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Hi all I’m new here and I have a somewhat complicated situation. I recently did an engine swap: put an H22(which I rebuilt myself B) ) in my 6th gen accord coupe and did an obd2 – obd1 conversion. At first it only had an issue with high idling, everything else was seemingly okay. The car did, and still does have a CEL. However my car doesn’t seem to have a service connector at the passenger side and I can’t scan using a obd2 tool. I tried a different chip in the ecu, the engine starting to bounce instead of just idling high…then I saw my life fladh in front of my eyes when smoke started to rise from the engine bay. To my dismay it was from the wires and not the exhaust. So that’s where im at. The wiring harness starts burning after a minute of running, I believe it may be linked to the distributor since all other gause work except the tach, I open up the distributor and changed the icm but still no rmp signal and I cant check the code. I am in desperate need of help with this. Anyone wirh any good advice please chime in.
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[quote=”Kenpachi” post=100180]Hi all I’m new here and I have a somewhat complicated situation. I recently did an engine swap: put an H22(which I rebuilt myself B) ) in my 6th gen accord coupe and did an obd2 – obd1 conversion. At first it only had an issue with high idling, everything else was seemingly okay. The car did, and still does have a CEL. However my car doesn’t seem to have a service connector at the passenger side and I can’t scan using a obd2 tool. I tried a different chip in the ecu, the engine starting to bounce instead of just idling high…then I saw my life flash in front of my eyes when smoke started to rise from the engine bay. To my dismay it was from the wires and not the exhaust. So that’s where im at. The wiring harness starts burning after a minute of running, I believe it may be linked to the distributor since all other gause work except the tach, I open up the distributor and changed the icm but still no rmp signal and I cant check the code. I am in desperate need of help with this. Anyone wirh any good advice please chime in.[/quote]
Wow that’s pretty crazy…by wiring harness I assume you mean a bundle of electrical wires somewhere in the engine bay? If so, why didn’t the high amperage burn a fuse?
Yes, its insane im honestly stumped…the wiring harness that connects everything; injectors, alternator, sensors. I cqn see blue smoke coming from the bay. I also was curious why the fuse didn’t burn…I don’t let it run for too long after a minute I get scared. Just got finished unhooking the wiring harness to observe for possible shorts. I found two things to help my previous problems with idling and the tach but no sign of why the harness is heating up…could it be the ignition coil?
Well the primary side pulls some amps but the secondary side of ignitions is high voltage with just milliamps of current.
From what you’ve said it seems like there has to be a short AND that short has bypassed the fuse box. Therefore it must be happening upstream of the fuse box.
An example of this would be like if your main positive battery cable was pinched into another wire BEFORE it runs into the distribution box. Therefore it wouldn’t blow a fuse.
I think you need this http://www.amazon.com/Tool-Aid-25100-Short-Tester/dp/B000RFLR0U/ref=sr_1_1?s=automotive&ie=UTF8&qid=1402239266&sr=1-1&keywords=short+circuit+finder
Then you need to hook that circuit breaker into the wiring and energize the system so that the shorting occurs. The circuit breaker will just keep tripping and tripping every few seconds until you locate the short.
Thanks for the suggestion. Definitely gonna try ad get this tool. Im still not clear on how exactly this operates. I would need to go from wire to wire?
When I hear a story like yours I immediately think grounds. Grounds are easy to overlook when doing an engine swap but they are all necessary. The engineers size the grounds for the amount of current they will carry. And, they put the ground wire right in the bundle with the other wires. So, leave a ground or two off and now the other grounds are carrying more current then designed for and they get hot. BTW, no fuses in grounds to pop but if they get hot they can burn up the rest of the harness.
Thats an interesting point you mention, will review possibility. I was very careful not to hack up my wiring harness just added a few wires and I only have one grounding wire from the original motor that’s not connected. ..its the one by the driver mount. The car used to run for long periods 15+ mins and not have any issue apart from high idling after the swap. Problem started after I tried a different ecu and tune.
