All Spark and No Bark

[FridgeFreezer]

On 12/31/2021 at 10:07 PM, Chazza said:

Mine doesn't have any ticks now after a full rebuild; I did have the exhaust manifolds faces sanded flat and I use high-temperature silicone as a manifold gasket. Perhaps that is the reason,

Quite possibly - I'd love to pull my manifolds off and get them machined flat but it's a bit of a glory job compared to all the other stuff on the to-do list. Likewise I want to notch & re-angle the top of the downpipes to make them mate properly but that involves a lot of faffing about in a small space, plus my MIG is still dead

I didn't know HT silicone would live with manifold sort of temperatures, although my exhaust guys do use it for the other joints downstream.

[Bowie69]

11 minutes ago, FridgeFreezer said:

didn't know HT silicone would live with manifold sort of temperatures, although my exhaust guys do use it for the other joints downstream.

There's special 'copper' silicone which is very high temp made specifically for this case, should be good for any LR product, often seen on turbo flanges which get quite a lot hotter exhaust temps that you would expect on a lazy NA V8.

[Chazza]

I used a Loctitie product.

[ThreePointFive]

Defintely not an exhaust leak - since messing around with the starter heat shield it now does have a driver's side leak (which I will fix) and it is not what I'm hearing 'in' the engine.

I hate posting here relying on everyone else to solve my problems but I've done some science and have some results. Before I go any further, I have confirmed that all cylinders are getting spark using a tester. I can remove any HT lead from the passenger side and it'll make little difference. I can tell it's not right but it is far from rough and will hold an idle. I can remove any lead from the driver's side and it is badger's arse time. I've taken two videos showing this below, which also do a pretty good job of picking up the harshness of the clicking noise on the first. I am not touching the accelerator in either video.

Passenger side:

 

Driver's side:

Worse, I can remove any two leads from the passenger bank and it will run like the driver's side with one missing, if I remove two from the driver's side it just won't run.

I used an IR thermometer that I don't necessarily trust for specific numbers but it's saying all cylinders are at 200c on the headers so I don't have any major differences.

I know I need to do my own work on this and reading more threads on here to find my own answers, but what does this behaviour suggest? 

[Bowie69]

Honestly can't hear anything wrong....

[ThreePointFive]

I'm putting the noise aside for the time being, I'm never going to get to the bottom of it until something obvious breaks.

Now I just need to get it running right. What are your views on the way it's dying with a right hand HT lead removed but not with a left hand one?

[FridgeFreezer]

2 hours ago, ThreePointFive said:

Now I just need to get it running right. What are your views on the way it's dying with a right hand HT lead removed but not with a left hand one?

If you're on wasted spark / coil packs is there a coil pair / pack that's common to that side?

[Bowie69]

18436572, so essentially, no, coils are paired to opposite sides.

If you have 200C on each runner soon after start then it is running on 8, ignore the roughness and get it going.

 

 

[Chazza]

I can't hear anything mechanically wrong either. Certainly doesn't sound as if anything is going to break.

Get it tuned and see what happens,

 

Cheers Charlie

[smallfry]

You really are having no fun with this at all. Dont be concerned about running ideas across the forum, as I, and probably most of us know how dispiriting this type of thing can be.

How does the engine feel when its running with everything connected ? Does it feel smooth or a bit lumpy ?

By what you say about pulling HT leads on left or right bank, it tells me that the passenger side bank is not pulling its weight for whatever reason. When you pull any one V8 lead, it is not really noticeable like it would be on a four cylinder.

All the cylinders are firing, or you would not have more or less equal temps on the exhausts. I cannot help with the Megasquirt, as I know F all about electronics, but is it batchfire on alternate banks ? Possible that one bank is not getting quite as much fuel as the other, despite what the computer says ?

My next move would be to compression test it, both hot and cold, and carefully note, and write down the pressures, just to confirm the valve train is working properly.   

[FridgeFreezer]

13 hours ago, smallfry said:

is it batchfire on alternate banks ? Possible that one bank is not getting quite as much fuel as the other, despite what the computer says ?

Depends what he's set it to - the injectors are wired as two banks but the ECU can fire them alternate or as one, but it won't squirt a different amount each side. They're on the same fuel rail so not much danger of one side getting the wrong amount of fuel that way. Only potential ways it could happen are a wiring problem or electronic fault / bad connection in the ECU itself.

Which reminds me, @ThreePointFive if you want to borrow an ECU or EDIS unit for testing any time just let me know.

[ThreePointFive]

In terms of symptoms, it's smooth at idle up to about 1000rpm but at around 1500 it's rough and might be missing. Holding it at those kinds of revs is not too pleasant.

It then improves above that but I wouldn't call it smooth. This gets worse with temperature, though the idle starts off lumpy when cold and then improves. Basically the roughness swaps ends of the rev range.

It smells rich to me but it doesn't want any less or it starts to hunt and get very unhappy.

I've just run it up to temperature and done a compression test on the front 4 cylinders (I can't get to the rear ones while hot as there isn't enough room for hands). I'm not happy with it - 120 is about the max and 110 is the low, on an engine with brand new rings I am slightly alarmed by this.

Fridge - thanks and will keep that in mind...

[ThreePointFive]

Is there any way to accurately test that the injectors are getting signal? I know an ecu change might do it I'm wondering if the wiring itself is to blame. Sticking a multimeter on it just makes it go crazy.

I've just gone back out to have another go and it's running like a pig. I give up.

[FridgeFreezer]

2 hours ago, ThreePointFive said:

Is there any way to accurately test that the injectors are getting signal?

