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17 MPG - What should i look for/Diagnose? by Zanson
Started on: 07-08-2013 12:21 PM
Replies: 25 (377 views)
Last post by: 2.5 on 07-15-2013 10:05 AM
Zanson
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Report this Post07-08-2013 12:21 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
So i've been driving the car for a week, and i know it smells a bit rich, but i filled up again this morning and found i am getting about 17MPG

The question is, what should i look at or is there a thread i missed that can help me fix this obvious dump of fuel into the system. Any help would be appreciated, i'll be taking my car to my brothers shop in a few weeks to fix everything i can in a day so this would be on that list of things to do. if i need new parts, i wanna make sure i have everything ahead of time.
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2.5
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Report this Post07-08-2013 01:18 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
Stock 2.8 or?
Could be 02 sensor, any codes or service engine lights?
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Zanson
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Report this Post07-08-2013 04:28 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yea, Stock 2.8

No CEL. need to read the codes still (but that wont happen for a few weeks. i don't have the equipment for that)

i have noticed some electrical strain on the car, (slow windows, diming lights ect, Battery is new) so i need to go through and rerun some of the grounds. but im not sure how that would effect the MPG on the car.

How much do O2 sensors run on this car?
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steve308
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Report this Post07-08-2013 04:34 PM Click Here to See the Profile for steve308Send a Private Message to steve308Edit/Delete MessageReply w/QuoteDirect Link to This Post

How much do O2 sensors run on this car?[/QUOTE]

rockauto.com will have your answer to that question
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skuzzbomer
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Report this Post07-08-2013 04:55 PM Click Here to See the Profile for skuzzbomerSend a Private Message to skuzzbomerEdit/Delete MessageReply w/QuoteDirect Link to This Post
To read the codes stored in a stock ECM, you need a paperclip.
http://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

O2 sensor could be bad.
Is the engine running cold or does it get up to temp properly?
You say it smells rich - does it still have a catalyst installed/is it functioning properly?
Any noticeable power loss?

As much information as there is on here, tracking down the problem shouldn't be too difficult if you know all the symptoms and where to start looking.
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Zanson
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Report this Post07-08-2013 05:00 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks Steve, that site will come in handy.

so you guys think the o2 would be the 1st thing?

also, is there a 2nd o2 after the cat? i know the Cat is going bad on this car. or would it just be the 1st o2 sensor that would effect the fuel?

engine seems to get to temp (rad fan comes on over time) although i need to fix the temp gauge to get a better fix on whats happening. i assume the temp sensor is working but i need to apply the temp sensor wire fix to the car.

Power loss i can not tell, i have only had the car a week, and don't know what the normal power output feels like. It seems to have a good amount of power though. if i hit the gas it goes pretty well, hasnt seemed sluggish. at idle it seems to slightly sputter. there was a period of time the car was run for only a few miles a day so carbon buildup may be in the engine as well.

[This message has been edited by Zanson (edited 07-08-2013).]

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dobey
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Report this Post07-08-2013 05:03 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Stock size tires? Auto or 5 speed? 17 MPG is city, highway, or combined?

If city, then 17 MPG is about where it should be for a stock 2.8.
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Zanson
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Report this Post07-08-2013 05:07 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
some city some highway. a good mix of both going to work and back. (little to no traffic)

stock tires, Automatic.


Thanks everyone for the help. i appreciate it.

[This message has been edited by Zanson (edited 07-08-2013).]

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92wastheyear
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Report this Post07-08-2013 05:13 PM Click Here to See the Profile for 92wastheyearClick Here to Email 92wastheyearSend a Private Message to 92wastheyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Zanson:

some city some highway. a good mix of both going to work and back. (little to no traffic)

stock tires, Automatic.


Thanks everyone for the help. i appreciate it.



I am getting 18-20 mpg on 87 GT w/Auto ...also a mix of hwy/city

Here is what the gov has to say

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jimbolaya
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Report this Post07-08-2013 05:46 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:

Stock size tires? Auto or 5 speed? 17 MPG is city, highway, or combined?

If city, then 17 MPG is about where it should be for a stock 2.8.


This /\/\/\, you are probably right on target for MPG. The only way you are going to get better is mate it to the 5 speed isuzu tranny that came with the 2.5, instead of the 3 speed auto it comes with. Other than that, stay off the gas or drive it 90% of the time on the highway. Even then you're only going to get 20-21.

