After 3 years of almost trouble-fee motoring my '31 has just acquired an issue with it cranking but not starting intermittently. A problem which has been bought up many times before on the forum, now it has happened to me. So a brief run down of what has happened since it occurred / what has been done so far to try & rectify:
- Fueled up 40 or so liters of BP 98 before an hour long trip - Car starts & runs completely normal upon leaving - Get to destination, car sits for 30-60 minutes - Before having to quickly move it, turn key car starts immediate however not bursting into life as usual - Park car up leave it overnight, restart the next day & it's cranking but not starting - Can be revved continually however as soon as RPM drop car stalls - "Engine electrical system" will display upon stalling ONLY if you attempt to keep the revs up
Now I should mention that the car has a 12 month old new OEM fuel pump ECU, 6 month old leads, 12 month old fuel pump (now changed), 18 month old distributor caps & rotor buttons, 2 year old iridium plugs (now changed), Denso 02 sensors a few years old, OEM 200,000 km service 8 months ago etc.
So far I have replaced the following parts since the issue occurred: - New Walbro GSS342 fuel pump - 2 leaking caps in Mine's ECU replaced (rest will be replaced once I receive the caps in the mail) - Close to new OEM coil packs - New standard series NGK plugs - Cleaned IACV & fitted new bearings
Since this, the car can now keep idle & run if you give it a rev or two straight after start-up but will not keep idle without the assistance. And it will drive like normal once out on the road. Disconnecting the AFM shows no difference in idle etc. I have yet to change the fuel filter, however will be in the next coming days.
I will be picking up a spare AFM & igniters tonight also just to rule them out if they aren't part of the problem. Should have them as spares regardless.
So coincidentally the only change to the car was the new fuel, prior to this the car was in perfect running order. I only changed the oil a week before, other than that no changes.
If I have left anything out I will further add to it, in the meantime I look forward to reading some opinions.
Remainder of the caps have arrived today. They'll go in tonight & tested in the car tomorrow.
As I had temporarily only replaced the 2 caps that were leaking, upon closer inspection after re-opening the ECU again I missed the lone 100uF 10v on the upper board which has blown out the bottom of the cap. The leak did not spread & was contained right under it so it was an easy miss on my behalf. Hopefully this cap is the cause to my issue.
If the fully re-capped ECU does not rectify this, I will be draining the old fuel from the tank as I fit the new fuel filter to rule out it being bad fuel. Then refill with some Shell 98 this time around.
Today I also tested a known working AFM & igniter, they can now also be ticked off the list of not being part of the problem.
ECU re-capped with no difference. Bypass the 12 month new FP ECU & car starts without an issue.
Now since I have the car running, I've noticed the IACV is no longer "clicking" once the engine has shut down after cleaning it & replacing the smaller of the 2 bearings. The unit was in working order before removal & was only removed as part of the process of elimination due to my main issue at hand. Wiring is all good, connector is fine, have yet to test with a multi meter. Though surely removing it couldn't have all of a sudden made it faulty.
Quick update - got very lucky tonight & scored another ECU from a '31.
Took it home, opened it up briefly to check it's state - all good so continued to install it. Removed FP ECU bypass & turned key, a little rough upon startup as before however managed to idle at a steady 850 RPM off the bat by itself. Let it run for a bit, shut it off & started again shortly after. Second start it bursts into life, sitting on 1000 RPM & slowly dropping back to 850 upon warming up. Very smooth & seemingly as it once were & what it has always idled at since ownership. Shutting the engine down the IACV now clicks again as well, so with this standard replacement ECU in it seems the two have communicated & relearned unlike with the other.
So leaving it for tonight, I'll check again tomorrow for consistency. At this point it really is looking like the Mine's ECU as the culprit.
As of a week ago, the day after - it started & ran without an issue. However after replacing the Walbro pump with the previous generic pump, I then went to take it for a proper drive & made it as far as the end of the street before turning back again. Spitting & coughing under acceleration & wanting to cut out, which it did twice then not wanting to start again once I pulled up at the bottom of the driveway along with "Engine electrical system" making an appearance. Gave it a minute & retried, to which it started & accelerated up the driveway no problem.
I have yet to swap the pump out again, which I plan to do next week when I've shaken the flu. Along with the filter & completely new fuel.
So to recap - the Walbro made no difference as the first attempted repair, then the car seems cured upon the replacement ECU (new pump still in). Swap the Walbro out & the car barely drives but idles & starts fine.
Further updating this, since my previous post the following has been done:
- Mines ECU refitted
- Completely emptied the fuel tank & refilled with fresh 20 liters of Shell 98
- New aftermarket fuel filter (couldn't even blow through the old filter)
- New Denso fuel pump
- New Denso 02 sensors
With this the car now starts every turn of the key & will run hard & strong when test driven - no more spitting & coughing or cutting out this far. The engine electrical error has not shown up & the car is free of error codes. However there is still a couple of issues that need ironing out regarding the idle.
#1 When started occasionally the idle will exceed 1200 RPM, other times it will fluctuate between 1100-1200 when fired up. Once the car reaches normal operating temp at half way on the gauge the RPM will drop from 1100-1000 to 850 but not gradually - the idle won't slowly lower as the temp rises it will just drop.
#2 After returning from a test drive around the block more times than once the idle has lowered to as low as 600 RPM (may have even been less) once coming to a stop, engine barely audible however does not cut out. Continue to drive a meter or two & come to a complete stop again the idle will sit back at 850.
Despite the rebuilt IACV it seems like it could be at fault? Should there be a need for me to remove & re-adjust for the 7th time as I thought they adjust themselves over a period of start-ups/drives?
Following up on this again, today I took the car for a proper run out of town since curing the firing issue. As I posted earlier, I was experiencing random idle speeds once the car would come to a stop to as low as 600 RPM however without stalling. Though as of yesterday after 20 minutes of driving & slowing down to turn into a driveway the engine cut out, I heard the warning bong but didn't have time to look down & check, but I could only assume that it was the electrical error warning once again. So starting it up a minute later after parking it I gauged the idle, it sat on 600 RPM as soon as it was fired for 5 or so seconds then randomly corrected itself & rose back to 850 RPM, all while in park.
After letting it sit for a few hours I headed back home, within 2 minutes of reaching the first roundabout it was wanting to cut out again. So all the way back I was having to stall it up at every stop & low speed turn to prevent it from stalling.
Basically in any drive gear the problem occurs once at normal operating temp. Which to me seems like the IACV is still at fault & needs further adjustment? Keep in mind that I have never experienced this issue before since removing the IACV for when I was going through the troubleshooting process from the beginning.
In the meantime I will swap ECU's & if no different then remove the IACV & replace with a clean untampered unit.
Giving this thread some closure. After replacing the IACV with another replacement all is fixed. 500 km later with multiple starts & stops along the way it's so far so good with consistent firing & idling. Cold idle at 1000 RPM, warm idle 850 RPM & 800 RPM when in drive or reverse etc. Now running better than ever with everything else that was replaced along the way too.