after taking my mpg's tonight i got kind of concerned......im only getting 11-13 miles a gallon out of my mostly stock 305 tpi!!!!! its got 160xxx miles on the engine and from what i know no rebuild. im gettin anywhere from11-13 and am starting to think there might be a problem. is this common for this motor and if not then what are some more common problems associated with it??? i also feel my engine is not as powerful as it should be, especially with the few mods i have on it.

help!!!!

 

keep your foot out of the gas pedal.

 

well i might have a problem every once in a while but mostly i just cruise around town......and even if i was hard on her all the time i feel i should be putting around 15 at worst, am i wrong?

 

I used to get average about 18 with my modded 305 TPI.

I'd say a tuneup is in order.

 

got fresh plugs and wires along with a cap and rotor last march. they should be fine im guessing. oil is always changed but i dont know what else is the matter. especially with gas at 2.08 i cant stand this anymore

 

If the car is running good I would think its just your mileage. I have a 96 nissan truck thats got 290k on it. It runs great but I noticed a drop in performence and gas mileage at 190k I went from 23mpg to 17mpg, but I take good care of it( tune up, oil change, etc. at oppropriatte times) it just isnt the way it was back in the day. Still chuggin though.

 

my 305 tbi gets 24mpg when i drive nice.

:lala: :lala: :lala:

 

I doubt it's the mileage on the car. But you said this is "around town?" City driving should get you at least 15-16, maybe a bit more if you're a good boy. So you're not far off.

You said you've given it a tune-up, but you're not the original owner, right? So who knows where that car's been? Your engine just might need some good cleaning.

Try a powerful fuel system cleaner like BG44(I think that's what it's called). And believe it or not, Chevron Techron Total Fuel System Cleaner works very well too if you get an "off the shelf" product. And a product that's good in your oil is an engine cleaner by CD2. You'll feel that working right away. You can add it right into your existing oil, no need to change first.

Then when you change to fresh oil after you've cleaned, use Valvoline MaxLife. No matter how good synthetics are, our engines are OLD, and they need high-mileage oils. MaxLife is the best. And it's available in synthetic now too. So you can get the best of both worlds.

Ok, that's my diagnosis, lol. Take two bottles, clean and rinse, fresh fluids, and call me in a few months.

 

O2 sensor maybe?

 

sounds like oil treatment and fuel cleaner is in the midst....

i sure hope it isnt my o2 sensor....im not throwing any codes but i havent scanned the car since ive had it and who knows, the light could be burned out!

 

O2 may not throw a code. I never got a code but I could tell mine was running rich and mpg was down. O2 had been in there over 40k miles so I popped in a new one and problem solved. I just used the $20 Bosch from Autozone. Easy as changing a spark plug.

 

Check your light by turning the key to the on position. Does your check engine light come on? It should. Or start the car. The light should come on for a second or two and then go off.

 

check engine light working...check! i dont think it would be my o2 sensor but i may be wrong. i was backfiring (i guess running too rich) but then removed my AIR system (which i heard leans the car out a little bit) and it quit backfiring. i checked timing yesterday and im at 7* advanced, arent i supposed to be at 6???

 

Everyone keeps dancing around it...

Sounds like a combination of ignition and the o2 sensor...replace the o2 sensor with a Delco unit (more reliable than Bosch) and verify that you don't have a bad plug wire or need new plugs.

Another possibility is that you have an injector or fuel pump going out. Use a FP guage to check the FP and use a multimeter to verify the resistance of each injector.

Doing this troubleshooting should easily narrow it down for you.

 

please lord tell me its not a fuel pump!!! injectors wouldnt be as bad but a fuel pump!!! oh no.......

 

*deep resonant voice from the heavens* "It's not your fuel pump, my son." Sorry, I couldn't resist, lol.

When my fuel pump went, it just went--no warnings, nothing. Others on these boards have encountered some very serious driveability issues when theirs were going out. But you've expressed no such symptoms, so I doubt it's your fuel pump.

Many on these boards over-react to problems, taking unnecessary actions that usually end up causing them more problems. Don't be one of them, lol.

Start simple. Before you go pulling injectors and screwing around with sensors and settings, use a good fuel system cleaner and an engine detergent, as I suggested earlier. You'll notice a difference. Sometimes additives are necessary, and some really work. Just don't use them often.

