95 Civic EX Idle Problems. Help ASAP!

[Tuner620]

Hey. Heres the situation. After replacing the cylinder head on my d16z6 engine, it idles fast (~2000rpm) and has a weak cylinder. When starting the car: it cranks up and bogs badly at 200 rpm for 2-4s, and then rises to 2000rpm. After checking several things (vacuum leaks, FIV, IACV, Ignition, Injectors), came to the conclusion the the ECU is bad, but need advice before I buy another.

The full account, its a long one.

On a 3 hr drive to my parents, my car loss power and began to run on 3 cylinders. After determining there wasnt anything I could do, I went ahead and drove it the rest of the way ~30min. The next day, we tested the compression in the dead cylinder(was getting spark) and found it had 0 compression. Pulled the cylinder head off and found that it had a badly burnt exhaust valve, with every valve looking terrible. Several mm of build up on each. So we switched the head/valves with another that I had, but kept the old camshaft and rocker arm assembly due to the other cam being broke. Reassembled with new head gasket, exhaust gasket, and intake gasket. We also cleaned the TB with TB cleaner.

Now, we have discovered that the same cylinder is firing, but it is very weak. Unplugging the spark plug or fuel injector barely causes the engine to bog. We tripled checked the ignition system, and cleaned/switched around the injectors, problem remained with the same cylinder.

Also, we can not check the timing due the engine idling very fast. It will not idle below 1500 rpm. It is generally between 1500-2200rpm. Checked the FIV and IACV. The FIV is fine, however not sure about the IACV. When unplugged, the engine idles a bit slower (~1500rpm) and lopes a little. When plugged in, it idles faster but smoother.

Checked the MAP sensor following a service manual I found online, and it points to a bad ECU. Two of the MAP connector terminals did not have 5V between them. Checked the corresponding terminals on the ECU (terminals D17 and D21), and they did not have 5V either. No error codes.

I need to fix this tonight. Driving the 3hrs again tonight. Does it sound like the ECU could be bad? If so, why didnt this problem exist beforehand. Also, is there anything else that it could be? Anyway to repair the ECU?

Thanks for any help!

EDIT: Forgot to add: only mods are I/H/E.

[bella2009111]

The ECU is removed from the mounting bracket and the back cover is removed. The cover is held on by four Torx 10 screws. Two ECU’s repaired - the fix; using the repaired Trace method.

[Tuner620]

Thanks for the help bella. However, I looked over every inch of the computer, and didnt see one broken trace. Nothing looked burnt or broken. (did find 3 "holes", rings that were not soldered, but these were on the edge of the board, with no traces going to them.)

[Tuner620]

UPDATE: After getting the car to a drivable condition, I drove the 3 hrs and now it is very hard to start when hot. I discovered a leaking injector, repaired it, and no change. I have an adjustable fuel regulator, so I played with the fuel pressure, and found that if I increase the pressure to around 40psi, it will start, but just so. Checked the ECU again and it checked out fine.

I did a compression check also: 90 110 130 90. (in order of cylinders-1 2 3 4) This is with a new head gasket. I poured some oil in the cylinder 1, and it increased from 90 to 110, so dont think it is rings.

I also remembered that after the head was on, I could not get the TDC mark on the cam to line up while TDC on the crank was lined up. It was off by about 2-3mm. I got the timing set pretty well, and the distributer is in the center of the adjustment range, so I dont think it is off a tooth.

Any suggestions at all?

[lesliegfoster]

Just a guess , sounds like when you put the timing belt on you didnt have the crank in time with the cam. check the proceedure again and make sure you have the marks for the cam gear and crank gear at the right spots. Good luck!!