Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > V6
Register Forgot Password?

V6 Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 04-14-2008, 02:24 PM   #1
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Erratic idle, very rich. 1990 3.1L

Hi, just joined, I have a problem that I have to get fixed, so I can sell
this car - the gas mileage was eating my son up, so he bought a Celica.
Idle is very rich, will eventually die if I leave it idling. (Probably running
rich at all speeds, I am getting 13.7 MPG with a light foot)
This is strange:
I pulled the IAC to clean it, ended up breaking the pintle and had
had to install a new one. It idled rough for about a minute, I hit the throttle
and right after I let off, it was rough for about 5 seconds, then I heard it
smooth itself out, idling like brand new. I drove it around for about 30 minutes,
ran great, no stalling at red lights, very smooth idle. Parked it overnight,
and it's right back like it was.

Only code it has ever thrown is O2 sensor, I have changed it 3 times in
the year I've had the car, the rich running is burning them out.
Got a new one on it yesterday, no change in idle - found a split vacuum
line to the MAP sensor, fixed it - no change. I am going to change the
CTS, cause it's pretty cheap, but I doubt that's the trouble.
What has me stumped is the way it cleared up temporarily.
Any ideas would be appreciated.

Tookie
Tookie is offline vBGarage Page   Reply With Quote
Old 04-15-2008, 11:26 AM   #2
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Can anyone point me to an F-body forum that may be able to help?
Tookie is offline vBGarage Page   Reply With Quote
Old 04-15-2008, 10:24 PM   #3
Junior Member
 
CamaroKingpin's Avatar
 
Join Date: Mar 2008
Location: NE Philly
Posts: 52
Car: '92 camaro rs
Engine: 3.1 v6
Transmission: stock tranny
Axle/Gears: stock gears

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

plenum gasket. i got a 92 3.1 and i got the same issues. mechanic said gasket i say gasket. 14.99 autozone
__________________
25th Anniversary Maro RS 3.1
MSD IGNTION,BOSCH PLUGS&WIRES, HOLLOW CAT, DUAL EXHAUST,AGGRESSIVE DRIVER

CAMAROMENACE92@GMAIL.COM
CamaroKingpin is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 01:32 AM   #4
Senior Member
 
ohiotemplar's Avatar
 
Join Date: Sep 2007
Location: Lancaster, Ohio
Posts: 301
Car: 1992 Camaro RS V6
Engine: 3.1 V6 MFI
Transmission: 700R4
Axle/Gears: 3.23 stock

Classifieds Rating: (0)
Send a message via AIM to ohiotemplar Send a message via Yahoo to ohiotemplar
Re: Erratic idle, very rich. 1990 3.1L

what's a plenum gasket? What's a plenum for that matter?
ohiotemplar is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 04:04 AM   #5
Junior Member
 
CamaroKingpin's Avatar
 
Join Date: Mar 2008
Location: NE Philly
Posts: 52
Car: '92 camaro rs
Engine: 3.1 v6
Transmission: stock tranny
Axle/Gears: stock gears

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

its short for=intake manifold gasket.if that helps dont have pics, but im sure you can look it up
CamaroKingpin is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 05:11 AM   #6
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

I sprayed cleaner all around the plenum with no change in idle,
but I am going to pull the plenum to test the injectors this weekend,
so it will get new gaskets then.
Tookie is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 05:20 AM   #7
Junior Member
 
CamaroKingpin's Avatar
 
Join Date: Mar 2008
Location: NE Philly
Posts: 52
Car: '92 camaro rs
Engine: 3.1 v6
Transmission: stock tranny
Axle/Gears: stock gears

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

let me know if that works, if that was the injectors. and if you change them search in the v6 forums, theres been tak of for 2.9 motor injctrs that work better than gm stock. and so far all good reviews. def worth checking out.
__________________
25th Anniversary Maro RS 3.1
MSD IGNTION,BOSCH PLUGS&WIRES, HOLLOW CAT, DUAL EXHAUST,AGGRESSIVE DRIVER

CAMAROMENACE92@GMAIL.COM
CamaroKingpin is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 11:41 AM   #8
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

I am trying to sell the car, so if I find a bad injector(s), I am only
changing the bad one(s) $$ - if they are all bad, then I will possibly
look at swapping to the 2.9s.
I doubt it's the injectors, if they were bad, it wouldn't have cleared
up and ran correctly that one time - I am thinking sensor or wire/
connector issue. I don't know how long it's been running like this, I knew
about the bad fuel mileage, but I haven't driven it in a long time.
I just inherited it from my son, who says "well, it didn't die TOO many
times when I drove it."

