TR 2.6L Starting Issue

[Cruiser]

I've owned my Second Gen for about a year next Friday, and other than having what sounds like a tractor engine in it (Yep, It's an Astron), it's been fine.

Over the last couple of weeks it's been having difficulty starting. Normally, it would crank but wouldn't fire when the key was turned to "START", but a second try of returning to "ON" and switching back to "START" would start it up no worries.

This morning was by far the worst though. It cranked, but didn't fire. Attempted a second try, and this time it fired, but it was running incredibly rough, like it wasn't getting sufficient fuel or the plugs weren't firing as they should. Then it stalled. On the third attempt, it started, and with a bit of a blip of the accelerator, it was off and idling normally.

Since it's an intermittent issue present only on that first startup, it's difficult to trace the fault. When I have some time later on, I'm thinking of going over a few areas, notably:

- Check the Dissy Cap, Contacts and Rotor
- Throw a Multimeter on the battery and check the voltage drop when cranking
- Open the ECU and inspect the Electrolytic Capacitors
- Remove the Spark Plugs and check their condition
- If I can, check the ignition switch contacts in the column / barrel
- Check 4-Pin connector on top of Distributor

I suppose it could also be the injectors or fuel system needing a clean out, since its regular driver likes to run it down to Empty... :face palm

For the most part, it's not a bad engine. It doesn't appear to burn oil, and it doesn't leak any oil or coolant, so fouled plugs are certainly possible, but I'd be surprised. It chain rattles like any Astron does, and I've noticed within the last few weeks a strange whistling noise coming from the front of the engine (timing case side) which sounds like a tensioner or pulley. If it's the alternator, then I could possibly have a potential culprit right there.


I won't have access to the car until this afternoon, but until then, any ideas of what this could be?

[MadMax]

I would suspect the ignition coil/power transistor, from past experience with the Astron motor.
Unhook one of the plug boots, put an old plug in with an enlarged gap, and put the plug on the cylinder head, and crank.
A healthy coil will throw a spark at least 1 cm, seen a TS coil on a test rig throw a 2 cm spark.

[Cruiser]

Well, I know what an ignition coil is (thankfully) but the power transistor... wouldn't happen to be one of these attached pieces, by any chance?



As it turns out, I kept the one from my old TR. ( Kept the Distributor, ECU, TCU, MAF Sensor and ISC as well, along with Radiator, Hoses, Rocker Cover, Water Pump... ) Would be brilliant if this turned out to be the issue.

EDIT: Would help if I read it first, written right on the side of the module, "J121 POWER UNIT". That looks to be it.

[MadMax]

Yep. That is it.
Keep the two together, I replaced a failed ignition coil with a new one ($90) which blew soon after. Went to the wreckers, got the coil and power transistor ($15) off a car, went fine for years afterwards. Lesson learnt.

PS The metal attachment is an ignition noise suppressor so you don't get ignition noise on your radio.

[puma]

If your still having an issue, give the TPS connector a quick look too, I know for a fact I chased all through my ignition and fuel systems only to find the TPS connector corroded to shit

[Cruiser]

A quick update. The Magna died completely last night. It would crank, but no fire. Disconnected a lead and stuck in a spare spark plug rested against the block - no spark.

I took the ECU out, found some leaking capacitors, so I swapped in a later revision ECU that I had around. Great preventative maintenance, but it didn't solve the problem. So I removed the Coil and Power Transistor and swapped in my spare unit, still didn't work.

After a half hour of cursing, I thought that perhaps the Coil / Power Transistor wasn't receiving a signal from the Distributor, hence no spark. I took the plug off the top of the Distributor and found a huge amount of corrosion. Almost had the entire connector block filled with it. Sprayed it down with electronic cleaning solvent and used a wire brush to clean the connections on the Distributor and on the loom. Reconnected and voila - she started up.

It still hard starts though, and while it'll usually catch the first time now, it doesn't want to idle properly until I blip the throttle or let the idle smooth out by itself. Once that's done though, it seems to go fine, so this is a brilliant start.

Looking at the connector on the Distributor, the pins seem to be rather loose. I could have sworn the dizzy pins were rather rigid, but even wiping these with a cloth would move them back and forth slightly, so I'm wondering if the distributor's corroded internally as well.



The great news is that I have a spare distributor off a later model TR here as well. The bad news is that I haven't changed a distributor before in my life, nor do I know whether it will actually solve the problem or not, but since it was definitely what was keeping the engine from starting, I think I'm on the right track. It seems simple enough - mark the old distributor with white-out, pull the old distributor out, make sure to line up the replacement exactly the same as the old one and tighten it up. Anything else I should know?

Presumably I'll also have to get a replacement oil seal as well. Does anyone have a Mitsubishi part number for one of these, or are we just using a tube of gasket sealer these days?


Puma: Cheers for reminding me. I'll have to check the TPS connector, in this case I wouldn't be surprised if it was corroded as well.


P.S. Looks like my water pump is on its way out as well, seems to look awfully white and corrode-y. Will probably swap that out at the same time. Gotta love how easily accessible the parts are on this engine.



EDIT: Oh, and for reference, the ECU that came out is a 1992 Mitsubishi AW319647 (Bosch 9 260 060 023), and the one that went in is a 1993 Mitsubishi AW335189 (Bosch 9 260 060 046). The only physical difference is that the ECU label on the later 1993 ECU has blue stripes through the label, while the earlier one is just text. Both came out of TR 2.6L Automatics.

[Cruiser]

It's still running, but deteriorating again. Went alright over the past week other than the occasional failure to start, but now it's idling incredibly rough. Feels like it's about to stall, and occasionally it will (mostly when reversing out of a parking space).

I think it's all related to the spark issue it had last week. The Power Transistor and Coil both check out, but the Distributor's still suspect. I need to look over it later today. I'll be checking the TPS and connectors, Distributor and connectors and the cap and rotor. I know the 4-pin connector on the Distributor can have issues, so I'll solder the terminals back on if I have to. If that fails, then I suspect the sensor inside the distributor may be on its way out, and I'll have to swap the lot.

Any tips to keep in mind while changing the distributor on a 2.6L Astron? It doesn't look difficult, really just a matter of making sure the gear is lined up correctly inside the engine. Mostly thinking along the lines of how hard it is to remove, if it'll need to be pried-off, and making sure I don't knock it out of time while doing so. I don't have a timing light unfortunately, so it'll be a case of lining it up with the position of the old one.

[Cruiser]

Hopefully this is the final update.

I checked the hall effect sensor in the distributor and it seemed fine, so I decided not to go ahead with the swap. Used a small wire wheel to clean up the corroded terminals on the distributor and TPS, but it still didn't want to run or idle.

Out of curiosity, I swapped my old ECU back in, and voila - perfect start, perfect idle. So my new ECU is faulty. Decided I'll just change the capacitors in the old one and the TCU at the same time.

Also gave the belts a quick check and adjustment, tightened up the tensioners, checked over the fluids, wrapped the TPS and distributor connectors in new electrical tape to better weather shield them, and did some preventative maintenance on the Power Transistor - the old thermal grease had dried out, so I replaced it with some Arctic Silver 5 I had around. Works a treat.


UPDATE: Astron's still charging away. Engine's running cooler as well, which makes me wonder if the malfunctioning ECU was leaning out the fuel mixtures. The whistling noise from the rear belt tensioner's gone as well after tightening. Consider this one fixed.