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Intermittent EST / Code 42 — 1989 K5 Blazer 5.7L TBI, 700R4

I always try to buy the best plug wires I can, not just the cheapo parts store units.
I've been zapped by HEI before, and its not fun.
 
It had been a long stretch without a code 42

Got an EST SES today. Engine wasn't fully warmed up, coming to a stop light, pointed down hill, it stalled but started right back up. I needed to pulse the throttle to keep it running at the stoplight.

I pulled over, turned it off for a minute or 2 and it started back up with timing working fine. Then I drove it around town doing errands for 3 hours and it was fine.

:shoulder-shrug:
 
I have had 43 show up on mine (intermittently) as well. Whenever it occurred, the Blazer started running/driving like s***. I would basically pull over and stop and then fire it up later and it would be fine.

There is a small tube that looks like a piece of macaroni... it bolts to the transmission bell housing on the passenger side... if I recall correctly one of the EST circuit wires runs through it. My macaroni tube piece was missing and my wire had a pretty significant nick in it. I wrapped it in heat-shrink and reinstalled the tube to protect it better. I haven't had a code 43 show up since then (a year or two ago).
 
I think code 43 is for ESC, the knock sensor, and the ESC sensor wire goes through the macaroni tube.

2 years ago my k5 was throwing code 43s until I replaced the ESC sensor, it's 1 wire connector, the ESC module and it's connector.

I'm not sure if an ESC issue (code 43) can cause an EST issue (code 42).
 
Iirc the code 42 is going to set everytime the engine stalls, no matter the reason. If by chance the egr was stuck open and stalled while coming to idle, code 42 will set.
 
I think code 43 is for ESC, the knock sensor, and the ESC sensor wire goes through the macaroni tube.

2 years ago my k5 was throwing code 43s until I replaced the ESC sensor, it's 1 wire connector, the ESC module and it's connector.

I'm not sure if an ESC issue (code 43) can cause an EST issue (code 42).

Agh, my bad! I got the two circuits confused a bit there.
 
Back on the 7th, timing was lost, SES turned on, ran poorly for about 2 seconds and then stalled. I believe the timing issue caused the stall, not the other way around.

Yesterday we drove it for 15 minutes, parked it for an hour and then when leaving and getting back on the main road, it backfired! No SES.

Backfiring is caused by bad timing or lean fuel, right? Anything else that could cause a backfire?
 
spark leak across spark plug wires, carbon traces/crack in cap. Yes a rapid lean condition could cause a back fire.
 
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