Ok, i just spent $1,400 in repairs for my 1986 IROC Camaro (305 TPI "LB9"). It was basically a "tune up" for that price.

Now, when i got my car back from the mechanic, it would not idle. If i let the car warm up it would idle, but until it reached operating temperature, it would die if i let off the gas.

I jumped my idle speed up to around 1,500 RPM in neutral, to solve this problem. When im in gear, it normally stays level with 900 RPM. If say, i put it in park, it jumps back up to 1,500.

Could this be causing my poor fuel mileage?

Also, i adjusted the TPS to .78 volts, (so it would hit over 4.0V on WOT).

These things, and the new O2 sensor i had installed are the only things i can think of to check! What should i do? I am planning on picking up a new IAC, and installing it. Then adjusting the TPS back to .54 (and check to see if i can get it to hit over 4 volts during WOT). Is there anything i can do to check the O2 sensor easily? It's new, with less than 400 miles on it.

Anyone have any other suggestions for what could be causing my poor gas mileage? I do know when i let up on the gas it makes a gurgly sound, and sometimes i hear popping too. Is that the sound of unburned fuel igniting in the headers + y-pipe?

Thanks guys! 11 MPG for a 305 isn't so great, i know something has to be up. Any suggestions or opinions will be greatly appreciated!

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1986 IROC Camaro
305 TPI "LB9"
3.23 gears
Doesn't know enough about cars.
AIM: jesusathome

 

if it ran bad after your $1400 tuneup take it back and tell them to get it right.
Andrew

 

Yea! I second that.

 

Nah, im too trusting of mechanics. The one i took the car too, really seemed to know about my car.
I wanted him to install a new harmonic damper, and y-pipe.

He called me up, and said, "you really need a tune up, new spark plugs, CAT, etc" so i said, "it really does? ok, do it then".

Then he added on fuel injector cleaning too. I purchased a set of shocks/struts, and had him install those too.

I thought it was kind of fishy that the guy always wanted me to call before i showed up to check on my car. When i did show up, the car was always running. (I have had problems with cold starts forever, never idles!)

I also asked them to check the coolant temperature sensor, and wire the car fan back up to the original specs.

When i got the car back from the guy, it was running of course when i showed up. When i paid for it, (and signing a long sheet of paper, still kicking myself for not sitting down and reading it, im a moron) on the way home, my voltage jumped to 18-19 volts when i accelerated! I pulled into a gas station and filled up (they has about ten drops of gas in it) then drove it back. They checked it out. The alternator was dropping below 14 volts as the RPM was raised.

They apologized and said, "we forgot to tell you about that". Forgot? how do you forget something like that?

Anyway, so they told me that it "wouldn't hurt anything". I wasn't about to let them touch my car again, so i took it home, and pulled the alternator out. The bolt which connects to the positive cable was loose, so i tightened it, and made sure the connection was good, and it hasn't spiked sense.

Still, as far as the coolant temperature sensor goes, all they did was wire the fan to always be on, when the car is in "accessory" mode, or on. Another job they didn't do right.

The engine did sound really good when i got it back from them though, so i wasn't too pissed off. I went to the emissions place a few buildings down, to get tested, and the guy laughed when i told him where i went for repairs. He said they were huge rip off artists.

Of course i found this out after the fact.

Anyway, I do not want to take my car anywhere near these people again. It would be pretty hard for me NOT to shoot them if i did.

So back to the original problem, Do the injectors have some kind of idle setting or something? I don't see how raising my idle up like i did would cause the gas mileage to go down so much, If that is even the problem.

Thanks!

[This message has been edited by Christos (edited July 19, 2001).]

 

its probably your idle air control valve. i have the same problem but i just raised my throttle stop a little and its fine. mine doesn't fluxuate though
Andrew

 

Read the tech articles and start from the begining with resetting the IAC and TPS. When checking for 4.0 volts at WOT do it from inside the car using the pedal not your hand on the throttle body. Sometimes with my car and my friends IROC we can't get it to 4.0volts from outside but the pedal pushes it to over 4.3volts.

 

With that kind of mileage, I'd say you are running rich enough to wash out the rings and hog out the cylinder.

What did the emissions guy say? Was the car able to maintain a decent air/fuel ratio?

Sheesh, I get 22 MPG with my 14.04 second, 100 MPH, Carburated, 3.73 equipped 305. Around-town mileage is 14 to 15 MPG.

You should exceed or at least equal that kind of mileage.


------------------
Daniel Burk
View my third-gen hobbyist performance page!
View my reader's ride!
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff., Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Turbine Technologies 2500 stall converter, underdrive pulleys, Crane Hi-6 & more.
1.05g skidpad verified.
Best of 14.039 at 100.82 MPH in Stanton, MI
New!Full 1LE brake upgrade! Details at website above.

 

Arrgh. I got off work early to work on my car.

I pickedup a new IAC for my car. It is the huge-socket version of the IAC. 1-1/4.

I whipped out my chiltons, and it said to simply use a 1-1/4 wrench to get the IAC out. It didn't look like there was much clearance between the IAC and throttle body though. I was right! i dropped the alternator, pulled off it's bracket, and got the huge 1-1/4" socket i bought perfectly straight against the front of the IAC, but the socket was either too thick, (by about 2mm) or the plenum was too close to it. I couldn't get the socket to fit it, in otherwords.

What the hell? How do i get this thing off? totally disconnect my throttle body? Somehow pull off the vaccume plenum below-the-throttle-body-where-the-IAC-is-connected thingie? I figured it would be a matter of unscrewing it with the socket i bought. No WAY a wrench would fit in there if the thin socket wouldn't.

Any ideas?

Also, will running my car rich like this really screw with things? (Got a code 45 already yesterday, 'rich exhaust'. Ohh comptuer controls, how useless you are...)

Thanks guys!!!


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1986 IROC Camaro
305 TPI "LB9"
3.23 gears
Doesn't know enough about cars.
AIM: jesusathome

 

Taking the throttle body off is a no-brainer. There are 4 10mm bolts, 2 coolant hoses, and 3 cables. Don't forget to get a new gasket.

As for the IAC, with the TB off, you should be able to remove it with an adjustable wrench.

While the TB is off, also remove the TPS and liberally clean the TB inside the throttle bores with carb cleaner and a stiff brush (an old toothbrush works).

This will help your idle problems.

Reset the TPS to .54 volts at idle with the key on-engine off.

You also need to go kick some @ss at the garage you went to. I would comsider small claims court.

Obviosly they repaired things that didn't need repairing, and the things that did need repair wasn't done right.



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Mike L.
It ain't pretty.......

1987 IROC Z TPI 350 A4 3.27 Borg-Warner.

Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, homemade cold air, Relocated MAT sensor, Gutted MAF, 160* thermostat, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, 3" MAC mandrel intermediate, custom dual !cat Y-pipe. airfoil, ported plenum. !smog

http://www.MichaelLasiuta.home.att.net

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