Jim

[This message has been edited by jimbolaya (edited 07-08-2013).]

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92wastheyear
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Report this Post07-08-2013 06:21 PM Click Here to See the Profile for 92wastheyearClick Here to Email 92wastheyearSend a Private Message to 92wastheyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:


This /\/\/\, you are probably right on target for MPG. The only way you are going to get better is mate it to the 5 speed isuzu tranny that came with the 2.5, instead of the 3 speed auto it comes with. Other than that, stay off the gas or drive it 90% of the time on the highway. Even then you're only going to get 20-21.

Jim


I hear people occasionally talking about a 4 speed auto ....where are they getting them (what car)?


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Zanson
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Report this Post07-08-2013 06:27 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Got ya, i just thought it was off seeing some numbers in the high 20's.

Thanks for the info
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skuzzbomer
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Report this Post07-08-2013 06:46 PM Click Here to See the Profile for skuzzbomerSend a Private Message to skuzzbomerEdit/Delete MessageReply w/QuoteDirect Link to This Post
I averaged 23mpg combined with a fresh ignition system in my 85 (and I beat the living hell out of it). Have recorded 28mpg in the past, all highway.

Replace/remove your bad cat, check out any potential issues, and get it running correctly before you assume it's normal. Unless you're regularly running it at redline, you should be doing better than that, I believe.
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Report this Post07-08-2013 07:03 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by skuzzbomer:

I averaged 23mpg combined with a fresh ignition system in my 85 (and I beat the living hell out of it). Have recorded 28mpg in the past, all highway.

Replace/remove your bad cat, check out any potential issues, and get it running correctly before you assume it's normal. Unless you're regularly running it at redline, you should be doing better than that, I believe.


23 combined is probably 70% hwy/30% city. And was that a 4 speed or auto car? It's certainly possible to get better than 17-18 combined in an auto V6, but it's not common or average.
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Report this Post07-08-2013 07:05 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post

dobey

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quote
Originally posted by Zanson:

Got ya, i just thought it was off seeing some numbers in the high 20's.

Thanks for the info


100% highway you should get around 25-26 MPG in a stock V6 with auto. Maybe a little higher if you avoid hills and keep the speed down.
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Report this Post07-08-2013 07:49 PM Click Here to See the Profile for skuzzbomerSend a Private Message to skuzzbomerEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


23 combined is probably 70% hwy/30% city. And was that a 4 speed or auto car? It's certainly possible to get better than 17-18 combined in an auto V6, but it's not common or average.


Automatic GT. And that's probably half and half but "city" driving here is usually 45mph, however the lights are timed so you hit pretty much every single one. Also, the A/C never worked so it was always windows down.

Call it what you want but, when everything was functioning as intended, that was my average. The point is, 17 sucks and there's got to be a reason it's not even touching the low 20s.
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Report this Post07-08-2013 08:18 PM Click Here to See the Profile for mrfred8Click Here to visit mrfred8's HomePageSend a Private Message to mrfred8Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 92wastheyear:

I hear people occasionally talking about a 4 speed auto ....where are they getting them (what car)?



http://en.wikipedia.org/wik...bo-Hydramatic_440-T4

http://en.wikipedia.org/wik..._4T60-E_transmission

[This message has been edited by mrfred8 (edited 07-08-2013).]

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Report this Post07-09-2013 08:53 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Zanson:

... i know the Cat is going bad on this car. ...



I picked up a few mpgs with a new distributor cap/rotor and wires, plugs too. Thats on an 88 2.8 5 speed.

If you know your cat is going do that first. If you see your dist cap/rotor and wires are old do them too, could need plugs too.

On my old duke car the 02 sensor was sucking mileage and didnt light up a code.
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Report this Post07-09-2013 10:00 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:
If you know your cat is going do that first. If you see your dist cap/rotor and wires are old do them too, could need plugs too.


A new coil probably wouldn't hurt either. People tend to keep the same one until they just stop working, but they do experience some wear over time, and aren't able to deliver as good a charge to the plugs, as they did when new.

I recently got a Honda del Sol, and given the mileage on it, and no idea of what the service record for it was, one of the first things I did was a tune-up using a kit from Accel, which included cap, rotor, wires, and a coil. It immediately picked up about 2.5 MPG, and I drive it 90% city. Lots of stop and go, and mostly under 50 MPH.
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Report this Post07-09-2013 11:32 AM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniEdit/Delete MessageReply w/QuoteDirect Link to This Post
Make sure the TCC is locking up. Definitely lose a few mpg if it's not working correctly.
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Zanson
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Report this Post07-09-2013 12:58 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Hudini:

Make sure the TCC is locking up. Definitely lose a few mpg if it's not working correctly.


