90 Grand Wagoneer - chasing cold start hesitation/rough idle

[Theodore]

If I'm reading the BLM plot correctly, the average BLM is Lean (above 128). The other plots look mostly normal.

I'm currently working on a International Harvester (IH) TBI conversion using an EFI Distributor from Performance Distributors ( https://performancedistributors.com/.../distributors/ ). The IH will have computer controlled timing. The IH is using the second generation TBI Computer 16197427. The 1227747 is a good TBI computer, the 16197427 is better because has a faster processor, more tuning parameters, and very affordable.

I built custom EFI Harness, send me a Private Message (PM) if you would like me quote a harness.

dave w

Hey, DaveW - on BLM, agree you're reading it right - average BLM for the entire log period is 135.83. Before we look at ditching what i have, thinking out loud,

Given the age of the system, and the fact that i don't know what the .bin has defined. Have been wondering about what it takes to read the chip to understand what's programmed vs. assuming/guessing? i know AFI originally built the system, but i don't know where the chip came from, and whether it's original, or not. Truth be known, now that i think of it - i really don't know if the two actually went together, or just happened to be sold together... I'm not really interested in burning chips myself, but would love to know how things are supposed to be set, based on the programming. To date, i've read just enough to wonder, but i don't want to spend $100's either on curiosity right now. I feel like we're close to a solution, but can't tell how close.

Also, i've thought about taking it to a shop & having a full vacuum test run (intake & exhaust), and see about putting the leak question to bed. Given the conversations around running 'lean', it seems it's a question of not enough fuel, or too much air.

Right now, i have new battery & ground cables on order - am planning on waiting to see what we get w/that & go from there.

[dave w]

The Moates.net Burn 2 can read the 1227747 chip. https://www.moates.net/burn2-chip-programmer-p-197.html

The 1227747 uses a 2732 chip. The 2732 has variants, 25V, 21V and 12.5V. The 2732 used in the 1227747 is an EPROM which can be erased with a UV light and then reprogrammed. The Moates.net Burn 2 Can Not program a 2732 chip. The Moates.net Burn 2 is READ ONLY for a 2732 chip.

If you want to know what is programmed in your chip, likely the best option is to find someone local to you with a 2732 chip reader.

dave w

[Fast355]

The Moates.net Burn 2 can read the 1227747 chip. https://www.moates.net/burn2-chip-programmer-p-197.html

The 1227747 uses a 2732 chip. The 2732 has variants, 25V, 21V and 12.5V. The 2732 used in the 1227747 is an EPROM which can be erased with a UV light and then reprogrammed. The Moates.net Burn 2 Can Not program a 2732 chip. The Moates.net Burn 2 is READ ONLY for a 2732 chip.

If you want to know what is programmed in your chip, likely the best option is to find someone local to you with a 2732 chip reader.

dave w

Dave,
The AFI system I tuned had a Moates adapter and an Amtel 29C256 flash chip installed. Not sure if he did them all like that or if someone else had done it.

[Theodore]

Hey, DaveW, et.al., Question: i've heard the term 'computer controlled timing', which in my mind, says the ECM is controlling the timing vs. what i'm thinking i have here is the ICM (Ignition Control MOdule) is controlling the timing, true? or, are both versions 'computer controlled timing', since there's no vacuum advance?

Thanks for the help - i feel like i'm heading down a rabbit hole - not sure how much further it is to bottom.

[dave w]

Every project ultimately has to reach a decision; is good enough, really good enough or is there something better?

The ICM cannot be programmed to optimize the timing (Spark Advance).

See sample 1227747 timing table below. The 1227747 controls the Spark Advance via the ignition control module. 1227747 timing tables use a metric vacuum scale call Kilo-pascals (Kpa). WOT Kpa is 100 (kind of like- nearly Zero Hg), and coasting down a 3 mile long 10% grade is 10 Kpa (kind of like nearly 20 Hg). Cruising on a level grade at 70 MPH is usually between 50 Kpa to 70 Kpa.

Better just might be the ability to optimize the timing (Spark Advance) at WOT, Cruise, and Idle?

GM Ignition Module / ECM schematics are also attached below.

dave w

[Theodore]

Thanks for the background - this stuff's new to me. Reading/learning more everyday. Have read quite a bit that EFI systems are susceptible to flakiness due to bad electrical connections - i suspect a lot of the issues i've seen to date have been due to a large number of bad splices & the voltage drop associated with them, not to mention, a myriad of vacuum leaks i've found/fixed to date. When i started this journey last summer, ECM reported battery voltage was ~12.1-12.5V. Today, it ranges 13.8-14.2V. Am planning on replacing battery cables & adding an engine to frame ground strap this weekend pulling another log, and going from there. Am thinking a good next step is having a formal vacuum test run to ensure i have no leaks in intake or exhaust, then proceed to looking at the .bin for mismatches, like the EGR's enabled, but doesn't exist, wrong injectors defined, etc.

[In-Tech]

Thanks for the background - this stuff's new to me. Reading/learning more everyday. Have read quite a bit that EFI systems are susceptible to flakiness due to bad electrical connections - i suspect a lot of the issues i've seen to date have been due to a large number of bad splices & the voltage drop associated with them, not to mention, a myriad of vacuum leaks i've found/fixed to date. When i started this journey last summer, ECM reported battery voltage was ~12.1-12.5V. Today, it ranges 13.8-14.2V. Am planning on replacing battery cables & adding an engine to frame ground strap this weekend pulling another log, and going from there. Am thinking a good next step is having a formal vacuum test run to ensure i have no leaks in intake or exhaust, then proceed to looking at the .bin for mismatches, like the EGR's enabled, but doesn't exist, wrong injectors defined, etc.

Hello,
At any point in time this has all been new to all of us. Wiring issues have been around since there was wire, lol. In an automotive environment never be afraid to add more grounds, actually in most cases. Injector information is almost a waste of time these day, having an injector flow test machine has proven that to me so it goes back to "give it what it wants".

It really sounds like you are on your way to having a nice vehicle when you are finished.