Also, what grade of gas are you using? Don't skimp because the price is so high. It's high for all grades, but the price difference per grade is still the same(usually about .10/gal). So an entire tankful of premium is still only $1.50 more than a tankful of mid-grade. And IMO, though many disagree, you should be using premium anyway.

So give that stuff a try for a few weeks and see what happens before you take more drastic actions.

 

lol thanks deep resonant voice from the heavens. well i always use premium, every tank all the time. ive used fuel injector cleaner every once in a while and am in the process of flushing and filling my coolant system because all of my antifreeze turns a brownish color after drivig then seems to settle and be green with brown "trails" throughout.

maybe an entire fuel system cleaner is in order?

 

Gee, I guess that standardized troubleshooting of the sensors, fuel system and ignition system constitutes "overreacting" and may be "unnecessary actions"

The whole with troubleshooting is to eliminate possible sources of the problem. While using a fuel system cleaner is never a bad idea (I would use Seafoam), if your engine's carbon buildup is bad enough to give you 11 MPG, the thing won't run....ROFL...

My experience with multiple cars over the years has shown that if your mileage sucks, the tuneup is the 1st thing. If that doesn't significantly help, then replace the O2 sensor...over time they get sluggish and WON'T set a code, but are too slow to effectively show proper data to the ECM.

Also, if you have leaky injectors, they may test fine with an ohmmeter, so you would have to use a FP guage on the fuel rail to determine if the system is holding pressure or not. Then narrow it down to either a leaky injector, bad FP regulator, or the fuel pump.

Simple things, simple answers...I guess the troubleshooting flowcharts in the GM Service manual are a waste of time too, right?

 

How about verifying the mechanical condition of the engine with a leakdown tester or at least a compression gauge. No good mechanical, No good perfomance. Five bucks says your timing chain is shot. Probably want to change that. Very easy. Electronics can not make up for an engine that is shot. Next, verify fuel pressure ( the great unknown ) that no one ever checks and change the fuel filter. Make sure all ingnition components are good. I.E. Cap, Rotor, Plugs, Wires. Just replace them. Then get a scanner and check injector pulse width and e-mail me with what you find. Shoud be 128 on the integrator. O2 sensor should be ranging between 200mV and 900mV, around 15-20 cross counts. Then maybe you can do some of this........

 

His words were "around town." If he was getting 11mpg on the highway, then his running condition would probably reflect a more serious problem and would probably be easier to diagnose.

He's done the basic tune-up, except for the O2 and fuel filter, yet people keeping saying to change the plugs and wires. I'm sure he's at least double-checked, even triple-checked them.

It could be the injectors, it could be the O2, it could be the fuel filter, it could be the timing, it could be other things too, like the EGR or a vacuum leak(which he mentioned on another topic). Now he's worried because it was suggested that it might be the fuel pump.

I never said anything was a waste of time. But not everyone on these boards are "professional" mechanics and "techs." They can be overwhelmed by the "check this and test that" people. And I'd guess that if he had the means at hand to test everything, he'd have done it already. But if he doesn't, then it means more time and money for having it done.

I know from my experience with my own cars, that most problems are simply solved. That's why I said many people end-up creating many of their own problems. But I also have the advantage of being my car's original owner. So I know everywhere it's been and what it's been through.

CamarosRUS has had some problems with his car, and its beginning to cost him. It's apparently been neglected by its previous owner, so chances are that it's pretty dirty inside too, and simple thing like an additive or two might be all that it needs. But whatever's wrong with it, it's probably been that way for quite awhile, so it's probably not going to hurt worse to take a couple of weeks, one thing at a time, as he can afford to.

 

I thought my suggestions were sound. If you don't know what you are doing then pay someone who does. I'm tired of whiners that can't fix their vechile but expect that it should cost them $10 to take it somewhere. Repairs cost money because cars are expensive and hard to fix. New vechiles are 30-40K dollars and people b!tch about $1000 to fix their car. If you can't afford to drive, stay home and if someone gives you free advice don't complain because you may be expected to pay something or someone.

Not trying to be a d!ck but people need to wake up to reality.

 

And neither was I. But when we type, sometimes the context of what we're saying can be misunderstood.

Actually, I liked what you had to say Mike.

 

camaromike i hope that wasent aimed at me....i know you werent trying to be a D1CK but i never mentioned anything about it costing too much to fix and never once complained i might have to take it somewhere. o and i would love it to be able to do some of this hell......just doing it second would get me off

anyway i am mainly concerned with the bottom end of my engine. i will hopefully have a new vortec top end with pretty much almost new everything. and later this summer when i have the money i will build a 350 or 383 to strap my new top end on to. i may try to change my o2 sensor however i dont want to waste money if i get a 350....are they interchangable? also is it as simple as unscrewing the old one out and screwing the new one in?

