1993 Mitsubishi Minica Toppo H31A 4A30

Around a year ago I purchased this little green baby as a learning tool. Every time I try do anything on it I struggle to find info on the internet, so I thought I’d make a post here to try help someone else with the same issues in the future.

The car is a Mitsubishi Minica Toppo RT (High Roof) H31A with the 4A30T engine. 4 cylinders, 660cc, 8500rpm rev limit, 5 valves per cylinder! and a turbo!

It had an expected dead motor after the failure of the timing belt tensioner. I dismantled the motor and found there to be no major damage, other than some minor marks from the pistons giving a couple valves a kiss. I spent weeks with my Machinist trying to find the bearings. I ended up buying some from Amayama and some from Megazip.net after translating an OEM Mitsubishi workshop manual found online. Be aware that Megazip will charge you then check stock then refund for missing items, while Amayama will check stock then charge you. So always contact Megazip to double check stock before ordering, otherwise you might lose your transaction fee if they have to refund you the whole order.

I had purchased “Mitsubishi Pajero Mini & Bravo 4A30 Engine Service Manual 1994-2002 - Paperback” by James Danko and it was wrong so many times when compared with the OEM manual, I just had to throw it in the trash. Tolerances, torques and processes were wrong…

The engine went back together relatively easily. I did however find my ebay gasket kit was garbage, and I should have just tried to get every OEM gasket I could. Mitsubishi Japan (through Amayama) still had most gaskets including the head gasket that I purchased, but not the complete kits as one item. I also had a single piston ring snap on install, which cost $5 to replace with an aftermarket 60mm x 1.25 C ring that I then sanded down to fit, as Mitsubishi wouldn’t sell me 1. I 3D printed a tapered ring compressor to get the pistons in.

I purchased a 3L ultrasonic cleaner to help with the cleaning. It worked great, but I wish I had bought a larger one. It especially helped with the hydraulic lifters. They were thoroughly cleaned then prefilled with diesel oil as per the manual (weird, I know.)

Once the engine was reinstalled I set the timing using the normal Mitsubishi diagnostic ground terminal in the engine bay and the absolutely shit front cover markings. Apparently they improved this for the next year, or so says my 1993-94 changes manual.

Now that the car was running I needed some better speakers, so I installed a sony head unit with some cheap Rockford Fosgate P142 Punch 4" 2 way speakers, and P152 5.25" 2 ways with 3d printed brackets for the front 4 inch speakers and the plastic adapter plates that came with the speakers for the rears. The internals of the doors and body are bare, so they could definitely do with some sound mat.

After driving the car for a while I noticed a very slow coolant leak and it getting a little hot under load at highway speeds. I proceeded to replace every coolant hose I could. Mitsubishi basically had no coolant hoses other than the most major lower radiator hose, so I had to use a lot of generic 8mm and 13mm coolant hoses and some generic bends. I also noticed the aircon had no gas, so I just removed the whole system excluding the compressor to make working in the engine bay easier, which I am very glad I did. I can add it back later once everything else is 100%. I 3d printed some adapter plates to keep the AC line holes clean.

After pressure testing the coolant system (buy a cheap coolant pressure tester, they’re the best) and test driving the car I tried a few full throttle runs and realised the car was stuttering and not accelerating passed ~6500rpm, which is before where the peak power is meant to be. The engine would free rev to the redline no problem, so I presumed it was a fuel issue. This may have contributed to the heat on the highway if the fuel pump was having issues. There is no pump access hole in the car, but thankfully the tank is very easy to remove. I have dropped the tank and measured the pump. It appears to be a good fit for the BOSCH 0986580979 universal EFP007 fuel pump. That or any 1993 Mitsubishi lancer pump. I have ordered the pump and will report back when I go to install it.

I also noticed the intercooler foam had disintegrated so I stacked some heat resistant plastic foam tape to replace it. You can buy the whole vent from Mitsubishi but not the foam.

