Bad gas mileage pics of plugs.

[phenomic]

I am getting shoddy mileage on a 97 z28 with 113k miles. I tuned up just about everything i could think of except o2s. I got 2.73 gears and am only gettin 10-11mpg while not driving crazy. I got my maf screen still and have a 180 stat. New plugs and wires.

I pulled a few of my plugs and they all look like this: http://www.clanbbw.com/publicimg/data/images/large3.JPG
They have a whiteish gray at the tip. Is this a sign of anything? I changed them about 2k miles ago. I was thinking running a little lean. Do i need new o2s or are my injectors clogged or something?

Also, here is a pic of my old plugs next to a brand new ngk. The old one appears to be running a little rich.
http://www.clanbbw.com/publicimg/data/images/large2.JPG

Can anyone analyze the spark plug condition for me?

 

[theguru]

Would help to get a better view of the top and ceramic insulator. Dont need to see the whole plug and thread.

From the bit I could see it looks like it is running rich.

 

[mechtech]

Get rid of that 180 thermostat, first. Your heat of combustion is being used to heat the cyl head and walls [trying to reach homostasis], then the radiator, instead of being used to propel the piston down the bore. Also, your coolant temp sensor will give readings that will cause the ECU to run richer, and waste fuel.
A good injector cleaning is next, because if one or more are laying down, the O2 sensor will signal to richen up the others more than necessary, to get an average reading that is acceptable.
Cold weather will hurt mileage by a few MPGs. That is to be expected, for a number of reasons.
Check you inlet air temp, and engine coolant temp sensors, and you TPS funtion and accuracy.

 

[427Z06]

Isn't the stock thermostat for that engine rated at 180F?

 

[Jon]

I don't think any cars have a 180 F thermostat in US due to regulations. Some dealers in the south have in the past replaced the 195 with the 180 but I think that's no longer done.

195 is definately where you want to be.

 

[kenw]

quote:

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Originally posted by Jon:
I don't think any cars have a 180 F thermostat in US due to regulations. Some dealers in the south have in the past replaced the 195 with the 180 but I think that's no longer done.

195 is definately where you want to be.

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you can buy many different "temps" of t-stats at most parts houses to install yourself to your heart's content. iirc, when I replaced my son's a few weeks ago (93 Accord EX), there were 3 to choose.

I prefer to stay with stock.

 

[phenomic]

Stock was 180. Car came with 160 from previous owner. ITs debateable but supposed to make car a little faster at the cost of gas mileage. I changed it back to the 180 when i swapped my fuel pump.

 

[kenw]

the old plugs look more like oil fouling than rich. PCV?

 

[phenomic]

It is possible that the old ones were fouled rich due to the pcv i did change the pcv valve on them about the same time i changed the plugs.

 

[427Z06]

quote:

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All current LT1s come from the factory with a relatively low 180 degree temperature thermostat.

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LT1 Engine Article

 

[mechtech]

427 - The coolant flow [after four decades of small block] was reversed in those LT1s. That's why the 180 is used - to remedy a situation, and maintain the same temps at the cyl walls that was there before.

 

[427Z06]

quote:

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Originally posted by mechtech:
427 - The coolant flow [after four decades of small block] was reversed in those LT1s. That's why the 180 is used - to remedy a situation, and maintain the same temps at the cyl walls that was there before.

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I already knew that. I was diplomatically trying to inform everyone else.

 

[phenomic]

I think it just may be the trip i drive. My school is about 2 miles away and my job is 2 miles from school. All my friends and most stores i go to are very close to me as well. I am down to the conclusion that nothing is wrong because my car runs great and its just the short routes/warming up and all can anyone verify that?

 

[WI70W31]

Sounds like it's time to fill 'er up and take a road trip and find out

If you have short trips like that and especially if you let the car run to warm it up before taking off, your mileage isn't surprising.

 

[mechtech]

Phenom - Why keep this germane info secret until now? Those short runs are killing your mileage!
427 - On second look, I saw and read that link in your post. You were so polite I didn't get it at first!

 

[BlazerLT]

quote:

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Originally posted by phenomic:
I think it just may be the trip i drive. My school is about 2 miles away and my job is 2 miles from school. All my friends and most stores i go to are very close to me as well. I am down to the conclusion that nothing is wrong because my car runs great and its just the short routes/warming up and all can anyone verify that?

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Ah, short trips, you found your fuel economy problem.

Best to stick to the AC delco plugs though, don't go to the v-groove plugs or anything.

 

[TheTanSedan]

Take that Chev and run 25-30 miles out of town. Fill up and run another 100 highway miles refilling at same pump/same station.

In town, drive around a bunch one day, using similar method (station/pump).

 

[1 FMF]

I'm going to post my mileage in the near future, 2002 SS. I've been getting an average of 18 mpg per tankful- that includes cold start, time to warmup, and intown driving till I get on highway to go to work, over the past 2 years. I have an excel spreadsheet for last 15000 miles. Car has 26k now. If the car's hot, and I fill up then do a strictly highway trip (have done to upstate NY, 350 miles) then fillup to get mileage I get 25-27mpg. Big difference.
I just started working a different job and when driving the car I'm doing 45 miles each way to work. I've always filled up with cheapest gas available- either stop&shop or ** 's club, 93 octane. Last tank I filled up with Amoco 93, and will continue to run it for a bit then switch back to the cheaper 93 octane. Initial impression is the amoco is giving me much better mileage! Not sure if it has Ethanol or not

Don't know how they do the fuel up where you are, but it's severly hindered here in the Northeast for emissions. Many people have told me that they get many more miles per tank when they fill up in NJ vs CT. Definitely consider your fuel before jumping to any other conclusions. But at 113k, I wouldn't be suprised if it were O2's.

 

[phenomic]

I got it on the highway a day or two ago and i guess it did pretty good. I filled it up and drove 50 miles highway with the cruise set at 65. The needle was past full and didnt move the entire time so i probably got 20 mpg or more which isnt bad. I am torn apart whether or not to change the o2s because im not getting any error codes and it seemed to do ok on the highway and i don't want to spend 100$ on them if i don't need to.

My area doesn't do emissions, maybe they mess with the fuel though so that way emissions are still down.