No start (spark?)...

[astkgse]

All my plugs look good as far as I can tell. I have not traced all the wires from plug to plug. Of the ones I have and can see I don't see any breaks. The only break in a wire I see is in the coil ground by the injectors. It didn't seem to be enough to cause a no spark. Is it?

I have read tsrm and followed it as far as I could. The only readings out of spec was for the coil resistance. It read 1.0 above spec. (.3-.5).

 

[tsupranami]

Replace that ground strap. The coil packs are completely insulated from the cam covers by rubber isolator bushings. That ground strap is their primary ground. Without it, no spark....

 

[jetjock]

^ Well, you're half right...

 

[87nasupra]

I told him I would be happy to go by and help him check it out. Will try and updayte to see what the culprit is

 

[tsupranami]

"^ Well, you're half right... "

So which half is right. Isolated from ground? No ground-no spark, or what? I thought Toyota put that strap there for a reason, not just to pad the parts list...correct me if I'm wrong.

 

[hvyman]

Get someone to crank the car over for you while you jiggle the cps wires and the other mess of wires right there.

Buddy got stranded at the junkyards one day with the same problem and code 12. I jiggled them and it started right up. My car does it sometimes and many other people have had this problem. All the heat from the exhaust just ruines the wiring over the years.

---------- Post added at 12:45 PM ---------- Previous post was at 12:44 PM ----------

Replace that ground strap. The coil packs are completely insulated from the cam covers by rubber isolator bushings. That ground strap is their primary ground. Without it, no spark....

Not true on the no starting part. I drove around with the coil pack ground off for a year and 30k+ miles didnt notice one difference from grounding it or doing the ignter mod.

 

[jetjock]

So which half is right. Isolated from ground? No ground-no spark, or what? I thought Toyota put that strap there for a reason, not just to pad the parts list...correct me if I'm wrong.

The half about being isolated is correct. The no strap = no spark isn't. On the other since the strap is there for a reason you're now 2/3rds right

"Primary" in this sense would refer to two things: 1) a "main" ground or 2) part of the primary ignition circuit. Neither would be correct. Primary circuit grounding is provided by the igniter.

The only connection shared by the plate and packs are the mounting screws used for bonding each pack's core laminations to the plate. The strap is there to suppress foucault currents in the plate and while it should be installed the ignition system will make plenty of spark without it. Any that doesn't has something else wrong with it.

Put another way since no connection exists between any part of the primary ignition circuit and plate why would grounding it be required for current to flow through a pack's primary winding? And even if one side of each pack's primary was grounded through the plate what would be doing the triggering? Certainly not the constant +12 connected to the other side of each primary.

Understand I'm not picking on you. I'm impressed by your posts and hope you stick around. Knowledgeable guys like you, mkiiichip, and a handful of others are needed here...

 

[tsupranami]

My Bad. Toyota did include it for no reason then. I guess we can get rid of all ground straps, as the wiring harness has several grounds already in it. That should make it lighter and faster.

Seriously?:icon_surp

Are you sure your insulators were good and truly isolating the coilpacks from the camcovers? My car wouldn't start with that strap disconnected. I know several 7M owners who do away with them when they fail since they are part of the coilpack assembly and aren't available from Toyota seperately ($$$$).

Running without a factory installed ground strap (or equivilent) is foolish at best. Maybe an electrical engineer can describe how and why cars use ground straps better than I can, but this I do know; if it was there from Toyota, it was probably included for a very specific reason.

Ignotor Mod. Useless on a 7M. It is already grounded. Engineered right from Toyota to work adequately. 20+ years of corrosion can reduce the effectiveness of the ground, but simply cleaning and re-installing properly should provide adequate grounding.

Anyways, back to the OP's problem. I have jiggled the wires just as you have done to "fix" my no-spark problems as well.

This does not "fix" it. This just gets it running. It will fail again unless you correct the interrupted connection problem, ie. fix the bad wiring.

Check wiring. Check continuity. These are free tests. No money, no parts, just spending the time and using your intelligence will go a long way to solving most problems like this.

Good luck!

 

[jetjock]

Not sure if that was sarcasm or not but I *am* an electrical engineer and just told you the specific reason it's there. I'm also the originator of the igniter grounding mod. Sure, cleaning the igniter case to chassis connection works but it's still a crappy setup and one that *will* cause a no spark condition.

Someday where you're bored meter the plate (or better still use a scope) referenced to battery negative/chassis ground with it floating and grounded while under decent load/rpm. If you're really bored look at the secondary ignition waveforms. You'll see why the drain wire should be installed but make no mistake, the ignition system will function with it missing.

I'm sure you can find any number of people here who are running, or have run, without it including myself. If yours didn't there's something wrong. And you can bet I knew if my plate was grounded. Not to mention we're talking about a simple circuit here, one shared by just about every car out there. It's not rocket science.

I'll agree with one thing though: many of the engines I've seen have the plate no longer isolated. Stuff gets lost or mickey moused over the years. Especially on these cars.

 

[tsupranami]

The half about being isolated is correct. The no strap = no spark isn't. On the other since the strap is there for a reason you're now 2/3rds right

"Primary" in this sense would refer to two things: 1) a "main" ground or 2) part of the primary ignition circuit. Neither would be correct. Primary circuit grounding is provided by the igniter.

The only connection shared by the plate and packs are the mounting screws used for bonding each pack's core laminations to the plate. The strap is there to suppress foucault currents in the plate and while it should be installed the ignition system will make plenty of spark without it. Any that doesn't has something else wrong with it.

I fixed several broken wires at the same time I installed the strap, so it could have been something else that caused my no-spark condition, granted.

