Engine doesn't like E4ME proper dwell setting?? - Third Generation F-Body Message Boards


Carburetors Carb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.

Engine doesn't like E4ME proper dwell setting??

Reply
 
Thread Tools Search this Thread
Old 06-07-2017, 06:06 PM   #1
Junior Member
Thread Starter
 
turboguard's Avatar
 
Join Date: Jun 2016
Location: Upstate SC
Posts: 81
Car: 1985 Pontiac Firebird Trans Am
Engine: 305 LG4
Transmission: 700R4 Automagic
Axle/Gears: No clue

Engine doesn't like E4ME proper dwell setting??

As title says, if I adjust my mixture screws and idle air bleed valve to get the proper 30 degree dwell, my car idles like crap...vacuum drops about an inch every second and sounds like its missing. However, if I adjust the mixture to make it more rich, the idle evens out wonderfully and holds at 21 inches of vacuum, but the dwell meter is pegged at 54!

I also just installed a brand new AC Delco O2 sensor and the Bosch one that was in there was pretty blackened, although it was also only a few months old. The new sensor didn't seem to make a difference in the readings.

What in the world is going on here?

Forgot to mention that all of the emissions devices have been removed except for the EGR (smog/air pump/tubing, evap canister, and cat) but the engine otherwise is stock.
turboguard is offline vBGarage Page   Reply With Quote
Old 06-08-2017, 10:01 PM   #2
Member
 
Join Date: Dec 2013
Location: Scottsdale, AZ
Posts: 141
Engine: 350-TPI
Transmission: 700-R4
Axle/Gears: 3.27 Posi

Re: Engine doesn't like E4ME proper dwell setting??

When you made the adjustments, were they done per the FSM? Vacuum/exhaust leaks? Any play in the throttle shaft bushings?
backtothe80s is offline vBGarage Page   Reply With Quote
Old 06-08-2017, 11:37 PM   #3
Junior Member
Thread Starter
 
turboguard's Avatar
 
Join Date: Jun 2016
Location: Upstate SC
Posts: 81
Car: 1985 Pontiac Firebird Trans Am
Engine: 305 LG4
Transmission: 700R4 Automagic
Axle/Gears: No clue

Re: Engine doesn't like E4ME proper dwell setting??

It's a "brand new" throttle plate from Cliff's I got to clear up the last of my vacuum leak issues. I might still have a slight exhaust leak where the manifolds connect to the Y-pipe (I tried to patch it up best I can until I can afford headers), but wouldn't that cause the O2 sensor to read slightly lean instead of rich anyway?

Also the engine decided to throw a couple of codes today when I got home from work and was just idling in the car...the idle sounded high for some reason then suddenly it dropped down to normal and threw codes 13 and 45. This is getting very irritating...
turboguard is offline vBGarage Page   Reply With Quote
Old 06-09-2017, 12:16 AM   #4
Member
 
Join Date: Dec 2013
Location: Scottsdale, AZ
Posts: 141
Engine: 350-TPI
Transmission: 700-R4
Axle/Gears: 3.27 Posi

Re: Engine doesn't like E4ME proper dwell setting??

Quote:
Originally Posted by turboguard View Post
...and threw codes 13 and 45. This is getting very irritating...
Yes, it would cause it to be lean. It could be adding to your driveability issues. I'm not sure. Diagnose the code 13 before doing anything else. I had that on my `89 and it turned out the wire going from the ECM to ground for the O2 sensor circuit was open. Easy fix.

It's very important to prep the car per the FSM before making adjustments to the E-Qjets. I'm not sure about your car, but on some, you have to block certain vacuum lines coming from the evap canister before adjusting mixture.

I feel your pain! Keep at it!
backtothe80s is offline vBGarage Page   Reply With Quote
Old 06-17-2017, 08:55 PM   #5
Junior Member
 
Join Date: Aug 2015
Posts: 63

Re: Engine doesn't like E4ME proper dwell setting??