88TPI406GTA you said something about a injector leak well i heard a hissing sound coming from around my intake the other day after a drive and was wondering if this would contribute to a horrible engine. couldnt tell where it was from but i heard it. doesnt do it all the time either.

and LAFireboyd could that hissing sound possibly be a vacuum leak?


fuel filter was recently changed (about a year ago)

 

CamarosRUS:

IN NO WAY was that aimed at you. You are politely asking for help.

LAFireboyd:

Thank you for the compliment. Your quote kind of hit me wrong. Maybe I am being a little sensitive but I think what I typed needed to be.

 

I would agree with CamaroMike and verify the mechanicals as well. Typically though, with leaky injectors, over time, can kill the O2 sensor, the cat and shorten the life of the rings, as well as bad gas mileage.

LAFireboyd: Lucky for you that simple answers solved the problem...I am usually never that lucky


CamarosRUS: If you have a vacuum leak around the intake or one of the vacuum lines is bad, it would certainly cause drivability problems...

Add that one to the list to check out

 

My milage driving around town with stop and go traffic is maybe 13 or so, it sux. If you have a heavy foot it will be worse.

Mileage on the freeway, OTOH, is well into the 20's, and that's at 70 mph. This is with a 155k mile LB9 IROC.

If you can get the car up to speed and into 5th gear, and hold it there for some time, the mileage is respectable. If you do a few full throttle accelerations, you can watch the gas gauge drop.

 

I hit 27MPG in my LO3 Firebird.

 

I average 16mpg in my stock 305TPI auto Formula. I do about 70/30 Highway/City driving.

 

Don't guess, go and check. These cars have a habit of frying wires, and that would help reduce mileage.
Also, do the O2 and the fuel filter, the sooner the better as both will also affect mileage. Your in the city and admit to getting on it, don't expect much better until you learn throttle control. The better mpg you see are generally from combined or mostly highway driving.


Yet is this not why this is a <i>tech</i> board? If they don't know they ask. We answer (if we know). I agree that some things can be overwhelming, but if you take it one step at a time most will see they are not insurmountable. You must be able to do the simple 'check this and test that' stuff before you even try to 'pull this and swap that'. Also, when they do the checks, the problems invariably surface.

 

Well, in retrospect, I guess, lol. But I've had my share of major problems too--most of which have left the car on the back of a tow truck. They never happen close to home!

But also, until I found this site, I never realized the amount of problems and the strangeness of some the problems that people have. Compared to what I read here each day, yes, I've been very lucky.

And Mike, after reading that quote, you're right, it looked bad, and I apologize. If we'd been talking, it wouldn't have sounded like it looked.

CamarosRUS, I haven't encountered that hissing problem you're having. Someone suggested on your other thread that it might be a vacuum leak. And since a vacuum leak could also cause your engine to run similarly to the way it's running, it seemed to make sense as something else to look into.

But after all this, umm, interesting chat, I think we all agree that your problem probably isn't a major one, so no worries. When you finally solve it, you'll probably be like

 

man i hope so. im not getting any strange sounds, strange smells, dying engine problems, or anything major like that but besides being a high mileage engine i konw i have some problems somewhere because i know i dont have the power i should (i cant spin tires in second....as i mentioned a million times ) and im gettin horrible gas mileage.

man i hope it surfaces soon...

 

man i hope so. im not getting any strange sounds, strange smells, dying engine problems, or anything major like that but besides being a high mileage engine i konw i have some problems somewhere because i know i dont have the power i should (i cant spin tires in second....as i mentioned a million times ) and im gettin horrible gas mileage.

man i hope it surfaces soon...

 

man i hope so. im not getting any strange sounds, strange smells, dying engine problems, or anything major like that but besides being a high mileage engine i konw i have some problems somewhere because i know i dont have the power i should (i cant spin tires in second....as i mentioned a million times ) and im gettin horrible gas mileage.

man i hope it surfaces soon...

EDIT: another question for you all that are helping (which i cant thank you all enough)...ive got horrible sludge in my coolant. it used to be brown all the time and after flushing a million times it is now brown after a good drive then settles to the normal coolant color with a trail of brownish liquid.......any ideas of what this could be?