While waiting on parts I also purchased some “RS-R SUSPENSION DOWN 1SET FOR MITSUBISHI TOPPO H31A B001D” Lowering springs from Black Hawk. I have installed the rear so far and dropped 4.25cm. The install was extremely easy. However they are a bit soft, so my 165/70R13s rub on bumps at highway speeds. The rear guard lips will need rolling and I might need to run lower diameter rear tyres. Photos to come once the fuel pump is done and the fronts are installed and aligned.

I’m excited to get back to driving it. Its already been a useful hauler for my drift car’s bits.


So the generic Bosch pump fit perfectly, but sadly did not fix the hesitation. The car still wouldn’t accelerate passed ~6000 rpm in third gear. Maybe its a boost leak, maybe its dying coils? Not sure what to check next.


After pulling the plugs I noticed Cylinder 1 was looking quite different to the other 3. No where near as rich, which makes me think its running lean and the ecu is compensating by richening up all cylinders. I took the fuel rail out to clean the injectors but decided to get them flow & leakdown tested professionally instead. I will get a professional opinion on the plugs too.

Edit: Took it to a professional who is gonna give the injectors a test. They think it might actually be sticky valves, which wouldn’t surprise me as the engine was rebuilt entirely because of that being a possibility. The valves were measured to be straight, but they’re also probably some of the smallest valves of any car ever, so I wouldn’t be surprised if the tester was inaccurate. Might be valve guides or something binding too. Next test is a compression test once my new tester turns up.


Interesting little thing, didn’t even know they existed.

The injectors’ patterns were trash so they were professionally cleaned, and I replaced all the orings and gaskets. I also installed a new fuel filter: RYCO Z440. This was 1/4 the price of the OEM Mitsubishi filter.

I am pretty certain this is not the issue though, as while I was warming the engine after reinstalling everything I noticed the pop/cylinder compression noise I could hear through intake stopped after a few minutes of idling. I revved the engine a bit and the pop came back temporarily. I think this means the issue is either a failing hydraulic lifter on cylinder 1 where it is not holding pressure or a valve is getting stuck. Not quite sure how to figure out which issue it is, so I think I’ll take it to a dyno.

Here is a video of the intake noise. You can also hear whatever top end issues cylinder one is having.

I compression tested after warming and all 4 cylinders had exactly 155 psi, so that’s good at least.

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Alright so the mechanics basically said the hesitation was the hydraulic lifters being old and sad after 300,000km and that they couldn’t source new ones from Mitsubishi, so :person_shrugging:

The car ran great going to and from the mechanic on the highway, so its not the end of the world if I can’t rev it to 8500 anymore provided I can drive it. Peak power is meant to be at 7500, but its more like 6000 now. If it comes to it, there are a few much lower km engines for sale in Japan.

Anyway, I installed my RS-R lowering springs & then noticed the rear bump stops are completely gone. I have ordered some OEM ones from Amayama, but it’ll be another month of it sitting in the garage not being driven :sob:. The front bumps were a little sad but still complete, so I’ll get some harder aftermarket ones later.

The springs resulted in some hectic tyre rubbing but that might just be because of the lack of bump stops, we shall see!

I also invested in a couple caramel wheels to try get the branding off. Wow they are magical! A little hit with the heat gun then the eraser wheel and the branding came off no problem. The whole car needs a wet cut and polish, which is up next.

Edit, here is a photo of said missing bump stops & the RS-R springs installed in the rear.


While waiting for bump stops I decided to start to determine what aftermarket wheels I can fit on the Toppo.

To my surprise the internet is wrong, and the Toppo is actually 4x114.3 not 4x100. It just so happens I had some aftermarket 4x100/4x114.3 multi fit and some Honda Integra wheels that came off a Suzuki Cappuccino to try on.

Integra Wheels:

Aftermarket Multifit (Speedy Wheels.) I didn’t have wheel nuts that fit, so I couldn’t actually put the car on the ground with the 14s.

