Hi everyone- desperate need of help-
Mr2 2zz swap- recent purchase!
Has been misfiring, losing power intermittently for 24 hours. I noticed the coolant was low, so topped up and bled it- now there is an engine light on and very rough idle + misfires. Coil packs are dry/ engine appears to be heating up. Then I noticed when the car was warming up (?? On closed loop) started misfiring badly. Noticed a radiator leak/ pipe leak.
Could this cause the symptoms? Possibly an airlock?
Help! I'm hoping it's not worse than that?!
How would people suggest trouble shooting this?
Thank you 🙏
Get an OBD dongle and Torque Pro and see what gives in terms of codes and sensors.
.
I'd also be pulling spark plugs for inspection and (I'm afraid) I'd run a compression test for possible head gasket issues.
Thank you Carolyn -
What's strange is that it runs perfectly fine when cold, but v rough and misfires when hot
I'll run the checks you suggested
As is the way here.
Always start at the simple (cheap) end of the wedge.
Air filter?
Maf clean
Plugs?
You get the jist
Quote from: H2zzMRA on November 8, 2025, 19:28Thank you Carolyn -
What's strange is that it runs perfectly fine when cold, but v rough and misfires when hot
I'll run the checks you suggested
Symptomatic of that which
@Carolyn suggests!
Throwing up a DTC P0410 code - a malfunction in the secondary air injection (SAI) system
Cleared code and running fine?! Any ideas? Haven't yet checked plugs/ compression test- will do so today.
Could a coolant leak in radiator cause this? Sizeable leak going on
Quote from: H2zzMRA on November 9, 2025, 10:49Throwing up a DTC P0410 code - a malfunction in the secondary air injection (SAI) system
Cleared code and running fine?! Any ideas? Haven't yet checked plugs/ compression test- will do so today.
Could a coolant leak in radiator cause this? Sizeable leak going on
I can't give you chapter & verse, but that code is only pertinent when in the original car. The secondary system is not used when fitted in an MR2. I don't know if it can be prevented, but I have seen owners saying it comes on periodically & they clear it.
Where's the coolant leak from & have you asked the previous owner if they knew about it?
The misfires, - are the coilpacks Denso? The 2zz's coilpacks are prone to cracks down them, & it's sometimes a sign of internal failure.
Toyota coil packs - not sure if they have been replaced ever but I doubt it - denso are v dear but I may have to buy some.
Thank you - I'll change em out
Toyota are made by Denso. I think they own the company. Don't change without knowing, - as you say they're not cheap.
The reason I asked is because usually if a coilpack is faulty the OBD can pick up misfires, but I've heard it said that non o/e will not show.
If you have misfiring but no codes suspect the maf. Shop carefully, the same maf is used in loads of Toyotas.
Is this a case where if you pull the lead from a coil pack and does not change the engine note, that indicates a duff pack - then if you swap the the pack with another and the fault moves...
having run the car / cold start approx 15 degrees ambient temp the total fuel trim is -8 (approx 3 mins after starting engine)
Read outs from MAF= 5-6 g/s
Engine load 20% at idle of 1500
Does that seem about right for closed loop?
Seems to be leaning the engine out after starting? I suppose that would be the case if the MAF was dirty/ undereading?
Would you bother cleaning or just swap? I've read cleaning can deliver poor results
Cleaning it doesn't do harm. A quick-drying alcohol is what you need. Protect the sealing o ring from the alcohol.
You may not have done it before....the sensor is not the visible 'blob' (but clean it too). The main one is up inside the plastic.
Quote from: H2zzMRA on November 9, 2025, 21:56/ I've read cleaning can deliver poor results
Where have you read that
There is no way to know how well the maf is working short of trying a known good one and observing any difference.
I read it on an MR2 chatroom- one person option I guess
Quote from: H2zzMRA on November 11, 2025, 19:38I read it on an MR2 chatroom- one person option I guess
If that means f/book be wary of a one-off opinion, - there is a lot of guff on the groups, - people spouting uninformed stuff.
Having said that I'm on them more than I am here, - just the way car-groups have gone.
