Issue with hesitation on cold start

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KJ Ryu
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Re: Issue with hesitation on cold start

Post by KJ Ryu »

:-bd
Ron

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1977 SJ J10, 4v360, T18, D20, 37x14s, SOA & SF on tons, still ugly.
1978 SJ Wagoneer, 4v360, QT, 33x12.5s, lift by Sawzall :-bd NOT Running :(
1977 SJ J10, SniperEFI 401, QT, D44s, 31X10.5s :fsj:
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

Theodore wrote: Fri Nov 15, 2019 4:43 am
babywag wrote: Thu Nov 14, 2019 10:23 am Timing control isn't hard to add. Just some wiring and couple parts.
You need the hardware to read and burn a new chip though.
Or buy one...

Really need to reset initial timing though. If you're @ 0° that is a huge power killer.
Thanks for recommendation & patience with the questions - learning a lot in the process. ? - do you know, off-hand, what you have initial timing set to? So far, we've had initial set on the low end 0-5 & as far out as 17-18 initial, based on various recommendations - and, to date, the story reads like Goldilocks... sounds like we've just not hit 'just-right' yet.

Am looking into getting a vacuum gauge to hopefully zero-in on it to minimize the amount of tinkering required to get to 'just-right'.
Set timing to ~10 and leave it be.
Briefly looking @ logs, you have some issues.
#1 ecm battery voltage is low, should be much higher than 12.x
#2 it looks lean have you checked your fuel pressure?
#3 o2 sensor data is dropping out/falling out of where it should be...where is sensor mounted? Uber lean and/or cooling off?
#4 IAC counts seem pretty high, have you done initial setup procedure? (minumum air/tps adj.)

Need much much more data to get an accurate idea of what is going on.
-Tony
'88 GW (aka Babywag)
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

I'll add *if* it is very lean when cold, and you really hammer the throttle do you get a "pop" out of the throttle body?
-Tony
'88 GW (aka Babywag)

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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

babywag wrote: Sat Nov 16, 2019 10:31 am
Theodore wrote: Fri Nov 15, 2019 4:43 am
babywag wrote: Thu Nov 14, 2019 10:23 am Timing control isn't hard to add. Just some wiring and couple parts.
You need the hardware to read and burn a new chip though.
Or buy one...

Really need to reset initial timing though. If you're @ 0° that is a huge power killer.
Thanks for recommendation & patience with the questions - learning a lot in the process. ? - do you know, off-hand, what you have initial timing set to? So far, we've had initial set on the low end 0-5 & as far out as 17-18 initial, based on various recommendations - and, to date, the story reads like Goldilocks... sounds like we've just not hit 'just-right' yet.

Am looking into getting a vacuum gauge to hopefully zero-in on it to minimize the amount of tinkering required to get to 'just-right'.
Set timing to ~10 and leave it be.
Briefly looking @ logs, you have some issues.
#1 ecm battery voltage is low, should be much higher than 12.x
#2 it looks lean have you checked your fuel pressure?
#3 o2 sensor data is dropping out/falling out of where it should be...where is sensor mounted? Uber lean and/or cooling off?
#4 IAC counts seem pretty high, have you done initial setup procedure? (minumum air/tps adj.)

Need much much more data to get an accurate idea of what is going on.
Thanks for taking a look. I agree i have issues :-) Just today, I was going to take a look at the power steering pump squeal/vibration & had the mounting bracket sheer off as i turned the wheels... See post for details on the ongoing debacle: viewtopic.php?f=7&t=17942. Looking at the bracket, it looks like a previous owner left out a bolt that goes into the block, that would've created a triangle, thereby reinforcing the bracket. Ugh.