Stock Wheels:

I liked the fitment of the 15s, but the Integra offset is a bit aggressive, plus the 195s don’t fit within the guards. I also need to double check the rim width, as in NZ we have to abide by the LVVTA Tyre Size to Rim Width Compatibility document. I think I’d run 175/50/R15s if I went 15 inch, or 165 if I went 14 inch.


Stopper Bums installed (lol), and we’re good to go! I’m surprised by how reasonable the ride is with the lowering springs. Its a little bouncy, but the car settles quickly and has far less body roll. There is some slight rub with on the front inner guards when turning occasionally, but not bad enough to bother fixing.

The engine is also running great and its totally usable for highway and city driving, even with the sad lifters! It has no issue holding 100kmh, and is fun to choo-chooing around town with the BOV venting to atmosphere.

I purchased some wheel nuts and a key to fit the aftermarket 14s, but they are far too wide and the offset is way off so I might need to buy new wheels… any recommendations for reasonably cheap 15x6 or narrower 4x114.3 with pathetic offset?

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The Toppo is a cute little kei car, but if you had to trade it in for another kei, you might want to consider the Minica Dangan ZZ - a sportier alternative for sure, and one whose claim to fame is being the world’s first road car powered by an engine with a 5-valve cylinder head.

Hey also have a mitsubishi with a 4A30T engine. Having a lot of trouble trying to find a good manual, pdf preferably, but wondering if you might know anything about the torque specs for the crankshaft pulley bolt. TIA.

The 98-10 engine manual (1039G23) for the 4A30 says 118±5nm for the front crankshaft pulley bolt for both the SOHC and DOHC engines.

I bought my copy off Yahoo Auctions via Jesse Streeter/Streeter Corp, though Buyee is probably cheaper for booklets.

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After taking the Toppo for its Warrant Of Fitness test, it failed on rear brake issues. I took the rear brakes apart and found both drum cylinders were leaking and the fluid had gone nasty.

After a bunch of shopping around I found that Nissan Tiida brake drum cylinders fit without any modification other than bending a brake line slightly tighter. It may have the wrong throw but it fits and works, so good enough.

Rear brake drum part number: KWC20217

Also: There was a recall for Minicas as the Minica rear hub castle nut torque was not being used during installation so they were crushing the rear bearings: 保証期間延長等のその他のお知らせ | リコール等の重要なお知らせ | MITSUBISHI MOTORS JAPAN
The actual torque should be 59±19. Thankfully my bearings looked great!

Also my manuals from Yahoo / Jesse Streeter Corp turned up finally! Turns out the Mitsubishi Minica Toppo manual doesn’t have any torque specs in it, but does have detailed images of the engine that I had not seen elsewhere. It also basically contains the full engine manual, so in the future I only need to buy the car booklet. A real workshop manual would be nice, but Googling in Japanese with Google Translate to find torques will have to do for now.


Its been a while!

So the 4A30 had always sounded terrible from the lifters ticking, and it never wanted to hit 8500RPM like it should have. I decided after the last WOF that I’d remove the engine and head again and see what state everything was in.

After a leak test the valves seats and valves obviously needed to be recut, oops. I took it to my new machinist and they advised it really needed 20x new lifters ( MD133954 ). After purchasing some from an Australian company for a reasonable $400, they arrived and they were incorrectly sized. Sadly they had no luck getting another correct set from their supplier, so I sent them back and got a refund. That meant I had to buy the painfully expensive lifters straight from Mitsubishi. $1300 later, they’re on their way now. I probably should have got some off Alibaba… I also purchased 20 valve stem seals from “Mechanging Chenyu Engine Gasket Store” off Aliexpress ( MD179175 ) for $30NZD.

image (5)

At the same time I wanted to fix a gearbox leak, so I purchased a F5M1 manual transmission manual ( 1039926 ) off yahoo through Jesse Streeter again, and the lock nuts for the ends of the gears. They get torqued to 15.5kgm, ~150nm!. The gearbox was actually quite easy to take all the way down and back up, once I knew how the pins worked.

