Another TBI running rich

[Insert Quarter]

I'm thinking the Bosch O2 might be my issue as it was the last thing I replaced.

I don't recall the truck had this cold start issue before the new O2... and I've heard in some applications the 1 wire Bosch units don't light off fast enough.

My buddy scanned it and said the O2 readings were correct during the problem times but my gut says try a different O2 sensor...

FWIW - #15 - https://harristuning.com/Tbi/recommended-350-tbi-mods/

 

[opus]

I don't Google. They're evil. Just tell me if the problem occurs during closed-loop, or open-loop operation

You're connected to the internet, you've forfeited everything, dont blame Google.

Open

 

[Dave11]

I bet a dollar to a dozen Krispy Kreme doughnuts, it’s gonna be the ground wires at the thermostat housing not making a good connection. Or the one that’s on back of the passenger cylinder head. It’s not a chassis ground problem, it’s a ecm ground. I normally take all them grounds on thermostat housing cut the eyelet terminal off strip them all back and put them on one terminal and ground it to the engine.

 

[opus]

I bet a dollar to a dozen Krispy Kreme doughnuts, it’s gonna be the ground wires at the thermostat housing not making a good connection. Or the one that’s on back of the passenger cylinder head. It’s not a chassis ground problem, it’s a ecm ground. I normally take all them grounds on thermostat housing cut the eyelet terminal off strip them all back and put them on one terminal and ground it to the engine.

I have removed and cleaned then 5 times. I did not cut the ends off because everything ohm'd out ok.

The ground is not on the thermostat housing. Guess I can replace them for giggles.

 

[Schurkey]

Open

In Open-loop operation, the computer is ignoring the O2 sensor. Not likely to be an O2 sensor fault, then.

 

[Redneckgeriatric]

block the map and try it. when u disconnect the tan wire (timing ), you are taking the icm, esc, and map out of the equation. you are also forcing open loop. some may call this "limp mode".

do some research (not on google ), lol, on how and when the ecm tables are written. start at cranking enrichment, warm up, open and closed loop, etc. now, look at reference points that are used to dictate which tables it is running on at what times. what causes the transistions between tables?
hint: temperature and timer. temperature being the one we notice. the engine temp is THE most crucial input of all sensors.

homework: how would you smooth the transistions between tables?

 

[opus]

block the map and try it. when u disconnect the tan wire (timing ), you are taking the icm, esc, and map out of the equation. you are also forcing open loop. some may call this "limp mode".

do some research (not on google ), lol, on how and when the ecm tables are written. start at cranking enrichment, warm up, open and closed loop, etc. now, look at reference points that are used to dictate which tables it is running on at what times. what causes the transistions between tables?
hint: temperature and timer. temperature being the one we notice. the engine temp is THE most crucial input of all sensors.

homework: how would you smooth the transistions between tables?

Temperature isnt doing this [I dont believe]. Its all over in less than 2 mins from cold start. I think its only 1 transition point. I would edit that one fuel table leaner. I dont know though, I'm a carb guy. I'd open the choke sooner.

I'm going to add a ground today and try it. I'll block the MAP too, but I think I've done that. I'm going to unhook the EGR as well. That I have tested but....

As far as research, all I have is the internet.

 

[Stillruns]

In my instance, it seems as though the rich stumbling issue happens just as the ECM goes closed loop.

I checked ecm ground at t-stat bolt which was clean and not corroded at all. Wire to crimp terminal solid...

I did replace coolant temp sensor with a Standard Motor Products replacement and it seems to function normally.

The problem is so consistent both in behavior and time of occurrence, my brain is telling me either O2 not heating fast enough or ecm issue.
Btw... I replaced the entire exhaust system from manifolds back... All stock

I'll update after O2 replacement...

 

[Erik the Awful]

I have removed and cleaned then 5 times. I did not cut the ends off because everything ohm'd out ok.

Be careful when ohming. A single wire making a connection will give you 0.0 ohms on your meter, but under a load you can effectively have an open circuit. That said, if the wires are clean and unbroken and the crimp is tight, I'd trust it.

 

[opus]

The temp out side was such that it wouldnt even start unless I unplugged the timing wire. I unplugged EGR, MAP, Charcoal filter, EGR....same problem.

When its doing its thing, standing on the bumper, I hear a clicking, as in a spark plug wire grounding out, not as loud though. I sprayed carb cleaner to find if there was a spark....nothing. Its not a wire grounding out, do the injectors click?

I'll start it after dark just to double check.