Extreme Terrain
4x4Wire Trail Talk Forums: Jeep, Toyota, Mitsubishi, Pajero, Isuzu, Kia, 4WD, 4x4, SUV, Off-Road and OutdoorWire Forums


Search

Recent Posts on TrailTalk
Gen I 1989 Broken Hood Latch Solved!
by polar - 01/14/21 08:42 PM
1989 Montero Broken Hood Latch Cable!
by polar - 01/14/21 08:40 PM
torsion bar question
by rxinhed - 01/14/21 02:07 AM
suzi the psychic
by rascott - 01/11/21 06:28 AM
Sway Bar delete.. ???
by Trailmonkey - 01/07/21 05:29 PM
Vet over his Head
by chadzeilenga - 01/04/21 03:56 PM
β€˜89 Monty SWB - 1100 idle at start, -500 eventual
by chadzeilenga - 01/04/21 03:51 PM
Support 4x4Wire
New Topics on TrailTalk
Gen I 1989 Broken Hood Latch Solved!
by polar - 01/14/21 08:42 PM
torsion bar question
by tcb762 - 01/12/21 11:02 PM
β€˜89 Monty SWB - 1100 idle at start, -500 eventual
by BrooklynOpus - 01/04/21 03:14 PM
SOLD! New 1990-1995 Toyota 4Runner 4Dr Carpet
by code33 - 01/03/21 03:52 AM
Vet over his Head
by SATXGuy - 01/02/21 05:07 AM
KM145: What have I done wrong?
by TresMon - 12/28/20 05:45 PM
4x4 Gallery
Photos of rig
Attila
99 Monterrible Sport
Scar the Cylon Raider
Mercenary Sergeant: Code Name "Sapphire"
More News on the 'Wire

4x4Voice
4x4Wire
MUIRNet-News
OutdoorWire
Who's Online Now
0 registered members (), 96 guests, and 4 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums37
Topics138,168
Posts1,080,940
Members15,144
Most Online907
Dec 28th, 2019
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
Injector Volatge? #1103187 03/14/17 10:45 PM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
Sure hope there's still people watching this forum as it's way down on traffic.

I am trying to diagnose a no fire on cylinder #4. It has compression, spark (new plug & wires), but no fuel, so it is not firing at all. I have done a continuity test on all the injectors and they are good. OHM test is also good. So I don't know if the injector is getting voltage or not.

Several months ago the injectors were sent out for test and cleaning. I am only able to test through the harness connector as I don't want to remove the intake plenum. The manual says the injectors fire by a signal from the ECU which provides "battery voltage". I am assuming that means 12 volts.

I want to momentarily apply voltage to each injector to see if I can hear the click, but I don't want to over voltage. Can anyone confirm that 12v from battery will be safe to fire the injectors?

Also would it be possible to connect my noid light to each pin (+ grnd) of the harness connector and turn the engine over to confirm power?

Thanks


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Support our sponsors
Re: Injector Volatge? [Re: pcc] #1103188 03/14/17 10:59 PM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
OK sorry, but I was able to get them to fire with a 9 volt battery.

But I still need to see if I can confirm the 12v supply voltage from the ECU by testing at the connector harness. I have a noid light but also a 12 volt LED that I may be able to back probe into the connector. I would prefer to connect to the disconnected harness and just turn the engine over.

Anyone think that will work?


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Re: Injector Volatge? [Re: pcc] #1103190 03/15/17 12:54 AM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
LOL, I guess I can't wait for a reply. I have worked it out.

While idling was able to back probe the harness connector then using alligator leads connect my home made back probe pins to the noid light. Back probed both sides of the harness and got pulses.

So now I know the computer is working and there is a connection to the injector because of the 9V battery hookup that gave me the clicks. Still no fuel on #4.

Can only be a blocked injector preventing fuel from squirting.

No breaks on this job, will have to pull the intake plenum and get #4 injector checked again.

Maybe this thread will help someone else.


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Re: Injector Volatge? [Re: pcc] #1103191 03/15/17 06:36 PM
Joined: Sep 2006
Posts: 2,613
OldColt Offline
Roll Me Over
*****
As you found a 9V battery is a preferred method to open an injector.
The injectors get 12V from the main relay and then are grounded by the ECU to fire them.
The injectors have a last chance filter in them, this can be checked once removed from the fuel rail. The filter is a tiny basket slid in place from the top.

You can swap the injector positions around to see if the dead cylinder follows, damn lot of work on these 6 cylinders.

You can also backflush the injectors, rig up something to spray cleaner into the outlet and open the injector with the 9V battery. Let the cleaner blast through.



Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in 1989
95 Montero SR 3.8 DOHC First one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Will a 94 Macrocab Twin turbo with a 6 speed be next?
Re: Injector Volatge? [Re: OldColt] #1103192 03/15/17 07:14 PM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
Thanks for follow-up.