That's why I joined this chat room- it seemed the only sense I could find was on here
Thank you for all the help btw- it's a great community
Can't wait to get this car running smoothly again
Quote from: H2zzMRA on November 11, 2025, 22:05That's why I joined this chat room- it seemed the only sense I could find was on here
Yep.
Having cleaned MAF- all readings seem consistent with a working MAF.
Still backfiring/ misfiring when in closed loop-
When I unplugged the upstream o2 sensor the backfires stopped?
Voltage swings from 0.01-0.8 on sensor.
Runs fine with sensor unplugged- with sensor I'm running rich scenario and combined fuel trim is -8 to -10% during and after warm up
1)Gonna replace the sensor
2) only issue it doesn't solve is a 'bounce' when letting off throttle (in neutral) at 1500rpm before setting at 800rpm
Any ideas regarding the bounce? Is this normal dashpot behavior ' or am
I missing something here?
Thank you again everyone!
Not got the answer, but if sensor is outputting a variable voltage (swinging) that suggests to me it is working. If a flat 0 or flat 1, perhaps not.
Are these readings all done stationary?
Just wondering if temp or circumstances are enough to allow system to switch from closed to open loop.
Fluctuating idle is usually caused by the Idle Air Control Valve in the throttle body. Removing the t/b is a PITA.
Idle problems can also be caused by air in the system. The radiator bleed valve is top left as you face looking-in.
Definitely worth trying that first.
Quote from: Ardent on November 15, 2025, 21:45Not got the answer, but if sensor is outputting a variable voltage (swinging) that suggests to me it is working. If a flat 0 or flat 1, perhaps not.
Are these readings all done stationary?
Just wondering if temp or circumstances are enough to allow system to switch from closed to open loop.
Yeah done stationary. Thanks for the advice
Think I've found the culprit - intermittent misfire on 1 cyclinder from coil pack. Usually occurs only after 55/60 degrees coolant temp.
Sheesh
Bit of a mine-field finding a place that sells genuine denso 0104 coil packs?
Where is 'safe' to buy these?
Onlinecarparts.co.uk have them on for £65 each- seems like a counterfeit price
Online car parts are in the same group as Autodoc.....probably just a different website taking you to them.
Tcbparts
Mr2ben (usually upper range prices)
J-spec if wanted to try a used one.
Rogue?
Have to keep reminding myself. Check twice buy once same part on 2zz vs 1zz.
Best shop buy part number.
ebay is usually my first port of call, but interestingly NO Denso listed...
Quote from: Gaz mr-s on November 17, 2025, 22:51Online car parts are in the same group as Autodoc.....probably just a different website taking you to them.
They don't seem to be authorised Denso distributers when I checked the denso site- hence wondering if they are all setting counterfeits
Quote from: H2zzMRA on November 18, 2025, 10:40They don't seem to be authorised Denso distributers when I checked the denso site- hence wondering if they are all setting counterfeits
I can't comment on that....no idea whether that makes a difference. TCB sells genuine Toyota parts usually cheaper than Toyota.....
Lucas are a lot cheaper on eBay, I'd be tempted to try theirs if it was me.
Having done some digging and called a distributer denso coils are currently out of stock in DENSO warehouses- no idea when they will be in stock again
Anyone have any experience of NGK or Bosch?
Does the 2zz ge run ok with NKG? Will I need to replace all 4 coils or should I get a decent used coil and fit until denso ins rock ?
So the denso coils DIC 0104 are out of stock at denso Hq
Not sure when/ if they will come back into stock
Anyone recommend NGK/ Bosch?
Or just use a good used denso coil
Any running/ heatsoak issues with NGK?
Also would I need to replace all of the plugs with NGK?
It has been said on here that Denso is the go to manufacturer, particularly for Sensors, likely because Mr T owns Denso.
But, Denso also make spark plugs and there is not the same insistence/ advice to use their plugs!
I never had need to replace the coils on my 2 , but I did replace a total of two sensors with NGK as and when needed.
When I first had need of a replacement sensor I asked a family member, who maintains high end European vehicles, as to whether I should replace all three sensors, his advice was replace only as required and with a branded product, his preference being Bosch ( European).
