ok heres the car:

its a 91 L03 camaro vert

i would say its down on power, but its a L03, and frankly i cant tell the diff between the stock slow L03 and the down on power L03.

its not running overly rich as far as i can tell. it doesnt smell rich in the exhaust, and frankly, for a L03 to be using that much fuel, it should smell rich.

the car has fresh plugs, airfilter, cap, rotor, new bosch O2

thinking the exhaust was clogged, i took it off for testing purposes. it drives the same (athough louder and "sounds" faster ) and i may even be getting WORSE miliage...

ive since put the converter back on, but the catback is still off. the cat was not clogged.

WHY am i getting only 7mpg? it doesnt smoke rich, smell rich or have black soot in the exhaust.

it is NOT throwing any codes.
it is basicly stock. it has a GU2 rear, 700r4.

the tranny IS going into all gears, and the converter Does lockup.

going down the hwy, RPMs are around 2k.


the TBI didnt show a great spray pattern, so i put in good injectors that were matched from a friends 91 L03. they now spray perfectly. athough i must admit, that looks like ALOT of fuel for such a low output motor...

the only real "mod" on the car currently is a open element. the air temp sensor is underhood on top of the blower box now. it may read slightly higher temps now since its in the compartment, but that would make it run LEANER anyway, right?
the Pass side valve cover now has a push in breather.



why is my car using so much fuel?!

ideas? this one has me stumped.

 

Your odometer isn't showing as many miles as you're actually traveling, perhaps?

 

sorry... i should have mentioned that.

my VSS was replaced about a month ago. because i used the sensor from a friends old tranny, i checked it by using the mile markers on the Hwy... its correct.

 

Vacuum leak?

 

none that i know of, but i can check.... how would that effect my fuel economy though?

 

i have a friend with winALDL... heres the only log i have on this PC... this is from a few weeks ago, but the car was behaving just the same then as now.

http://josh.swoca.net/board/MrDude/short_ALDL_LOG.txt


in anycase, i didnt see anything wrong when i was running winALDL.. atleast nothing stood out to us.

 

I had the same problem. Here was what I did... and it sounds like it's possible for you too...
I swapped an L05 into my car (350) and got hideous gas mileage. Well for one thing I messed up the spark plugs wires and had 6 on 8 and 8 on 6. so 2 plugs weren't firing right at all.. That killed my gas mileage seriously... If you just replaced the wires and stuff I'd make sure that you didn't accidently mess that up.


I had this problem happen again too.. This time 4 valves in my cylinder heads collapsed. but that was pretty major I think you'd feel that one.

Let me know how this turns out.

-Justin

 

checked and rechecked the firing order.

car has been this way for awhile, so ive had time to try everything i could think of. this post is kind of a last ditch effort.


ive never pulled the valve covers off this motor (yet)..... athough now that i think about it, i can set the valve lash... the engine probly never had its covers off..

 

I wish you luck!
I know these things can be DAMN frustraiting (I installed my headers and then the damn car wouldn't start all the sudden).

Worst case scenario you could always get it down to a dealership and see if they can help you.. of course if it's an engine problem it might end up costing you an arm and a leg.

I wish I could help you past this point but those are the only two things I could think of.

If it IS a collapsed valve in the cylinder heads, let me think what I felt.

The car still seemed to perform fairly well (it could have been better) but the idle was VERY VERY rough. I mean the whole car shook and I was afraid one of my doorskins was going to fall off because of the vibration.. Your car doesn't do this does it??

-Justin

 

nope. idles fine.

and i would never say that even a perfectly running l03 performs fairly well...

 

And you wonder why PMD never needs gas for his car.

Pull a plug or 2 and see how they look.

RAW:KNOCK_CNT
Is that showing knock counts, if so this could be your problem.

 

it got one knock count when i mashed the gas from a stop.... then it never got another one, so i figured it was a fluke.

you dont think it sees one knock, and pulls alot of timing out, and keeps it out, do you??

 

Have you tried the obvious, like a new O2 sensor?

 

No, it should not be a problem if your only got 1 or 2 knock counts.
But there might a problem with the computer and it’s not advancing the timing like it should. Put timing light on the car and rev the motor up and see if the timing is getting advanced like it should be.

Have you looked at the tank to see if it shows any signs of leaking?
7 miles to a gallon is really bad, the only thing I can think of is you are pig rich or it's leaking or the trip meter is off.


Check the oil to see if it has a gas smell to it.
Pull a few plugs and see if it's running rich.
Check the mileage meter, use the mile markers on the HWY and make sure that it is working right. I know the one in my car is off a little bit.
Check the fuel system to make sure it's not leaking, it might be doing it when you are driving down the road and that maybe why you can not smell it.

Now way you should only be getting 7 miles to a gallon, if it’s really using that much gas then the plugs will show up really rich.

 

timing is fine, just checked it...


get this though... i checked my oil level, and its friggin quart and a half over... out of nowhere...

now heres whats wierd. it does NOT smell like gas... and i didnt see any water on the stick... im changing the oil right now, and i'll look for water in the oil or somthing.......

but i wonder if the gas was dripping into the oil or what.. i have no idea how that got that high.

trip meter and speedo are almost exactly on. i checked it when i replaced my broke VSS with PMDs old one.


im positive that its not leaking.


by any chance do you have a fuel pressure gauge though? id like to barrow it.


also, when im looking at the TBI with the air cleaner off, and the engine running, its spraying a awful lot of fuel into the motor......


i'll pull the plugs after the oil change..


please keep the ideas comin..