[quote=”Kenpachi” post=100256]Thanks for the suggestion. Definitely gonna try ad get this tool. Im still not clear on how exactly this operates. I would need to go from wire to wire?[/quote]
I think it comes with good directions if I remember right, but basically the circuit breaker part is connected between power and whatever wire or circuit is shorting out (this keeps you from blowing fuses and helps protect the circuit while it is energized). The little meter needle pulses when it is close to the short and helps pinpoint the short.
[quote=”barneyb” post=100259]When I hear a story like yours I immediately think grounds. Grounds are easy to overlook when doing an engine swap but they are all necessary. The engineers size the grounds for the amount of current they will carry. And, they put the ground wire right in the bundle with the other wires. So, leave a ground or two off and now the other grounds are carrying more current then designed for and they get hot. BTW, no fuses in grounds to pop but if they get hot they can burn up the rest of the harness.[/quote]
This brings up a question for me about the way an electrical circuit works. So you are saying there are no fuses in grounds which is true, but if the ground is carrying current then it would have to be getting it from some positive wire that is fused so this should still blow a fuse (again, unless it is upstream of the fuse box). Although voltage is dropped downstream of the load the current in a ground always equals the current in the positive and since fuses blow from current and not from voltage I would think that a ground carrying too much current should still blow a fuse somewhere. Am I right about this?
However, electricity does funny things and I agree that the weirder the problem usually means there is something weird about a ground causing the electricity to hunt for alternate paths.
I’m not saying grounds are the problem, I can only make a suggestion of a possible thing to look for in this case.
The thing about fusing is every circuit has a fuse or fuseable link but devices share grounds. On the car I drive there have been cases where the major ground to the engine was left disconnected and when starting the entire harness was smoked.
Well, I just got done reconnecting the wiring harness. I checked all the connections to the sensors, none of them look burned, which I could use a tarfet to try to narrow down the possibilities. What I did find though is two of the wires on the obd2 to obd1 conversion harness were disconnected. ..could this possibly cause the problem? I have now ordered a new conversion harness.
Hi,
I advise you to use BitKar for troubleshooting the problem with your car. You can manage the maintenance and repair life cycle of your car, search for local repair shops,diagnose car problems, estimate repairs, track your service history etc.
Here is a link to the BitKar website – bit.ly/1n3yoDG
Link to download iOS app – bit.ly/Sv72N5
Link to download Android app – bit.ly/1u1vt12
I looked at the app, its pretty good but I dont believe it will benefit me since my circumstance is unique, the issues found on the app are for a oem configuration. I have heavily modified my car: has an engine and transmission from a prelude, chamged from automatic to manual transmission, and has an ecu from a civic…I need help from someone who does custom work.
You do need help from someone that does custom work. In situations like yours you’re out in deep water and there is very little help that you can get if I’m honest. It’s kinda, ‘you made your bed, now lie in it.’ Even as an experienced Honda tech I would have a difficult time with this problem. Mainly because it doesn’t fit into a stock diagnostic process. Nothing is where it’s suppose to be. The one thing I suppose I can offer is that ground problems don’t often act like this. To me it sounds like a short. Given that you’ve made so many changes it’s very difficult to tell the effected circuit. About the only thing I can offer is to have a buddy activate the system while you look under the hood where the smoke is coming from. That may help you isolate the effected circuit. After that well, good luck.
More info on solving electrical problems here.
http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems
Good luck and keep us posted on your progress.
Update!
I appreciate ypur comment and to a great degree you are right. However, what i did here is nothing too extreme, as I’m sure you know honda parts are pretty much interchangeable. I finally got enough motivation to put my electronics certificates to use and solved the problem…and it demonstrates how much we think we really know about electricity…it was the car battery. Im not 100% sure why but it was giving too much current. The voltage was low, so I started using my DMM to check to see it I had continuity. I changed setting from volts to Amps and the leads to the DMM started heat…just as how the wiring harness did while the car ran. Changed battery. ..no more burning wire. However my original problem is still there, at start up idle jumps to 4k rps and wants to climb but is limited by rev limiter. I appreciate all the feedback and suggestions I got in trying to pin point the issue.
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