Pennock's Fiero Forum
  Technical Discussion & Questions
  Fuel injectors/ECM problem

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


next newest topic | next oldest topic
Fuel injectors/ECM problem by DaveK1987V6
Started on: 06-12-2014 09:20 AM
Replies: 7 (224 views)
Last post by: DaveK1987V6 on 06-12-2014 02:23 PM
DaveK1987V6
Member
Posts: 27
From: Erin, Ontario,Canada
Registered: Oct 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-12-2014 09:20 AM Click Here to See the Profile for DaveK1987V6Click Here to Email DaveK1987V6Send a Private Message to DaveK1987V6Edit/Delete MessageReply w/QuoteDirect Link to This Post
OK so I've got both injector fuses good. I've got 12 volts at the injectors, but my noid lamp shows no ground signal from the ECM when cranking (no flashing). The rev counter jumps to around 500 rpm so I guess my ICM is OK. I can hear the injectors firing if I manually ground them. Also ( and this is where I'm confused) if I ground either bank of injectors it grounds ALL of them - surely it should only ground that bank?

I also have one bad injector - doesn't fire and has only about 1.5 ohms resistance, all the others are around 15 ohms. (All measured directly at the injector)

I think my ECM may have fried the injector drivers and have another ECM coming, but not here yet.

Anything else to suggest - thanks for ANY help!
IP: Logged
PFF
System Bot
theogre
Member
Posts: 29212
From: USA
Registered: Mar 99


Feedback score: N/A
Leave feedback





Total ratings: 549
Rate this member

Report this Post06-12-2014 10:02 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
ECM won't ground injector(s) till first see reference signal from ignition.

See my Cave, HE Ignition and ECM Heat

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

IP: Logged
DaveK1987V6
Member
Posts: 27
From: Erin, Ontario,Canada
Registered: Oct 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-12-2014 10:51 AM Click Here to See the Profile for DaveK1987V6Click Here to Email DaveK1987V6Send a Private Message to DaveK1987V6Edit/Delete MessageReply w/QuoteDirect Link to This Post
Yes I know, and have checked that the rev counter moves when cranking so there is an ignition signal.

Also I still don't understand the strange effect of grounding all injectors at the same time.

Thanks for the message
IP: Logged
fierofool
Member
Posts: 11753
From: Auburn, Georgia USA
Registered: Jan 2002


Feedback score:    (13)
Leave feedback





Total ratings: 150
Rate this member

Report this Post06-12-2014 11:09 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Pull the harness connectors from the ignition control module and be sure the contacts are fully visible. Sometimes they strike the module pins and get pushed back inside the harness. On a couple of occasions I've found that to be the cause of a fuel pump not running. If the right one gets pushed back, the ECM won't see a reference signal, as Ogre pointed out.
IP: Logged
DaveK1987V6
Member
Posts: 27
From: Erin, Ontario,Canada
Registered: Oct 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-12-2014 11:21 AM Click Here to See the Profile for DaveK1987V6Click Here to Email DaveK1987V6Send a Private Message to DaveK1987V6Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks - I've done that and everything seems OK.

Any comment on my grounding issue?
IP: Logged
phonedawgz
Member
Posts: 17009
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post06-12-2014 12:19 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
I've seen harnesses where the cross wire the two injector outputs. I am sure that is why you are seeing one injector bank grounding the other.

Does the ECM have power?

If the ECM has power it will light the SES light key on engine off.

If it is getting power the ECM will turn on the fuel pump relay for two seconds when you first turn the key to on but don't crank. Note this test does not apply if the key hasn't been off for at least 45 sec so don't take alarm if it doesn't do the test in rapid succession.

---
Does the ECM get ignition pulses from the ICM?

After the ECM has passed the above two tests then just bump the starter. Don't crank it since that will close the fuel pump relay and confuse the test. Just turn it to crank enough to barely start to engage the starter. Since the engine turned at least 1/3 rotation the ECM should have seen an ignition pulse and the ECM should again turn on the fuel pump relay. The relay should stay on for two seconds and then turn off. If it does that then the ECM is getting ignition pulses from the ICM.

---
If the ECM is working, and is getting ignition pulses but not firing the injectors - It still could be a TPS problem. If the ECM is reading the TPS as 100% then the ECM is programmed not to fire the injectors. This is only during start up. Unplug the TPS to see if this is potentially the problem.

---

If none of the above then I would replace the ECM. Make sure you swap your PROM from the suspect ECM into the replacement ECM.

[This message has been edited by phonedawgz (edited 06-12-2014).]

IP: Logged
DaveK1987V6
Member
Posts: 27
From: Erin, Ontario,Canada
Registered: Oct 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-12-2014 01:01 PM Click Here to See the Profile for DaveK1987V6Click Here to Email DaveK1987V6Send a Private Message to DaveK1987V6Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the helpful reply.
SES is On with key on.
Fuel pump relay runs as described, but still no injector signal.
Sorry to be stupid but how do I unplug the TPS?

I've disconnected the injector harness at the 6 way connector and there is no "cross wiring" in that section from connector to the injectors. I'll disconnect the ECM and check that harness as well. Could the common ground happen in the ECM if the drivers are dead?

THX again!

IP: Logged
DaveK1987V6
Member
Posts: 27
From: Erin, Ontario,Canada
Registered: Oct 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-12-2014 02:23 PM Click Here to See the Profile for DaveK1987V6Click Here to Email DaveK1987V6Send a Private Message to DaveK1987V6Edit/Delete MessageReply w/QuoteDirect Link to This Post
Figured out the TPS and tried that as well, still no signal. I've disconnected the ECM and checked that harness for cross wiring as well and it seems clean, in which case the grounding issue was inside the ECM.

ECM installed is not the original - I'm currently waiting for my replacement and know I have to exchange the PROM and CALPAC chips into the new one.

Now I'm going to continue to fix the basic problem that started everything - the bad injector. It's the front right with almost no resistance across the terminals and it doesn't fire when grounded. Will continue to remove the fuel rail so that I can get to it.

Will update later when I'm there.
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