Rep Power: 304

Needs some help diagnosing this problem…

The other day while driving my car home, the alternator tension bracket bolt snapped. (see attached pic) After the that, the car drove really rough, wouldn’t accelerate normally and would run really rich (9-10). The next day I fixed the broken bolt and restarted the car to determine if that resolved the problem.

Now the car starts but the idle jumps up and down from 1000-1500 rpms. The check engine light blinks at the same time that the car revs. I hear a clicking from the ecu/glovebox area. It proceeds to do this about 12 times. After that the reving stops and idle stabilizes. Unfortunately I can’t see what the idle is because my tachometer and engine temp gauges are no longer powered up. My speedometer and fuel gauge still work perfectly fine.

The car is hardly drivable, it lurches a lot , feels like a constant load on the motor. My A/F ratio at idle is in the 9s and continues to drop. I cannot go into boost because the car leans out severely. This was a very difficult time going up a bridge lol. I barely made it. Lastly and what leads me to believe my ecu is screwed, I cannot read DTC codes (check engine light) anymore. My reader just says ‘FAIL’. I did previously have a CEL on due to a bad o2 sensor. Any possible way you guys think it could be the alternator? I’m going to pull it out today and have it tested. So far I have not seen anything like this happen before. Let’s see what you guys can come up with.

 
Rep Power: 811

well i can tell you that an alternator would not cause problems just being broken. i drove 20 mins to a shop on just battery power when mine burnt out. unless something strange happened and you got a power surge, which would explain alot. have you tried pulling the battery cable and seeing if that resets things? the clicking sounds like some relays took a crap. but the rpm changing usually means the tps voltage is too high (out of range). there are all things you could check but its gonna take time. if you really think its the ecu, try and find another civic that could trade with you. but i think somehow the alternator made too much power and overloaded some sensors.

 
Rep Power: 304

the problem with trading is that with a new ecu I couldnt start it without bringing it to honda to get the key reflashed.i tried both pulling the ecu fuse and disconnecting the battery, same thing happens. im pulling the alternator today to have it tested. I will have another ecu on the way,if the test turns out to be ok then I will will try to get honda to reflash my keys. hopefully but unlikely it is the alternator. all this trouble and wasted money over a .50 bolt.

 
Rep Power: 0

When you reset the ECU, disconnecting the battery or pulling the ECU fuse, you have to drive the car for about 3 miles so the ECU can "adjust" the sensors. If you have a clicking noise from the glove box, (that should be a relay) the two relays that are behind (or under) the glove box are the main relays of the fuel injection system.
If you have a manual, you can see one of them is the "main relay 1" and the other the "main 2". One of them is for the ECU and sensors, the other for the fuel pump. Check those relays, maybe the drop of voltage cause damage to those relays.

 
Rep Power: 0

When you reset the ECU, disconnecting the battery or pulling the ECU fuse, you have to drive the car for about 3 miles so the ECU can "adjust" the sensors. If you have a clicking noise from the glove box, (that should be a relay) the two relays that are behind (or under) the glove box are the main relays of the fuel injection system.
If you have a manual, you can see one of them is the "main relay 1" and the other the "main 2". One of them is for the ECU and sensors, the other for the fuel pump. Check those relays, maybe the drop of voltage cause damage to those relays.

And a .50 bolt, but it causes an instanly drop of voltage from about 15V to just 12V (or battery voltage). And if you was on high RPM or load...

 
Rep Power: 811

well 14 to 12v more likely but still I didn't have a problem driving the car in battery power but i kept the rpm below 4k. i thought everything was meant to operate on 12v +/- 1v.

 
Rep Power: 304

well i was actually coming to a stop, no more than 30 mph and less than 3k rpm. i'll check the relays to make sure too. thanks for the help people. im really missing my boost.

 
Rep Power: 304

UPDATE on progress...

I did some more testing. NO ONE in my area can test my freakin alternator.. not autozone, not o'reilly, not napa. None of them have connections/parameter settings for it. I hooked the car up on battery power only and it does the exact same thing, so I think I can rule out the alt. I movied onto the relays for injectors/fuel pump under the ecu. I ordered some new ones and gonna replace them to make sure that they are not the problem before i spend more money getting the car to honda. (Towing,reprogram etc etc) Yea so i'm waiting on that so I can continue the troubleshooting.. I'm really hoping the relays are at fault so that I dont have to deal with honda giving me **** about reflashing my ecu. Wish me luck.