Tookie is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 12:07 PM   #9
Junior Member
 
zeusalmighty's Avatar
 
Join Date: Jul 2006
Location: Lexington, KY
Posts: 27
Car: 1990 Firebird
Engine: 3.1L V6

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

I actually just got finished looking for the same problem. My problem was a brake booster line that had just barely slipped off the connecter. Check for vacuum lines (my best method so far has been to put my ear up in the engine while it was running). Other things I was told to look for were:
-EGR Valve
-MAP sensor
-O2 Sensors
-Idle Air Control Valve
-Throttle Position Sensor
-PCV valve
-Throttle body inside plate - the EGR puts exhaust right into the throttle body, can get dirty as hell inside
-Vacuum Leak
-Incorrect Timing
-ICM
-Spark Plugs/Wires

I would check Spark Plugs/Wires, Throttle body, Vacuum leaks (inspecting alll hoses and connections) first. Then start looking at the sensors. Hopefully it's not a EGR - you have an electronic one right? That **** is like $230. Hope that helps.
zeusalmighty is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 01:47 PM   #10
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Quote:
Originally Posted by zeusalmighty View Post
EGR - you have an electronic one right? That **** is like $230. Hope that helps.
I thought that price was bad, I scanned my sons Celica, and got a
code for a bad MAP sensor, so I told him to go buy one.
271.00 for a Toyota MAP sensor!!!

And thanks for the list, lots of good things to check there.
I actually may have a brake booster issue, I checked the other day to make
sure vacuum line was good, and if I pull the line from the booster and plug
it, the idle goes down a fair amount - I'll have to plug it and go drive it around
to see if it is an issue

Last edited by Tookie; 04-16-2008 at 01:50 PM.
Tookie is offline vBGarage Page   Reply With Quote
Old 04-16-2008, 02:53 PM   #11
Junior Member
 
zeusalmighty's Avatar
 
Join Date: Jul 2006
Location: Lexington, KY
Posts: 27
Car: 1990 Firebird
Engine: 3.1L V6

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Be careful - if you plug it, you won't have power brakes. Is the master cylinder full?
zeusalmighty is offline vBGarage Page   Reply With Quote
Old 04-17-2008, 02:38 PM   #12
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

It gets stranger - O2 sensors have been averaging 3 months to burnout,
and when pulled, are full of black soot, plus I can see that the car
is running rich at idle, it will start putting out light black smoke if
it sits long enough (not to mention the fuel mileage)
So I changed the distributor cap and rotor, and pulled the plugs,
expecting them to be really sooted up, but they were spotless!!
I don't see how this car can run that rich and have clean plugs
Anyway, a couple of plug wires broke pulling them off the plugs, so
I guess it was time for new wires anyway - I'll be putting them on
tomorrow.
Tookie is offline vBGarage Page   Reply With Quote
Old 04-18-2008, 11:21 PM   #13
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Put on the new wires, and changed the CTS - no change in idle, will
die most of the time coming to a stop, runs rich enough to water your eyes
Tookie is offline vBGarage Page   Reply With Quote
Old 04-23-2008, 02:59 PM   #14
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Update: changed the TPS, no change in idle
Tookie is offline vBGarage Page   Reply With Quote
Old 04-23-2008, 03:29 PM   #15
Junior Member
 
zeusalmighty's Avatar
 
Join Date: Jul 2006
Location: Lexington, KY
Posts: 27
Car: 1990 Firebird
Engine: 3.1L V6

