TBI ALDL info?

[udidwht]

Just want to get a better perspective of the fuel map...

Pulled these from my 454 TBI how do they look? Typed below the (low-high reading for each) This was while cruising down the highway.

IAC position - 129.0

IAC desired - 129.0

Coolant - 215.0

Battery voltage- 13.4

TPS volts - 1.353 -

MAP - 59.8 - 60.907

O2 Sensor mVolts - low of 79.56 - high of 791.18 (mostly in the hundreds range)

Barometric - 97.069

Vehicle speed - 56.0mph

Fuel pump - 13.0 volts

Engine speed - 2650rpm

EGR duty - 72.XX - 74.XX

Seconds - 11147.0

Desired idle - 750rpm

TPS % - 20.784

Spark advance - 33.047 - 34.805

Knock count - 103.0

INT - 127.0

Rich/Lean - 3.0 - 73.0 (consecutive count)

BLM Cell - 10.0

BLM- 136.0

Knock retard - 0.0

BPW - 3.311 - 3.51 (ranged btwn)

Actual EGR - 40.0 - 41.961 (ranged btwn)

CCP Duty - 99.608

MAT F - -40.0

Channels 1, 2, 3, 4 (no Data)

[NomakeWan]

Instant readings don't tell you much when you're analyzing a dynamic system like an engine. My recommendation would be to provide a log of the engine running as CSV or XML or some other importable, graphable format so that you can graph the various parameters over time and compare them to other values as they change.

That said, it would appear your manifold air temp sensor is disconnected. Also, generally a BLM over 128 is indicating a lean condition, though again only seeing a tiny instantaneous reading doesn't tell us much about how the BLMs are reacting over time. Still, 136 is on the lean side of 128. If the majority of your BLMs are that far over 128, you may want to see about adjusting the injector constant to compensate and work from there.

[udidwht]

Instant readings don't tell you much when you're analyzing a dynamic system like an engine. My recommendation would be to provide a log of the engine running as CSV or XML or some other importable, graphable format so that you can graph the various parameters over time and compare them to other values as they change.

That said, it would appear your manifold air temp sensor is disconnected. Also, generally a BLM over 128 is indicating a lean condition, though again only seeing a tiny instantaneous reading doesn't tell us much about how the BLMs are reacting over time. Still, 136 is on the lean side of 128. If the majority of your BLMs are that far over 128, you may want to see about adjusting the injector constant to compensate and work from there.

This RV doesn't have an intake air temp sensor on it. I was curious as well as to the -40 reading. I've looked high and low and definitely there is no IAT on this engine. As for the BLM, didn't have much of a run but was under the impression that 136 wasn't an issue. But with (29yrs) 74.XXX miles on this and the TBI haven never been rebuilt perhaps the regulator diaphragm is weakening. I'll be rebuilding it shortly here.

I've replaced pretty much all the rubber items and sensors due to age using Delco parts. Rebuilt the distributor replacing the ICM, Pick up coil, cap and rotor. Engine runs strong and no codes thrown.

[udidwht]

With respect to the BLM and/or INT what would typical numbers look like given varying condition/s?

[NomakeWan]

If you are unsure of the condition of the engine components, the first thing you should be doing is replacing the O2 sensor. If this engine is still using the old TBI unheated one-wire O2 sensor, those are really not that great and don't last nearly as long as the heated O2 sensors that were introduced along with the sequential-injection LT1 in '94. So if you don't know if they've been replaced and you're unaware of their condition, just replace them. No sense chasing your tail looking at INT and BLM if the O2 sensor is not reacting accurately.

As for fuel, just hook a pressure gauge up to the port on the rail and watch it under load. I'm not intimately familiar with TBI engines so I can't tell you what the proper base fuel pressure is for a 454 TBI. If you know the correct value, then a pressure gauge is an easy and cheap way to confirm. Plus you can check to make sure it's actually able to hold pressure while you're at it. Again, no sense chasing your tail over bad readings if the underlying problem is something mechanical and not the tune.

If there's no IAT sensor, I'd wonder why that data is in the datastream. Hopefully it's just a bad datastream definition. If the ECM is actually trying to make corrections based on an IAT that doesn't exist, obviously that could be a problem. But again, I don't know enough about your engine to say.

Good luck!

As for BLMs, you should be looking for 124~132. Preferably 128 or lower. If you start seeing things going to 136 or higher, that's lean, so you'd be best to avoid that. But again, make sure your O2 sensor is actually good and your fuel pressure is solid before you try to mess around in the tune.

[udidwht]

If you are unsure of the condition of the engine components, the first thing you should be doing is replacing the O2 sensor. If this engine is still using the old TBI unheated one-wire O2 sensor, those are really not that great and don't last nearly as long as the heated O2 sensors that were introduced along with the sequential-injection LT1 in '94. So if you don't know if they've been replaced and you're unaware of their condition, just replace them. No sense chasing your tail looking at INT and BLM if the O2 sensor is not reacting accurately.

As for fuel, just hook a pressure gauge up to the port on the rail and watch it under load. I'm not intimately familiar with TBI engines so I can't tell you what the proper base fuel pressure is for a 454 TBI. If you know the correct value, then a pressure gauge is an easy and cheap way to confirm. Plus you can check to make sure it's actually able to hold pressure while you're at it. Again, no sense chasing your tail over bad readings if the underlying problem is something mechanical and not the tune.

If there's no IAT sensor, I'd wonder why that data is in the datastream. Hopefully it's just a bad datastream definition. If the ECM is actually trying to make corrections based on an IAT that doesn't exist, obviously that could be a problem. But again, I don't know enough about your engine to say.

Good luck!

As for BLMs, you should be looking for 124~132. Preferably 128 or lower. If you start seeing things going to 136 or higher, that's lean, so you'd be best to avoid that. But again, make sure your O2 sensor is actually good and your fuel pressure is solid before you try to mess around in the tune.

Much appreciated for the reply.

I replaced the O2 sensor with a Delco one (single wire) just a few years ago. The engine runs great just getting a feel for the proper tune. This only has the (1) O2 which is before the muffler. I also have a fuel adapter fitting that I will install on the TBI inlet (replace the OE one) which I will then install a fuel schrader valve. This way I can quickly check the fuel pressure if need be. Bought the following...

https://marine-performance-parts.com...843505774.aspx

https://www.dieselorings.com/schrade...-1-8-mnpt.html

Being a step above a traditional carb set up I'm curious why they were not leaning these engines out more at part throttle condition (say 15-16afr) to get it to run cooler given they had the ability with the advanced timing. In the air-cooled engine world VW/Porsche we can achieve cooler running temps with an AFR at 16:1 than at 13:1 with a vacuum advance and part throttle condition. The hottest zone would be 14-15afr under load/WOT...Deathzone. Given I'm rebuilding the TBI and replacing the regulator diaphragm that may aid in the pressure holding more steady and help the afr.

The following illustrates this....https://www.advancedpilot.com/articl...articleid=1844

[TriumphR3]

The '94 - '95 units run at 30 psi versus 13 psi for the previous units.

[udidwht]

Correct. 26-32psi to be precise.

[In-Tech]

Hiya,
Your EGR passage is partially plugged causing the computer to add fuel.

[udidwht]

How'd you come up with that?

EGR is fairly new (1.5yrs) AC Delco. It is an electronic EGR (linear).

Anyone know the EGR passage diameter & length of passage? I'll get a long flexible tube brush and run down it with some 'Deep creep'.

Didn't appear to have excess build up when I replaced the EGR (due to age).