engine shutting down after going REALLY lean!?

Decipha's custom GUFX strategy covers all 89-93 foxbody ecu's including the 88 mass-air california ecus.
efloth
Posts: 274
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Re: engine shutting down after going REALLY lean!?

Unread post by efloth »

I've found turning the key on and then tapping on the relay, wiggling wires, messing with ignition will reveal a poor connection if the fuel pump primes again. I was chasing a battery drain issue and that was how I found it was the relay
canuck1
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Joined: 2021 Mar 31, 17:29
Location: Victoria, BC CANADA
Vehicle Information: QH, TunerPro RT 5, GUFX_220418.xdf, A9L2_220405, DECIPHA_220505.ADX, 395w, AFR 195CC Renegade heads, Comp XE274HR cam, Siemens-Deka V 80lb/hr (shorties), Mass-Flo-EFI style 4bbl throttle body with GM maf on top. Custom long tube headers, sidepipes, 5 spd manual.

Re: engine shutting down after going REALLY lean!?

Unread post by canuck1 »

While I've run it several times since testing electronics, verifying fuel pump/pump pressure and vacuum connections (fixed line to regulator), I have had another recurrence of the engine dying while at cruise rpm:
aug 31 2022 NSVFD to home cut out.xdl
(664.19 KiB) Downloaded 241 times
Just before 9:36 on the log is the last time the HEGO voltage registers above .400 until I restart it. It remains below .400v for 7 secs until I roll to a stop at the side of the road and turn the key off. I think the engine quits right around 9:36, but I don't think I can point to the exact moment.

What would cause loss of fuel, despite Lambse ramping lower (along with increasing injector PW) to try to get HEGO's to switch above .400v with no effect? Keep in mind I've been driving while logging it every other day for an hour or more to see if I can replicate the stalling and this is the only instance I managed to log. If its mechanical (fuel pump, sock, filter, contaminants) how do I explain the intermittent nature of the problem?

Sean
decipha
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'19 F-150 3.3L

Re: engine shutting down after going REALLY lean!?

Unread post by decipha »

it obviously ran out of fuel

either the relay or the pump dying

could even be a clogged up filter
entity-unknown
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Location: Mesa, AZ
Vehicle Information: 87 Bronco FSB Eddie Bauer w/ 89 Mustang MAF Swap / C3W PCM w/ A9L2 BIN from Decipha / 347 FRPP BOSS Block (Part# M-6009-347) / AFR 165cc heads / 42Lbs Green(Active) & 30Lbs Red(Shelf) Bosch Injectors / CompCams 35-510-8/FW XE258HR-12 / AOD fully beefed up / King 2.5" Suspension w/ Bump Stops / 5.13 Gears Front/Rear on Auburn Pro LSD / 35"(Active)/33"/37" Tires / Very Custom Built Bronco aka Bonnie

Re: engine shutting down after going REALLY lean!?

Unread post by entity-unknown »

I've had this issue before and I'm having it now. I'm thinking it's a combination of power to fuel injectors AND an O2 sensor issue. The original issue years ago was fixed w/ just an O2 sensor but the fuel injector wiring might still been a problem. What stands out for your issue is your graphs and the odd changes in the voltage.... It's a bit of a story but here's where I am:

Years ago it was basically a stock 302 w/ MAF. It would race around NP but when it came to any hill it would starts boggin out and eventually could barely limp. I just pulled over so didn't give it much time to die but I'm certain it would. Even when getting back to all flat road, if this issue happened, it would never recover until I shut it down for about 10-15 minutes. 1st time she ever went to a mechanic and they said she had a broken cam...
I just replaced my O2 sensor w/ a brand new Bosch but I dropped it from like 6 inches before this issue started. I read the box and it said DO NOT DROP IT!!!. A 6" drop can't hurt an O2 sensor!!! BS Yes it can! >:( A new O2 sensor fixed it and I was VERY careful not to drop it :)

Now I've got a brand new everything which should be in my sig and this issue is back. It's all tuned really nicely and hauls ass! Until I hit a f'in hill..... Now I can monitor things w/ QH/TunerPro and I see my A/F Err correction go way out of bounds and keeps going even when I hit a flat road. It runs lean and keeps getting worse until I shut down for a bit then it's happy. ECT is 178-180 solid too.

I also have a brand new Bosch O2 sensor and it did slip out of my fingers installing it from about 6inches above the ground again....
Also my MAF conversion was soldered in beautifully over 20 years ago and the solder joints still look beautiful. PO def did a solid bench job. I checked continuity on either side of the joints and the continuity was very low despite she can haul ass. One injector wasn't working at all which is why I discovered the wiring issue. It would barely light up a noid/test light.

I fixed the 1 injector's wiring and the noid light lights up the whole garage now. I did not bother with the others tho. I was able to get everything tuned and running AWESOME!!! (more fine tuning left) and that's when I began the hill tests and failing again...

Now I can see stats w/ the tuner, I figured it was going into some Open Loop Limp Mode but it doesn't; it's Closed Loop the whole time. I'm using Decipha's default log data set too.

