Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Discussion and technical advice for 84-89 AW10 & AW11 MR2. 3A-LU, 4A-GE, 4A-GZE.

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Sharpfish
Posts: 371
Joined: Fri Jun 03, 2005 6:29 am

Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

I've searched the internet high and low for info on this but found nothing, all I can find is NA dizzies and even then no specific model number for just the pick up coils

One of the pick up coils in my SC dizzy is showing infinite resistance/dead and the car won't start (having ruled out/replaced pretty much everything else including cleaning up grounds). I also tested the wire from connector to close to the pickup and it was ok(not broken) so have to assume the coil itself and its windings are gone. I can't find anywhere that actually says why the SC has 3 pick ups (NE,G1 and G2) vs the NAs 2. It's not a 6 cyl of course so wondered if it was a separate one for the timing choice fitted to some (US?) SCs for fuel type, or is it because the ECU converts 1 360 revolution to 2 so needs 2 signals per rev? (scratches head...)

My GZE is JDM and I've gone in many circles this past month - can't even buy a new SC distributor (and were super expensive when you could looking at one old discontinued toyota parts page $600) but can't find the pickups either to just fit inside myself as the dizzy itself is good. This is quite low mileage 60k if that and I've had it nearly 20 years (the engine at least - it's gone from a Japanese import SC to 2 NA's - one rusted out - so it's currently in a conversion and yeah it used to start and run good till left in my garage for a few months without starting). Yes to every q you may ask (from brand new battery to new coil/ignitor/grounds check/dizzycap/rotor arm/new spark plugs, fuel OK drained old fuel and put brand new in - pump working - no spark! Though once testing I did get spark (with a tester so wouldn't know if would start up cos had the EFI fuse out for test) - next day tested again with tester NO SPARK! damaged wiring could be something else in the loom but It's been treated well and I've checked most points with a multimeter back to ecu etc...) it's driven me crazy cos it's a good engine and car but has spluttered to life only twice (then cut out again asap) and then just cranks. Intermittent spark (though does spark when switching back to run for 2 sparks) should be attributable to this one dead G2 pick up right?

FTR I've got a ton of spares from my previous 2 MR2s (all Dark Blue Pearl 88/89) not that that's important ;) but I've got 3 ignition coils with ignitor packs and swapped them all on to rule that out - surely all 3 couldn't be dead (Coils checked out for resistance test and power is at the coil in 'run' (12.4v) and 9.6v while cranking. Battery is
a BRAND NEW Yuasa YBX 60ah/450a and it has NO problem cranking (very strong).

If it's not the one 'dead' dizzy pick up coil, then my ECU must be damaged? (or maybe the loom/wiring) - I did notice some moisture inside the ecu from a slight leak but not sure if it's damaged any chips :(

So basically I'm looking to find/buy/replace one pickup in the distrubtor but can't find them anywhere in the world it seems. Even some mR2 specialists have scratched their heads. I can find NA dizzys new and used no problem (but not individual pick up coils) but can't tell if they are the same pick-up (just different wiring and only one 'g') and could be retro fitted somehow? Is there a part number for the OEM Pickups on the 88 4agze?

I've also got the BGB and done pretty much everything in there to test... it's not much help with THIS issue as it just says replace dizzy (but you can't actually buy them). I did the (two) na > SC conversions/engine swaps myself so know they were done right, and as said it would start first time everytime for 10 years (inc many years just in the garage while I didn't need it) right up until I had to move house and it wouldn't start ;)


Thanks for any info.



EDIT.... Weird, the spark plug tester started working, possibly cos I had the EFI fuse in this time ;) but no start... so looks like I'll be checking fuel again (but still the dead pick up is confusing me both what it's used for and if it would start up with just one pick up working but run terribly)

Lastly, if I had a vacuum leak from intercooler (rubber pipe basically split in half and taped up) would that stop it starting.. I think it would at least catch. Have had the IC pop off before at over 100 (test track ;) ) and died straight away....
BMR2L
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Location: Argyll and Bute, Scotland

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by BMR2L »

Sharpfish wrote:Lastly, if I had a vacuum leak from intercooler (rubber pipe basically split in half and taped up) would that stop it starting.. I think it would at least catch. Have had the IC pop off before at over 100 (test track ;) ) and died straight away....


Did you get to the bottom of your problem?

My experience with a leak as opposed to disconnected IC hoses is that it will start and run but refuse to rev much beyond 3k or so.

Used to get that problem periodically when I was using the SC on my daily commute (in Tokyo!).
Sharpfish
Posts: 371
Joined: Fri Jun 03, 2005 6:29 am

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

Nope not yet, though developments are... I now have a consistent spark, every test, with spark plug tester or with HT cable from coil to (half inch from) ground. So all that side checks out!

Which means I'm still none the wiser as to what the G2 pickup is for or if it even matters that it has inifinite resistance vs G1/NE.. cos it's still sparking while cranking (whether it sparks while running is something I can't say as it won't start yet).

Which now leads me back to fuel again (or gigantic vacuum leak due to split/taped hose - need to source some to try without buying a full samco kit just yet) and I'm thinking it's the injectors, either signal/ground to them or blocked. I was getting fuel in the return pipe last check, and pump appeared to be working. So barring a damaged ECU I'll be looking at injectors next time I get out on it (this week).

I also managed to find somewhere that will sell me a compatible distributor pick up to self fit/wire but need to check if the ohms rating is going to work.

