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Intermittent EST / Code 42 — 1989 K5 Blazer 5.7L TBI, 700R4
- Thread starter clutch2k3
- Start date
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.
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:
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).
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).
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.
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?
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.
Hey @Wes Harden @dyeager535 @Fastereddie — what's y'alls opinion on replacing an 89 TBI setup with Megasquirt 2?
I've been chasing this intermittent code 42 for over a year now and I'm done troubleshooting it.
It shows up between every 10-20 startups. Feels like ~55% of the time it kicks off within a mile of startup, ~40% of the time while it's at operating temp sitting at a stoplight, and the other ~5% who knows. Sometimes it leads to it stalling on me.
So I've decided this 37 year old ECM has done all it's gonna do for me. The stall is the real dealbreaker — I don't feel right loading the family up for a road trip knowing I could randomly lose power steering and brakes. We want to tow a small camper with this thing too, so "probably fine" isn't good enough anymore.
So I've narrowed it down to two options:
**Carb swap** - non-computer HEI, regulator, manual TCC toggle. Cheap, zero electronics, fixable on the side of the road with hand tools. Downside is it tosses everything I've already got — TBI unit, injectors, IAC, all the sensors and pigtails I've sunk money into.
**Megasquirt 2 ** - keeps all that existing hardware, plus I get an actual adjustable idle target (the stock ECM is hard coded around 525 RPM and fights me every time I need ~650 RPM for the AC compressor and alternator), TCC lockup, and data logging. Runs TunerStudio, so I'd be doing my own tuning.
I'm leaning hard toward the MegaSquirt. Curious if anybody here has run one on a TBI 5.7, or if y'all think I'm nuts and should just throw a carb at it and be done.
I've been chasing this intermittent code 42 for over a year now and I'm done troubleshooting it.
It shows up between every 10-20 startups. Feels like ~55% of the time it kicks off within a mile of startup, ~40% of the time while it's at operating temp sitting at a stoplight, and the other ~5% who knows. Sometimes it leads to it stalling on me.
So I've decided this 37 year old ECM has done all it's gonna do for me. The stall is the real dealbreaker — I don't feel right loading the family up for a road trip knowing I could randomly lose power steering and brakes. We want to tow a small camper with this thing too, so "probably fine" isn't good enough anymore.
So I've narrowed it down to two options:
**Carb swap** - non-computer HEI, regulator, manual TCC toggle. Cheap, zero electronics, fixable on the side of the road with hand tools. Downside is it tosses everything I've already got — TBI unit, injectors, IAC, all the sensors and pigtails I've sunk money into.
**Megasquirt 2 ** - keeps all that existing hardware, plus I get an actual adjustable idle target (the stock ECM is hard coded around 525 RPM and fights me every time I need ~650 RPM for the AC compressor and alternator), TCC lockup, and data logging. Runs TunerStudio, so I'd be doing my own tuning.
I'm leaning hard toward the MegaSquirt. Curious if anybody here has run one on a TBI 5.7, or if y'all think I'm nuts and should just throw a carb at it and be done.
