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Thread: 1G GTE hard start stalling intermittently - baffling issue

  1. #1
    Forum Member 1st year Apprentice
    Join Date
    Jan 2017
    Kuala Lumpur

    Default 1G GTE hard start stalling intermittently - baffling issue

    I have a GZ20 soarer with a gen3 1g gte automatic trans. About a month ago, I was preparing to leave from work, and I turned the key to start, and the engine cranked strongly yet wont fire up. I popped the hood and messed with the AFM wires, and it started right up. This did happen 2 years ago but the problem hasnt returned since I extended the AFM wires, and I thought it was solved, seems its not. So i proceed to drive home, about 10 mins later, I was stuck in heavy traffic, while rolling slowly in idle suddenly the engine stalled. I proceed to put trans in N and attempt to restart and to my surprise it started up right away, and I drove the rest of the 30km home with no incident.
    On Sunday it started easy and I drove to a mall. In the parking lot as I stopped and preparing to go into reverse, engine stalled. I put trans in N, restarted and it started up again. Proceed to park the car, do my deed, and restarted and left for home without further incident. Thinking perhaps a vacuum leak I tightened all the intake hoses.
    Drove without incident on Monday, then on Tuesday car wouldnt start in the morning, I pulled the AFM cables, again it started. For the day, no other hard start or stalling.
    The next 2 days no incident, then on Friday while wanting to leave from work, it wouldnt start. So this time I bridged B+ Fp to make sure the fuel pump is working, It is, yet it wouldnt start. Even before bridging fuel pump I could smell petrol fumes, so the injectors are firing .Again i pulled AFM cable it started.
    While nearing my home I was stuck in traffic, figuring out that it would be better to put the trans in N to lessen the load at idle to prevent stalling, no luck, while at idle in N, the engine suddenly stalled. Attempt to restart immediately and it restarted , drove home and talked to my mechanic. Because it only happens at idle and starting, he thinks its just a dirty throttle body. So he cleaned all the idle air passages and the throttle body itself and bypass passages. Got back the car the in the evening. Drove the next day without incident.
    On Saturday and sunday, I dropped the trans pan, change the trans filter and added atf, changed engine oil and filter. On Monday drove to work, no issue throughout the day. Was crossing my fingers that the TB cleaning solved the issue.
    Tuesday was a holiday so no driving around.
    Wednesday went to work no issue. After work started up easy and left for home. While nearing my home, I stopped by an abandoned petrol station to check my atf level while leaving engine running in P with ac off. While in the process of putting back the trans dipstick , suddenly the engine stalled. Since i was outside of the car and have not put back the dipstick, it took me at least 15sec to get back to the drivers seat to attempt a restart. To my horror it wouldnt restart, cranks were strong, and I tried at least 5 times cranking for about 4 to 5 seconds each time. Again checked fuel pump, it was ok. Since it worked before, I then pulled on the afm cables just behind the afm plug, attempted a restart and it fired up. Drove to my mechanic and we talked a while. Now we agree need to check other areas like distributor , coil and wiring.

    Now to reiterate, The engine has no misfire, no hesitation, pulls very smoothly and makes good power when prodded, never stalled when the car is moving above 5kmh.
    So in summary: hard starts usually after car sitting for a long time, 6 to 12 hours. Stalls happen sometimes, but ONLY at idle, even in N. When stalls do happen, engine is hot. If stall happens, immediate restarting attempt works, if wait too long, hard starting again.
    So the one thing in common here is low rpm. When the car is in the process of starting, rpm is low, when it is idling rpm is low up to 700rpm.
    Which makes me think it something to with the distributor either primary or secondary coils, igniter, or ignition coil. Also perhaps verification from somewhere not going back to the ecu in low rpm. I am not well versed with the ecu operation, so perhaps some of you would know better . There are no error codes at all. And oh yeah, the AFM cable is right under the plug for the distributors 4 small wires which is going through the same loom from AFM-distributor across to the intake side. So pulling on the AFM cable upwards also tugs on the distributor small wires. Could the signal from the G side be interupted causing the hard start and stall , because at low rpm some of the time its somehow not transmitting these signals ?
    I am stumped. Intermittent issues are the hardest to diagnose.

