Immediate Closed Loop
12-17-2014, 11:43 AM
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Car: 1991 Z28 Vert
Engine: 305 TPI
Immediate Closed Loop
Just started data logging while I wait on Christmas cash to buy myself an Ostrich. 
The car sat for a year while I replaced the fuel pump, injectors and intake gaskets in my spare time (none).
Two things jump out at me while I watch the car idle...first, it goes into closed loop immediately. Never even blips over to open for a second as far as I can tell.
Second is that BLM starts in the upper 130's and creeps to 159. I've got an exhaust leak right after the cat and I've read that can cause high BLMs. Any advice?
The car sat for a year while I replaced the fuel pump, injectors and intake gaskets in my spare time (none). Two things jump out at me while I watch the car idle...first, it goes into closed loop immediately. Never even blips over to open for a second as far as I can tell.
Second is that BLM starts in the upper 130's and creeps to 159. I've got an exhaust leak right after the cat and I've read that can cause high BLMs. Any advice?
12-17-2014, 02:04 PM
#2
Re: Immediate Closed Loop
I assume this is a factory PROM?
In which case, closed loop is both time dependent and coolant temp dependent in the $8D. How's your coolant temp sensor? What's the readout in the data log compared to the gauge on the dash? If it's reading higher than actual, could fool the ECM into thinking you're up to temperature when you're not.
Not sure how it's circumventing the time dependency though. Even if the engine was fully warmed up, shut off, then re-started, from memory, I believe it would still take a minute or so of running before it went into closed loop.
You're saying you're NEVER in open loop even for a second? Even when starting cold in the morning?
Want to figure this issue out first before analyzing the 159 BLM...
Do you have a datalog export to post? Maybe .csv format that can be pulled into Excel?
In which case, closed loop is both time dependent and coolant temp dependent in the $8D. How's your coolant temp sensor? What's the readout in the data log compared to the gauge on the dash? If it's reading higher than actual, could fool the ECM into thinking you're up to temperature when you're not.
Not sure how it's circumventing the time dependency though. Even if the engine was fully warmed up, shut off, then re-started, from memory, I believe it would still take a minute or so of running before it went into closed loop.
You're saying you're NEVER in open loop even for a second? Even when starting cold in the morning?
Want to figure this issue out first before analyzing the 159 BLM...
Do you have a datalog export to post? Maybe .csv format that can be pulled into Excel?
12-17-2014, 02:35 PM
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Car: 1991 Z28 Vert
Engine: 305 TPI
Re: Immediate Closed Loop
Factory PROM for now. Coolant temp is spot on with the gauge. Fan cycles on and off perfectly.
I'll double check to see if it even flashes open on start. I can tell you in the time it takes me to scroll to the bottom of the page where the status is, it's closed.
I'll sneak out tonight and start gathering some logs.
I'll double check to see if it even flashes open on start. I can tell you in the time it takes me to scroll to the bottom of the page where the status is, it's closed.
I'll sneak out tonight and start gathering some logs.
12-20-2014, 05:42 PM
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Re: Immediate Closed Loop
I found the closed loop issue..a bad radiator cap!
I'm waiting on a replacement battery for my laptop so I can get some logs. It won't run on an inverter.
I'm waiting on a replacement battery for my laptop so I can get some logs. It won't run on an inverter.
12-22-2014, 09:27 PM
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Car: 1991 Z28 Vert
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Re: Immediate Closed Loop
OK. Here are a couple of logs from today. My Ostrich is on its way. I can't wait! The first one has idle for the first six minutes. There's one WOT and the rest is in traffic cruising.
The second has more WOT in it.
https://drive.google.com/file/d/0Bxr...ew?usp=sharing
https://drive.google.com/file/d/0Bxr...ew?usp=sharing
Thanks for taking a look!
The second has more WOT in it.
https://drive.google.com/file/d/0Bxr...ew?usp=sharing
https://drive.google.com/file/d/0Bxr...ew?usp=sharing
Thanks for taking a look!
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