Bad mpg. Idk why.
If you have tried everything then I suggest 2 more parts that are $12 a piece.
Intake air temperature sensor, it will never trigger a check engine light. Mine was reading -117 degrees and it was dumping fuel like crazy. The replacement units are brass and have a much better construction
Coolant temperature sensor. It's located on the driver side head next to the first header primary. I hit mine when I was installing new plugs and broke it, they are very sensitive. However if your ls1 is a 1998 only a dealer and oreilleys carry the correct 3 Prong replacement unit
If you have tried maf, o2's, those sensors, your next step is going to be checking to see if your car has a leaky injector. Symptoms of that however is the car has rough starts. Get some seafoam and go to town cleaning, my cam stall 98 gets 220 to a tank all city
Intake air temperature sensor, it will never trigger a check engine light. Mine was reading -117 degrees and it was dumping fuel like crazy. The replacement units are brass and have a much better construction
Coolant temperature sensor. It's located on the driver side head next to the first header primary. I hit mine when I was installing new plugs and broke it, they are very sensitive. However if your ls1 is a 1998 only a dealer and oreilleys carry the correct 3 Prong replacement unit
If you have tried maf, o2's, those sensors, your next step is going to be checking to see if your car has a leaky injector. Symptoms of that however is the car has rough starts. Get some seafoam and go to town cleaning, my cam stall 98 gets 220 to a tank all city
Correct. They are botH long shots however thought I would suggest them. Since they are cheap and the cars temp can control how much fuel the car thinks it needs to send to compensate for density
Make sure you have a new fuel filter and that you use actual seafoam fuel cleaner. The other stuff doesn't work
Make sure you have a new fuel filter and that you use actual seafoam fuel cleaner. The other stuff doesn't work
Staging Lane
Joined: Mar 2012
Posts: 79
Likes: 0
From: Traverse City, Michigan
My bet is on the rear o2 sensors. I cannot be for sure because I don't know much about the electronics on your car, but in my truck IT MATTERS BIG TIME. There is no point in having any o2 sensors, its a closed system. It reads the front ones before the cat, and then the ones after the cat and makes a call based on them numbers. If them numbers aren't there it can't work. Most people underestimate the importance of these sensors. I made a few changes to my truck and average 30 on the highway and 22-25 in the city. I think outta a 2000 silverado with a 4.8 V8 is good. I haven't done much though, I will get it way past 30 with the next secret weapon.
Anyways my bet is o2 sensors. Just because they don't throw a code doesn't mean there working right. There is a HUGE tolerance before it will trip the o2 sensor. Mine were bad, no code and i averaged around 14-18 and changing them brought me up to around 25ish.
Anyways my bet is o2 sensors. Just because they don't throw a code doesn't mean there working right. There is a HUGE tolerance before it will trip the o2 sensor. Mine were bad, no code and i averaged around 14-18 and changing them brought me up to around 25ish.
Thread Starter
TECH Fanatic
Joined: Mar 2011
Posts: 1,050
Likes: 2
From: Odessa, TX
I asked frost when we were emailing about my mail order tune. He said rear o2s have nothing to do with mpg. Knew it just double checking. And chrysler kid I went to get the 2 sensors. The only brass one that are available are the coolant temp one. Is that the one you were talking about when you said its made out of brass?
Are there any other sensors that might affect mpg that could be replaced?
I am seafoaming Thursday.
Are there any other sensors that might affect mpg that could be replaced?
I am seafoaming Thursday.
I asked frost when we were emailing about my mail order tune. He said rear o2s have nothing to do with mpg. Knew it just double checking. And chrysler kid I went to get the 2 sensors. The only brass one that are available are the coolant temp one. Is that the one you were talking about when you said its made out of brass?
Are there any other sensors that might affect mpg that could be replaced?
I am seafoaming Thursday.
Are there any other sensors that might affect mpg that could be replaced?
I am seafoaming Thursday.
SeaFoaming.........you mean in the gas tank right? DO NOT clean your top end with it.....it does almost nothing. But you can possibly destroy the entire engine in 2 seconds.
Gas tank only.....pour it in 1/8 tank. Then change the fuel filter.
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Verdad Gallardo There's allot of write-ups.......some are terrible and should be deleted. SeaFoam being poured into the brake booster line is so stupid its not worth talking about anymore.
The only pistons that get cleaned doing that method are the rear two......6 others get NOTHING.
The way you can totally destroy your engine and have to have it removed and rebuilt.......you pour too much into the brake booster line and you fill one of those rear pistons too much and you "hydralock" the engine....good bye engine.
Go buy some MCCC or any other type of real "FOAM" top end cleaner. You spray it into the vacuum line at the FRONT of the intake with the engine idling so the incoming air from the TB distributes the foam to all 8 cylinders. SeaFoam going into the back of an intake...lol...as a heavy liquid cannot fight upstream incoming high velocity air to move forward. Its not sperm or salmon swimming upstream......lol
The people who THINK they are getting cleaned out......the smoke show they see.....its from all the SeaFoam liquid pooling in the back of the intake. When they start it up later, that liquid slowly gets sucked up by the rear pistons and it makes a smoke show.
Use a product that is designed to clean a top end.....not SeaFoam which is NOT designed to clean a top end. Introduce it into the FRONT vacuum port........its allot easier to do it that way too. These brake booster lines are old, they break easy and they're a bitch to get off sometimes.
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There actually is a good way to use SeaFoam to clean the top end, and get all 8 cylinders equally. But it requires removing the intake and the spark plugs. But then you actually get a chance to clean all 8 runners on the intake too, while its off.
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Staging Lane
Joined: Mar 2012
Posts: 79
Likes: 0
From: Traverse City, Michigan
Do you have a scanner to tell if the engine is in open loop or closed loop? As I am to know if there are o2 sensors just "missing" the engine cannot go into closed loop. In that case it just defaults and doesn't use the o2 sensors. Also have you monitored voltage from the o2 sensors to diagnose them and see if there working right?
It looks to be you can easily get around it, the rear ones from the little research I did seem to run @.5 volts. So thats about halfway of their range. You can get a simulator and set it to .5 and call it good. It won't always be perfect and you might have a few ecu problems with conflicting numbers every now and then, but its the cheapest way to fix it.
My bet is on the rears as the engine can't go into closed loop. Again this is my limited knowledge on it but yea.
It looks to be you can easily get around it, the rear ones from the little research I did seem to run @.5 volts. So thats about halfway of their range. You can get a simulator and set it to .5 and call it good. It won't always be perfect and you might have a few ecu problems with conflicting numbers every now and then, but its the cheapest way to fix it.
My bet is on the rears as the engine can't go into closed loop. Again this is my limited knowledge on it but yea.