Been a frustrating year on this truck since I dropped a valve into the cylinder during timing belt service with valve seal change. Replacement water pump shaft seal failed and then new head gasket failed with coolant into cylinder #4. Eventually used "Steel Seal" which has fixed the coolant breach but now this no fuel from injector #4 seems more than a coincidence.

I wasn't sure if injectors fired with grounding or applied 12v, not much in the FSM. With ignition on I get about 9 volts at the harness. Having to remove plenum for injectors is a pain, but compared with my two previous tear downs the past few months not that bad. It's as if the truck has a death wish.

I hope I find something definitive when I pull the injectors. Hate testing and finding nothing.


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Re: Injector Volatge? [Re: pcc] #1103193 03/15/17 08:01 PM
Joined: Sep 2006
Posts: 2,613
OldColt Offline
Roll Me Over
*****
9V in the harness seems low. The engines utilizing Low Z injectors have a resistor mounted to the firewall to drop the injector voltage but yours should be battery voltage. I would check your harness and battery cables to see if you have voltage drops somewhere, I have found resistance in the engine ground cable down by the AC compressor that made all sorts of issues. I doubt this is your current problem but you should be seeing close to full battery voltage there.

I hope you did not use a Felpro head gasket, I have had a 100% failure rate with them. For these engines I use the later MLS gaskets with good luck.


Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in 1989
95 Montero SR 3.8 DOHC First one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Will a 94 Macrocab Twin turbo with a 6 speed be next?
Re: Injector Volatge? [Re: OldColt] #1103194 03/15/17 08:38 PM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
Yes, Felpro :>( I hope this breach is the last, no way I'm going to tear this down again.

I usually keep my grounds in good shape. The AC ground cable has been done twice since June 2016 due to two WP replacements, but I'll further check it.

I wondered about the 9V but since the other injectors are firing properly and all harness pins gave 9V I didn't think much about it since I was just on ignition, not engine running. I'll retest and see if I can get 12V.

Good info, thanks


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Re: Injector Volatge? [Re: OldColt] #1103195 03/15/17 09:51 PM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
Originally Posted by OldColt
9V in the harness seems low.


OK, I cleaned the ground cable connections, even the one that bolts to the frame about midway to the battery.

Retested and got 9.5 volts from + pins to injector ground at harness. Then I grounded direct to the engine and got 11.5 volts. Looks like I may need to clean the computer ground.


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Re: Injector Volatge? [Re: pcc] #1103196 03/15/17 10:16 PM
Joined: Sep 2006
Posts: 2,613
OldColt Offline
Roll Me Over
*****
Check the voltage from engine block to battery negative again, but also from Bat + into the fuses. The stacked terminals at the battery can hide problems.
Check bat+ to where you got the 9V at the injectors, if you are loosing power somewhere you want to check Pos to Pos and try to find all the ΒΌ V drops. May years ago I was working on a customers problem child Volvo, it had little hidden issues that could not be found till you looked for a drop along each wire or across each bolted terminal. I have found voltage drops in crimped connectors, not the push together part but between the wire and the crimped on terminal. These can be cleaned with an acid or using CLR cleaner.


Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in 1989
95 Montero SR 3.8 DOHC First one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Will a 94 Macrocab Twin turbo with a 6 speed be next?
Re: Injector Volatge? [Re: OldColt] #1103197 03/15/17 11:46 PM
Joined: Mar 2005
Posts: 1,006
P
pcc Offline OP
Body Damage is Cool
OK, so cleaning the computer ground got me to 10.5, another volt. I also cleaned the negative battery terminal.

Yes the ground strap to the AC bracket/frame/body has crimped connectors for the bolt connection and I can see where that could have corrosion inside the crimp. I cleaned as well as I could with carb cleaner and wire brush as well as sandpaper for the bolt connection.

I'll check your other suggestions. Even though with a measured volt drop the engine runs fine except for the #4, which today I double confirmed is the dead cylinder. Would I get a full 12v when the engine is running? Don't know how to test as the ground is switching too fast for DVM. So would muriatic acid be OK to clean those crimped connections?

This truck has been in NC for the past 20 years. No real salt/water corrosion caused issues. Whole body has no rust.


92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles
Page 1 of 2 1 2







4x4Wire Social:

| 4x4Wire on FaceBook |


OutdoorWire, 4x4Wire, JeepWire, TrailTalk, MUIRNet-News, and 4x4Voice are all trademarks and publications of OutdoorWire, Inc. and MUIRNet Consulting.
Copyright (c) 1999-2019 OutdoorWire, Inc and MUIRNet Consulting - All Rights Reserved, no part of this publication may be reproduced in any form without express written permission
You may link freely to this site, but no further use is allowed without the express written permission of the owner of this material.
All corporate trademarks are the property of their respective owners.

Powered by UBB.threads™ PHP Forum Software 7.7.3
(Release build 20190728)
PHP: 7.2.34 Page Time: 0.035s Queries: 16 (0.010s) Memory: 2.8928 MB (Peak: 3.1634 MB) Data Comp: Off Server Time: 2021-01-17 00:01:27 UTC
Valid HTML 5 and Valid CSS