I wanted to buy valve springs from Mitsubishi, but sadly MD310128 and MD196139 are both no longer stocked or manufactured. I had a look around Alibaba, but no one seems to specifically produce Mitsubishi valve springs and custom spring orders have to be quite large. We will have to shim the originals I guess.

Hopefully I can drive my car again soon :cry:


And we’re road legal again!

Getting the head back from the machinist took forever. He cut the valves and seats again, and replaced the valve stem seals and re-machined the head surface. He had to buy some more stem seals as the aftermarket set I bought only fit on one side.

After pulling the turbo apart to check its health I noticed a couple of the compressor fins were a little bent, so I decided to buy a new core. I went with a brand new aftermarket replacement core from Tanboress, through Alibaba. It arrived promptly, was well packaged and landed it cost $185NZD. For some reason it did require the small semi-circular keyway on the compressor side to be filed slightly before it fit, but it was correctly sized otherwise. I also had to get a new compressor paper gasket cut by a local shop for like $6.

The gearbox functions perfectly after the rebuild, and no longer leaks oil!

When reinstalling the engine I noticed the reverse switch was terribly designed so the wires had been damaged. A quick trip to pick-a-part got me a CB5W Mitsubishi Lancer reverse switch which fits perfectly, works (after splicing in), has a much more robust plug design and only cost $9nzd. It looks like Mitsubishi quickly realized their mistake with the exposed wires on the original switch.

Once again I used my cooling system pressure tester kit + a spray bottle of soapy water to test for leaks before filling it with coolant. Absolutely buy yourself one of these kits if you can as this saved me so much time once again. I also used the vacuum assisted fill tool to fill the system with coolant which appeared to work quite well as I didn’t get any bubbles like I have previously.

Now its time for an exhaust and an intake I think!


The Toppo made it to its first cars & coffee since I bought it in 2021!

It was hesitating in third at wide open throttle, so I tested the coils and one was millions of ohms out of spec. The 3.5L V6 Mitsubishi Pajero V45W shares the same Diamond F-722 wasted spark coils. A quick trip to the local pick-a-part solved that!

My coil plugs are ruined, so I tried to take the plugs from the Pajero but they instantly disintegrated when I tried to re-pin them (which can be done with just a small flathead). I’ll purchase some when I get new coils that actually still have their plug retaining pins lmao. The coil plugs are known as “2 PIN DENSO COIL CONNECTOR” or something similar.

I was also having some issues with water temps rising above >80kmh. I removed and tested the (new) thermostat and it passed, so I removed the radiator and thoroughly cleaned and flushed it. IIRC 4A30T Pajero Mini are renowned for being bastards to burp so I spent a few hours making sure the coolant system would be free of air bubbles. This basically solved the temp issues, so I can drive at highway speeds again!

After visiting the cars and coffee event I noticed that Mitsi Evo 3’s have a steam/gas release port on their thermostat housings which the Toppo does not have, even though the housings are quite similar. That would probably solve the burping issues, but the Toppo housing also has to hold the top-mount intercooler up.
Screenshot 2024-01-15 084725

Now I can get to putting an intake & exhaust on it!


Modding time!

First up was a pod filter. I CADed up an adapter and 3d printed a few concepts in PLA, then the final print was printed in the pink eSUN ABS+. I was very surprised just how loud and clear the turbo boost noise is through the more open intake. It’s now hilarious to be on boost and even funnier to let the blow-off vent to atmosphere off boost.

Being a flimsy tin gong, the Toppo was pretty uncomfortably loud at 100km/h. The next “mod” was a good application of sound deadening. This was quite a fun process as the panel resonant frequencies changed so dramatically with each additional sheet of deadener. The doors are now REALLY hefty, and make for a satisfying thunk when closing. The highway sound has improved dramatically.

I didn’t take the dashboard out but I definitely need to now that the rest of the car is deadened. Some actual sound blocking foam would be good for the floor and firewall too. The wind noise near the A pillars is the next loudest area that needs attention. The big antenna on the drivers side A pillar probably isn’t helping but I’m not quite sure what to do next.

Also this is how you access the oil filter lmao.