At the time I considered the cost options and bought NGK. And similarly when a second was required.
I've used Parts in Motion a few times and all been fine. Seem to be competitive generally. 20% discount via Ebay platform at the moment.
Quote from: rusty0273 on November 18, 2025, 11:48I've used Parts in Motion a few times and all been fine. Seem to be competitive generally. 20% discount via Ebay platform at the moment.
I've used Parts in Motion for shock absorbers, no problems and brake hoses. The hoses I was unhappy that the ferrule ens differed, different batches or some such. They replaced/ refunded can't recall but again not a problem.
A single. They'll all be made to a spec, but some will be more durable. I have experience of a non-Denso not showing a misfire code. How common that is with other brands, I don't know.
I ordered Denso ones from rockauto(usa) in the past. The Part-No there is 6731305. They seem to be in stock. Highly recommended. My old ones were cracked on the side. I did put some Tape on it for temporary fix. But endet up to replace all four plugs and coils. And the Valvecover gasket including sparkplugshaft-gaskets. If there is a small Oilleak in the shaft you will get misfire sooner or later.
Soooo.. after thinking I had it sorted the new MAF didn't help- the dodgy coil packs turned out to be oil in the well of 1st coil
Pack -
and a heavily damaged rubber seal on the top of the coil
Plan is to replace cover gasket and all seals + new coils and plugs
Can anyone advise on the NKG equivalent coils?
Going to replace the spark plugs with BKR7EIX - I noticed rogue gapped them to 1.1mm
Should I do this or leave them at the standard gap?
Thank you
@H2zzMRA This may be of interest:
https://ngksparkplugs.com/en/resources/set-gap-when-installing-new-plugs
The plugs you state are Iridium...I don't think the gap is supposed to be altered. A 2zz compressor runs happily on copper plugs.....
The chances of you getting someone with a 2zz car who's used NGK coilpacks is pretty slim.
They are a recognised top brand, - it'll work.
I'd think twice before adjusting iridium plugs. Can you not get bkr7eix-11 with the correct gap? However, is IFR6T-11 not the recommended plug for 2ZZ or if you want a cooler plug then IFR7G-11KS? I run IFR7G-11KS but my car has a supercharger so they're recommended.
On the coil packs, I've used NGK on other cars with no issue whatsoever. I suspect Denso have stopped making them (driving price up in recent years) and NGK probably picked up where Denso left off.
The rocker cover gasket i replaced, was from Mr T, no more expensive (£15) than anywhere else at the time.
I know I'm referring to the 1zz again, but have been reported issues with unknown brand blue coloured gaskets. Stick with oem
Plugs are comparatively cheap. So not a bad thing. But with a clean etc, do you need to replace all the coil packs?
Good practice? Definitely. Absolutely required? Hmmm maybe not.
Quote from: Ardent on November 18, 2025, 20:52The rocker cover gasket i replaced, was from Mr T, no more expensive (£15) than anywhere else at the time.
I know I'm referring to the 1zz again, but have been reported issues with unknown brand blue coloured gaskets. Stick with oem
Plugs are comparatively cheap. So not a bad thing. But with a clean etc, do you need to replace all the coil packs?
Good practice? Definitely. Absolutely required? Hmmm maybe not.
The coil pack is failing/ misfiring a lot, could a clean/ sort the oil flooded plug well out cute that?
Or is the coil likely to be dead. Never throws a misfire code oddly?
Any ideas
The coil will be defective. You can wrap it with tape and clean the oil. This may initially reduce the symptom. The coils break due to the hot-cold cycle. If the coil is cracked, the crack will widen as the engine temperature increases, resulting in misfires. This explains why your car runs well when cold, but misfires when warm. Have you checked Rockauto? It's a US trading platform that accesses various warehouses throughout the US. You can get all the common wear parts there. They have brand-name products like Denso, but also cheap junk. I've ordered from them at least 50 times (I live in Germany). The parts arrive here within 3-5 days. Take a look.
