1987 454 TBI stalls at idle after a short time

[Bill USN-1]

Thanks,

Mike

Been a couple weeks, any progress?

 

[beady]

Been a couple weeks, any progress?

Sorry, was too damn cold to do anything for seemingly weeks, then I had the flu this week.

I bought a new Bosch 12014 single wire O2 sensor (didn’t want to mess with adding other variables with 3-wire, and cheap) and installed it today. Computer not seeing the O2 sensor it seems, reading still never changes from .451 v and nothing gets populated on the o2, blm, or int tables.

I cleared all codes and it is not showing any codes now. Should it throw a code not seeing any O2 signal change? I let it warm up to operating temp with the same result.

Guess I’ll look for the ecu pin out and see if I can read changing at the ecu connector pin and/or check continuity from ecu connector pin to the O2 connector.

I’m open to other suggestions on what to check.

Thanks,

Mike

 

[gmbellew]

Sorry, was too damn cold to do anything for seemingly weeks, then I had the flu this week.

I bought a new Bosch 12014 single wire O2 sensor (didn’t want to mess with adding other variables with 3-wire, and cheap) and installed it today. Computer not seeing the O2 sensor it seems, reading still never changes from .451 v and nothing gets populated on the o2, blm, or int tables.

I cleared all codes and it is not showing any codes now. Should it throw a code not seeing any O2 signal change? I let it warm up to operating temp with the same result.

Guess I’ll look for the ecu pin out and see if I can read changing at the ecu connector pin and/or check continuity from ecu connector pin to the O2 connector.

I’m open to other suggestions on what to check.

Thanks,

Mike

seems I remember somewhere about issues with Bosch O2 sensors not working well.

constant .45v means the ECM and wiring is ok. but for some reason the O2 voltsge isnt changing. I'd try an AC Delco O2 and see if that fixes it.

 

[Bill USN-1]

seems I remember somewhere about issues with Bosch O2 sensors not working well.

constant .45v means the ECM and wiring is ok. but for some reason the O2 voltsge isnt changing. I'd try an AC Delco O2 and see if that fixes it.

Nope.
Unplug your O2 and the aldl will still show .45mv

 

[Bill USN-1]

Sorry, was too damn cold to do anything for seemingly weeks, then I had the flu this week.

I bought a new Bosch 12014 single wire O2 sensor (didn’t want to mess with adding other variables with 3-wire, and cheap) and installed it today. Computer not seeing the O2 sensor it seems, reading still never changes from .451 v and nothing gets populated on the o2, blm, or int tables.

I cleared all codes and it is not showing any codes now. Should it throw a code not seeing any O2 signal change? I let it warm up to operating temp with the same result.

Guess I’ll look for the ecu pin out and see if I can read changing at the ecu connector pin and/or check continuity from ecu connector pin to the O2 connector.

I’m open to other suggestions on what to check.

Thanks,

Mike

All the wiring diagrams are in the injection forum on binderplanet.com
Here's the pinout with the key on test you can perform.
Just back pin the connector.
I normally remove the blue comb to make it easier.
So, unplug connector from ECM, find pin D7 and read it from connector to your O2 connector.
Then check the O2 sensor gnd to eng gnd.
Error codes are based on specific criteria.
Normally you won't get an O2 error until you drive it fully warmed and the ECM is waiting for a specific reading.
This can also include VSS input like the EGR test uses.

 

[beady]

All the wiring diagrams are in the injection forum on binderplanet.com
Here's the pinout with the key on test you can perform.
Just back pin the connector.
I normally remove the blue comb to make it easier.
So, unplug connector from ECM, find pin D7 and read it from connector to your O2 connector.
Then check the O2 sensor gnd to eng gnd.
Error codes are based on specific criteria.
Normally you won't get an O2 error until you drive it fully warmed and the ECM is waiting for a specific reading.
This can also include VSS input like the EGR test uses.

I went and drove it while you were posting that to see what happened. I did get a few hundredths change and it populates 3 cells of the O2 table. The truck has what look like aftermarket cast manifolds. The O2 sensor is on the driver side collector, o2 reading only changed when I got on it a few times so I’m guessing it isn’t getting hot enough.

I found the 3-wire sensor and adapter I had (GM 19178959), I’ll try it tomorrow. I have a ‘93 OBS 2500 350 TBI Suburban also (it’s totaled tho), I had bought the sensor from Harris maybe 2 yrs ago but never installed it.

Oh yeah, it is showing O2 error code after driving.

Thanks,

Mike

 

[Bill USN-1]

I went and drove it while you were posting that to see what happened. I did get a few hundredths change and it populates 3 cells of the O2 table. The truck has what look like aftermarket cast manifolds. The O2 sensor is on the driver side collector, o2 reading only changed when I got on it a few times so I’m guessing it isn’t getting hot enough.

I found the 3-wire sensor and adapter I had (GM 19178959), I’ll try it tomorrow. I have a ‘93 OBS 2500 350 TBI Suburban also (it’s totaled tho), I had bought the sensor from Harris maybe 2 yrs ago but never installed it.

Oh yeah, it is showing O2 error code after driving.

Thanks,

Mike

If you drove it, you should have logged data and BLM.

 

[beady]

If you drove it, you should have logged data and BLM.

I went ahead and installed the 3-wire O2 but just rigged up the power to it temporarily. There are more O2 sensor readings now, but it doesn't change a lot.

It still populates zero cells in the BLM or INT tables. I don't know why. It does populate the O2 table cells though.

I took a short drive up the country road and back and logged with the 3-wire O2 active, log attached to this post.

Mike

 

[beady]

I went ahead and installed the 3-wire O2 but just rigged up the power to it temporarily. There are more O2 sensor readings now, but it doesn't change a lot.

It still populates zero cells in the BLM or INT tables. I don't know why. It does populate the O2 table cells though.

I took a short drive up the country road and back and logged with the 3-wire O2 active, log attached to this post.

Mike

You must be registered for see images attach

 

[Rusty Nail]

Hello again, I have this new to me 1987 454 TBI suburban that I’ve been chasing problems down in. Today’s issue is stalling after a few mins of idling.

The previous problem was power being way down, to the point where it would max out at 47 mph and you could only use literally the first 1/4” of throttle travel before it would rev seemingly ok, but make even less power. This turned out to be a loose/worn distributor/cap. I replaced distributor and more, and it ran pretty well for a week. I put maybe 50 miles on it, but last week I started it and walked away and it stalled a minute or so later. Now seems to be the truck’s MO. What I’ve replaced or checked:

Brand new:
DUI distributor, coil, wires
Delco plugs
MAP sensor
Delco injectors
Delco FPR rebuild kit

Fuel pressure was 13 psig after filter
Timing set at 4-5 dtbc with ignition wire disconnected

Here’s a video of it stalling I took earlier today:

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The last thing I did was the distributor, coil, plugs, wires all at once. The idle sounds great, nice and smooth, no bounce or bauble. I’d love any thoughts or ideas on what to do/check next.

Thanks,

Mike

This is High Quality posting Mike..lemme have a look.