To answer your questions with what i know right now:
re: #1 - battery voltage @ ecm: did check battery voltage and it reads 12.51, but given the ongoing issue w/power steering, i can't start the jeep to test voltage at the alternator. Will take a look once i get the PS issue fixed.
re: #2 - fuel pressure: i've not been able to check it yet. A few weeks ago, I bought a Actron fuel pressure gauge & the TBI schrader valve, but it appears the schrader valve may be bad. It's plumbed in just after the fuel pump, but the gauge reads no fuel pressure. Pushing in on the schrader valve doesn't release fuel. Haven't gotten a chance to troubleshoot it any deeper to date.
re: #3 o2 sensor dropping in/out: sensor is mounted in the driver's side exhaust pipe about a foot below the manifold, just about even with the bottom of the oil pan.
re: #4 IAC counts seem pretty high, have you done initial setup procedure? (minumum air/tps adj.): i followed the instructions re: pintle adjustment, etc., but i admit i'm new at this.

Right now, the focus is on power steering & finding a mounting bracket to get the Jeep back road-worthy. Once i get parts replaced, and going again, will be back on this.
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Am back in business & have a running/driving Jeep - got the power steering pump issue fixed today. A forum member PM'd me from El Paso a few days back; Received the power steering parts on Friday in good shape & got everything installed today. Test drove the Jeep this evening - it's never driven so well - has always had a mystery squeak & an intermittent jerky steering wheel - all that's gone now.

Update on the cold start hesitation issue... The vacuum gauge order arrived from Amazon on Monday, but porch pirates decided they needed it more than i did; leaving the empty shipping materials on the porch. Filed a claim w/Amazon, item was out of stock & is now on backorder with no target date to ship. Hurrumph - so, it'll be a few more days before i'll have a chance to look at it. Hopefully, it'll arrive before cold weather does.
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Hey babywag, ? - saw your comment about setting initial timing at ~10 & leaving it; and it made me wonder how you got to that number? A few weeks/months (time flies...) back, i was reading about timing in the owner's manual, & service manual, and following circular references that eventually led to the 'Emissions Sticker' under the hood. To date, we've bounced back & forth from 0 initial (per AFI's owner's manual) - assuming ECM control & Factory Spec otherwise. At 15-17, we saw severe hesitation & lack of power, max speed of ~60mph & missing. At 0, it runs much better, but with hesitation when cold. So far, i've not had a chance to try ~10 - it'll be a couple of weeks before i can do anything else w/it.

The Emissions STicker calls out 17+-2, but it wasn't until tonite that i saw a few articles online about timing for high altitude areas, which made me run outside & check our sticker, and what do you know? - It's a High Altitude sticker, and we're in a low altitude area (~1200 ft). Assuming retarding 2deg/1000ft, gets us back to 11+-2, which is within the ~10 degrees you'd called out earlier.

For curiosity's sake, does anyone have a pic of a 'low altitude' sticker for a 1990 360? So far, i've not been able to find one online.

Here's our Emissions sticker, from our 1990 GW w/360 engine.
Image
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Poking around tonite, I found a low altitude sticker on a sister forum, showing 10+-2.
Link to image: cant get it to pull via original link, for some reason:
http://www.diplomat-b.de/Jeep/base%20emission.jpg

Screenshot & pulled into imgur:
Image

Link to entire post:
http://ifsja.org/forums/vb/showthread. ... ost1345926
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

I say 10° because as you found that is stock.
If you're using a stock distributor many times more results in pinging. They need to be checked/adjusted before running higher initial.

It's important to verify FP and do initial setup as well.
More so because the log you posted appears lean.
Timing won't "fix" a fuel problem.
-Tony
'88 GW (aka Babywag)

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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Thanks, Will take a look when I get back in town.

Re: fuel pressure - I have an Actron gauge with the TBI Schrader valve inline connector in the fuel line just before the filer, if I remember correctly, but for some reason am not able to get a reading. ? - with the car running, and gauge not connected, I assume I should be able to push in the center pin & get gas to spray..., true? Trouble is: I dont. Havenot yet had a chance to talk to Acton tech support.

Re: initial setup: Am planning on starting over once timing is set to 10, now that I have a scanner.

Thanks for,the advice - will let you know.
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Theodore wrote: Sat Nov 16, 2019 12:21 pm
babywag wrote: Sat Nov 16, 2019 10:31 am
Theodore wrote: Fri Nov 15, 2019 4:43 am

Thanks for recommendation & patience with the questions - learning a lot in the process. ? - do you know, off-hand, what you have
initial timing set to? So far, we've had initial set on the low end 0-5 & as far out as 17-18 initial, based on various recommendations
- and, to date, the story reads like Goldilocks... sounds like we've just not hit 'just-right' yet.