  2. #2
    Forum Member Grease Monkey
    Join Date
    Apr 2019

    Default Re: 1G GTE hard start stalling intermittently - baffling issue

    Could be a broken wire in the loom, I would start the car and start tugging on wires and see if you can get it to stall, if you can make it stall repeatedly with a wire tug it will make it a little easier to find the fault

  3. #3
    Junior Member Backyard Mechanic jondee86's Avatar
    Join Date
    Dec 2008
    Wellington, NZ

    Default Re: 1G GTE hard start stalling intermittently - baffling issue

    What he ^^^^ said. Problems of this type are often caused by a wire that has flexed for 239,739,234 times
    until the copper wires fatigue and break. But the outer plastic cover is still intact and holds the broken ends
    close enough to make some contact.... most of the time. Depending on how your car is wired, the most likely
    places to look are where the wiring loops out of the engine loom and connects to the distributor and/or AFM.

    If there is a loop hanging free it will move about with the motion of the car and engine vibration. So check
    any hanging wires for soft spots... places where the wire flexes much more easily than it should. Right where
    it enters the distributor, and even just inside the distributor if the factory support is missing. If the engine
    does not get an rpm signal from the distributor for even a very short time it will shut down.

    Likewise with the AFM. It probably has a switch inside that provides a ground signal for the ECU when the
    flap inside is open (engine cranking or running). If there is no ground signal the engine will not start or run.
    Same thing if the idle air bypass screw has been messed with and the engine rpm drops low enough to
    allow the switch to open (=stall). Also same thing if the ground wire from the AFM has a poor connection
    to chassis ground due to corrosion (check, clean and tighten).

    Bear in mind I have no idea how your engine is wired so treat these comments as generalisations that
    apply to a lot of older Toyota's

    Cheers... jondee86

  4. #4
    Forum Member 1st year Apprentice
    Join Date
    Jan 2017
    Kuala Lumpur

    Default Re: 1G GTE hard start stalling intermittently - baffling issue

    Thanks for the suggestions. I did try to move the wires around to cause it to stall but it wouldnt. Last week, Out of desperation I checked the distributor inside, and I heard a crack when trying to remove it, to my horror the cap is cracked near the bottom bolt. I am unsure I cracked it or it was already cracked when I got the car. I replaced a used uncracked cap, sanded the calcified contacts inside the cap and put it back. The inside of the distributor pick ups look very good.
    I also cleaned the igniter, and E2 ground points which is below the cold start injector at the intake manifold. I am glad to report I had no hard starts or stalling for 5 days in row, from 16th to 21st august. I am cautious about saying the problem is solved, so I wont say that it is at this point in time, but it looks promising, but I feel like sanding the E2 grounding point (which Jondee86 mentioned) surface on the manifold, and sanding the wire eyelets seem to have made the biggest difference. The E2 ground eyelet and the bracket was heavily oxidised, with a layer of black dry grime over the mating surfaces.

    I just had a look at the ECU caps and they all look good with no leakage. The next coming weekend I plan to change the negative battery terminal as it looks oxidised and somewhat rusty. Lets see how it goes this coming week. If the next 5 days of driving 23rd to 27th August 2021 yields not a single hard start and or stall then I will declare problem as solved.
    Last edited by alcyon; 21-08-2021 at 11:30 PM.

  5. #5
    Forum Member 1st year Apprentice
    Join Date
    Jan 2017
    Kuala Lumpur

    Default Re: 1G GTE hard start stalling intermittently - baffling issue

    Update. its now the 27th. Every day,for the last 2 weeks, every turn of the key brought trepidation to my heart. I thought perhaps the problem will recur.
    To my surprise it did not recur.
    I think what solved it was the ground cleaning/sanding. I did change the dist cap but I dont think that solved the problem.
    Looking at the diagram, which i tried to post here but unsuccessful, it looks like the distributor is earthed to this point, as well as the ISCV. So If the ISCV and or dist is not getting a good ground, it could cause the dist signal to ecu to be weak,causing the spark to shut off, or the weak voltage caused the ISCV not able to do its job properly.
    Whatever it is, the car is now back to its old self.

    I am still going ahead and changing the negative leads cause the old one is oxidised.

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