Pennock's Fiero Forum
  Technical Discussion & Questions
  Abnormally Fast Idle, 4.9L

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Abnormally Fast Idle, 4.9L by JohnT328
Started on: 08-11-2013 12:29 PM
Replies: 6 (138 views)
Last post by: JohnT328 on 08-12-2013 11:20 AM
JohnT328
Junior Member
Posts: 4
From: Winter Springs, FL, USA
Registered: Aug 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-11-2013 12:29 PM Click Here to See the Profile for JohnT328Send a Private Message to JohnT328Edit/Delete MessageReply w/QuoteDirect Link to This Post
I drive a 1985 Fiero with a 4.9L conversion from the Fiero Factory. The following upgrades were added shortly after the install of the 4.9L:
• Vss signal connected to the Caddy ECM.
• Also had my MEM-CAL Chip reprogrammed by Fiero Addiction.

Fast forward several years and I had to have the injectors replaced, but another problem appeared and may be a coincidence.

The engine starts on fast idle (2000 Rpm) and drives normally with no stalling, but idles at 1200-1500 RPM. I have twice replaced the ISC motor following the adjustment procedure, replaced the ECM, checked and reset the TPS setting, checked for obvious vacuum leaks, cleaned the throttle plate, and ran several code scans, with no improvement whatsoever.

If you have any ideas or recommendations I would really appreciate your response

------------------
JT328

IP: Logged
PFF
System Bot
Raydar
Member
Posts: 38994
From: Carrollton GA. Out in the... country.
Registered: Oct 1999


Feedback score:    (12)
Leave feedback





Total ratings: 455
Rate this member

Report this Post08-11-2013 01:14 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
Are you sure it's really idling at 1200+?

Mine is a Fiero Factory conversion. They did nothing with the tach to accommodate the additional cylinders.
My actual RPMs are 3/4 of what the tach reads.
IP: Logged
JohnT328
Junior Member
Posts: 4
From: Winter Springs, FL, USA
Registered: Aug 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-11-2013 11:04 PM Click Here to See the Profile for JohnT328Send a Private Message to JohnT328Edit/Delete MessageReply w/QuoteDirect Link to This Post
Raydar,

It never occurred to me that the tach in the car is reading incorrectly. I will check with an external tach, however it seems fast when you listen to the engine. Did you ever resolve the issue of the wrong tach reading?

Thanks
IP: Logged
olejoedad
Member
Posts: 14850
From: Clarendon Twp., MI
Registered: May 2004


Feedback score: (5)
Leave feedback





Total ratings: 195
Rate this member

Report this Post08-11-2013 11:44 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
Forum member JGunsett does a superb job on tach recalibrations.
IP: Logged
Raydar
Member
Posts: 38994
From: Carrollton GA. Out in the... country.
Registered: Oct 1999


Feedback score:    (12)
Leave feedback





Total ratings: 455
Rate this member

Report this Post08-12-2013 05:23 AM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JohnT328:

Raydar,

It never occurred to me that the tach in the car is reading incorrectly. I will check with an external tach, however it seems fast when you listen to the engine. Did you ever resolve the issue of the wrong tach reading?

Thanks


It *sounds* like it's correct. It really does. Except at idle and "redline".
Mine idles at ~1200 (indicated) and likes to shift at ~5500 (indicated). A 4.9 does neither.
A scan tool shows that the tach is reading 4/3 of actual RPM.

Having said all that, I found that my 4.9 idled too low to suit me (I have a manual tranny.)
I bumped my idle speed up to ~900 RPM. Stock is around 750.
It also fixed the "low oil pressure" light.
IP: Logged
JohnT328
Junior Member
Posts: 4
From: Winter Springs, FL, USA
Registered: Aug 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-12-2013 11:16 AM Click Here to See the Profile for JohnT328Send a Private Message to JohnT328Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by olejoedad:

Forum member JGunsett does a superb job on tach recalibrations.


IP: Logged
JohnT328
Junior Member
Posts: 4
From: Winter Springs, FL, USA
Registered: Aug 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-12-2013 11:20 AM Click Here to See the Profile for JohnT328Send a Private Message to JohnT328Edit/Delete MessageReply w/QuoteDirect Link to This Post

JohnT328

4 posts
Member since Aug 2013
Olejoedad and Raydar,

Thank you for the additional details.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock