarely disagree with him and this won't be one of those times.

This is your lucky day; I happened to take a few pictures of just the things you're talking about and upload them this morning. So grab a pencil and paper, make a few notes, and here we go:

First, here's a late model MK1 instrument cluster for identification purposes.
Note the tach, which means it's not from an ER or automatic transmission type car:
Now take a look at the back.
Circled in red is a rectangular white plastic piece held in with two phillips screws. It is the VSS (vehicle speed sensor). Also, I've pointed out with white arrows the 'other half' of the cluster to get when you buy one. These white plugs with a length of wire help if you plan on splicing into a wiring harness (e.g. for a DOHC or turbo engine transplant).
Now, let's look at the MK2 speedometer.
This one is particularly interesting.
It's in MPH, so it's not a Canadian version, and
it's probably pretty rare, as it goes past 85 mph to....120 mph:
Let's take a look at the back.
It would appear that Suzuki did not reinvent their earlier model ('85-'88) VSS.
Indeed, it's the same part, looking at it from the back, circled in white:
If you have a problem with the later model ('89-'94) speedometer cable, the transmission oil can creep up the cable and interfere with the VSS, causing a 'code' to blink while you're driving. The fix is covered elsewhere on this site. Additionally, drivers complain that oil is soaking their carpets, shoes, and under the dash.
Now, one last time, take a look at the two instrument 'clusters' from the back.
Note the boxy, square early version on the top (MK1) and the lower and wider profile of the MK2.
Yet they both have the same vehicle speed sensor!
In conclusion, there are VSS in all the Suzuki products with ECMs (North America MK1/2/3). The automatic transmission cars may have them in a different place, but still they're there. Notable exceptions may include early MK1s with Aisin carbs, but I don't have a cluster from one to compare. Perhaps someone in Canada or Northern Europe has a spare and can post some pictures for you to see.

Regarding your 'Oxygen Sensor Harness':
You've seen many pictures and a lot of time and effort helping you with your neat little car, not only in this thread but many places on this site. Why not help the membership and add to your album or post links to pictures of what's under your hood. It shouldn't take more than ten minutes.
Then we can point out to you where the various wires come and go!
:wink: :wink: :wink: :wink: :wink:
8) 8) 8) 8) 8)
:lol: :lol: :lol: :lol: :lol:
Or think of it this way:
Be less 'esoteric'; bring your car to the site and we'll help you fix it!

Author:  meenhaj [ Tue Jul 06, 2010 11:05 am ]
Post subject:  Re: POOR fuel economy?

I can't emphasize how helpful you have been. Indeed I will take pics if that helps (I've been taking pics of my horn coz it was relocated on another thread). I will have to say it was my fault about the VSS, I had the notion that these older cars with speedo cable wouldn't have a VSS. Either way I'll take a picture of the engine bay area including the headers. Thanks again!

Author:  Phil N Ed [ Tue Jul 06, 2010 11:17 am ]
Post subject:  Re: POOR fuel economy?

My VSS post was just a little information, especially for swift 13b, so don't take offense.
The picture of the exhaust manifold with the hole for the oxygen sensor is a stock set up and readily available on line for $75 or so.
If you have a custom built exhaust manifold (what most people call a 'header') your O2 sensor may be in a different location.
Here's a chrome header with an O2 sensor hole barely visible on the side where the #4 cylinder exhaust runner has its second bend, about a third of the way between the two white circles:

That's why we can help more if we see what you've got.
Don't worry if it doesn't look like a show car; few here have something like that.

Author:  meenhaj [ Tue Jul 06, 2010 11:32 am ]
Post subject:  Re: POOR fuel economy?

Here are some pics I just took. Seems like there IS something sticking out, although it doesn't look anything like a sensor bung...


The last two pics with the red circles are of harnesses that are randomly left lying around.

Author:  Phil N Ed [ Tue Jul 06, 2010 9:46 pm ]
Post subject:  Re: POOR fuel economy?

Here's a couple shots for you:
89 GTi:
-arrow points to white wire w black stripe for O2 sensor
(maybe it's black wire with white stripe...kinda dirty, eh?)
Your brown coupler is plugged into a coolant temperature sensor in the thermostat housing.
This probably would help your mileage.
and here's the O2 coupler in black:

92 GT:
Brown coupler again going to coolant temp sensor for emphasis...
Next white arrow points to black wire coming from O2 sensor.
Black O2 coupler visible below two additional coolant temperature with a blue coupler, and the other with a small black coupler and a yellow wire.
You should be able to get 38ish mpg without trying once your wires and sensors are all hooked up.

Your header is not stock, like in my first picture, but as long as you find the bung hole for the O2 sensor and plug one in, you should be good to go. When the car is idling, listen for hissing where the header bolts to the head. Exhaust leaks in that location are a sure way to burn valves needlessly.