Quote from: H2zzMRA on November 19, 2025, 10:33The coil pack is failing/ misfiring a lot, could a clean/ sort the oil flooded plug well out cute that?
Or is the coil likely to be dead. Never throws a misfire code oddly?
Any ideas
Apologies, I should have been clearer. Replace the dodgy one yes. I meant, was is ness to replace all as you were suggesting.
Perhaps go east if not west.
https://www.amayama.com/en
Despite some issues I had with autodoc, I will say, their website is handy for cross reffing part numbers.
Same part different ref across manufactures and usage.
To illustrate, I have an MR2, I have also had a gen 2 prius and an RX400h. Guess what, they all used the same maf. So is the coil pack more widely available than at first appears. IDK but just a thought.
I just searched for '1ZZ denso coil pack' and loads came up.
Then I realised it was 2ZZ coil packs we were looking for. So I tried again. Found quite a few.... not cheap though!!
My only niggle, does the 1zz and 2zz share the same pack?
My gut says yes from a manufacturing point of view. But IDK.
I think they look similar on top, but 2ZZ Coils have longer Shaft.
They are different diameters, 2zz slimmer if I remember correctly.
So mr2 Ben have managed to get hold of denso coil packs- from Japan- 7 day lead time £110 each
Apparently only 10 left in stock in denso Japan
At that price, I wouldn't. Autodoc have them. (according to website)
If you bought a cheaper one on ebay.....say Lucas, in the unlikely event it didn't work, you'll get your money back no problem.
Quote from: Gaz mr-s on November 20, 2025, 18:38At that price, I wouldn't. Autodoc have them. (according to website)
If you bought a cheaper one on ebay.....say Lucas, in the unlikely event it didn't work, you'll get your money back no problem.
I got a refund from Autodoc for some suspension (rubber) bushes that I changed my mind about. You pay a nominal amount extra for a no quibble return. Reasonably straightforward but slightly long winded.
NB I got Suoerpro bushes from TCB.
If mr2Ben can buy them from Japan and sell in UK for £110 each, surely that means that they are available via the Japan dealers that I've read about on here.
£440 seems an awful lot of money to my mind for such items.
As Gaz above suggests:
https://www.ebay.co.uk/itm/357673240639?_skw=Lotus+Elise+2zz+DENSO+Ignition+Coils+OEM+Toyota&itmmeta=01KAHK4TMBPZZS0NQ88MJ3W1EE&hash=item5346fc883f:g:2DYAAeSwUBVo18gu
Quote from: Joesson on November 20, 2025, 21:19https://www.ebay.co.uk/itm/357673240639?_skw=Lotus+Elise+2zz+DENSO+Ignition+Coils+OEM+Toyota&itmmeta=01KAHK4TMBPZZS0NQ88MJ3W1EE&hash=item5346fc883f:g:2DYAAeSwUBVo18gu
I wouldn't buy that make. Maybe unlucky, but I had something by Lemark before.... an O2 sensor I think. It worked for a very short time & died.
NTY (NGK)
Magneti Marelli
Bosch
Lucas
been around for years.
They might all be made in the Chinese factory though....... ::)
Quote from: Gaz mr-s on November 20, 2025, 21:55I wouldn't buy that make. Maybe unlucky, but I had something by Lemark before.... an O2 sensor I think. It worked for a very short time & died.
NTY (NGK)
Magneti Marelli
Bosch
Lucas
been around for years.
They might all be made in the Chinese factory though....... ::)
How about these?
https://www.monkeywrenchracing.com/product/toyotalotus-denso-oem-coil-assembly-1-2zz-ge-new/
They'd probably charge at least $25 to send it. The names I said above are all on ebay......
2ZZ Denso Coils on Rockauto 35,75£ (Choose GTS model)
https://www.rockauto.com/en/catalog/toyota,2001,celica,1.8l+l4,1432905,ignition,ignition+coil,7060
Quote from: Gaz mr-s on November 20, 2025, 22:46They'd probably charge at least $25 to send it. The names I said above are all on ebay......
For sure other suppliers and/ or manufacturers are available at rather less than £110 an item!