The transmission definitely locks up, when putting the car in gear it dose lurch at times (definitely not a smooth change to reverse or drive) and when engine cold it drops the RPM to the low 700's and has stalled once. Gear changes are smooth though. i swear this car idles at 15-20 MPH (haven't tested and is probably lower but it's pretty damn strong idle)

Plugs will be changed, We are gonna run a stand alone cleaner through the system (disconnect fuel, run the cleaner/fuel mix) to get rid of all the crap, so after doing that we will be changing the plugs, i may do the wires and distributor then (may wait to see if this helps) It was always kept in a garage so the amount of corrosion is minimal but i think i will be replacing a lot of the main electrical in the car and fixing all of the ground points.

The cat will be removed. Emissions exempt in PA so i will do that as well.

[This message has been edited by Zanson (edited 07-09-2013).]

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Report this Post07-09-2013 01:16 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Zanson:
i swear this car idles at 15-20 MPH (haven't tested and is probably lower but it's pretty damn strong idle)


Vacuum leak?
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92wastheyear
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Report this Post07-09-2013 03:29 PM Click Here to See the Profile for 92wastheyearClick Here to Email 92wastheyearSend a Private Message to 92wastheyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Zanson:


The transmission definitely locks up, when putting the car in gear it dose lurch at times (definitely not a smooth change to reverse or drive) and when engine cold it drops the RPM to the low 700's and has stalled once. Gear changes are smooth though. i swear this car idles at 15-20 MPH (haven't tested and is probably lower but it's pretty damn strong idle)




I had some of that before I changed the Intake Air Temp sensor and the Coolant Temp Sensor....once I swapped both of those out the car no longer tried to stall when cold and the idle dropped to a steady 950rpm regardless of load. Both sensors cost me about $50 locally (about $35 from rock auto if you have the patience)

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Report this Post07-10-2013 01:29 AM Click Here to See the Profile for bulldog85043Click Here to Email bulldog85043Send a Private Message to bulldog85043Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Zanson:


The transmission definitely locks up, when putting the car in gear it dose lurch at times (definitely not a smooth change to reverse or drive) and when engine cold it drops the RPM to the low 700's and has stalled once. Gear changes are smooth though. i swear this car idles at 15-20 MPH (haven't tested and is probably lower but it's pretty damn strong idle)



The transmission lock up is not when it "hooks up". It's when you're driving at a cruising speed for a period of time and the tranny seems to go into a "4th gear". That transition is actually the TC locking and providing some relief to the motor. You should be able to see a drop in the RPMs when it kicks in.

BTW, I usually see about 23-25 in my 86 SE with its stock 2.8 during the cooler months. I'm getting about 21-22 with the A/C running and all city driving. (Freeway was killing my mileage with the stop-and-go during rush hour.
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Zanson
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Report this Post07-10-2013 03:14 PM Click Here to See the Profile for ZansonClick Here to visit Zanson's HomePageSend a Private Message to ZansonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by bulldog85043:


The transmission lock up is not when it "hooks up". It's when you're driving at a cruising speed for a period of time and the tranny seems to go into a "4th gear". That transition is actually the TC locking and providing some relief to the motor. You should be able to see a drop in the RPMs when it kicks in.

BTW, I usually see about 23-25 in my 86 SE with its stock 2.8 during the cooler months. I'm getting about 21-22 with the A/C running and all city driving. (Freeway was killing my mileage with the stop-and-go during rush hour.


ahh got ya, thank you for the clarification. i'm not very good with mechanical terminology (slowly learning) i assume you mean when cursing at a given speed for a bit the RPM drops a bit and when pressing the gas it kicks back up to give more power? dont know if it's at a specific speed or not but i have noticed it. When changing through gears i would hear 1,2,3 and sometimes the RPM drops and was thinking "is this 3 or 4 speed?" knowing it's a 3 speed transmission.

Hopefully that makes some sense.
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Report this Post07-15-2013 10:05 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Zanson:


When changing through gears i would hear 1,2,3 and sometimes the RPM drops and was thinking "is this 3 or 4 speed?" knowing it's a 3 speed transmission.

Hopefully that makes some sense.


Yep thats exactly it.
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