90 Grand Wagoneer - chasing cold start hesitation/rough idle

[Theodore]

Am looking for help w/an issue i've been chasing since we owned the Wagoneer: rough idle/hesitationat cold start, and hesitation/backfire - when running at highway speed & letting off the throttle, coasting a bit, then getting back in it.


Jeep is a bit of a Frankenstein, with parts making quite a long-strange trip before being mated together in East Tennessee. From what ive been able to piece together, the AMC 360 engine was in a Grand Wagoneer (not sure the year), when AFI's EFI (1227747 ECM) were installed in 2006 in NJ. The engine & EFI was eventually sold to a Jeep junkyard in NC 3-4 years back (not sure what happened to the original Wagoneer), and subsequently sold to the previous owner of my Jeep, to mate with a body he'd found in Atlanta. To add to the mystery, from the high elevation sticker under the hood & the lack of rust, am thinking the body was originally out West somewhere.


With that out the way, over the last couple weeks, have dug in & fixed a myriad of issues relating to voltage drop & the ECM reading low battery voltage (~12.5V). By performing voltage drop tests on the 3 power-related ECM connections (pins A6, B1, & C16), tracing wires, removing short splices of wire & re-splicing, cleaning grounds, cleaning electrical connections with DeoxIT D100 contact cleaner, finding/fixing a cracked/corroded fuse, etc., i've seen battery voltage reported by the ECM rise from 12.5V to 14.2V, resulting in a better running, quieter engine. Overall, it's never run better.


But, i'm still chasing the:
- hesitation at cold start
- intermittent dying when going from park to drive
- backfire at speed problem,
that it's had since day one.


Over the last few days, i've noticed that when comparing voltage measured by back-probing the ECM connections w/multimeter vs. what the ECM reports, that there's a .2-.4V variance - the ECM reporting lower. Am wondering if i have a bad connection with one of the pin connectors in the ECM harness?


Here's the car we're working on:



Cracked fuse worth ~1V! Battery voltage reported by ECM jumped from 13.2 to 14.2.



ALDLdroid dashboard after the wiring cleanup effort - Battery Voltage - lower right.



Attached are the latest set of data logs, would appreciate your taking a look & see if anything jumps out. One thing i notice in the logs is voltage drops the longer the engine runs... So far, i'm only driving it in a 6-10 mile loop that includes in-town & highway driving, so am wondering how far it would continue to drop if i drove longer/further? Am planning on taking it out later on this weekend, for a longer test drive & see what happens.


Right now, the ECM is in mounted in a box under the hood, on the driver's fender where the rear window washer bottle should be. Given the hacked up nature of the EFI harness, am planning on getting a new one & moving the ECM to inside the Jeep - just wanted to get it running properly first. Am wondering, given all the trials/tribulations dealing w/the existing harness, whether i might be better off, to get a new harness & start over?


Wondering: could engine heat be affecting measured voltage? Such that, we could expect an improvement once i move the ECM into the cabin?

Thanks.

[dave w]

Does the Wagoneer have a Vehicle Speed Sensor (VSS)?

dave w

[Theodore]

Does the Wagoneer have a Vehicle Speed Sensor (VSS)?

dave w

Hey, Dave, honestly, I don’t know. Reading thru the AFI owners manual, VSS shows as optional. May have to do some wire tracing to figure it out. Fortunately I found the ECM pin-out diagrams elsewhere on the site to give me an idea of where to start.

[ony]

jeeps an guns use to have jeeps,might contact him

[Theodore]

jeeps an guns use to have jeeps,might contact him

Thanks, ony - will do. Am thinking he's who took a set of Wagoneer leaf springs i had to give-away a few months back.


BTW, a couple aspects worth knowing, is: IAC, TPS, & MAF are new. The EGR valve is there, but no vacuum line is connected. EGR Vacuum port was uncapped, when i got the Jeep; i capped it a few months back when i replaced all vacuum lines to prevent dirt from getting in it. The vacuum switch that the EGR vacuum line would connect to is missing.