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Isn't light black smoke an indication of oil burning in the chambers? Could it be blowby? Could you have low compression on your cylinders because of worn piston rings or something? If your compression was low, that'd definitely cause the rough idle + running rich problem. Have you checked the compression on all the cylinders?
zeusalmighty is offline vBGarage Page   Reply With Quote
Old 04-23-2008, 03:40 PM   #16
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Oil would be whiter than this, plus no oil loss, low miles (under 80,000),
clean plugs... and I can smell it's running rich. Just pulled the plenum off,
gonna see what I can find
Tookie is offline vBGarage Page   Reply With Quote
Old 04-23-2008, 03:45 PM   #17
Senior Member
 
kurfbird's Avatar
 
Join Date: Dec 2004
Location: washington state
Posts: 712
Car: 1992 Firebird v6 1992 formula v8
Engine: 3.1, 350 TPI
Transmission: both 700 r4

Classifieds Rating: (23)
Re: Erratic idle, very rich. 1990 3.1L

Get a fuel pressure tester and check for leak down. Put on the tester and check to see if it loose pressure after you shut it down.

If it loose pressure quickly you can have bad injectors or a ful pressure regulator.

HOw about a bad timing chain. jumped a tooth. Mine did that and ran like crap. Put a new one on.
kurfbird is offline vBGarage Page   Reply With Quote
Old 04-23-2008, 04:53 PM   #18
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Just checked the injectors - they all OHMed out to around 13.5,
hooked up a pressure gauge to the fuel rail, got 47 PSI, lost maybe
4 or 5 PSI over 20 minutes, I guess next thing is to block off the
EGR and see how it does - but I would think a bad EGR would
cause a lean condition, not rich? Also have to change that stupid
little fitting just under the thermostat cover, that has the hoses going
to the plenum - been leaking for a while, broke off in my hand when I
was taking the hoses off

Tookie is offline vBGarage Page   Reply With Quote
Old 04-29-2008, 03:32 PM   #19
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

I think I got it. I think the EGR is bad, and leaking a little thru to the intake. I made a block off plate, and put it into the line where the EGR meets the intake, like a gasket but no hole thru it. Car seems to be idling much better, no surges so far. Had to make new Plenum gaskets, because every parts store I went to pulled a plenum set with 2 different size gaskets in the box, neither of which fit my car, theirs looked like this.
Click the image to open in full size.


But before I put it back together, I had to drill out and retap
the manifold, where the fitting for the heater/ coolant to throttle body was.
The fitting corroded and just crumbled when I took it apart, I just left off
the throttle body lines and went straight to heater with it.

For the (very few) people on this board who offered advice, thanks.
This car will be posted for sale very soon, 1990, auto, air, pwr locks/drs,
cruise, tilt, 77,000 miles, passenger door has some dings, rest of body
fairly straight, when I post in for sale, I'll include some pics
Tookie is offline vBGarage Page   Reply With Quote
Old 05-04-2008, 03:22 PM   #20
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Got it all back together, went from 13.7 before, to 20.7 now
Tookie is offline vBGarage Page   Reply With Quote
Old 05-06-2008, 10:48 AM   #21
Senior Member
 
92camarorv6's Avatar
 
Join Date: Jan 2007
Location: delaware
Posts: 513
Car: 92 camaro rs
Engine: 3.4v6 sc
Transmission: 700r4
Axle/Gears: 9 bolt 3.73s

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

put ap26 autolights primin it i had a air/ful thing like that than go to the computer and egr
92camarorv6 is offline vBGarage Page   Reply With Quote
Old 05-06-2008, 12:34 PM   #22
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Quote:
Originally Posted by 92camarorv6 View Post
put ap26 autolights primin it i had a air/ful thing like that than go to the computer and egr
Huh?
Tookie is offline vBGarage Page   Reply With Quote
Old 05-06-2008, 12:36 PM   #23
Supreme Member
 
Street Lethal's Avatar
 
Join Date: Jul 2003
Location: New Jersey
Posts: 7,300
Car: 1990 GTA
Engine: 5.0L Turbo V8
Transmission: 700R4

Classifieds Rating: (12)

Re: Erratic idle, very rich. 1990 3.1L

^
__________________
'90 Trans Am GTA: Worked 305-TPI, EBL-P4, w/T-72 Turbo Charger...