 

heres some pics of my coolant and coolant bottle....the coolant has a little trail of brown throughout and the bottle has actual physical brown sludge...........looks like damp dirt (mud). doesnt really have a taste either. i dint know my block could house so much crap, what is it?

 

heres the coolant bottle

 

Ummmm...what do you mean by "taste"

 

mine had the same crap, i flushed the radiator and its fine now.

 

well ive flushed it about 5 or 6 times and it just wont go away.....anyhow, after careful inspection of my wires i found that the nu,ber 2 wire is frayed. not cut or anything so it couldnt really affect anything but the insulation is cut off in a place, so its not even frayed really.

 

LOL

What? The insulation is just for looks? Replace the wires...

 

yea i know they need to be replaced but until i do (which will prolly be tomorrow after work at 11pm) i know that isnt my problem......man i wish it was cut through!!!!

o yea....when i was trying to do a compression test i pulled off my number 1 plug but when i started the engine it sounded and revved up the exact same as when all 8 were firing....i thought it was weird. shouldnt i have noticed a major change or very rough idle????

 

Just out of curiousity, did you do the compression test with the engine running? Did you unhook the coil? What was your procedure?

 

Wow, it looks like I missed some good stuff while I was out! I sure wish I still had the desire to be out playing with my engine at MIDNIGHT!!!

And I'm sorry RUS, but... taste??? Umm, ok, I'm glad to know there's no taste to that stuff. Thanks for saving Adam and me from ever thinking about tasting it, lol.

And DUDE! I supported you when you said your plugs and wires were good! I remember even saying something like, I'd think you've double-checked, even triple-checked them, lol. Change your wires!

 

Not to hijack...but I have run in to "taste" before...

About 10 years ago, I needed to get a used TH350 for a 78 Z28 I owned...went to a rural junkyard that was a REAL dive...even for a JY. This guy at the counter said to go out back near the stack o trannies and wait for another guy. About 15 min later (sitting in the 95 degree HOT sun BTW), this guy comes up, about 6'5", 350 wearing leathery pants with no shirt and a big beer belly and tattoos. I explained what I wanted using "sir" a lot...he went to a stack of TH350s and TASTED the dipstick from about 5 of them, not even wiping it on a rag 1st ROFL...and pronounced the 5th one to be good. I was dumbfounded...I loaded up the trans, paid and left. The trans did work though. I later learned why he tasted it, but you can smell the burnt clutches if you know what they smell like

So...how did the coolant taste?

 

my cats seem to like it.

 

Well...keep feeding it to them then


Thread content: Seriously...tune up the car and check any/all of what CamaroMike and I posted as troubleshooting stuff...and don't "taste" too much else...It may give you a tummy ache

 

OMG! You had me ROFL when you described the guy, let alone what was to follow! I'd have been way to scared to laugh though, lol.

RUS, I'm only teasing, you know that, right?

But back to your coolant... I checked out your thread on the Cooling boards, and I saw that Danno replied to you. Like Trickster is da man in Electronics, Danno seems to be da man in Cooling. I'd follow his advice, which was a chemical flush.

 

Yeah...sounds like the flush wouldn't be a bad idea to get the rust out there...

But before you do that...bottle up some the nasty coolant and send it to CamaroMike, LAFireboyd and I to "taste test" as well. After all, maybe we are missing out on something here...

Or did you mean "taste" in the strictest platonic sense

I need some sleep...

EDIT: Was it tough to get your tongue into the overflow tank
Sorry...I can't help it...

 

LAFireboyd: No problem.

RUS: Oh, and I have gotten a mouthfull of coolant before. Very dry and sweet. Kind of like Ectocooler (Hi-C). Spitting and Petewwee sounds......

Keep up posted. Well get it fixed no matter how much it costs you! J/K

 

you guys are great.....had me ROTFL with every post

but as far as tasting....i tasted the "mud" and solid gunk (just a little speck) that came out of my engine, not the actual antifreeze.........although ive done it before on accident who hasent???

88TPI406GTA at first i wasent sure how to compression test so i just pulled the first plug inserted the gauge and fired her up. however ilke i said it ran the exact same as when i had all 8 plugs in, why is that?

so then i read a little more and found out the correct way (but when i tested the first plug my compression gauge needle kept falling after i cranked it about 7 times so i think its broken too......damn

 

Most compression gauges have a schrader valve in the end. Just take it out with a tool from your local parts store and stick one in from a tire valve stem.