Am looking into getting a vacuum gauge to hopefully zero-in on it to minimize the amount of tinkering required to get to 'just-right'.
Set timing to ~10 and leave it be.
Briefly looking @ logs, you have some issues.
#1 ecm battery voltage is low, should be much higher than 12.x
#2 it looks lean have you checked your fuel pressure?
#3 o2 sensor data is dropping out/falling out of where it should be...where is sensor mounted? Uber lean and/or cooling off?
#4 IAC counts seem pretty high, have you done initial setup procedure? (minumum air/tps adj.)

Need much much more data to get an accurate idea of what is going on.
Thanks for taking a look. I agree i have issues :-) Just today, I was going to take a look at the power steering pump squeal/vibration & had the mounting bracket sheer off as i turned the wheels... See post for details on the ongoing debacle: viewtopic.php?f=7&t=17942. Looking at the bracket, it looks like a previous owner left out a bolt that goes into the block, that would've created a triangle, thereby reinforcing the bracket. Ugh.

To answer your questions with what i know right now:
re: #1 - battery voltage @ ecm: did check battery voltage and it reads 12.51, but given the ongoing issue w/power steering, i can't start the jeep to test voltage at the alternator. Will take a look once i get the PS issue fixed.
re: #2 - fuel pressure: i've not been able to check it yet. A few weeks ago, I bought a Actron fuel pressure gauge & the TBI schrader valve, but it appears the schrader valve may be bad. It's plumbed in just after the fuel pump, but the gauge reads no fuel pressure. Pushing in on the schrader valve doesn't release fuel. Haven't gotten a chance to troubleshoot it any deeper to date.
re: #3 o2 sensor dropping in/out: sensor is mounted in the driver's side exhaust pipe about a foot below the manifold, just about even with the bottom of the oil pan.
re: #4 IAC counts seem pretty high, have you done initial setup procedure? (minumum air/tps adj.): i followed the instructions re: pintle adjustment, etc., but i admit i'm new at this.

Right now, the focus is on power steering & finding a mounting bracket to get the Jeep back road-worthy. Once i get parts replaced, and going again, will be back on this.
Finally had a chance to get back on this. Have done a lot since we spoke last. To date, i've:
- reset initial timing to 10 degrees
- initial setup for IAC
- initial setup for TPS
- reset idle to around 650-700 warm
- cleaned battery terminals, alternator connections, & ground wire
- checked fuel pressure - its showing 12 lbs
- not done anything w/o2 sensor.

Wagoneer is running the best it ever has, when warm, but i still have the hesitation when cold - other than the idle is slower, i can't really tell a difference. I pulled another data log going from home to work: engine was cold; outside temp was around 40. Had to feather the gas to pull out; again, once it warmed up to around 100, i could gun it w/o issues.

Babywag, et.al. - do you see anything in the data log?
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

Still looks lean...
Can up fuel pressure 1-2psi, add to VE tables, etc.
Voltage still a little low should be a little higher.
-Tony
'88 GW (aka Babywag)

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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Am wondering whether I have a fuel pressure regulator issue. Didn’t strike me til yesterday, but when I turn the key, the fuel pump kicks on to prime the system for a couple seconds, then kicks off, and as you can see in the attached movie clip, the pressure bleeds off. Cold start takes 8-10 engine rotations before it starts.

Video of fuel pressure gauge at cold start:
https://imgur.com/gallery/hyS8BOq
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

Theodore wrote: Mon Mar 09, 2020 6:31 pm Am wondering whether I have a fuel pressure regulator issue. Didn’t strike me til yesterday, but when I turn the key, the fuel pump kicks on to prime the system for a couple seconds, then kicks off, and as you can see in the attached movie clip, the pressure bleeds off. Cold start takes 8-10 engine rotations before it starts.