'96 Chevy Corvette: Worked 350-LT1, FAST-XFI, w/D1SC Procharger...
Street Lethal is offline vBGarage Page   Reply With Quote
Old 05-06-2008, 01:10 PM   #24
Junior Member
 
Xoferif's Avatar
 
Join Date: Aug 2007
Location: Reading, PA
Posts: 96
Car: '91 Camaro RS
Engine: 3.1L

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

If you have a junkyard nearby, you can get an EGR valve for about $5...MAP sensors, as well...that's what I did.
Xoferif is offline vBGarage Page   Reply With Quote
Old 05-07-2008, 01:11 PM   #25
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Quote:
Originally Posted by Xoferif View Post
If you have a junkyard nearby, you can get an EGR valve for about $5...MAP sensors, as well...that's what I did.
Yes, I think that's what I'll try, if I have a spare I can clean it
real good before installing.
I have a service engine light on now, scanned it and it says
"EGR malfunction" I didn't think it would throw a code, because
I blocked it off at the intake, but if I can't find a used one, I can live
with it until I sell it - I can't believe how much a new one costs
Tookie is offline vBGarage Page   Reply With Quote
Old 05-07-2008, 05:13 PM   #26
Senior Member
 
kurfbird's Avatar
 
Join Date: Dec 2004
Location: washington state
Posts: 712
Car: 1992 Firebird v6 1992 formula v8
Engine: 3.1, 350 TPI
Transmission: both 700 r4

Classifieds Rating: (23)
Re: Erratic idle, very rich. 1990 3.1L

The resaon your o2 are going out because of the rich condition. It causes the o2 sensors to go bad. Mine did it when I ahd a bad timing chain.
kurfbird is offline vBGarage Page   Reply With Quote
Old 05-07-2008, 06:15 PM   #27
Junior Member
 
CamaroKingpin's Avatar
 
Join Date: Mar 2008
Location: NE Philly
Posts: 52
Car: '92 camaro rs
Engine: 3.1 v6
Transmission: stock tranny
Axle/Gears: stock gears

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

would you still need th o2 if your cat is hollowed out?
__________________
25th Anniversary Maro RS 3.1
MSD IGNTION,BOSCH PLUGS&WIRES, HOLLOW CAT, DUAL EXHAUST,AGGRESSIVE DRIVER

CAMAROMENACE92@GMAIL.COM
CamaroKingpin is offline vBGarage Page   Reply With Quote
Old 05-07-2008, 06:17 PM   #28
Senior Member
 
kurfbird's Avatar
 
Join Date: Dec 2004
Location: washington state
Posts: 712
Car: 1992 Firebird v6 1992 formula v8
Engine: 3.1, 350 TPI
Transmission: both 700 r4

Classifieds Rating: (23)
Re: Erratic idle, very rich. 1990 3.1L

Yes The o2 tells the computer to go into open loop. Better gas mileage
kurfbird is offline vBGarage Page   Reply With Quote
Old 05-07-2008, 06:33 PM   #29
Junior Member
 
CamaroKingpin's Avatar
 
Join Date: Mar 2008
Location: NE Philly
Posts: 52
Car: '92 camaro rs
Engine: 3.1 v6
Transmission: stock tranny
Axle/Gears: stock gears

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

thought so thanks
__________________
25th Anniversary Maro RS 3.1
MSD IGNTION,BOSCH PLUGS&WIRES, HOLLOW CAT, DUAL EXHAUST,AGGRESSIVE DRIVER

CAMAROMENACE92@GMAIL.COM
CamaroKingpin is offline vBGarage Page   Reply With Quote
Old 05-09-2008, 09:24 PM   #30
Junior Member
 
Join Date: Apr 2008
Posts: 28

Classifieds Rating: (0)
Re: Erratic idle, very rich. 1990 3.1L

Quote:
Originally Posted by kurfbird View Post
The resaon your o2 are going out because of the rich condition. It causes the o2 sensors to go bad. Mine did it when I ahd a bad timing chain.
Yes, I knew that was why they were burning out, the challenge was
finding the reason for the rich condition
Tookie is offline vBGarage Page   Reply With Quote
Old 05-09-2008, 09:24 PM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > V6

Tags
1990, 31, 31l, 92, camaro, condition, firebird, fuel, idle, irratic, mpg, pressure, regulator, rich, v6
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 04:08 AM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.5.2
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details