To your graph concern and possibly the relation to my issue, I see the mVolts for the injectors (running state/bottom graph) typically is very mountainous and constantly changing when it's happy but when it craps out, it's more hills and valleys with extreme changes WHEN it does change. I also see the Volts for the O2 sensor (Dyno/top graph) react at the exact same time so mountainous or hills/valleys, both O2 and Injectors coincide all the time. When it craps out, it tends to be extreme variances vs. normally they tend to sit "somewhere in the middle". I posted 2 graphs below, 1st is when it craps out, the 2nd is when it's running normal. I have a lil more fine tuning w/ MAF AD Counts but you can see it's pretty good.
I wonder if you see something similar?

Current Theory at least for me: My O2 sensor probably failed due to the VERY short drop AND my injector wiring is heating up more on the hill due to load and killing the power connection.
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mechanicalmatch
Posts: 88
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Vehicle Information: 00 F150 4.6L Extended cab
CVAF1
4R70 3.08

Re: engine shutting down after going REALLY lean!?

Unread post by mechanicalmatch »

Something I have found to find these types of issues is to check the relay sockets for proper drag. Easy way to do it would be to cut terminals off a relay and hold them with a small pair of pliers or solder to something rigid that will allow you to insert and pull back out. I have found when relays fail and get hot, the clamping force of the socket to the relay terminal drops off and you can get intermittent loss of connection and also arcing on the socket and on the contacts inside the relay. What I would recommend is replacing all your relays (all of them) with good quality relays and check the terminals for proper drag so that you know they are making proper contact with the new relays.
Intermittent issues will drive you nuts trying to find. Relays are cheaper than a tow.
canuck1
Posts: 67
Joined: 2021 Mar 31, 17:29
Location: Victoria, BC CANADA
Vehicle Information: QH, TunerPro RT 5, GUFX_220418.xdf, A9L2_220405, DECIPHA_220505.ADX, 395w, AFR 195CC Renegade heads, Comp XE274HR cam, Siemens-Deka V 80lb/hr (shorties), Mass-Flo-EFI style 4bbl throttle body with GM maf on top. Custom long tube headers, sidepipes, 5 spd manual.

Re: engine shutting down after going REALLY lean!?

Unread post by canuck1 »

Deleted double post
canuck1
Posts: 67
Joined: 2021 Mar 31, 17:29
Location: Victoria, BC CANADA
Vehicle Information: QH, TunerPro RT 5, GUFX_220418.xdf, A9L2_220405, DECIPHA_220505.ADX, 395w, AFR 195CC Renegade heads, Comp XE274HR cam, Siemens-Deka V 80lb/hr (shorties), Mass-Flo-EFI style 4bbl throttle body with GM maf on top. Custom long tube headers, sidepipes, 5 spd manual.

Re: engine shutting down after going REALLY lean!?

Unread post by canuck1 »

Thanks for the help. I have not yet resolved the issue, but my driving season only runs March to October, so I’m done for the season. I see the changes on the graphs, but I’m not experienced enough to be able to interpret what they mean. I have new Bosch HEGO’s in there, and my harness is a new custom EFI harness made for my car by Mass-Flo-EFI. I don’t see anything that indicates something physically wrong with the components. My HEGOs are a bit farther back than a stock setup (custom long tube headers) but not really far enough away that it would cause the issue I’m having. I had already replaced all relays, I still am not certain if it’s normal for them to be as warm/hot to the touch as they are. I have also tested for voltage drop at various points and cleaned all my ground points. I am tempted to try just shutting DFSO off, but won’t get a chance to test it again until Spring.
entity-unknown
Posts: 80
Joined: 2022 Aug 04, 00:13
Location: Mesa, AZ
Vehicle Information: 87 Bronco FSB Eddie Bauer w/ 89 Mustang MAF Swap / C3W PCM w/ A9L2 BIN from Decipha / 347 FRPP BOSS Block (Part# M-6009-347) / AFR 165cc heads / 42Lbs Green(Active) & 30Lbs Red(Shelf) Bosch Injectors / CompCams 35-510-8/FW XE258HR-12 / AOD fully beefed up / King 2.5" Suspension w/ Bump Stops / 5.13 Gears Front/Rear on Auburn Pro LSD / 35"(Active)/33"/37" Tires / Very Custom Built Bronco aka Bonnie

Re: engine shutting down after going REALLY lean!?

Unread post by entity-unknown »

NP :) Def not hijacking your thread. It made more sense to add my issues here since they're similar vs. creating a 2nd post. So I fixed the injector wires. The result was I ran very lean after. I figured I'd be running rich but whatever. So I had to re-tune. I got it more or less close for the 34 mile run home but it still crapped out on the highway after about 10 miles and sure enough the moment I hit a small incline. I picked up my new O2 sensor (I wanted to test 1 thing at a time ) and installed it. Afterwards my MAF tuning was way off again running extremely lean to the point it was crappin out immediately with any acceleration. I could feel it was starved of fuel too.
I adjusted the MAF tables to accommodate and now it's running a lil too rich but she hauls ass again! I gotta do a lil more tuning again after the O2 sensor change but this made a huge difference.
I swear after my history w/ O2 sensors, dropping one from chest height on the ground will kill an O2 sensor.
I'll report my final conclusions after more testing but hopefully this story helps you/someone else :)
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