Put another way since no connection exists between any part of the primary ignition circuit and plate why would grounding it be required for current to flow through a pack's primary winding? And even if one side of each pack's primary was grounded through the plate what would be doing the triggering? Certainly not the constant +12 connected to the other side of each primary.

The ignitor triggers the spark by shuting off voltage to the coil, or so I thought.

Understand I'm not picking on you. I'm impressed by your posts and hope you stick around. Knowledgeable guys like you, mkiiichip, and a handful of others are needed here...

Am I incorrect then, that when current flows from the ignition switch, through the windings in the coil, then to ground, it builds a strong magnetic field inside the coil. I thought the primary circuit was switched by the ignitor (in place of points), but the curent generated in the coil came from the electricity passing over the windings to ground?

I thought it would be similar to my motorcycle coils (which must be grounded by mounting through the case, similar to the Toyota coilpacks). Without this ground, the primary windings will not generate the magnetic field required to increase the voltage.

I understood the ignitor acted as a switch (i.e. points), collapsing the magnetic field around the secondary windings by shutting off electrical power, thus releasing the higher voltage from the coil to the spark plug. Is this not correct? The ignitor actually provides the ground for the primary circuit to generate the increased voltage, and a ground to collapse the secondary windings (time the spark)?

Also, where did you get the information regarding Toyota's use of the ground strap solely to supress eddy currents? I am not an electrical engineer, but I am capable of understanding some of the basics and would like to know more.

I'm not wanting to pick on anyone either, I'm just looking for a more thorough understanding of this system and would like to share such knowledge with others.

 

[jetjock]

We're not talking about motorcycles.

Your understanding of the primary circuit is correct other than needing the core grounded. Why would I suggest you meter the plate while floating or do secondary waveform analysis if I hadn't already done it? And how could I have done it if the engine won't run? Was there some part of "you can find any number of people including myself" that wasn't clear?

 

[CajunKenny]

Just tell me to 'Shut Up' if I'm jumping in the middle of something here...

Without adequate Coil Pack Grounding the delivered energy will be less; but, it will be enough to fire. Likely to be somewhat intermittent especially under a higher load. The electricity will find ground. Whether it's through the grounding strap, or through the spark plug/block, or someone's hand/body. Ask me how I know about the latter...

As the coils are energized/de-energized, there is an inductive kick. My guess is that the coil pack strap is there to help shunt/dissipate this spike in energy to ground in order to keep it from disrupting the timing of the firing.

 

[jetjock]

Shut up Kenny

I never said the drain should be left off. The question was whether a missing one will cause a no spark/no start condition. It will not. Period.

Sigh. I could have just left it at him being half right. Next time I'll simply correct any error for the benefit of the membership and leave him in the dark...

 

[CajunKenny]

Oh, well you know how these things can get going...

Sorry for disrupting the flow of things.

 

[jetjock]

Just kidding buddy. And yes, there is a flyback effect in the primary when de-energized. About 350 volts.

Don't get me started about spark finding "ground". The fact is you could put each plug of a pair (in a waste spark system) into two different heads without any connection between them and both will fire. Maybe someone wants to explain why that is...

 

[CajunKenny]

Just kidding buddy. And yes, there is a flyback effect in the primary when de-energized. About 350 volts.

Really...only 350?! It felt more like 1.21 Jig-A-Watts! I think I even piddled in my boxers! :biglaugh:

Don't get me started about spark finding "ground". The fact is you could put each plug of a pair (in a waste spark system) into two different heads without any connection between them and both will fire. Maybe someone wants to explain why that is...

I'll have to get back to you on that one...

 

[tsupranami]

Sorry, didn't mean to offend anyone or insult anyones intelligence. I was just looking for answers that I did not have.

For that I thank you.

But as you would prefer to leave me in the dark rather than to explain something to me...Well, that's real nice.

Thank you.


BTW, My point to the OP was this: Running without ground straps that were designed for a purpose is wrong. Period.

And, who knows, he might even stumble across the "real" problem while he works on that strap.

Anyways, sorry if I bruised any egos in my attempts to enlighten the OP.

 

[jetjock]

Kenny: I'll never tell. Lets just say it has more to do with real physics than basic electricity.

I'm a bit puzzled by post #28. First he's saying it's OK to get rid of other grounding or maybe that was sarcasm. But then he argues how missing the plate ground will prevent spark (that's what started this remember) and goes on to say his car won't start without the strap. Yet "I know several 7M owners who do away with them when they fail". Do those owners have non-starting engines? I'm confused

Anyway, anyone who has been reading my stuff during the years I've been here knows I don't advocate removing anything on the car willy-nilly and they all know how I feel about doing electrical things right. To imply I think the ground should be done without is just wrong. On the contrary.

My point was simply that missing it will not prevent spark from being generated. Reading some of the stuff in post # 30 shows that while he understands how the primary circuit basically works he's lacking in the finer points of electrical savvy. He comes across as a smart guy though and I hope he sticks around.

Lol...probably feverishly pounding away on his keyboard searching for a way to prove me wrong but that's OK. Maybe he'll get distracted by some porn site and end up finding something more pleasurable than busting my balls


Edit: It's all good dude. You and I actually think a lot alike. Stick around!

 

[astkgse]

I am glad my issues sparked (no pun intended) all this banter. I only wish I could follow it. Maybe down the road...

For what it's worth I put a new wire on and....nothing....still no spark.

Since I don't have a scope nor a line on one at the moment can I ask whether the ground issue in the igniter could play a role right now for me? I read something about it in another thread and thought I'd pitch it in the dialogue.

 

[jetjock]

Forgive me if this has already been asked but does the tach flicker when it's cranked? Do you hear the injectors? Do you have 12 volts on the coil packs? Did you fix the ground wire?

You can always remove the CPS and spin it by hand while trying to figure this out. Save wear and tear on the battery and starter...