Clash0901

Okay I am going to give as much information about this as possible because the issue is getting to be unsolvable with me and my local car guys.

First I will tell you what the car does and when:

1) The idle bounces but not like a bad iacv. It bounces spontaneously. There is no pattern and it goes from ~800rpm to ~1400rpm. Usually it sticks to 800 for a few seconds then bounces and sticks at 800 again. One thing I will say is the when it's at 800rpms it feel like there is a shaking/misfire. The weather/operating temperature does not play a factor here.

2) At the most random times while driving the car it gets this issue where it bogs and does not like throttle below 3k rpms. This happens about once in a given 20 miles of driving the car. The weather/operating temperature does not play a factor here either. This issue will last for about 2 miles and go away back to being pretty normal until you come to a stop and then the issue above is comes back.

3) There is no real check engine lights.

Here is what has been done to the car so far:

1) OBD1 d16z6 full swap with engine harness. There is an oem p28 ecu with an obd1>obd2b jumper. The distributor is plug and play with the exception of the vtec wires being spliced by my friend to make vtec work.

2) There use to be 2 codes, one was for vtec which was fixed and the check engine light is now off. The other is for "fuel delivery" which only flashes if I jump the codes. CEL does not actually stay on.

3) New cap, rotor, wires, plugs, rear o2 sensor and fuel filter. Fuel pump has not been tested for pressure but i'm not sure that could be causing the issue. Only because there is an idle problem as well as the other problem. All injectors are 12 ohm z6 oem injectors. Compression is great as well as timing.

What could be happening here? What should I check and how?

Thanks a million!

Checkmarks

Can you identify if there is a "mis-fire" (no spark) during the let us call them events?
1. Hook up timing light on each spark plug wire. (one at a time)
2. Look into the blue flashing light. (use some dark sunglasses if necessary)
3. Does the 'flow' of flashing directly correspond to the mis-firing?

This trick resolves the very first basic required questions; does it have proper fuel and or is the problem the spark.

HondaPartsHero

So what engine harness did you use again? Did you convert the IACV to 2 wire? What injectors?

Putzman02

The idle bouncing could be a number of things. FITV, IACV, vacuum leak, air bubble in coolant. Speaking of coolant, does it get to normal operating temp, or does it maybe run cold? Have you tested the coil? How does the O2 sensor look?

Clash0901

02 sensor is new as well.

I do not have a timing light. The harness is all cut up but I had my friend wire everything in correctly. I do not know if the iacv is converted to 2 wire. Injectors are oem z6.

Should I get a new harness? As of right now there are a few random plug hanging behind the intake manifold but everything on the engine is plugged in.

hondaman64

check your tps
vot

Clash0901

What should I check for on it? I am a noob with wiring. Should I just throw a new one on there lol.

Clash0901

Frustrating!!!

Fnix

iTrader: (1)

Other then coolant bubble which happened to me on my swap, check the TPS cause I have a feeling that is it.

How to Check the Voltage on your Throttle Position Sensor.
After performing a swap, many times the throttle position sensor on the engine is broken, forcing you to use one from your old d15 or d16 (or whichever you pulled). The Honda TPS has three wires coming from it: green/white , a red/blue , yellow/white. Your primary focus will be on the red/blue wire, as this is the one that sends a voltage to the ECU telling it how open or closed your throttle is. The ECU expects .5 volts to be closed throttle and 4.5 volts to be Wide Open Throttle (WOT). The red/blue wire goes to pin D11 at the ECU. Rotating the TPS will change the voltage, when you take it off, you'll notice that the holes are slotted so it can move. If you are fortunate enough to have Hondata Datalogging or an Apexi V-AFC you can use their inbuilt functions to read the TPS voltage. If you do not have such a device, you can use a Voltmeter or similar device. Ground one lead on the chassis somewhere and use touch the (+) lead to the pin on the TPS (should be the center pin) and measure the voltage. Rotate it until it reads .5 volts, then tighten it down. Have a friend press the gas pedal to the floor and also check that WOT reads 4.5 volts.

Clash0901

Thanks i'll check this asap and report back!

Clash0901

I am getting nothing... No changes in readings, just a slight increase from .0 to like .0237 when I touch the red/blue wire.

HondaPartsHero

Just to be sure, you did test it with the key in the accessory position correct? And you are using a good ground as well? Make sure your meter is on DC voltage as well.
Here is a good thread on calibrating the TPS but shows good pics on how to check the voltage

https://honda-tech.com/forums/tech-misc-15/diy-how-calibrating-voltage-your-tps-sensor-2947986/

Clash0901

Yes on the key, yes on the ground, no on the dc voltage but I scrolled through every possible setting on it so i'm sure one of them was DC.

Clash0901

Purchased a new throttle body with good sensors. Installed and to no avail.

Car still runs poopy...

HondaPartsHero

HondaPartsHero

Any check engine light codes?

Clash0901

No check engine lights, no idea what harness, no idea on the iacv, stock z6 injectors, all tested at about 4 ohms. I am assuming the obd2b harness was used on this obd1 engine.

HondaPartsHero

if you didn't do the 3 to 2 wire conversion at the IACV and the ECU you might want to start there

Clash0901

I will try to mess with this tomorrow. How do I get those wires out of there? Also i'm running a p28 w/ an obd2b to obd1 jumper harness. Will I be doing this on the factory harness side still?

Clash0901

Do you guys think the jumper I have is pre-designed for this iacv wiring issue?

Or do I have to also mess with the jumper?

Clash0901

No luck. Still having idle and bogging issues...

Marvin1985

iTrader: (5)

I didn't read all the comments but a new Rear o2? Guess what the ecu isn't even using that sensor. On obd1 only the primary o2 is in use. So switch the o2 to the front.

Clash0901

The front one is already new. As far as the rear one is concerned it was just me ruling everything out lol.

This is the worst problem i've seen on a Honda. The wiring looks decent too and my friend looked it over with me to confirm it was done right.

Marvin1985

iTrader: (5)

On the TB(if a z6 tb) check/clean the fitv and then check/clean the iacv. Burp the coolant if necessary. Check all vacuum hoses/lines. Check rad cap. Um that's all I can think of thus far. Check plugs, wires and cap. Run higher octane gas for a full tank. How's the idle? Maybe needs adjusted.

Clash0901

Clean fitv already, cleaned iacv and tried a known working iacv, coolant flush as of a few days ago and properly burped, vacuum hoses seem good but will double check them again asap, rad cap is good, plus, wire, and cap are brand new, will try a tank of 93 next time I fill up.