RB83L69: new plugs, cap, rotor, O2, VSS...


heh, just thought of somthing... can my MAP sensor be off and make it over compensate?

btw, why the hell doesnt my car see itself as rich? i mean, its a new, WORKING O2... is my car in open loop as im going down the HWY?

 

I missed that.... sorry.... ignore me

 

I got a pressure gauge, I could stop by sometime this weekend and bring the scanner too.

When my MAP was going bad the car felt soft but the BLMs stayed normal, I changed it and it went back to running right.

Let me know what you find out with the oil, that's a lot over full and can cause a loss of power.

 

well, i dont know how or why it said it was higher, but i changed it, and it was fine... no gas smell, no water.

the pressure gauge you have, is it for TBI or TPI? TBI needs a "special" one from what ive been told...


it would be great if you can come over sometime and help us figure it out...


btw, party at the house of Deenus the fourth of july... your welcome to come... pool party....

 

I will stop by.
I will bring the fittings that came with the pressure gauge, maybe on of them will work.

 

cool.... hey if you have one, could you bring a Vac gauge too??

 

I grew up with carbs so I have one and will bring it.

 

Wow, I am in the process of putting an LO5 in my car right now. The reason i was switching because i was getting 3-8 miles a gallon depending on how i would drive, and if i were you i would do a compression test, because i had burnt a piston ring, and there was a black soot all over the cylinder walls. So dropping a LO5 in there sounds like a good idea to me. Although i added a 750 Holley, and L98 exhaust

 

swapping engines is out of my budget right now, but the car eventually will get a performance engine in it...

thoughts are either a LT1/T56 combo... that would be ideal.

otherwise, im going to grab another 400 small block.... i dont like wasting time on thoes small 350s

seriously though, thats off topic.... right now i need to get this one running correctly...

theres no black soot or anything, a compression test wouldnt be a bad idea, but i have to get a gauge...

hopefully Zghost can help

 

Lemme know what you find because I have had horrible mileage since I've owned it. Which is almost 2 years, but I get horrible mileage no matter what. (10 with highway driving.) Thats what I got on my 305 also.

New motor
New 350 Injectors
New computer
All new (engine mounted) sensors
Changed gauge cluster
Good fuel pressure
Seemingly no vacumn leaks
Car runs strong
Modest gears

HELP!!!!

If I cant fix this problem by the end of summer, the TBI setup goes on ebay and TPI is going on. I'm sick of messing with it.

 

oook, put the car on the scanner.


nothing, i mean NOTHING is wrong.

its apparently running great.


pulled a plug. looks damn near perfect.

tried Z_Ghosts vac gauge... un fortunatly..... it broke so i dont know if the vac has anything to do with it...




well, im going to go on the theory that theres a small leak in my fuel system when the car is moving... im going to put it up on jackstands tomarrow, and start it.... then crawl all around and find the damn leak.

i dont smell fuel, but the engine IS running right..



i hate mystery games.

 

I had the same problem, its a race between your feul gague and your speedo, I replaced my fuel pump, filter, pcv valve, and belive it or not I get at least 14 or 15 mpg, and my driving habits have not changed at all.

 

anyone have anymore ideas?

 

ahHA!!!!!!!!!!

coming home tonight, on the hwy, where im getting my terrible miliage, i got a SES light..... it went out after i started driving on the city streets... but i pulled the code when i got home:

i think its my MAP sensor...


i mean, that could make the computer think it had to dump more fuel in, right??

and since it was only at low RPM under load, we never picked it up on the laptop as i drove around on the city streets....


hehe, im going to get a few MAP sensors from the 'yard tomarrow and see what happens

 

Congrats man :lala:

 

32 is egr... Probably jsut clogged. If the map was disconnected/malfunctioning, youd know. Anyway, from your data the baro looks fine, so do the blms, and so do the integrator values. All in all it looks like its running ok from the computers standpoint. The O2 seems to be bouncing around normally as well. looks like its pulling around 20 inHg at idle from the data as well. The onyl thing i can sugest is getting a new O2 to be safe, checking for timing issues, and checking to make sure the exaust isnt plugged up. It looks like you have a fair ammount of knock counts, maybe try retarding the base timing by about 2 degrees. A blocked EGR vavle will also cause this and judging by your code 32, its probably blocked.

 

You might also want to replace some of your vacuum lines, some of them did not look that good.

I checked my shop manual and it's saying EGR.
I have a vacuum pump that we can hook up to the EGR and see if it's working, should have brought that over with me when I came by Friday.

 

i havent touched the EGR yet...

athough i yanked my map sensor off

i was going to put another one on, they both said GM and 466 on them so i thought they were the same

but the 3 prong connector was SLIGHTLY diffrent, so i took my stock one, tapped it afew times to knock it loose if it was sticking or whatever, and put it back on...



i got much better miliage.... i think im going to get a new map sensor as soon as i can.


if you wanna come over somtime and help me check out my EGR though, that would be great. if its anything like any other EGR valve ive seen, it probly just needs to be cleaned out.