2g #3 injector losing ground signal.

[Diamond Star Werks]

Okay I have a car I'm working on that will loses ground signal to #3 injector. It happens at random. Never happened while idling right few Times while city driving but most oftenly during Highway driving.
I can simply cycle the key and it will work again till it happens again. Which it may happen 30 sec-1min to 5 min later. It can happen alot during a few miles off Highway then I get off and city drive it and it take a good while for it to happen.
I believe is the injector driver in the ecu. Only thing I can think of. Looking to get another socketed ecu(ecu has link installed) but what more ideas/opinions before purchasing another ecu.

Swapped injectors(before I found it loses ground signal) and tried another power transistor at the same time. Still does it just the same.

 

[renovatdkitchen]

I have a similar issue, but I think its just an ECU ground.

Does it cause the MPI relay to click rapidly?

Using a zip tie to pull the top part of the ECU plugs downwards helped for me.. until today just before work.

 

[Diamond Star Werks]

No mpi relay doesn't click. Everything else works just fine. Just that single injector messes up. Nothing else does.

Now driving it to the shop this morning it is doing it alot during normal 45mph driving

 

[steve]

I didn't see many bad injector drivers but I did see loose connections on the harness causing the injector to drop out. Do you have a log while it's doing this?

 

[Diamond Star Werks]

I might have a log ill try and post it later but I doubt its a loose connection. I got it to do it near the shop and drive it back and checked it out. Wiggled didn't do any thing and it still clips on the injector. So not like the clip is broken.
Also as said all I have to do is turn key to acc then back to position and it quits for a bit. Doesn't matter If I cycle it fast either. Just a quick flick of the key and it quits. It's puzzling.

 

[boost97gst]

God i had this same problem. I think its the injector driver in the ecu. Then again, i havent had it happen in awhile. Though during hwy cruising sometimes i see combinedft suddenly go up quite a bit but no CEL for misfire. I would go through wiring and then crack that ecu open. Im going to open mine soon(eventually) and replace the fets or transistors thqat drive the injectors. It couldnt hurt.

 

[steve]

I might have a log ill try and post it later but I doubt its a loose connection.

I got it to do it near the shop and drive it back and checked it out.

Wiggled didn't do any thing and it still clips on the injector. So not like the clip is broken.

Also as said all I have to do is turn key to acc then back to position and it quits for a bit. Doesn't matter If I cycle it fast either. Just a quick flick of the key and it quits. It's puzzling.

IIRC there are cases where the ECU will cutoff an injector when it thinks the cylinder isn't firing to avoid pumping raw fuel into the exhaust but I would expect a CEL and fault code to go with.

While missing clips on the injector is common on a 1G a often causes them to be loose the 2G injector clip doesn't have to be removed to unplug just squeezed. I was thinking about the ECU connector.

When you were swapping parts was it always #3?
Always when the engine is hot?
Did the shop find anything when it was happening?

 

[Diamond Star Werks]

IIRC there are cases where the ECU will cutoff an injector when it thinks the cylinder isn't firing to avoid pumping raw fuel into the exhaust but I would expect a CEL and fault code to go with.

While missing clips on the injector is common on a 1G a often causes them to be loose the 2G injector clip doesn't have to be removed to unplug just squeezed. I was thinking about the ECU connector.

When you were swapping parts was it always #3?
Always when the engine is hot?
Did the shop find anything when it was happening?

I'm the one working on the car. Small time local shop I run privately. Anyways swapped in my ecu and for over an hour almost two of idling then driving short trips and idling short trip idling it didn't do it. Then it happened.
This time it wouldn't stop when i cycled the key. Felt like at one point it cut two cylinders. I got it back to the shop checked it and it was number 1 cylinder this time. Same problem too. It had lost the ground pulse but still had power to the injector. And spark was good as well.
This is with diff injectors, different power transistor, and different ecu. Ib have a spare cas I'm going to swap and see what happens.
Ecu plugs seem solid. Not loose or wiggly. Pins are good.
This is a 6 bolt swapped 2g btw

 

[Diamond Star Werks]

Also I made a log while it was happening. Will post it later tonight.

Edit: While is happening only issue I can find is that the injector has no pulse. Spark is always there, can't find a loose connection anywhere, and everything else seems to continue to operate properly.

 

[Diamond Star Werks]

Update: Didn't even get out of shop driveway after swapping the CAS and it happened again. Switched back to number 3 injector this time.
It doesn't seem to want to do it just sitting still though at idle. I've had this car here before with the same issue. But his turbo was bad and the turbos wastegate diaphram was blown.
He took it back and reinstalled his 16g setup and brought it back to tune. He had gm maf with translator. It wasn't reading hertz right though it seemed. I reinstalled the stock maf setup and recirculated it. It has been working much better now and am able to make progress on the tune. Just this one issue is holding me back.