I will be sure to update the thread for future ref if/when I get it sorted. cheers
SuperRedMR2
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Location: Wickford, Essex

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by SuperRedMR2 »

I have a JDM 4AGZE distributor for sale.

I issues with mine but it turned out to be the ignition coil itself. I thought it was the distributor as well. My injectors wouldn't fire but wasn't the dizzy at all.

Let me know if you need to purchase one rather than borrow one for a test.
Sharpfish
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Joined: Fri Jun 03, 2005 6:29 am

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

Cheers, well i have tried 3 diff coil/igniter packs with the same result + I had the infinite resistance reading on g2/ground (vs the stated ohms in the manual and as G1 and NE were)... Is there any way you could measure the resistance in the plug of the dizzy at all?

Looking into it with the large catch on top the bottom right pin is GE/earth... the other 3 pins should all measure similar resistance between them and the GE/Earth (something like 150 ohms but can't recall off hand).

thanks
SuperRedMR2
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Location: Wickford, Essex

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by SuperRedMR2 »

My dizzy was diagnosed and all readings were normal.

Are your positive and negative wires on the coil pack correctly? Mine had somehow been reversed.

I'll have a look
Sharpfish
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Joined: Fri Jun 03, 2005 6:29 am

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

Yes the coil pack had never been changed betweetn it starting and not starting.

Then I changed it to two others I had (with their own ignitor modules) same result.

I should say, in case I didn't above, I do actually HAVE spark now.. seemed related to something else. But no start, fuel pump appears working (return line bridging diagnostics) so my focus now is on injectors or the signal from ECU for injectors.. and that is where, I believe?, that 2nd pick up from the dizzy is involved - to ECU - to injectors (rather than sharing the same signal as on the NA?). I don't know cos literally NOWHERE , bgb, online etc even says what that G2 signal is for and why the SC has it but the NA doesn't. I even asked some dizzy makers and they couldn't reply. :/

And I siphoned the petrol tank dry then refilled with fresh 98... (via can of course). I've also gotta change the fuel filter when I get chance.
SuperRedMR2
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Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by SuperRedMR2 »

This sounds exactly what happened to mine.

I had spark but no fire. The injectors would just not work! I stripped the loom to see if anything had happened to it (during my engine rebuild). I replaced the loom, ECU, dizzy and AFM and it was none of those.

My mate did the diagnosis so all I can do is test the plug on my engine as it is now.

What are your earths like? Got crappy? What is the time frame from working to not working?
Sharpfish
Posts: 371
Joined: Fri Jun 03, 2005 6:29 am

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

Redid/checked all my grounds as best I could at this time, continuity tested, voltage drop test at coil while cranking etc... all good.

I've not been out in a while due to weather, but I'll be checking for a signal at the ecu and from it to fire injectors next... if none then I still suspect the G2 signal from the dizzy...

if only some MR2 expert knew/could explain what that extra pick up on the SC is for vs just 1 on the NA (cos surely that gets spark and injection pulse from just ONE G1 signal?)... maybe the G2 isn't even needed in the JDM models as it has no alternative fuel (low grade switch)..

time frame was a couple of months between starting/no start but sat in a garage (where it had been for almost 10 years BUT it would start everytime first time for much of that time.. and I'd put fresh fuel in etc.. and had brand new battery).

cheers for trying to help, appreciated! :)
jimi
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Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by jimi »

The NE coil feeds an rpm signal to the ecu
G gives an engine position signal to the ecu
This thread discusses the distributor coils ( among other things) and has info you may find useful
https://www.imoc.co.uk/forums/viewtopic ... 87fc4a3a6a

Edit
Just reread your post and missed the bit about G2, I'll have aread through my notes and various books and see if I have any info on it.
Last edited by jimi on Tue Dec 01, 2020 1:18 am, edited 1 time in total.
Sharpfish
Posts: 371
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Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

Thanks will take a look, yeah the NE/RPM is a known thing, and the G1 signal is same as the NA... but the G2 for the SC?... will take a look in the thread, cos my NE and G1 are fine, ohms wise, but my G2 is dead.. infinite resistance.
jimi
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Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by jimi »

Haven't had time to check everything I have yet, but I have found some diagrams showing the G2 coil on the 4AGZE distributor, it connects to the ECU. Unfortunately there's not much more info than that on the diagram. Still got more stuff to check.
You can download a copy of the diagrams from my website https://jlawson.co.uk/downloads/category/10-mk1
jimi
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Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by jimi »

I've found info in a manual giving a resistance value for G2 it should test the same as G1 and Ne i.e. 140-180 ohms.
I've uploaded a copy of the manual to my website and you can download it from here https://jlawson.co.uk/downloads/category/10-mk1 (same link as my last post) filename is 88AW1, if you go to page IG-7 under the Ignition System section you'll find the inspection procedure for the distributor and the coil values are on page IG-8
Also if you look on page FI-31 (EFI System) of the same manual, you'll see that both G1 & G2 are designated as "Engine Revolution Sensor"
Hope this is of some use to you
Jimi
Sharpfish
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Joined: Fri Jun 03, 2005 6:29 am

Re: Distributor and/or distributor pickup coils for 4AGZE (Super Charger)

Post by Sharpfish »

Thanks, I kinda already know all this as it happens (as stated above) and have the Big Green Book and all known diagrams. I know it goes to the ECU and the pin, I know what the ohms rating should be (and isn't), all I'm trying to establish is if other SC owners actually DO have the correct ohms rating on G2 and... as an aside, if anyone knows what it actually does compared to the NA only having 1.

Cheers
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