Irratic Idle.
Thread Starter
Senior Member
Joined: Oct 1999
Posts: 548
Likes: 0
From: Dallas, Texas
Car: 1991 Z28
Engine: 5.3 Gen III SBC
Transmission: 4L80E NTC 258mm Stall
Axle/Gears: Trick Chassis 9" 3.50 S-Strac
Irratic Idle.
Lately my car has been Idleing funny like a roller coaster. somtimes It will Idle smooth and sometimes it will jump around. also when in gear and I put it in neutral to come to a stop somtimes It will fall on its face and just die. I scaned my computer and found 34 & 42 what could be the deal?
------------------
91 Z28 5.7l Camaro
T-56,McLeod Street Clutch, Cross Drilled Brakes, KYB's,AFPR, 3.73 Gears, Borla Adjustable Cat Back, Hypertech Chip, Hooker Headers.
more to come....
My 91 Z28
------------------
91 Z28 5.7l Camaro
T-56,McLeod Street Clutch, Cross Drilled Brakes, KYB's,AFPR, 3.73 Gears, Borla Adjustable Cat Back, Hypertech Chip, Hooker Headers.
more to come....
My 91 Z28
Moderator
Joined: Mar 2001
Posts: 14,298
Likes: 197
From: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
You should have a MAP/SD system, not a MAF/MAS system.
Your irratic idle, pay attention to when it occurrs, if it is on warm up, or at a cirtain temp range it might be your temp sensor. If it runs great at a certain temp, and bad the rest of the time, temp sensor would cause this too.
If I understand the MAP system, leaks in your intake should not cause this.
Could also be caused from a dirty IAC. Or even a good PROM chip gone bad.
that would be where I start.
John
------------------
87 Formula Yellow/Black
Engine & Transmission
.040 over 5.0 converted to TPI, 9.5:1 Compression, SLP Cam Dur 206/212, Lift 480/487, Cent Line 112, SLP headers, SLP cat-back exhaust, K&N Airfilter, Modified Stock cold air intake, Ported & polished Stock TPI intake, Holley Adjustable Fuel Press regulator, AC Rapidfire Spark Plugs.
Gil Younger (no yo-yo) Shift Kit, Aluminum Driveshaft, 3.73 Posi gear
Suspension & Brakes:
Baer 12" brakes 4 wheels, KYB AGX Adjustable Shocks & struts, Hotchkis strut tower brace, South side machine frame connectors, Custom reinforced control arms and pan hard bar.
Interior:
Custom Leather interior, CUSTOM Yellow Gauge Faces, Kenwood Receiver, Pioneer Speakers, Kicker Substations, Kenwood 10 Disk Changer, Pioneer Amp.
87 Formula TPI (5 Speed) Yellow/Gray STOCK
1967 Buick Riviera 430hp Turns high 14's (Not bad for 4300 lbs)
83 Camaro (Parts)
83 T/A (parts)
http://www.3rdgenformula.com
Your irratic idle, pay attention to when it occurrs, if it is on warm up, or at a cirtain temp range it might be your temp sensor. If it runs great at a certain temp, and bad the rest of the time, temp sensor would cause this too.
If I understand the MAP system, leaks in your intake should not cause this.
Could also be caused from a dirty IAC. Or even a good PROM chip gone bad.
that would be where I start.
John
------------------
87 Formula Yellow/Black
Engine & Transmission
.040 over 5.0 converted to TPI, 9.5:1 Compression, SLP Cam Dur 206/212, Lift 480/487, Cent Line 112, SLP headers, SLP cat-back exhaust, K&N Airfilter, Modified Stock cold air intake, Ported & polished Stock TPI intake, Holley Adjustable Fuel Press regulator, AC Rapidfire Spark Plugs.
Gil Younger (no yo-yo) Shift Kit, Aluminum Driveshaft, 3.73 Posi gear
Suspension & Brakes:
Baer 12" brakes 4 wheels, KYB AGX Adjustable Shocks & struts, Hotchkis strut tower brace, South side machine frame connectors, Custom reinforced control arms and pan hard bar.
Interior:
Custom Leather interior, CUSTOM Yellow Gauge Faces, Kenwood Receiver, Pioneer Speakers, Kicker Substations, Kenwood 10 Disk Changer, Pioneer Amp.
87 Formula TPI (5 Speed) Yellow/Gray STOCK
1967 Buick Riviera 430hp Turns high 14's (Not bad for 4300 lbs)
83 Camaro (Parts)
83 T/A (parts)
http://www.3rdgenformula.com
Supreme Member
Joined: Jan 2000
Posts: 1,199
Likes: 93
From: Mississauga, Ontario Canada
Car: 1987 GTA
Engine: 5.7
Transmission: T5WC
Axle/Gears: 3:27
I had this problem. I changed my IAC. I also removed the throttle body off the car and completley cleaned all the crap out. It made a huge difference. Theres holes in there that channel air through the IAC for ideling. If there plugged youll have problems at idle. Also the throttle blades are almost closed. Not completley. If you hold the TB up to light and cant see light coming through the blades then you should clean that sludge out of it.
------------------
1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)
------------------
1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)
Thread
Thread Starter
Forum
Replies
Last Post