You need actual 02 and MC readings. If the exhaust leak is making 02 lean in closed loop ECM is going to enrich mixture. At extended idle most single wire 02's go back to open loop. There are standard adjustment setting tools for electronic controlled carb. That is good reference points. Basic float level adjustment is also critical. Leaking well plugs are common, make sure to seal properly. To many other factors and adjustments are critical as well.
Joe
JA411 is offline vBGarage Page   Reply With Quote
Old 06-19-2017, 08:14 AM   #6
Junior Member
Thread Starter
 
turboguard's Avatar
 
Join Date: Jun 2016
Location: Upstate SC
Posts: 81
Car: 1985 Pontiac Firebird Trans Am
Engine: 305 LG4
Transmission: 700R4 Automagic
Axle/Gears: No clue

Re: Engine doesn't like E4ME proper dwell setting??

I just decided to ditch the multimeter and timing light and do everything by ear/feel.
I decided to leave the ECM plugged in to the distributor since whenever I set to the proper number and hooked it back up, it ran pretty bad.

So I whipped out my vacuum gauge and first set the timing to maximum steady vacuum.

Then I further tweaked the carb air bleed and mixture screws for maximum vacuum with minimal missing/steady needle. I ended up turning the idle air bleed valve all the way in and the idle mixture screws 5 turns out each to give me the best vacuum pull and smoothest idle.

I could already tell it was way better driving to work today, I didn't have any of the hard shaking at idle or the chuggles I normally got at part throttle.

I'm guessing just the age of the engine and all the electronics just make them unreliable to tune by in these cars?
turboguard is offline vBGarage Page   Reply With Quote
Old 06-20-2017, 03:15 PM   #7
Moderator
iTrader: (14)
 
five7kid's Avatar
 
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 43,065
Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89


Re: Engine doesn't like E4ME proper dwell setting??

Quote:
Originally Posted by turboguard View Post
I'm guessing just the age of the engine and all the electronics just make them unreliable to tune by in these cars?
I wouldn't say that. My '82 Berlinetta LG4 with 304k miles on it tuned up and ran great when everything was set to factory specs (admittedly back in 2007). It did have a fully rebuilt carb on it, new EGR valve, replacement cat and was otherwise well maintained. But that's a lot of miles regardless of age (the engine had never been opened up). And it passed the roller sniffer emissions test here with flying colors (after failing before I set everything to factory).

Codes 13 and 45 indicate a problem with the O2 sensor. Figure that out. It may run fine in open loop without the O2 sensor working, but it won't when it warms up and goes into closed loop.
five7kid is offline vBGarage Page   Reply With Quote
Old 06-20-2017, 03:25 PM   #8
naf
Supreme Member
iTrader: (6)
 
Join Date: May 2004
Location: Lexington, SC
Posts: 4,729
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt


Re: Engine doesn't like E4ME proper dwell setting??

the ccc system will idle better with the settings on the rich side and in non-feedback mode. under normal open loop the ecm will be constantly hunting the 'ideal' mixture setting and you will see some variance in idle quality. You'll see this with the dwell meter swinging back and forth slightly around 30 degrees when properly set. your idle shouldn't be crazy but a slight variance of idle quality is normal, like barely noticeable from the cabin at a light maybe.

IOTW your rich settings are keeping it in open loop and your smooth, steady idle is likely masking the real problem.
naf is offline vBGarage Page   Reply With Quote
Old 06-21-2017, 05:30 PM   #9
Junior Member
 
Join Date: Jun 2017
Posts: 6

Re: Engine doesn't like E4ME proper dwell setting??

Quote:
Originally Posted by naf View Post
the ccc system will idle better with the settings on the rich side and in non-feedback mode. under normal open loop the ecm will be constantly hunting the 'ideal' mixture setting and you will see some variance in idle quality. You'll see this with the dwell meter swinging back and forth slightly around 30 degrees when properly set. your idle shouldn't be crazy but a slight variance of idle quality is normal, like barely noticeable from the cabin at a light maybe.

IOTW your rich settings are keeping it in open loop and your smooth, steady idle is likely masking the real problem.
I'm trying to set the mixture on my 85 Iroc using the dwell spec also but I'm unsure of how to hook up the meter and I can't seem to find any DETAILED info on how to connect it properly.
Trashman88 is offline vBGarage Page   Reply With Quote
Old 06-22-2017, 07:44 AM   #10
Junior Member
Thread Starter
 
turboguard's Avatar
 
Join Date: Jun 2016
Location: Upstate SC
Posts: 81
Car: 1985 Pontiac Firebird Trans Am
Engine: 305 LG4
Transmission: 700R4 Automagic
Axle/Gears: No clue

Re: Engine doesn't like E4ME proper dwell setting??