Summary: Changed power transitor, injectors, CAS, and ecu to no avail. Checked both ecu and injector plug connectors, both seem good. The CEL I get when it happens is random misfire.
Steve, I've heard of newer cars and experienced it once before I believe with them cutting of a cylinder due to misfire to save the CAT from raw fuel. I don't know or haven't read of that with a dsm yet.

 

[Diamond Star Werks]

http://codsm.org/forums/archive/index.php/t-1200.html
That is a very similar issue to mine. 2g with a 6 bolt stroker losing injector pulse. Though he traced to a wire on number 3 injector, I've had the car twice with this sane issue. First time I remember it was mainly number 1# cylinder acting up this time its number 3# and only one time been number 1. But has said it did seem like it lost two cylinders at one point while driving then only one.

Just bolted in a resistor pack and will see what happens. Last related spare part I have to try. Next ill have to start going through the wiring I guess. Do some continuity tests. Though being a random issue I would only find a problem while is happening. Otherwise it'd shoe normal results.

 

[boost97gst]

Kind of on topic: Found out why my #2 cylinder has been acting up. Bad bad bad news. I dont know what to blame yet. ECU or machinist. 5k miles and its toast. Idles and runs great too but the combinedft jumping was giving me clues and the cyl misfire cels i used to have at idle occasionally. I hope youre in better shape than me. Im still in shock dude. FML.

 

[Diamond Star Werks]

Pretty surw I fixed it. I forgot his ecu was a 95 and even though I unchecked misfire in dtc tab in link I also had to check "use non-95/96 cam sensor signal" under the misc. tab. Haven't had it come back yet and was able to tune it nicely.

 

[WES_393]

IIRC there are cases where the ECU will cutoff an injector when it thinks the cylinder isn't firing to avoid pumping raw fuel into the exhaust but I would expect a CEL and fault code to go with.

This would explain what happened to me last night. During a WOT pull around 6k rpm the engine let out a few nasty fireballs (but no CEL), so of course I let off. Right then I get a "Cylinder 2 Misfire" CEL. I pull over and check everything, but spark plug wires are fine and injector clips are tight (recently replaced my 95's clips with 2g clips). When I started the engine again she was firing on all 4 and has been fine ever since.

Checking the logs I didn't see anything except horsepower dropping like a rock a few hundred RPM before I let off. However, after reading the above, I checked the Raw Knock values and sure enough Cylinder 2 was being a little noisy right up until the event, then suddenly quiets down.

Below is a screen shot of the log. The top green and blue are airflow and horsepower, lower 4 are Raw Knock 1-4 with Blue being Cylinder 2. Airflow continues off the chart, so obviously the engine wasn't having any issues pumping air. But an injector malfunctioning and then being shut off would explain the drop in power. I've always had a pretty good hunch about my fuel injectors being a problem due to related issues, but it's apparently progressed to where the ECU thinks the engine is in danger.

 

[DSM1G90]

Gonna jump onto this thread, even it's back in September, but it's relating to an issue that I'm starting to experience with my 1G Laser with stock 450's:

Start it up, runs great for a good length to almost a good couple of days. Then for now reason, one cylinder starts to act up and my CEL light comes on.

This acting up will last a few minutes, then the motor will suddenly behave, run smooth and CEL goes out.

The next day the problem came about again, this time it never went away. I get home, making sure all the connections to the injectors were tight and all checks out okey.

Knowing I got a code retained in memory, I pull the code with my beep tester. Code is 41 "Injector" - either bad resistance or harness connection.

Good to know. Take out the VOM and check resistance across the terminals on each injector. All show resistance of 2.4 to 2.6 ohms, which is well within the range of these 450 injectors.

Thus, Now where to begin if I'm dealing with a harness connection. Now, I did have the ECU out a few weeks ago since I had to tear out the dash and similar to replace the heater core in my Laser, but on replacement of the ECU, I made double certain that all connections to the ECU all clicked in tight.

Thus, a bit stumped on this one...any help on this issue would be grateful.

EDIT: I found Steve's post back in 2009 on this above post on where to begin my search on my Code 41 issue:

http://www.dsmtuners.com/forums/newbie-forum/339959-fuel-injector-problems-engine-code-41-a.html#post151898977

Thx as always - DSM

 

[gofer]

Wes, I did some research on an issue similar to the one you described because I'm trying to tune a locals car that's doing the same thing but unfortunately it doesn't look like RawKnock1-4 pertain to any specific cylinder. ECMLink : RawKnock

Just because the connectors are "clicking" in to the ECU doesn't mean a injector pin isn't getting pushed. A friend was having a misfire issue on a specific cylinder and after sending his ECU off to ECMLink to find it was nothing we finally wised up and checked the harness.

Come to find out when he seated the connections to the ECU cylinder #2 injector wire was pushing out the back of the connector and not making a good connection.

 

[DSM1G90]

Come to find out when he seated the connections to the ECU cylinder #2 injector wire was pushing out the back of the connector and not making a good connection.

Thx for this tip, for I'm familiar with wire harness assemblies where, in an electronics assembly factory, I worked on a soldier station and assembled harnesses from pinned wire and "houses" (connectors).

You do get a pin where the locking tab on that pin will not seat in the house and will push out when connecting to its relative connector. Thus, we had to inspect the tab on the pins prior to assembly to ensure that they definitely locked into the house when we did the assembly prior to shipping them off to QA for final inspection.

I did the trick that Steve did on that one day: car sat over night in the garage to cool down, went out this morning and the unit fired right up without a hitch and idled smoothly. Now, makes me wonder if a resistor pack and/or injector is doing it's cold thing by keeping closed, but opens when it gets hot.

Sadly, all my injector wires are rock hard heading to the connectors for the injectors. Thus, if one wants to overhaul this section of this harness, where would be a good place to start, what gauge of wire to use since it has to be two strand braided wire ... and buy those connectors via that link that Steve put in his post.

thx again - DSM

 

[brads]

Sadly, all my injector wires are rock hard heading to the connectors for the injectors. Thus, if one wants to overhaul this section of this harness, where would be a good place to start, what gauge of wire to use since it has to be two strand braided wire ... and buy those connectors via that link that Steve put in his post.

You can replace the wiring with GXL or TXL automotive grade wire, available from Waytek Wire or similar places for a good price. I'd suggest their 18 gauge wire.

Do NOT use 20 gauge GXL or TXL. Most commercially available versions of this have inadequate strand counts and are not flexible enough. The 18 gauge stuff though, is a good strand count and good wire.

 

[Mischif]

You could always unplug the harness from the ecu and then remove the injector pin thats having the issue and then hook it up straight to the ecu pin. Should give you an idea if its making a nice tight connection when the harness is plugged in. Could also remove the case from the ecu and test from the injector harness to the actual pin on the ecu.

 

[steve]

Just measure the resistance across the injector when the car is hot and malfunctioning.
If it's the injector opening you'll see it. Same for the resistor pack.

 

[DSM1G90]

UPDATE: Found my issue. No.3 injector is the bad one.

I was running on three cylinders shortly after leaving work and hoping that the problem will get me home.

Soon as I parked it in the garage, out came the VOM and went across the injectors. No. 3 was giving me very low resistance (under an Ohm .. in the mOhm range) compared to the other three which were giving me 2.4 to 2.7 Ohms at hot.

Waited for a few hours til all cooled down and No.3 read 2.5 Ohms at cold. Hit the key and thing fired up immediately and a smooth idle.

Now, gotta find me a 450 blue top to replace it. Would it be practical to replace all four, or just the one baddie?

Thx-DSM

 

[steve]

Now, gotta find me a 450 blue top to replace it. Would it be practical to replace all four, or just the one baddie?

Thx-DSM

This was my excuse to play with the EVO VIII 560 injectors since they were a lot fresher. If you don't have any way to turn/reprogram the ECU you'll be limited to 450cc replacements. Remember that the 1G and 2G injectors differ so you can replace the bad one with a 1G 450cc or replace all four with 2G 450cc's to keep them all the same type for best results.

 

[DSM1G90]

Thx for the important tip, Steve, for I didn't know that the generation issue is an important factor in this equation, yet was leaning towards a full replacement across the motor if necessary since they were used in the first place.

(When I bought the Laser back in 2008, one can tell that this 4G63 was not the original motor installed, but a JDM Galant VR4 variety due to the different head cover, came with 510's and a B16G. The CAS was cranked all the way to extreme and ran terribly rich. Thus, I did a PM here on Tuners for a set of 450's to match the ECU, in which a 1G owner did have a set of 450s and I had to got to Mitsu dealership for "O" rings and seals. After the changeover, I retimed the motor to specs and the AF situation settled down to normal.)

thx- DSM

 

[Diamond Star Werks]

Just as a resolved write up. I got the car back again late last year for a retune after a different turbo was installed and I fixed the problem. Which was that the car had a 1g Cas and it was making the ecu think it was misfiring. And as you mentioned Steve, it was dropping that cylinder because of it. Inverted the signal(checked non-95 CAS box) and turned of misfire check in link and it fixed it.