Pennock's Fiero Forum
  Technical Discussion & Questions
  '84 2.5L coil problem or something else?

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


next newest topic | next oldest topic
'84 2.5L coil problem or something else? by David Hambleton
Started on: 04-04-2015 10:05 PM
Replies: 13 (185 views)
Last post by: David Hambleton on 04-11-2015 05:14 PM
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-04-2015 10:05 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
A few days ago, I was almost home and the engine quit. No unusual noise, no faltering, just off.

The fuel pump sounds like it's working normally, the injector appears to be delivering fuel normally, and the rockers are still rocking. Suspecting the coil, I swapped in another used but known good coil. The engine started up instantly then died within a second.

Both coils test ok with the 3 step factory service manual resistance checks.

Does this sound familiar to anyone?
IP: Logged
PFF
System Bot
Gall757
Member
Posts: 10651
From: Holland, MI
Registered: Jun 2010


Feedback score: N/A
Leave feedback





Total ratings: 88
Rate this member

Report this Post04-04-2015 10:09 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
ICM
IP: Logged
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-05-2015 04:10 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I replaced the ICM with one from a running engine & it didn't help.

The coil wire to the distributor shows continuity...

The engine started when I changed the coil, but stopped before I could say woohoo!

Is there something that could cause a good coil to fail immediately on start up?

[This message has been edited by David Hambleton (edited 04-05-2015).]

IP: Logged
Gall757
Member
Posts: 10651
From: Holland, MI
Registered: Jun 2010


Feedback score: N/A
Leave feedback





Total ratings: 88
Rate this member

Report this Post04-05-2015 05:27 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
when you try to re-start, does the tach needle move off of the pin? If it does, the primary part of the coil is working.
IP: Logged
Csjag
Member
Posts: 3170
From: Ocklawaha,Fl, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-05-2015 07:55 PM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
Even though you can hear the fuel pump running its possible that it isn't pumping enough fuel or that a hose fell off. Also check your grounds and the battery cable connections.
IP: Logged
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-05-2015 08:45 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:

when you try to re-start, does the tach needle move off of the pin? If it does, the primary part of the coil is working.


The tach needle moves.

The cap & rotor look ok & the coil wire shows continuity; maybe I should try changing them...

IP: Logged
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-05-2015 08:48 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post

David Hambleton

1441 posts
Member since Nov 2012
 
quote
Originally posted by Csjag:

Even though you can hear the fuel pump running its possible that it isn't pumping enough fuel or that a hose fell off. Also check your grounds and the battery cable connections.


The pump seems to be operating normally; it shuts off when the pressure is reached. There's fuel spraying into the throttle body.

When I swapped coils, it started right away but then stopped again in about one second. I'm thinking electrical...

IP: Logged
Csjag
Member
Posts: 3170
From: Ocklawaha,Fl, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-06-2015 07:06 AM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
Check the pickup coil to the distributor and the connector wires that go to it.
IP: Logged
edfiero
Member
Posts: 891
From: Coatesville, PA
Registered: Nov 2004


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-06-2015 07:40 AM Click Here to See the Profile for edfieroClick Here to Email edfieroSend a Private Message to edfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you have access to another ECU, it might be worth swapping that out as well to see if there is any change at all.

The ECU on my 84 failed, causing in the engine to simply shut off when other wise running perfectly without warning and without any check engine codes.
IP: Logged
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-06-2015 08:48 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Csjag:

Check the pickup coil to the distributor and the connector wires that go to it.


The pickup coil shows 1000 ohms resistance and no short to ground (per the service manual check).
The wires from the coil to the ICM connector are securely attached...

IP: Logged
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-06-2015 08:54 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by edfiero:

If you have access to another ECU, it might be worth swapping that out as well to see if there is any change at all.

The ECU on my 84 failed, causing in the engine to simply shut off when other wise running perfectly without warning and without any check engine codes.


I tested the coil output with a spark strength tester set at 20kv (about 1/2" gap). It lit up like lightning. I'm guessing if the coil is firing ok, the ECM is ok?

IP: Logged
PFF
System Bot
Csjag
Member
Posts: 3170
From: Ocklawaha,Fl, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-06-2015 09:58 PM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
Is your car a standard or automatic? This is a long shot but try this: If your car is a standard transmission unplug the connector to the clutch safety switch and jump the plug with a wire or a large paperclip then try to start the car. Its possible that the contacts inside the switch are corroded and when a large shot of current hits them they only work for a couple of seconds and after that its an open circuit. If its not that it could be in the ignition switch.
IP: Logged
Slammed
Member
Posts: 779
From: Sumner, WA
Registered: Mar 2015


Feedback score:    (8)
Leave feedback





Total ratings: 79
Rate this member

Report this Post04-06-2015 10:11 PM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
That would only help if it wasn't turning over...

Did you check for spark first before you started throwing parts at it?

Nvm. Saw your newest post.

[This message has been edited by Slammed (edited 04-06-2015).]

IP: Logged
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post04-11-2015 05:14 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by edfiero:

If you have access to another ECU, it might be worth swapping that out as well to see if there is any change at all.

The ECU on my 84 failed, causing in the engine to simply shut off when other wise running perfectly without warning and without any check engine codes.


Ding, ding, ding! We have a winner! edfiero had the correct answer! Woohoo!

A couple of years ago, I replaced the rattling 2.5L in my '86 with a 2.5L from an '87.
Today, I replaced the 31 year old 367,600 kilometer ECM in my '84 SE 4 speed with the surplus ECM from the '86.
The engine started right up and seems to be running normally.
As I suspected, the shift light comes on to suggest 5th gear, but since I don't have one, I tilt the wheel so I can't see the light.
The light goes off over 3,000 RPM; about 100 kilometers per hour or 62 mph.
I presume if I swapped the PROMs, that issue would disappear.

Thanks for posting, guys. I appreciate it.
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