My friend is having some major problems with his motor. He first had it built about 9 months ago, went through the break in period and founf out that his total seal piston ring had snapped, and destroyed his JE piston. He got that fixed and his electrical system started to die. So he replaced the old faulty ecu with a p28. Then his injectors went bad, with only 2 still squirting, so he replaced them with new gsr injectors. Now the car runs so rich, that it bogs out after 3000rpms and shuts off. He put new plugs in the motor, let it warm up for 5 minutes, turned off the car, took out the plugs and they were pitch black. His cam timing is 0,0 i believe.
Here's the setup:
b18a block stock bore
balanced, blueprinted bottom end
5 angle valve job and minor port and polish
stock valvetrain
je forged 12:1 comp 81mm pistons
eagle rods
gsr head
gsr intake mani/injectors
short ram intake
dc headers
The car is a 95 civic dx coupe

Another problem is that the vtec doesnt engage. The vtec solenoid was replaced and all of the oil lines are in place. The p-28 ecu is not chipped right now, it was put in to replace the old faulty one. Before the old ecu was replaced, there was a very bad surging idle problem, and the car would even completly shut off while driving sometimes.

We need to figure out the problem so he can drive his car to his new house in september.

The CEL has been on non-stop. Not sure if it will throw the right codes, considering the assortment of parts used to put this motor together. If you have any idea what the problem(s) could be, please, please help.

 

Sounds to me your wiring is majorly F*cked.. Thats where I would start looking before replacing anything else.

How did he come to the conclusion that the old ECU was bad??
What was the old ECU p28 or P72?
How is the idle? Bumpy? shaky? normal??

I would try to get a known good stock P72 ECU and troubleshoot from there and the wire harness.

 

He ordered a gsr engine harness from sohfast, but it was lost in the mail and they're going to refund him. The electrical guy at the shop has been sick lately so, the ecu hasnt been able to be checked. We found a diagram to make sure that all of the wires were in the right place for his swap, so he'll try that asap. The idle is normal as far as I know. Someone tried to wire in a field vtec controller into the ecu, so that might be part of the reason the electrical system is all jacked up. The unit is out now though. . . So what do you think? Interior harness, engine harness, or ecu?

 

I would still say check engine wiring. Even if you took off the vtec controller, make sure you dont have any exposed wires grounding or touching other stuff.

The only way to test the ECU is to borrow a friend's car and see if it runs ok with his car. (given the ecu and motor matches)

Where did you get this "diagram" for the wires?

 

just got back from his house. The idle is very bad, he says his car idles like he has untuned toda c's. Heres a pic of the ecu diagram:

 

OK the picture does checks out ok. You will need to ground the VTEC also (engine side).

If it idles bad.. then I may suggest check the timing. If you have cam gears; set them to 0 and make sure your timing belt is not off by a tooth or two.

Im not sure if the P28 will throw you the right codes.. but if you can plug a P72
ecu and see what codes you get that would be the best bet.

 

If your buddy has a DX the MAP sensor plug on the DOHC VTEC engine harness will not work (without modification). This is due to the fact that the DX has the MAP sensor and MAP sensor plug and wiring on the firewall. Take the MAP sensor plug from the firewall and plug it into the MAP sensor on the DOHC VTEC throttle body.

Next, find out what codes it is throwing and follow the troubleshooting procedure outlined in the Helms manual.

I bet you are thowing a code 3 and/or 5 for the MAP sensor. This will cause the rich running condition you described.

Also, a P28 ECU will indicate the same MILs (malfunction indicator light) or check engine light codes as any other ECU. Some ECUs have more or less codes due to more/less sensors or solenoids but the codes are the same for almost all Honda automobiles.

Good luck.

-kenji




[Modified by kenji, 6:46 AM 7/2/2002]

 

sounds like he switched the MAP and TPS plugs around ...

Greg

 

Mr. Banker Man,

That is another possibilty.

-kenji

 

we had to change the plugs today and put new injectors in, and I got a chance to look for the map wires on the firewall, and they are not there at all.
the map sensor is in the right place, as is the tps.


[Modified by 743teg, 7:00 PM 7/2/2002]

 

do what cheeta said swap your map and tps plugs because if there backward it would make the motor bogg after 3 or 4 grand. and turn the plugs pitch black because its to rich because your manifold pressure isnt reading right . and what year is the car is the lsvtec in if its none obd and 88-91 non si youll need to swap the outside wires on the tps senser.

 

i would chip your p28 to dohc, cause right now i bet your motor is running shitty, with sohc p28, my motor hasent had any problems at all, so if u want more info juat hit me up at my email lsvtec408@aol.com peace

 

do u have a vtec oil pump? b16 or b18c?

 

Damm what shop did your LS-Vtec conversion? Let me know so I won't go there.

 

It's not the shop's fault. My friend bought the car, with the ls/vtec motor in it already for cheap. The guy he bought it from thought he was a mechanic and an electrical genius, and the car was a MESS. There were live wires underneath the carpet with unconnected ends. We're all surprised the car wasn't seriously damaged. First thing my friend did was replace/repair all the messed up wiring. Then he brought the car to the shop to have the motor rebuilt. The main thing that caused the motor itself to go was bad injectors left over from the original motor, and a faulty piston ring. (total seal admitted the problem, wasn't only on this car)
Now the motor is finished, but the car is still plauged with major electrical problems. We're narrowing it down right now. The car hasnt been started in a while though, and we're worried about the spark plugs getting blackened again. The car needs to be tuned, but we can't drive the car to a shop until it can function normal. The map and tps are in the proper places, so that isn't the problem. However, since it is a dx and the original map wiring on the firewall isn't there, is there anyway that we can check to see if the harness was modified for the map sensor?

 

funny I just ordered a 96 ex harness from sohfast on may 11. To this day...the original one he said he sent out USPS never made it here..then just last week he sends me a 98 LX harness. He has been reliable before..but I dont know..lately he has been falling off.

 

Hopefully you're not spending more than what you paid for the car. I don't think I would ever buy a highly modd' car like that.

 

Some progress is happening on the car. Turns out a wire coming from the tps came out. The car revs freely all the way to redline now. The only problem is that the #3 cylinder isn't firing until about 5k. Is it possible that one of the contacts in the distributor could cause this? The plugs are brand new, as are the injectors, so we're looking past those 2 things for the problemo. We'll check the distributor to make sure everything is tight in there. If that's the case, than it's time to do a compression check. If everything checks out ok with that, than we'll start playing with the field sfc. Tech gurus, chime in on this if you have any ideas. . .

 

Well that's good that it's 'sorta' working good. But it is possible that the rotor is not touching the distributer. I've seen it happen before. My friends rotor was not installed properly and the thing wasn't going in circles. It was going like in an eliptical patern.

I'm having similar problems to my damm thing. I have Cylinder misfires. I can't figure out the problem either. I'm going to clean my injectors to see if it clears the problem. I've never cleaned them before (120,xxx) on it.