10-11/mpg normal on 5.7 tpi? - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old Dec 26th, 06, 08:05 AM Thread Starter
Jeff
 
Join Date: Dec 2006
Location: Kansas City, MO.
Posts: 6
10-11/mpg normal on 5.7 tpi?

Found an 88 IROC with 58k original miles that I couldn't pass up. Has the 5.7 and all the extras. Has a real strong gas smell after driving the car and is getting, at least what I think, horrible gas mileage. The engine is clean and strong. I am planning on tuning the car up to the best of my ability, but I am limited on automotive knowledge. No leaks that I can detect either. Would anyone have any pointers or suggestions, not even relating to the gas mileage question, that you think I should take in account or be aware of? I would truely appreciate any tips/advice!!
swampholley is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old Dec 26th, 06, 09:39 AM
Welcome Back - Senior Tech
David
 
Join Date: Jul 2005
Location: Ohio
Posts: 890
Re: 10-11/mpg normal on 5.7 tpi?

sounds like ur running real rich. 11 is horrible unless you have a lead foot. do the 88s have O2 sensors? if so it could be that. in any case you need a tune. Also make sure you dont have a hole in the tank. My 69 w/ a 350 gets 16 w/o overdrive.

the learning curve is....expensive
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

1969 Camaro
bearcat44 is offline  
post #3 of 11 (permalink) Old Dec 26th, 06, 09:51 AM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 31,584
Garage
Re: 10-11/mpg normal on 5.7 tpi?

Quote:
Originally Posted by swampholley View Post
Has a real strong gas smell after driving the car and is getting, at least what I think, horrible gas mileage.
Strong gas smell?
From the engine compartment? As if raw gas is being pumped onto the engine/ground? Might have a leaky injector(s). Look for evidence of raw gas leaking externally while engine is running anywhere the fuel rails are.

Also, underneath the car, are fuel lines and a fuel filter. Other sources of leaks, they are located on driver side.

From the tailpipes? As said, could be O2 sensor needs replacing. However, if overfueling, engine would run ragged, as if the choke was closed. Check to make sure the coolant sensor is plugged in. It is located underneath the thermostat housing, the item the upper radiator hose attaches to on the engine. It will be a two-wire connector.

Gas mileage should be, I think, 15-20 mpg, depending upon amount of pedal depressing.

Welcome to the Club! Be sure to turn out the light and close the frig door when you leave.

Give a man a rescued dog for the health of both their souls. May 2017 ROTM Winner - Thank you!
'
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CUBS - 2016 World Series Champions - maybe this year, 2019 ...
Everett#2390 is offline  
 
post #4 of 11 (permalink) Old Dec 26th, 06, 07:02 PM
Gold Lifetime Member
Harley
 
wiskeesour's Avatar
 
Join Date: Nov 2006
Location: A van. Down by the river.
Posts: 6,359
Send a message via Yahoo to wiskeesour
Re: 10-11/mpg normal on 5.7 tpi?

That car is a 'speed density' system guys....o2 could be telling the car 'more fuel' but, need to make sure the choke is opening fully after warm up. choke is prone to stick in these cars after sitting for awhile...

AE2(AW) Harley Moody, USNavy
"Master-at-Arms" for the CDWJB!!
November 26th, 2008 was my last day to serve my country as a member of the World's Greatest Navy.
Thanks Chief.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
wiskeesour is offline  
post #5 of 11 (permalink) Old Dec 27th, 06, 06:09 AM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 31,584
Garage
Re: 10-11/mpg normal on 5.7 tpi?

Granted, he has a Speed Density system. I described his problem as if the choke plate was closed.

I guess I did forget to say his engine does not have a choke plate, hence the mention of the coolant sensor. This device tells the ECM how cold/warm the engine is and adjusts fuel mixture accordingly. If a bad sensor, open circuitry in the harness, or bad ECM stage for the sensor, then the ECM will give max fuel, regardless if MAF or Speed Density.

I'm figuring he may have a leak somewhere if he smells raw fuel. If his eyes burn while standing at the rear, then engine is overfueling. But, if over fueling, engine would run erratic, or barely run at all.

Give a man a rescued dog for the health of both their souls. May 2017 ROTM Winner - Thank you!
'
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CUBS - 2016 World Series Champions - maybe this year, 2019 ...
Everett#2390 is offline  
post #6 of 11 (permalink) Old Dec 27th, 06, 07:08 AM Thread Starter
Jeff
 
Join Date: Dec 2006
Location: Kansas City, MO.
Posts: 6
Re: 10-11/mpg normal on 5.7 tpi?

Quote:
Originally Posted by wiskeesour View Post
That car is a 'speed density' system guys....
Would one of you explain to me what a 'speed density' system is? And would this be a good time to mention that my temp gauge doesn't work either? I assume that the temp sensor is bad and needs to be replaced (when I can find it on the engine.....). I have bought the Haynes manual but haven't had the time to dig into it yet. Honestly, I didn't really know where to start! Also, the gas smell isn't strong enough to burn my eyes (yet) but it is very strong.
swampholley is offline  
post #7 of 11 (permalink) Old Dec 27th, 06, 08:13 AM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,431
Garage
Re: 10-11/mpg normal on 5.7 tpi?

