initial cold start cranking, starter bucking like a crossfire

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Dr John
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Joined: Fri Oct 04, 2019 1:54 am

initial cold start cranking, starter bucking like a crossfire

Post by Dr John » Fri Oct 04, 2019 2:45 am

1992 Toyota Landcruiser, 4.0 liter, seems like ignition timing signal from PCM to igniter may be erratic possibly due to crank sensor located in distributor possibly causing premature firing of spark plug on cold morning start-up. Labors like a typical crossfire from moisture in distributor cap would act. Have not been able to capture signals during an event yet. Eventually engine will start after a few seconds but has a few times failed to start at all even after extended cranking by customer. No codes present. Checked and cleaned and inspected underhood grounds and PCM power and grounds = OK, connectors to Air flo sensor, TPS, Distributor and igniter and coil - all clean and acceptable. Battery/charge system acceptable. Scoped the IGT and CKP pulses and ignition primary with engine running and waveforms seem possibly concerning. Trying to find known good waveforms to compare with. Checked IATN and no luck at this time. Any thoughts or links would be much appreciated. Thanks - Dr. John

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TwoWaves
TwoWaves
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Joined: Thu Apr 24, 2014 8:32 pm

Re: initial cold start cranking, starter bucking like a crossfire

Post by Technician » Fri Oct 04, 2019 1:16 pm

Have you got a picoscope, if so use your log in details of the forum and look on the waveform library.

Dr John
Newbie
Posts: 2
Joined: Fri Oct 04, 2019 1:54 am

Re: initial cold start cranking, starter bucking like a crossfire

Post by Dr John » Fri Oct 04, 2019 5:32 pm

Do not presently own a Pico. In the process of obtaining a Pico. Presently using Autel maxiscope. When opening Pico library on my desktop it apparently requires a connected Pico to view cataloged waveforms. Any work around known?

Technician
TwoWaves
TwoWaves
Posts: 556
Joined: Thu Apr 24, 2014 8:32 pm

Re: initial cold start cranking, starter bucking like a crossfire

Post by Technician » Fri Oct 04, 2019 10:48 pm

No sorry, you need to have a PicoScope connected to your PC to access the waveform library. The value for money you would receive from owning a PicoScope outweighs the initial investment considerably.

Have a look here you will not be disappointed;

https://www.picoauto.com/products/automotive-oscilloscope-kit/overview

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