Video of fuel pressure gauge at cold start:
https://imgur.com/gallery/hyS8BOq
Long as it holds STEADY while running AND under HEAVY accel, it is working as designed.
There is nothing stopping pressure from bleeding off when the fuel pump isn't running.
-Tony
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Have seen a few articles that talk about similar pressure drops either being injectors leaking (checked & we are good there - no leaks), and failed check valve in fuel pump. With that, am wondering whether the check valve is the issue? When we started down the path, I noticed that the fuel filter was installed after the pump, such that the pump couldve picked up dirt from the tank. Am also starting to notice at cold start time, the engine will start and run for a few seconds then die, easily starts back. But, it is doing it more often lately.
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Its been a while since ive checked in, but am still working on this & struggling.

The $64,000 question to me is: should the fuel pressure drop to zero just after prime? or, should the pressure hold? Have read that fuel pumps contain a check valve to prevent backflow & hold the pressure.

Ive gone back & basically started over re: tuning w/ 1320electronics.com bluetooth OBD1 scanner on our Grand Wagoneer & have set initial timing (10 deg), base idle(750), along with IAC & TPS, and have it running the best it ever has, with 2 exceptions, that i believe relate to a fuel delivery issue, that im thinking relates to pressure dropping at prime.
1) at cold start, rough idle & hesitation on acceleration w/in 1 minute of initial startup
2) at high RPM, when running highway speeds (70mph) & let off gas, decel a bit & get back in it - there's a backfire thru the exhaust & hesitation - that sounds like popcorn popping.

When cold(sitting overnight), fuel pressure at prime shows 12 lbs.; once primed, the fuel pump cuts off, and pressure instantly drops to zero. To figure out which direction to look, i've run a few tests:
1) inspect the fuel injectors for leaking - so far, ive seen a nice pulsing spray pattern, with no leaks/dribbling.
2) crimped the supply line between the fuel pressure gauge & the throttle body: to see if the fuel pressure drops indicating an issue with fuel pump, or its check valve. Pressure rose to 60 lbs & held - indicating the issue is on throttle body side of the equation.
3) crimped the return line near the throttle body & saw the pressure rise to 60 lbs & hold, which which makes me think fuel pressure regulator. Installed a FPR rebuild kit a few weeks back, and really saw no change.

It seems like the fuel line should hold pressure at prime & not instantly drop off.
Everything i read says, that seeing a pressure spike when crimping the return indicates an issue with the fuel pressure regulator, and crimping the supply ahead of the throttle body proves the fuel pump check valve isnt bad.

Am wondering if the fuel pressure regulator rebuild is bad?

Where to go from here?
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

You're chasing a ghost.
TBI does not maintain pressure (w/ pump off)like later multiport/sequential systems.
The regulator housing has a bleed hole and it will NOT ever hold pressure unless you plug that hole.
-Tony
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Re: Issue with hesitation on cold start

Post by Theodore »

Am writing to follow up: After many days of poking around on the Jeep, digging into the wiring harness, cutting out & replacing 10-12 bad splices (anyone seen duct tape used as an insulator?), cleaning battery terminals, body grounds, engine grounds, as well as, the ECM ground. In addition, have read a myriad of forum posts & such, and i think i have a voltage problem, or said differently, i think the ECM is reading low battery voltage - i'm just not sure from where.

With the engine running: Battery voltage per ECM reads 12.5-13.2V, vs. measured with a multimeter shows 14.6V. I'm unsure where the ECM reads 'battery voltage' from.

I've got the ECM 'pink' power-on wire going to the positive terminal on the coil, which in turn is fed from the BAL (ballast resistor) terminal of the starter relay. In testing voltage w/a multimeter, the BAL terminal shows 12.5-13.2V with the engine running. At first, i thought i'd found the issue, but it turns out that's not where voltage is read from - keep reading...

So to prove whether or not battery voltage was being read from the coil, I disconnected the ECM 'pink' power-on wire from the positive coil terminal and reconnected it to the positive battery post to see what the ECM saw - no change: battery voltage reported in data logs still showed 12.5-13.2V, whereas battery voltage measured via multimeter showed 14.6V.

It seems like I'm missing something here, but i'm not sure where to look.