Here's an article from Car Craft that tells about "speed density" engine mgmt systems.
http://www.carcraft.com/techarticles...uel_injection/

...Dennis

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


"Don't take life so serious, you won't get out alive..."
DjD is offline  
post #8 of 11 (permalink) Old Dec 27th, 06, 08:32 AM Thread Starter
Jeff
 
Join Date: Dec 2006
Location: Kansas City, MO.
Posts: 6
Re: 10-11/mpg normal on 5.7 tpi?

According to the article DjD provided (thank you for that), the 'speed density' measurement system was used on all TPI systems from 90' - 92'. It states that the 'Mass Air Flow' measurement system was used on 85' - 89' TPI years. So wouldn't I have a Mass Air Flow sensor on my 88' instead of the Speed Density?

And (you just have to love us newbies!!!) the dealership salesman told me that they replaced the 'throttle body' when they got the car, said it idled really rough. It looks to me like a different air intake duct was put on as well. I say this because written on the side of it with a yellow marker it says "5.7 t.p.i. corvette". Hmmmmmm, am I getting in over my head????
swampholley is offline  
post #9 of 11 (permalink) Old Dec 27th, 06, 08:43 AM Thread Starter
Jeff
 
Join Date: Dec 2006
Location: Kansas City, MO.
Posts: 6
Re: 10-11/mpg normal on 5.7 tpi?

I guess I need to tell you all that I know about the car. Dealership that I bought the car from did an inspection on the car and it came back needing new tires and exhaust. They (dealership) threw on the cheapest tires they had and put a SINGLE cat-back exhaust. They also told me that they replaced the throttle because it idled rough. The temperature gauge doesn't work on the dash either. That's basically all I know about what is wrong/has been done to the car.

The car drives strong. The engine hesitates when I step into it and there is a slight kick when the car shifts into second gear. I honestly haven't driven it too much because I know the car probably needs some good maintenance performed on it. I will try and take some picture of the car and post them out here to help show what the dealership "replaced".
swampholley is offline  
post #10 of 11 (permalink) Old Dec 27th, 06, 09:31 AM
Senior Tech
 
Join Date: May 2004
Location: Southeast PA
Posts: 8,303
Re: 10-11/mpg normal on 5.7 tpi?

You'll probably want to spend some time searching through the tech articles and forums over at www.thirdgen.org .

http://www.thirdgen.org/technical-articles

I saw articles on the IAC (Idle Air Control) and O2 sensor that may be relevant.

Also, you may have to check the thermostat. Some folks install a cooler (160 degree) thermostat to keep engine temp down and trick the sensors and ECM (Electronic Control Module) into staying closed loop and running rich for a little more performance.

Eric
69 'vert project big block/TKO 600 RR
68 'vert driver RS clone -- gone!
Eric Kammerer is offline  
post #11 of 11 (permalink) Old Dec 27th, 06, 11:20 AM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 31,584
Garage
Re: 10-11/mpg normal on 5.7 tpi?

Quote:
Originally Posted by swampholley View Post
It states that the 'Mass Air Flow' measurement system was used on 85' - 89' TPI years. So wouldn't I have a Mass Air Flow sensor on my 88' instead of the Speed Density?
Yes, you would have a MAF system. A sensor, round in shape between the air horn mounted above the radiator and the large, 3 inch diameter, hose connecting to the front of the throttle body and this sensor has a connector going to it.

Make sure there is not a hole in the intake hose between the sensor and throttle body, however slight hole might be. This MAF (Mas Air Flow) semsor measures the amount of air entering the engine and helps, along with other sensors, to adjust the fuel volume delivered by the injectors. If a hole is present, then air is 'bypassing', and an incorrect volume of fuel is being injected into the engine because the MAF sensor is giving the wrong info.

Temperature gauge not working may mean there is no coolant or not enough, along with a broken sending unit for othe gauge, broken gauge, broken wire on the sending unit, or a fuse blown if other gauges don't work.

As said by Eric, a cooler thermostat may be used to 'cheat' the ECM in delivering more fuel for more performance reasons.

Read the Haynes manual several times and compare pictures to what is in frony of you.

Give a man a rescued dog for the health of both their souls. May 2017 ROTM Winner - Thank you!
'
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CUBS - 2016 World Series Champions - maybe this year, 2019 ...
Everett#2390 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
5.0 TPI to 5.7 TPI camaro3554gear Engine 3 May 7th, 07 04:47 PM
TPI Fuel Problems Hot 67 Engine 5 Oct 1st, 06 01:25 PM
1990 5.7 TPI Short Block: how strong are they? jsabowabo Engine 3 Aug 10th, 06 08:27 AM
MAF TPI rough idle shuanm Engine 1 Mar 27th, 06 03:23 AM
Tbi to tpi conversion help me please reaper317 Engine 26 Aug 10th, 05 11:53 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome