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Post by ES_97Sport on Apr 9, 2014 15:24:56 GMT -5
Clay, T,
I think both of you have run the AEM F/IC 8. Did either of you run across a problem on the injector side of things? I got mine wired in and now I have a persistent P0203, but only when the F/IC is plugged in. Don't get it when the loop-back plugs are installed. It's installed on a '97 Sport LS with a 3.5L swap.
I've installed two F/IC 8s, tested all the wiring and injectors as well as replaced #3 with a new injector and tried three different ECMs. Took injector #3 and rewired it to injector driver #7 on the F/IC. Had the dealership resistance check every injector, wire and the harness all the way to the ECM. Tested the Boomslang/F/IC harness. Everything looks fine, but immediately on key-on, P0203 comes up in pending codes and then later the CEL comes on and it's listed as a fault code.
I'm kinda stumped. Never heard of this with any of the DSM or 3g guys.
Edward
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Post by twood3006 on May 1, 2014 7:33:33 GMT -5
I've never had this code before, I did a quick search and found these to be the only issues:
-Bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes
-Open in the wiring to the injector
-Short in the wiring to the injector
-Bad PCM
My guess would be that is is a short in the wiring harness of the FIC-8, or perhaps in the FIC-8 itself, do you have a spare you can test with? Long shot I know. I would do this: unplug the number 3 injector and Test the ohm reading, then plug it back in and try testing the Ohms of injector number three with the ECU unplugged at the wiring harness and see if you get the same reading in ohms. I would try this same process with and without the FIC-8 plugged in and see what you get. I'm thinking you find that it's internal to the FIC-8. Hope this helps.
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Post by ES_97Sport on May 6, 2014 13:29:58 GMT -5
I've never had this code before, I did a quick search and found these to be the only issues: -Bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes -Open in the wiring to the injector -Short in the wiring to the injector -Bad PCM My guess would be that is is a short in the wiring harness of the FIC-8, or perhaps in the FIC-8 itself, do you have a spare you can test with? Long shot I know. I would do this: unplug the number 3 injector and Test the ohm reading, then plug it back in and try testing the Ohms of injector number three with the ECU unplugged at the wiring harness and see if you get the same reading in ohms. I would try this same process with and without the FIC-8 plugged in and see what you get. I'm thinking you find that it's internal to the FIC-8. Hope this helps. Installed new injector, tested old one and both tested out exactly the same. Nothing changed. Tested the entire harness for all the injectors all the way to the ECM (a couple times). Everything checked the same. Swapped ECMs. In fact I tried both rev 1 and 2 ECMs, and three different rev 2 ECMs. No difference. Changed injector #3 from injector driver #3 on the F/IC to $7. Still no change. In fact, the only thing I haven't done is swap the entire thing to my stock '97. Its not internal to the F/IC, or swapping to driver #7 would have fixed the problem. I haven't had so much as a hic-cup out of the other five circuits.  At this point, I strongly suspect it has to do with the '97 ECM. Either there's a coding problem - range is off somehow - or #3 has SLIGHTLY more resistance than the other five circuits, so that when you plug in the F/IC it exceeds the resistance range that's acceptable to the ECM. I know what the P020n check does, and that's the only thing that makes any sense to me. Anyway, its a moot issue now. I'm in the process of swapping in a '97/98 Montero ECM to replace the stock Sport ECM and F/IC. While the F/IC is a great box and does EXACTLY what they say it'll do (actually more), its just not working out for my application. Thanks for the assistance, though! Edward |
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Post by 6500rpm on Jun 20, 2014 18:28:05 GMT -5
For once I may be able to help, maybe not... All it takes is a few strands of wire to pass a resistance check. You need to load check the suspect wiring runs. Even though it has continuity it may not be able to carry enough amps to allow the injector to function (broken wires, poor connections at crimps). Feed B+ to one end of the circuit, put something like a headlamp connected to ground at the other-it should light normally. If it doesn't light or it's dim start checking for issues like the ones listed above. Also don't forget to do pin drag tests on terminals to make sure they make good contact, sometimes when your chasing a electrical problem all the connecting and disconnecting tends to open terminals and causing a fit that wont carry enough amps to make the device work. Check both b+ and ground sides of the circuit. I like to use headlamps because it takes a good amount of current to make them work, sometimes a hand held test light just isn't enough. Noid lights and high impedance test lights get easily fooled also. I'd be all over the circuit to your #3 injector if that's when the problem started and you're sure it's injector related. If not go back to basics and use a spark checker and verify compression on cylinder 3.
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Post by ES_97Sport on Jul 16, 2014 12:58:34 GMT -5
For once I may be able to help, maybe not... All it takes is a few strands of wire to pass a resistance check. You need to load check the suspect wiring runs. Even though it has continuity it may not be able to carry enough amps to allow the injector to function (broken wires, poor connections at crimps). Feed B+ to one end of the circuit, put something like a headlamp connected to ground at the other-it should light normally. If it doesn't light or it's dim start checking for issues like the ones listed above. Also don't forget to do pin drag tests on terminals to make sure they make good contact, sometimes when your chasing a electrical problem all the connecting and disconnecting tends to open terminals and causing a fit that wont carry enough amps to make the device work. Check both b+ and ground sides of the circuit. I like to use headlamps because it takes a good amount of current to make them work, sometimes a hand held test light just isn't enough. Noid lights and high impedance test lights get easily fooled also. I'd be all over the circuit to your #3 injector if that's when the problem started and you're sure it's injector related. If not go back to basics and use a spark checker and verify compression on cylinder 3. Been there, done that. We've ohm tested everything. Injectors, harness, etc. As a whole. In part. With and without the F/IC. I've swapped harnesses, F/ICs AND ECMs. I even tested it against the rev 1 and rev 2 '97 ECMs. I've run through it all and then I had the senior tech do it all again with his equipment. I've narrowed it down to the ECM. Something is just not quite right on that injector circuit. The '97 Sport ECM is an interesting animal - and not in a good way. Physically, its the same ECM used in the '97 Montero, but with slightly different programming. It is COMPLETELY different from the '98+ ECMs on both the Montero and Montero Sport. Totally different design electronically. Frankly, the '97 ECM is a POS. Looks like a bad design from the '80.  Anyway, I've given up on even trying to fix this issue. If I get the '97/98 Montero ECM transplanted in, I'll re-install the F/IC and see what I get. Bet some serious cash the problem doesn't show up. The electronics are on hold right now for a few weeks. Getting a 1 ton drag link installed, new CM shafts for the front and maintenance on the drive shafts. Always something. Edward |
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