se93

Hi guys:

After going to the dyno last sunday, i noticed that my A/C condensor fan was not working and when i got home, i checked the under engine hood fuse box and found that the fuse had blown. So i replaced it with a new one and all was fine. On Tuesday, i started up the vehicle and noticed that it started up kind of strange. I looked at the FJO Wideband display and started to see very lean A/F readings. This was strange as the car has been completely tuned and such a problem had never occured. I shut down the engine and took a look to see what i could find. I didn't find anything and thus restarted. The engine started up but with the intention of shutting off. My friend put his foot on the gas and i took a look at the engine bay to observe and i could see that my digitial battery charge post was only marking like 13.5volts, when he took his foot off of the gas, battery voltage when flat to 12 and 11.8 and the engine shut down.

We decided to change ecu's and put in my friends ecu/hondata system and started up the vehicle. The engine fired up perfectly and battery voltage was at a steady 14.10volts. Then we tested my car's P28/Hondata in my friends prelude and it started up and shut down, just as it did with my car. With this test, we concluded that for some unknown reason my P28 decided to crap out.

Fine, about an hour ago tonight, i got in an ecu from a friend of mine who just installed a Hondata S300 and i figured i would hook it up to my car and go for a ride. I connected it to my car and it started up normally with no problems. I did notice though, that A/F was a tad lean still and thus made immediate changes to the map and got it fine. I left the engine running and when to my room for a minute or so. When i came back to the garage, it was silent. The engine shut off again. There is a ghost messing with my vehicle.

Can anyone shed any light into this strange situation? I am afraid to recrank the engine with my friends ecu because i don't want to fry it as well.

There are no Check Engine codes and all fuses have been checked.

Help!!!!!!!!!!!!!


Modified by se93 at 6:09 PM 11/16/2006

se93

anyone?

98vtec

wow, uh......maybe check the voltage on your map sensor...?

do your lights go dim or anything?

This problems sounds completely electrical and sounds like a sensor is messed up that is used to determine fuel requirements. I would check the voltage on the map sensor and TPS sensor.

se93

I previously did not have any problems with lights dimming, but now i am completely hesitant to use any type of engine ecu as the one i originally had is no longer working and to install ecu after ecu and have them all go bad is a nightmare. The only thing we did before hitting the dyno that sunday was install an RPM Service throttle body. We calibrated the TPS with a voltmeter and got it to 0.045v as required.

I did not monitor if the charging system went haywire that second time i started up the engine with the other ecu, as i went to my room for a minute or so and when i went back to the garage the engine had shut down. Could a bad battery/alternator cause this?

I am pretty much in a lose to lose situation because if i plug in another perfectly working ecu and this unknown problems screws up the ecu's, i am in for a long, long migrane headache.

98vtec

have you tried putting your ecu in your friends car?

also check the grounding on the alternator.....there could be some corrosion not allowing it to charge the battery to its potential.

se93

I put my ecu with my S300 in his car and got the same results. His engine would startup and shut down. I even put in a brand new S300 module to check and still the same results. We checked the alternator 4 pin plug and positive wire that goes to the fuse box and all was tigtened and in good condition.

se93

Here is my electrical system setup:

I have 1 Red Top Optima for the engine and 1 Yellow Top Optima setup in the trunk for the audio system. My alternator is a 160amp Startech.

I also have a complete grounding system, which a friend custom made for me, which has 5 different points of grounds.

Basically thats it.

98vtec

hmmm...open up your ecu case and see if there are any parts that are fried. if there is a certain spot that is fried, you can trace what it is. You may have two wires grounding themselves out.

i hate electrical issues. So much **** to narrow down only to find out that its simple.

se93

I opened up my P28 ecu and there are no fried components. I am going to take it apart again and take a close look at the veins to see if there is some evidence of damage somewhere.

se93

I just removed the Optima Red top battery and got a cold reading via my voltmeter of 11.92 volts. I also measured my 1994 Accord S/W battery voltage and got 12.35 volts.

Can this be the culprit or part of the problem?