 
Rep Power: 811

yea it is possible. clicking usually means fried relays. was the noise coming from the ecu area?

 
Rep Power: 304

the clicking was the relays.. i felt them with my hands.. after a certain ammount of time (12-13 secs)the car gets the idea that the relays arent working right and proceeds to limp mode, its really crazy. I guess we'll see what happens when my new relays come in.

 
Rep Power: 304

Update! Tried new relays.. that didn't work. Got it over to Honda and it stayed for 2 weeks. After some troubleshooting, it was understood that the ecu was screwed. $313 later, I get my car back. Now its time to get back to business, clutch, exhaust install and hitting that dyno.

 
Rep Power: 811

that sucks but at least its fixed

 
Rep Power: 304

yeah, but not something I coulda did myself ya know. only charged for 4 hours labor which is a good thing, coulda been alot more.

 
Rep Power: 0

anyone know where i can get ex ecu 5 speed and key ??

 
Rep Power: 0

im having the exact same problem dont know what it is , i chabged ecu and alternator but havent changed relays yet

 
Rep Power: 244

Check your engine harness ground wires. That's what it was for me. It causes the relay to click and the engine to run shitty or not at all.

 
Rep Power: 0

where all those wires? i check wires under engine bay and all are connected

 
Rep Power: 0

anyone got a main relay for sale?

 
Rep Power: 811

does he mean the grounds in the engine bay?

 
Rep Power: 0

i dont know where else is there grounds? i already checked all the grounds in the engine bay

 
Rep Power: 244

Yes the grounds in the engine bay. Don't just make sure they are connected but check the connection for continuity with an ohmmeter by touching the wire where it's bolted to the engine and either the body of the car or the neg battery cable. In my case the ground bolt was not tight or clean.

 
Rep Power: 0

i changed the ecu on my car twice and it is still messed up only lasts like 10 mins, then something messes up the euc and it gives out no codes im having the exact same problem that xsr civic has the guy that started this thread

 
Rep Power: 0

can anyone give me any info on what i should do to fix my car im so fustrated ready to take it to the dealer, i was wondering if it could be the main relay or something like that

 
Rep Power: 0

i changed my ecu already and within 10 mins it stops working again, i dont think the new ecu i put in was bad so it must be the relays right

 
Rep Power: 0

Good thing its fixed. I hate it when there is something wrong on ur car and ur not sure what to do. Sucha unnerving feeling.

 
Rep Power: 0

Ok just for the people that read this post. I want everyone to know that I have the EXACT SAME PROBLEM. My alternator bolt came out of slot after a rebuild on my port and polish, the alternator not working I think IS THE PROBLEM! When the ecu doesn't see proper voltage it must fry. I changed my relays first and then bought my ecu, I need to go and get my key reflashed. But I think I'll be set after this.

 
Rep Power: 264

You paid $313 for the new ECU and everything ?

 
Rep Power: 0

im haiving the same problem and ibought the ecu from a scrap yard the same one for my car and now the car does not start but i put old one in and it works but rpm idle doesnt work ... how do i fix that problem

 
Rep Power: 0

I can tell you, for a fact, that the alternator pivot bolt on top of the component is the ground for the ecu. Mine is backing itself out (won't stay threaded in) and I have the same issues. It's called Limp mode and the clicking is your ecu trying to find ground. After so many attempts, it fails and disconnects the ecu from most components as a way to protect them from receiving damaging voltage spikes. Your injectors and fuel pump get only the minimal voltage in order to "limp" to a service center. That, in combination with the crankshaft position (directly next to crankshaft) sensor and potentially the crankshaft pulley need to be inspected/tested also, though. If crankshaft sensor is intermittent or crankshaft is moving separately from the pulley, fixing/replacing alternator won't fix problem. Draw straight line from one side of pulley to other, making sure to mark both the pulley and the shaft. Run car for awhile, even just parked, and then check to make sure you still have only the one line, not two separate lines, indicating pulley slippage.. this is my next course of diagnosis. Also, checking MAP sensor and MAF sensor is necessary. A/F Ratio is vital to proper ecu function and all..

 
Rep Power: 125

Thanks for your input, but please don’t revive a thread that’s been vacant for 14 years.