Appreciate any insight anyone can provide.

Thanks.
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babywag
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Re: Issue with hesitation on cold start

Post by babywag »

There are two battery wire connections @ecm if using 1227747.
You can check @ecm connectors to see what you're getting there.
Pins B1 & C16.
Ignition power @ecm is pin A6 to check that.

The coil+ is a bad location to use in my opinion.
I would move the connection to starter relay.
The coil+ may cause noise on the wire.
EFI is sensitive to noise, needs excellent grounds and clean power.

May want to reach out to affordable and see what they recommend? Never worked with one of their harnesses.
I have seen problems with Howell harnesses and have helped a few guys find issues with those.
-Tony
'88 GW (aka Babywag)

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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

Hey, babywag - thanks for the followup. Have verified that i've got a 1227747 ECM, and over the last couple weekends, i've been able to clean up the wiring (more on that below), and have seen voltages rise as measured by the ECM as changes were made; moving from ~12.5V (logs showed
ranges 12.2V-12.8V) to a high of 14.2V now. With all that, i still feel like i'm missing something here - voltages measured by multimeter show consistently higher by .2-.4V than what the ECM reports for Battery Voltage, and while the engine is running better than it ever has, we still have the base issue of hesitation at cold start, intermittent dying when going into gear, and high speed backfire when letting off the throttle at 70mph, coasting to 60, and getting back in it. Right now, am focused on getting the wiring fixed, and raising the battery voltage measured by
the ECM as high as possible.

Can you verify that voltages reported by the ECM match what you see when measured w/a multimeter?

When measuring battery voltage w/engine stopped & running, i see nearly no voltage drop between battery voltage tested w/a multimeter and whatever terminal i'm testing at the ECM, but the ECM reports .2V-.4V less than that. Am wondering if i've got a bad connection in the ECM harness
connector?

For example,
------------------- Engine ----Engine -----Measured per ECM
------------------- Stopped --Running ----& shown in logs
------------------- ---------- ---------- -----------------------
Battery Voltage 12.5 ------ 14.5-14.6 - 14.1-14.2
ECM Pin A6 ----- 12.5 ------ 14.45
ECM Pin B1 ----- 12.5 ------ 14.45
ECM Pin C16 --- 12.5 ------ 14.45

Over the last couple weeks, i've broken apart the wiring harnesses (factory & EFI) & run voltage drop tests, finding a myriad of bad splices/ connections along the way. As part of that, ive cleaned battery terminals, cleaned all the grounds i could find, found and connected a previously
unconnected 'green' 12-ga ground wire that was connected to the negative battery post - stuffed in the headlight hole. All of this got me from ~12.5V measured at the ECM to ~13.2.

After reading & re-reading your posts, and talking to AFI & Bill_USN1 on binderplanet, i worked my way to the ECM itself, the main relay & fuel pump relay & began cleaning connections there with DeoxIT D100 contact cleaner. Corrosion was pretty amazing, as evident from the bubbling. That's when i found a major cause of voltage drop - the ECM fuse. The mix of corrosion & cracked connection was responsible for ~1V.

Cracked fuse
Image

Battery voltage as reported by ECM jumped from 13.2 to 14.2, after cleaning ECM & relay connections and replacing the cracked fuse.
Image

DeoxIT D100 electrical contact cleaner
Image

i've also uploaded 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?

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 - wanted to get it running properly first.

Wondering: could engine heat be affecting measured voltage?
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Theodore
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Re: Issue with hesitation on cold start

Post by Theodore »

babywag wrote: Wed Jul 22, 2020 7:28 am
The coil+ is a bad location to use in my opinion.
I would move the connection to starter relay.
The coil+ may cause noise on the wire.
EFI is sensitive to noise, needs excellent grounds and clean power.
Following up on my earlier comments re: ECM ignition 'pink' wire being connected to the positive coil terminal - that's not true, it's spliced into the wire coming from the Starter Relay, and no directly connected to the positive coil terminal.

Also, re-reading thru the entire string, there was a mention a few months back about the o2 sensor dropping out; does that look better in the recent logs?

Thanks.
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