For additional context:
- initial timing is set to 10 degrees BTDC
- used bluetooth OBD1 scanner, with ALDLdroid to set up:
---- base idle (650-700 warm), IAC & TPS
---- initial setup for IAC
---- initial setup for TPS
- fuel pressure shows 12 lbs - steady
- fuel filter is relatively new
- not done anything w/o2 sensor

[dave w]

The factory specification for most TBI engines is ZERO degrees BTDC.

The VSS has caused some debate on the board over the years. Most members agree it not NECESSARY. Most members agree it NICE to have. Some members have reported unexpected stalling was NICELY eliminated with adding a VSS.

dave w

[Theodore]

The factory specification for most TBI engines is ZERO degrees BTDC.

The VSS has caused some debate on the board over the years. Most members agree it not NECESSARY. Most members agree it NICE to have. Some members have reported unexpected stalling was NICELY eliminated with adding a VSS.

dave w

Hey, Davew -

re: timing - have had it all over the place; in talking to AFI, they said, given my setup (separate distributor w/ICM & coil) vs. ECM-controlled spark, that 0 BTDC wouldn't work for me. I had it there for a while back last Fall & saw severe power loss. Truth be known, i've had the timing all over the place, 0, 5, 10, & 15, and saw severe running issues everywhere but 10. A few people over on the FSJ forum recommended 10, and it's run the best there. Eventually, i tripped across an original emissions sticker that showed 10+-2 at low altitude.



re: VSS - will take a look at that & see what i can find on the forum. Hadn't seen anything about that. Am assuming if i did something like that, that i'd need a new chip burned to account for it, true?

Today, i pulled & attached a 30 minute log for the car running at idle.

Thanks.

[tayto]

whatever you set your initial to must be reflected in the bin. while most stock TBIs are 0* initial, i found 10* worked well with faster cold and hot starting.

[dave w]

I did not realize the distributor timing Was Not controlled by the 1227747 computer.

Maybe another Nice vs. Necessary choice? Is it necessary for the TBI to have computer controlled timing, no it's not necessary. Would it be nice to have the Jeep engine running with 1227747 computer controlling the timing, maybe so.

If the budget is available for a VSS and Computer Controlled Timing / Distributor, I think it would be money well spent. Save some budget for a custom chip too.

dave w

[Theodore]

I did not realize the distributor timing Was Not controlled by the 1227747 computer.

Maybe another Nice vs. Necessary choice? Is it necessary for the TBI to have computer controlled timing, no it's not necessary. Would it be nice to have the Jeep engine running with 1227747 computer controlling the timing, maybe so.

If the budget is available for a VSS and Computer Controlled Timing / Distributor, I think it would be money well spent. Save some budget for a custom chip too.

dave w

In talking to AFI (the system is an early version from 2006), and uses what they called a hybrid setup: an AMC distributor 'stalk', with a GM cap/ignition control module, and separate coil. Am looking at getting a new harness to replace the hacked up one that came in the Jeep, but wanted to get it running well before changing too many things at once.

Went out day before yesterday, and traced grounds, and found i don't have one between the block & frame. Given the Frankenstein nature of this Jeep, am not surprised. Have ordered a new set of battery cables & ground strap to replace the mess i have now & go from there.

Finally had a chance to take a 30-minute test drive & pull a data log. Running-wise: engine died when first put into gear, hesitated when accelerating away from house, and back-firing at speed on the Interstate, when rolling at 70, let off, coast to 60 & get back in it.

For interest, i plotted scatter charts for the main sensors, as well as, uploaded the latest data log they go with - CLOSED loop occurs at data point 214. Would appreciate advice on which direction to proceed.

IAC:


Battery Voltage - ranges from 13.7-14.1


O2 Sensor:


Block Learn Multiplier:


Integrator:


TPS:


MAF:

[dave w]

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

[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.