You can get things called "noid lights" but basically it's a bulb or LED on a male injector connector so quite DIYable. A multimeter on DC will go mad because it's being pulsed with PWM from the ECU, on AC you'll get some rough average reading, if you get nothing that suggests a bad connection.

Since the 12v side is a constant supply you should at least be able to get a firm 12v on one pin of each connector.

[smallfry]

3 hours ago, ThreePointFive said:

I've just run it up to temperature and done a compression test on the front 4 cylinders (I can't get to the rear ones while hot as there isn't enough room for hands). I'm not happy with it - 120 is about the max and 110 is the low, on an engine with brand new rings I am slightly alarmed by this.

 

I would be alarmed by this too, BUT did you have the throttle flap wide open ? Someone holding the pedal down, or propped open ? A common mistake, especially if you have got the hump, or are in a hurry! Of course, I have never done this 

I wanted to check the basics first, just to make sure the engine is mechanically OK before looking at the Fuel and ignition. I did wonder about the ECU being faulty somehow ? As I understand it, they are "home made" of sorts, so plenty of scope for faults like a stray tail of solder or dry joint somewhere. I dont suppose anyone has a test rig ?

[FridgeFreezer]

4 hours ago, smallfry said:

I did wonder about the ECU being faulty somehow ? As I understand it, they are "home made" of sorts, so plenty of scope for faults like a stray tail of solder or dry joint somewhere. I dont suppose anyone has a test rig ?

They *can* be home made but I believe Sam's one came from Nige so was made by a grown-up not DIY... that's not to say faults can't happen of course but I think it's already been tested once (this thread has gone on so long I lose track!).

Since I have spares kicking around I'm happy to send a spare ECU over to prove one way or another.

[ThreePointFive]

Yep mine's a Nige edition, so not likely the culprit but always a possibility.

I think the first step is to re-run my compression test, I might have had the throttle cable set to slightly open as it helps with the idle while it warms up, I'm hoping that's the cause of the low compression, if it isn't then at least I know there is a bigger mechanical issue that I need to sort before moving on.

As I lapped the valves and fitted new springs when the heads were off, I wouldn't be surprised if that's an issue. I did so a leak test on them before refitting but given it was the first time I've ever done anything like it, it's highly likely I messed something up.

[FridgeFreezer]

I had a weird failure where one valve spring fractured due to minor corrosion pitting where the head had been sat off the vehicle for a while, ran like absolute ar5e and was really hard to spot as the spring just bent slightly, didn't snap.

At least that stuff can be looked at by just pulling the rocker covers.

[smallfry]

42 minutes ago, ThreePointFive said:

Yep mine's a Nige edition, so not likely the culprit but always a possibility.

I think the first step is to re-run my compression test, I might have had the throttle cable set to slightly open as it helps with the idle while it warms up, I'm hoping that's the cause of the low compression, if it isn't then at least I know there is a bigger mechanical issue that I need to sort before moving on.

As I lapped the valves and fitted new springs when the heads were off, I wouldn't be surprised if that's an issue. I did so a leak test on them before refitting but given it was the first time I've ever done anything like it, it's highly likely I messed something up.

There isnt anything that has been made, ever, that cannot be faulty, in the same way that everything is reliable, until it breaks down or wears out. I would take up Fridge on his offer to lend one, just to try, but no doubt the map will be different and possibly unsuitable.

Compression test MUST be run on wide open throttle to work. However, I have always taken the plenum chamber top off the Efi ones, as I found it easier, but its not important. DO make sure the fuelling and ignition is disabled.

If you have leak tested the valves, they should be OK. I check mine by installing the valves in the head, then tipping the head on edge, then pouring a small amount of petrol or thinners into the upturned ports, then observe the valve heads. If they are dry, then great, but sometimes you will get a slight dampness, which is acceptable to me, but any more than that needs redoing.

 

[FridgeFreezer]

20 hours ago, smallfry said:

I would take up Fridge on his offer to lend one, just to try, but no doubt the map will be different and possibly unsuitable.

That's the glory of Megasquirt, you just upload your settings to the new ECU and it should then be identical.

[Quagmire]

On 1/16/2022 at 2:49 PM, ThreePointFive said:

Is there any way to accurately test that the injectors are getting signal?

If you put a finger on them you can normally feel the injector bodies clicking as they fire. Hard to do for the ones under the plenum intake though.

Failing that pull the fuel rail off with the injectors fitted and run it in test mode into glass jars to see if they fire. This is obviously a bit of a fire risk so be careful, have extinguishers handy, etc.

A few years ago I did have a test rig setup with an old 10l paint bucket with lid on full of white spirit, an in tank pump and an old fuel rail from some four cylinder car (Vectra I think). A bit of plumbing and I could test injectors on the bench using the MS from the car. Obviously four at a time means swapping stuff about to check all eight connectors and injectors, but it was cheap and easy to do.

[Bowie69]

The old screwdriver to the ear trick works too.

[FridgeFreezer]

I believe @ThreePointFive has already had the injectors tested so it's unlikely to be them - it's purely a question of if the electrons are making it to all the injectors in a reliable manner.

[ThreePointFive]

Wot he said, they've been tested in terms of operation on a bench.

I know they are all meant to click when they prime just before start up, I can just remove all the plugs except one and work around the engine to make sure they're clicking. I've done it before but it's been apart and the wiring disturbed many times since then. Many, many times.

[FridgeFreezer]

If you remove unplug the D37 plug from the ECU you can beep it out with a multimeter to check continuity from the plug to each injector plug in turn.