Pennock's Fiero Forum
  Technical Discussion & Questions
  Rebuilt 2.8 running lean

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


next newest topic | next oldest topic
Rebuilt 2.8 running lean by spc15tdime
Started on: 05-09-2012 12:05 PM
Replies: 5 (354 views)
Last post by: Shonyman32 on 07-27-2013 07:02 PM
spc15tdime
Member
Posts: 229
From: Portage, Michigan
Registered: Jun 2006


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-09-2012 12:05 PM Click Here to See the Profile for spc15tdimeClick Here to Email spc15tdimeSend a Private Message to spc15tdimeEdit/Delete MessageReply w/QuoteDirect Link to This Post
My 85 2.8 in my 85SE, has a lean condition, doesn't seem to be bad, infact didnt notice it while driving, thought it was a little weak on power, but, when it came up for a plug change last week I noticed the tell tale engine is running lean evidence on all 6 plugs uniformly. Here's the mod list from rebuild.

1) Larger TB, forget actual size, not much bigger maybe 4-5mm
2) Ported upper intake
3) Comp Cams 252H cam
4) 9:1 Forged pistons
5) No Cat, Ocelot performance exhaust
6) Bored .030 over
7) Machine shop enlarged valves some, this was years ago, I dont recall by how much.

Think thats everything that could affect airflow. Oh, Car runs on 93oct

I had been considering a couple of solutions to this. I am trying to avoid another set of injectors, but, am interested to hear any other solutions to getting out of a lean condition with detuning the car at all.
IP: Logged
PFF
System Bot
Dodgerunner
Member
Posts: 9682
From: Lincoln, Nebraska
Registered: Sep 2004


Feedback score:    (61)
Leave feedback





Total ratings: 323
Rate this member

Report this Post05-09-2012 01:24 PM Click Here to See the Profile for DodgerunnerClick Here to visit Dodgerunner's HomePageClick Here to Email DodgerunnerSend a Private Message to DodgerunnerEdit/Delete MessageReply w/QuoteDirect Link to This Post
Stock ECM?
Idle speed OK?
Has FP been checked?
EGR been checked?
Log ECM?
IP: Logged
spc15tdime
Member
Posts: 229
From: Portage, Michigan
Registered: Jun 2006


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-09-2012 01:27 PM Click Here to See the Profile for spc15tdimeClick Here to Email spc15tdimeSend a Private Message to spc15tdimeEdit/Delete MessageReply w/QuoteDirect Link to This Post
ECM is Stock, Idle speed is normal, and rock solid, FP is 44psi, EGR throws code, however, upon following trouble shooting procedures in the 85 SHop manual, it is the test circuit. I have to track down my aldl cable, but will try to get a log up tonight.

I understand the engine is breathing better, but, was more curious if it isnt the increaded displacement that is causing the lack of fuel. I had considered merely adding a adjustable FP regulator and upping the FP a few pounds, but, wasn't sure of the outcome of said idea would be as desired.

[This message has been edited by spc15tdime (edited 05-09-2012).]

IP: Logged
Gall757
Member
Posts: 10743
From: Holland, MI
Registered: Jun 2010


Feedback score: N/A
Leave feedback





Total ratings: 89
Rate this member

Report this Post05-09-2012 01:49 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
So this is easy. Your computer thinks you have a stock engine and you don't. More air is going through your engine than the computer expects, so if you get a new chip that has been re-programmed, your problems will be over. You might get lucky and fix it another way, but it would just be guessing.
IP: Logged
phonedawgz
Member
Posts: 17011
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post05-09-2012 04:05 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Because the ECM calculates air flow based on RPM, Displacement, IAT and MAT, the only thing that will make the ECM miscalculate the amount of air flowing into the engine is the 030 overbore. That comes out to 1.6% different. 1.6% difference in air flow would easily be handled with a stock ECM chip and BLM tables.

If you are not getting a SES, look at the O2 sensor and/or exhaust leaks.

Best thing is to get your ALDL connector found and see what the ECM is seeing. What are your BLMs?
IP: Logged
Shonyman32
Member
Posts: 570
From: Shelbyville, IN
Registered: Jan 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post07-27-2013 07:02 PM Click Here to See the Profile for Shonyman32Send a Private Message to Shonyman32Edit/Delete MessageReply w/QuoteDirect Link to This Post
Phonedawgs: Could the computer compensate for a 3.2 (3.1 bored over to a 3.2)?

How much would an exhaust leak do?
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