Thanks for adding pictures to your album, and hope you're getting better quality help as a result. Don't forget, what you've added is just the tip of the iceberg. The more pictures you add, the better idea we have of what you've got. Again, this is so we can help you better!
:thumb2: :thumb2: :thumb2:

All the information you are being provided had to be learned by all of us.
So don't worry that you don't know it all.
Once upon a time, we had to ask that same question.

Before I forget, it looks like you have the EGR system on your engine. If so, you can make sure it's working properly as that will also boost your gas mileage.
The '89 GTi in the first two pictures of this post can easily get 44 mpg; but it's fun to drive it a little harder, so that's why I say 38 mpg should be a realistic goal for you.
Your album reveals this picture which bears more investigation.
Maybe someone has bypassed/disabled the O2 sensor by plugging it.
This may be the result; you will have to take a closer look and see if that is screwed into a 'bung hole'.

Some people have this attitude about 'smog nazi' etc.
:thwack: :thwack: :thwack: :screwball: :screwball: :screwball: :stupid: :stupid: :stupid:
and they disable ANY emissions equipment/vacuum lines. There are many threads here which bear me out, here's a recent example:
On a track/drag car, I can understand the elimination of the usual systems on our cars; on a daily driver, not so!
As you get older and learn, you will gradually find out that these systems were engineered to improve your driving experience, not ruin it.
Apparently, you've purchased a car from someone with those 'pre-emissions vehicle' attitudes. (An example: our stock '51 Chevrolet doesn't even have the PCV system so prevalent in today's cars.)
Check and see if the catalytic converter has been removed; there is absolutely no down side to having a catalytic converter on your car! Even performance oriented daily drivers can use a 'high flow' catalytic converter with no discernible loss of horsepower due to exhaust restriction. Can you say, "Better living through Chemistry?"
8) 8) 8) 8) 8)

You began this thread with a complaint of poor gas mileage. By returning some of the original emissions systems back to operational status, you should obtain at least 10 more miles per gallon. Your car is a fun car to speed around town, and you'll still be able to do that; however, for the 85% of the time when you aren't trying to pass the next guy, your engine will burn each gallon of gas much more efficiently than those who defeat the cat, bypass the EGR, etc. and you join the ranks of a responsible vehicle operator. Remember, a driver's license is a privilege not a right so temper your wisdom with a little responsibility!

Hope this helps... :wink: :wink: :wink:

Author:  meenhaj [ Wed Jul 07, 2010 9:49 am ]
Post subject:  Re: POOR fuel economy?

Thank you for clarifying up many things for me! Let me start off with the oxygen sensor. It looks like the previous owner plugged up the bung for good. Looks like I'll need to reweld in a new bung? :(
DSC05982.JPG [ 204.66 KIB | Viewed 45028 times ]

As for the brown coupler, I did manage to find where it is suppose to connect, however they don't size up. You can see from the picture that they are both different sizes. Either that, or that is not where the coupler is suppose to connect :oops:

DSC05984.JPG [ 128.07 KIB | Viewed 47110 times ]

When I bought the car it did not have any cat on it just a long (broken) straight pipe. I brought it to the muffler shop to put a glasspack resonater and a muffler on it. Another thing, you mentioned that my car had would I know if it was bypassed?
I greatly appreciate the help especially with the pictures, been VERY usefuly to me. You can tell I hardly know much about cars, but I certainly want to broaden my knowledge. Thanks again!

Author:  Tony_SS [ Wed Jul 07, 2010 10:38 am ]
Post subject:  Re: POOR fuel economy?

I'll try to help. In this pic, you are missing the thermostat fan sensor. It screws into that hole and the plug goes on the end. Its available from your local auto parts store for about $25. This tells your electric fan when to kick on to avoid overheating. HTH.


Author:  meenhaj [ Wed Jul 07, 2010 10:57 am ]
Post subject:  Re: POOR fuel economy?

Very interesting. That probably explains why the fan is ALWAYS on from the moment I turn the key to the first ignition. I will get the thermostat fan sensor then :). One thing though, wouldn't the thermostat fan sensor be connected to another thing from the other end?

Author:  Tony_SS [ Wed Jul 07, 2010 11:43 am ]
Post subject:  Re: POOR fuel economy?

The sensor is wired direct to the fan, it tells it when to come on.

Warning, looks like you have a plug in that hole, otherwise antifreeze would be dripping out. Remove the plug, retap those threads before you put a new one in, and make sure its wired direct to the fan and that the 'always on' fan wiring is corrected.

Author:  gamefoo21 [ Wed Jul 07, 2010 12:23 pm ]
Post subject:  Re: POOR fuel economy?

No, it looks like the sensor, just the idiot who owned the car before took a hammer and smashed off the connector, cheap and very stupid.

Check the wiring to the fan, it sounds like the numbnuts just wired it straight to the battery.

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