MPG Issue
03-02-17, 10:35 AM
#1
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MPG Issue
Hi guys,
I know this question has been asked in many other threads, and I have read almost all of them if I am not mistaken. A little background to help diagnosis. My SC used to get 20-24 MPG easily. Then my Driver side coil went out. I didnt know that was the issue, and thought it was cats. I gutted the front cats, and turns out that wasnt the issue. Finally got a coil pack got that fixed and cars back up and running. When I put back everything I think I forgot to put the air filter in, and it stayed that way for a couple hundred miles. Before I drove it I ran seafoam through the intake, and the gas tank. Not the crank case because my opil change was less than 800 miles old. I changed the spark plugs to auto lites after, (I know they arent the best), and then drove the car. Was getting horrible gas mileage in the 10-11 MPG range. The car runs ok, it smells rich, especially on startup but I think maybe cause I dont have the front cats. I HAVE NO CEL's!! I got an air filter, in the car. I changed the MAF sensor, I checked my ECT sensor. All looks good. I have ran some fuel injector cleaner dosent seem to help much. I fill up a tank about 17-18 gallons and barely get 200 if im lucky. The car seems to be running ok, I cant seem to think of what could be the issue. Any help would be greatly appreciated.
I know this question has been asked in many other threads, and I have read almost all of them if I am not mistaken. A little background to help diagnosis. My SC used to get 20-24 MPG easily. Then my Driver side coil went out. I didnt know that was the issue, and thought it was cats. I gutted the front cats, and turns out that wasnt the issue. Finally got a coil pack got that fixed and cars back up and running. When I put back everything I think I forgot to put the air filter in, and it stayed that way for a couple hundred miles. Before I drove it I ran seafoam through the intake, and the gas tank. Not the crank case because my opil change was less than 800 miles old. I changed the spark plugs to auto lites after, (I know they arent the best), and then drove the car. Was getting horrible gas mileage in the 10-11 MPG range. The car runs ok, it smells rich, especially on startup but I think maybe cause I dont have the front cats. I HAVE NO CEL's!! I got an air filter, in the car. I changed the MAF sensor, I checked my ECT sensor. All looks good. I have ran some fuel injector cleaner dosent seem to help much. I fill up a tank about 17-18 gallons and barely get 200 if im lucky. The car seems to be running ok, I cant seem to think of what could be the issue. Any help would be greatly appreciated.
03-03-17, 09:03 AM
#2
Some things I would take a look at to help figure it out.
1. check o2 sensors as there are quite a few and one or more could be fouled.
2. check your check engine light. unplug the maf or some other sensor to see if it triggers. the bulb may be bad.
3. reset the ecu. disconnect the battery, put your foot on the brake and let it discharge for a few seconds, then reconnect and let it reset its idle and baseline without touching the gas pedal. Make sure the car is warm before doing this.
4. gutting the cats is always a bad idea. either remove them or replace them otherwise you create turbulence in the exhaust which can kill gas mileage/performance/etc.
5. check your spark plugs for correct gap and heat range.
6. check to make sure the thermostat is functioning properly. If it never gets out of cold start mode due to the thermo being always open, the map never leans out to proper functionality.
hope those ideas help.
1. check o2 sensors as there are quite a few and one or more could be fouled.
2. check your check engine light. unplug the maf or some other sensor to see if it triggers. the bulb may be bad.
3. reset the ecu. disconnect the battery, put your foot on the brake and let it discharge for a few seconds, then reconnect and let it reset its idle and baseline without touching the gas pedal. Make sure the car is warm before doing this.
4. gutting the cats is always a bad idea. either remove them or replace them otherwise you create turbulence in the exhaust which can kill gas mileage/performance/etc.
5. check your spark plugs for correct gap and heat range.
6. check to make sure the thermostat is functioning properly. If it never gets out of cold start mode due to the thermo being always open, the map never leans out to proper functionality.
hope those ideas help.
03-03-17, 09:40 AM
#3
Alternatively, just turn the key to ON and see if the CEL lights up. Some unscrupulous people remove the bulbs so buyers aren't aware of issues, figuring most people aren't familiar with that startup diagnostic. I actually mentioned it recently to a friend who has wrenched on his own cars for years and used to work at a car lot, and it was news to him.
03-07-17, 09:32 AM
#4
I've never heard of pressing the brake pedal before - what's the purpose?
03-28-17, 06:49 PM
#6
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Some things I would take a look at to help figure it out.
1. check o2 sensors as there are quite a few and one or more could be fouled.
2. check your check engine light. unplug the maf or some other sensor to see if it triggers. the bulb may be bad.
3. reset the ecu. disconnect the battery, put your foot on the brake and let it discharge for a few seconds, then reconnect and let it reset its idle and baseline without touching the gas pedal. Make sure the car is warm before doing this.
4. gutting the cats is always a bad idea. either remove them or replace them otherwise you create turbulence in the exhaust which can kill gas mileage/performance/etc.
5. check your spark plugs for correct gap and heat range.
6. check to make sure the thermostat is functioning properly. If it never gets out of cold start mode due to the thermo being always open, the map never leans out to proper functionality.
hope those ideas help.
1. check o2 sensors as there are quite a few and one or more could be fouled.
2. check your check engine light. unplug the maf or some other sensor to see if it triggers. the bulb may be bad.
3. reset the ecu. disconnect the battery, put your foot on the brake and let it discharge for a few seconds, then reconnect and let it reset its idle and baseline without touching the gas pedal. Make sure the car is warm before doing this.
4. gutting the cats is always a bad idea. either remove them or replace them otherwise you create turbulence in the exhaust which can kill gas mileage/performance/etc.
5. check your spark plugs for correct gap and heat range.
6. check to make sure the thermostat is functioning properly. If it never gets out of cold start mode due to the thermo being always open, the map never leans out to proper functionality.
hope those ideas help.
03-29-17, 03:55 AM
#8
Ditch the Autolites
I would be very suspicious of the spark plugs you put in. EVERYTIME I put in non-oem parts it gives me a problem. Concentrate on the plugs they could have the wrong gap too. Which Autolites are you using?
Last edited by dogwisper; 03-29-17 at 03:57 AM. Reason: Misspelling
03-29-17, 11:36 AM
#9
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[QUOTE=dogwisper;9817751]I would be very suspicious of the spark plugs you put in. EVERYTIME I put in non-oem parts it gives me a problem. Concentrate on the plugs they could have the wrong gap too. Which Autolites are you using?[/QU
They are autolite double plats.
http://www.autozone.com/external-eng...lug/426104_0_0
They are autolite double plats.
http://www.autozone.com/external-eng...lug/426104_0_0
03-29-17, 07:13 PM
#11
i never put anything in a japanese car other then ngk or denso as per the owners manual.i have worked on several japanese cars that had other plugs and had problems,installed the required plugs and fixed the issues.
04-01-17, 03:15 AM
#13
I agree with jimbosr1 put in oem plugs. I have had issues in the past with cam sensor, temperature sensor, power steering fluid, enough that I know to by oem so it works properly. In your case look at what you have changed since the car last ran well, I think vipsoarer has an excellent protocol to go through. Take the steps he outlined and you'll narrow the possible cause down. As you probably already know the exhaust will have a more gas like smell due to no cats. Go through the steps and report back with the results.
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