Search found 67 matches

by canuck1
2022 Dec 17, 11:05
Forum: GUFX - 89-93 Foxbody ECUs
Topic: engine shutting down after going REALLY lean!?
Replies: 27
Views: 10392

Re: engine shutting down after going REALLY lean!?

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.
by canuck1
2022 Sep 07, 20:21
Forum: GUFX - 89-93 Foxbody ECUs
Topic: engine shutting down after going REALLY lean!?
Replies: 27
Views: 10392

Re: engine shutting down after going REALLY lean!?

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
by canuck1
2022 Aug 29, 23:11
Forum: GUFX - 89-93 Foxbody ECUs
Topic: Controlling lambse on decel
Replies: 46
Views: 10689

Re: Controlling lambse on decel

Looks like maybe a combination of things, mostly a vacuum connection to fuel regulator that had unknowingly pulled off. Everything looked visually right, but when i tugged on hose, i could see it wasn't connected to manifold barb fitting. Small vacuum leak and an operator who continued to make changes to MAF values made things slowly worse, until it no longer supplied fuel as demanded. Yes, I'm embarrassed, but at least I'm willing to admit I screwed up! Seems good now.

When I get home from brief vacay, I'll try a higher value for FN338.

Sean
by canuck1
2022 Aug 27, 16:04
Forum: GUFX - 89-93 Foxbody ECUs
Topic: Controlling lambse on decel
Replies: 46
Views: 10689

Re: Controlling lambse on decel

Gremlins gone. I can now see it dropping into OL on decel at the desired load value. I might try raising FN338 a little, just to experiment. Thanks again for the guidance on this!

Sean
by canuck1
2022 Aug 24, 17:35
Forum: GUFX - 89-93 Foxbody ECUs
Topic: Why does spark exceed spark table value (sometimes) on decel?
Replies: 2
Views: 1588

Re: Why does spark exceed spark table value (sometimes) on decel?

OK, looks like FN389 Dashpot CT spark multiplier is the culprit! the actual dbTDC value made me nervous but checking it against FN389 x SAFTOT, I can see it's adding timing to try and more quickly stabilize idle speed from closed throttle transition.

Sean
by canuck1
2022 Aug 24, 17:11
Forum: GUFX - 89-93 Foxbody ECUs
Topic: Why does spark exceed spark table value (sometimes) on decel?
Replies: 2
Views: 1588

Why does spark exceed spark table value (sometimes) on decel?

The highest value anywhere in my FN2200 spark table is 43, but for some reason, after moderate accel to 4000 rpm, followed by a closed throttle decel I have logged as high as 49 dbTDC, generally about 2 secs after releasing the go pedal.

Just wondering why this happens?

Sean
by canuck1
2022 Jul 26, 14:32
Forum: GUFX - 89-93 Foxbody ECUs
Topic: engine shutting down after going REALLY lean!?
Replies: 27
Views: 10392

Re: engine shutting down after going REALLY lean!?

I'm going through and checking all the main power supply and ground connections to be as sure as I can I've eliminated a feeble connection before I do anything that involves driving again. I don't want to end up having to call a ramp truck to get me home if it quits and then WON'T restart. Once the dash is back in place (everything tests fine back there), I'll proceed with road testing to see if the problem resurfaces. I'm still convinced its got something to do with a failing ground connection. I've been through all the ignition switch, EFI ground connection and my dash ground bus (where devices, switches or relays can tie into a common ground). The ground strap between my chassis & engine was clean, but a little looser than I expected. I'm wondering if engine movement may have caused the bolt there to loosen up? Kind of a long shot but it may be one of a number of items contributing to ECM or fuel pump losing power.

Sean
by canuck1
2022 Jul 23, 00:18
Forum: GUFX - 89-93 Foxbody ECUs
Topic: engine shutting down after going REALLY lean!?
Replies: 27
Views: 10392

Re: engine shutting down after going REALLY lean!?

Only time I flicked the key OFF in that log was after I figured it had already quit on me, then I flicked it back ON to get it going again. Could be a key switch issue, I'll give it the wiggle test to see if I can replicate it dropping power.

Relay tests fine on my bench with multi-meter. I'm going to pull the dash off later this weekend as there are a couple areas I can see may have been impacted by my reaching around up there to find/connect to other wires to hookup things like WB02 etc. I might have loosened a connector or damaged a wire. I'll have a closer look.

Sean
by canuck1
2022 Jul 22, 15:35
Forum: GUFX - 89-93 Foxbody ECUs
Topic: engine shutting down after going REALLY lean!?
Replies: 27
Views: 10392

Re: engine shutting down after going REALLY lean!?

jul 05 to fuel cutting out.xdl
(530.78 KiB) Downloaded 250 times
Here is a log of it happening several times. 3:21, starts to go lean, 3:31 dashboard shows ATMR go from 255 to 0 (because I shut the key off) and then start counting up from 0 again after I turn key back on and bump start it on the roll.

5:39, you can see the Fuel Error start to indicate leaner and leaner until ATMR cuts off at 137 (me turning key off again after I notice loss of power) then begin counting back up around 5:48 when I turn it on again.

Third example around 7:22 all looks normal, 7:26, starts going lean again and cycle repeats as before.

Sean