Quote:
Originally Posted by naf View Post
the ccc system will idle better with the settings on the rich side and in non-feedback mode. under normal open loop the ecm will be constantly hunting the 'ideal' mixture setting and you will see some variance in idle quality. You'll see this with the dwell meter swinging back and forth slightly around 30 degrees when properly set. your idle shouldn't be crazy but a slight variance of idle quality is normal, like barely noticeable from the cabin at a light maybe.

IOTW your rich settings are keeping it in open loop and your smooth, steady idle is likely masking the real problem.
Any clues as to what the real problem could possibly be? When set to factory it definitely has a noticeable "shudder" every second or so and sometimes surges at part throttle. The O2 sensor is a brand new AC Delco one. Carb has been rebuilt using Cliff parts with brand new sensors. Distributor is a brand new Spectra Premium unit from rockauto. Plugs and wires are new. Fuel pump is new "carter-style" from Orielly's. Doesn't seem to be burning oil, I don't get any smoke out of my tailpipes even on cold startups. The only thing I have yet to do is a compression test on the cylinders.

The only other thing that is giving me trouble is that it is overheating...especially with the A/C on. I have to turn the A/C off during my 30 minute drive home on hot days or it will actually read past the last line on the guage.

Last edited by turboguard; 06-22-2017 at 07:48 AM.
turboguard is offline vBGarage Page   Reply With Quote
Old 06-22-2017, 10:17 AM   #11
naf
Supreme Member
iTrader: (6)
 
Join Date: May 2004
Location: Lexington, SC
Posts: 4,729
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt


Re: Engine doesn't like E4ME proper dwell setting??

computer controlled dist? timing set to 0-4 degrees advanced with the esc unplugged and verified to be around 22ish at idle with the esc plugged back in?

verify all ignition components are working properly and timing is good before dickering with the carb.

next confirm that the TPS is set correctly to read near 0.40V at idle and near 4.0V at WOT.

A scanner that reads and displays 'real' time is helpful for troubleshooting.

the higher than expected run temps are likely the result of an out of tune motor.
naf is offline vBGarage Page   Reply With Quote
Old 06-22-2017, 12:19 PM   #12
Junior Member
Thread Starter
 
turboguard's Avatar
 
Join Date: Jun 2016
Location: Upstate SC
Posts: 81
Car: 1985 Pontiac Firebird Trans Am
Engine: 305 LG4
Transmission: 700R4 Automagic
Axle/Gears: No clue

Re: Engine doesn't like E4ME proper dwell setting??

Quote:
Originally Posted by naf View Post
computer controlled dist? timing set to 0-4 degrees advanced with the esc unplugged and verified to be around 22ish at idle with the esc plugged back in?

verify all ignition components are working properly and timing is good before dickering with the carb.

next confirm that the TPS is set correctly to read near 0.40V at idle and near 4.0V at WOT.

A scanner that reads and displays 'real' time is helpful for troubleshooting.

the higher than expected run temps are likely the result of an out of tune motor.
Yep I've been doing things by the book (literally, I have the FSM) to no avail. I even have the Thexton tools for the carb as well.

Would bad valve parts cause any of my issues?
turboguard is offline vBGarage Page   Reply With Quote
Old 06-22-2017, 01:02 PM   #13
naf
Supreme Member
iTrader: (6)
 
Join Date: May 2004
Location: Lexington, SC
Posts: 4,729
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt


Re: Engine doesn't like E4ME proper dwell setting??

which valve parts?
naf is offline vBGarage Page   Reply With Quote
Old 06-22-2017, 01:14 PM   #14
Junior Member
Thread Starter
 
turboguard's Avatar
 
Join Date: Jun 2016
Location: Upstate SC
Posts: 81
Car: 1985 Pontiac Firebird Trans Am
Engine: 305 LG4
Transmission: 700R4 Automagic
Axle/Gears: No clue

Re: Engine doesn't like E4ME proper dwell setting??

Quote:
Originally Posted by naf View Post
which valve parts?
Like worn valve guides, seals, springs, etc...

I would love to tear the heads off just to check the cylinders and do a valve job but its hard since this is my daily driver lol
turboguard is offline vBGarage Page   Reply With Quote
Reply


Go Back   Third Generation F-Body Message Boards >

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



All times are GMT -5. The time now is 10:28 PM.


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.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: