4 FOX SNAKES - Ross' 20vt 4kq

[chaloux]

You could still :-)

So I babied the car home as planned and stopped at Andrews shop to talk about rolling the fenders and to meet with dad and time the engine. Ended up changing to 77 after the trigger. It was out 2-3 teeth. We also realized that the spark wires were pretty close to the main harness and it seemed like moving them away stopped any stumbles altogether. Idle more stable and as last night, the car runs and drives perfectly.

I took the car to the park where my kids and wife were, flawless. On the way back the tach went mental. I had issues with the tach before so I thought nothing of it. I was in search of school supplies so I stopped at two places. The car started bucking and stumbling like crazy. It was near undriveable after the first stop and it got so bad I had to pull over on main street to see if something was crazy in the engine bay. Nope. Barely made it home, running the car at 4krpm going 50kph. So I had a break at the house for a few minutes and then pulled the car into the garage to check out vems. Now the car seems to be running fine.

What am I dealing with here.... A problem that send to come and go at will, I've done everything to remove interference from trigger, timing is on but seems like every time I set it it can vary.

W
T
F

[chaloux]

I removed, disassembled, inspected, and reassembled vems tonight. I don't know where else to look. Everything seemed fine.

Oh, did I mention I got a ticket today for expired plates? Ya rly

[vt10vt]

Just a thought but heat can change resistances right? Maybe the VR sensor is getting hot/going bad and giving a bad signal? Weird that after you let it sit and cool it was fine

[chaloux]

I also swapped the vr sensor... Same thing. But maybe I have to re route it or something. Just weird that this issue only popped up after engine swap #2

[bradyzq]

crap. Came up empty on the couch cushion search.

crap. Your car is still acting up.

I had a somewhat similar issue recently, and I gave up and ran new shielded wire from the crank sensor plug right to the ECU, and, even though I had basically been using stock wiring previously, this cured the problem.

If you're not going to use the knock sensors, I think you can cannibalize the sensor harness for a connector to use for the new shielded wire. Then you only have one bit of hacking the working harness, and it's at the ECU end.

[chaloux]

Brady I think that's what I'm going to have to do. Dad took the car today and while fine at first, it wasn't long before it started stumbling and was soon undriveable. He barely got it to the shop, where he began grounding everything. There ended up being like 8 grounds in the bay and back to the battery. And shielding - put the trigger wire in a conduit, had shielding over the coils, etc . The problem only got worse and eventually the car died and stopped seeing primary triggers altogether in the trigger logs. Somehow we got it to run which Marc says would be impossible with ptrig, so that's messed up. This is while trying different sensors as well. I'm going to have to run a new wire all the way back to the harness because this is messed up.

Also putting a scope on early next week with Craig.

[chaloux]

Car pretty much doesn't run. Checked all three wires from g28 to ecu and all are physically fine so replacing them with their own run separate from the harness tomorrow. Also checked all injectors and soak, everything is as it should be.

[chaloux]

Also removed this from the engine bay. I don't think I need an extra 3.5ft of batter cable in there (big red). Most of this crap was from the original wiring and wasn't hooked up to anything.

[chaloux]

And the car out in the wild (WHAT)

[Toph]

fuck yeah

[chaloux]

log upload

[chaloux]

Cool Tapatalk photo filter bro

So this morning we ran a shielded cable from the vr sensor to the ecu outside of the engine bay, totally isolated. Trigger problem still exists. We also pulled the wire for the g4 crank sensor out of the engine bay since it has a common ground and shared another wire . No change. We have the g28 is own ground to the battery, and the issues seem less severe. But not really, as the car will still stall on its own. But before, the room drops and ve drops were always coinciding, now they can be isolated as seen in the log. The trigger seems okay in the trigger logs in 1196,no errors reported and it picks up the missing teeth every 58 teeth /cycles.





But we have a second problem. For some reason I have a metric shit ton of fuel being injected. I have the injectors being fired individually. 5 is especially bad. Excessively bad. When the injector is plugged in the exhaust is unbearable. That happened kind of out of nowhere, perhaps yesterday when the car was barely running, I'm not sure. We changed injectors 5 and 4, no change. We have spark. Also ego seems to be working very hard. I didn't change any fuel settings so not sure what's up with that. The injector is not stuck open while testing and is not firing with another injector like my old problem.

Last thing. The ecu will not log primary trigger or start on the new firmware. Moving to 1196 works time and starts every time. All the newer ones i tried did not. Seems like a firmware issue for the no start or trigger problem at least, which kind of creeped up on its own. It was fine at first, wtf.

[chaloux]

So. Scope time.

[chaloux]

What are the chances of a faulty ecu

[Marc]

near 0. "its not vems, its you".

the last time I helped troubleshoot a similar issue for a customer (on econoseal with their own wiring) they had mis-wired the trigger shields into the wrong ground pin. all sensor grounds have to go to ec36-26. Wondering if in your process of wiring up the harness you might have accidentally moved a sensor ground to be directly connected to a high current ground point?

[Marc]

when you do scope this out, be sure to scope the primary and secondary trigger both at the trigger connectors themselves, as well as all the way back at the ecu.

[bradyzq]

Did you leave the shielding open at one end?

[chaloux]

Yes it was open and the shielding itself was not grounded, just the ground wire inside.

[chaloux]

But it was also entirely on its own outside of the car and harness.

[bradyzq]

Hmm,

Shouldn't really be an issue then.

However, I ground one end of the shielding.

[chaloux]

Yeah that's interesting. On the stock harness it isn't, the shielding ended a few inches from the pins in the connector

[bradyzq]

Right. But it's probably grounded at the other end.

[Marc]

Right. But it's probably grounded at the other end.

on stock motronic, the trigger shields are terminated at the ecu end. See AAN pin 19.

For econoseal stuff, we wire the shields to terminate at the ecu, ec36-26, no grounding on the block-side.

[chaloux]

So somewhere inside the cable the black wire connects to or becomes the shield... Makes sense. We gave it its own ground right on the battery. Maybe that is a bad spot for it?

[chaloux]

Dat ain't how it works. The shielding itself isn't grounded as far as I can tell. But all the sensor grounds (black) tie together into pin 19.