Hi guys.

I've just finished my swap to d16y8 obd2a, which originally was A/T. ECU is chipped p28 via OBD2a->OBD1 adapter. I've drilled new holes in the auto y8 intake manifold for IACV, also I took a throttle body from D16Z6 IM along with 2-wire IACV. The mainwire harness is adapted to for 2-wire IACV.

Engine starts and runs ok, but idle is bad. It is not even, though it swings around ~800rpm. I tried to fix it with idle screw adjustment, so as manual tolds, I disconnected IACV connector and engine stalled at once. No chance to keep it running even if started with throttle open - it stalls once throttle is released.

Just for the case I completely unscrewed the idle screw, so there is an open hole, and then started the engine. RPMs periodically shuffle between 0 and 1000, at 1000 there is a whistle of the air sucked into the idle screw hole. I plugged the hole with a finger and the idle RPM fixed at no more than 200, the same is if I put back the idle screw just to close the gap.

So I cannot adjust it to 500rpm with the idle screw as manual suggests.

Does not it look like the idle screw opening is not enough to have 500rpm at idle? Can this be that the z6 throttle body does not fit y8?

 

The line for 500 RPM is ritht above the 0. The first 1k RPM is a shortened sweep. 500 is not in the middle of 0 and 1000. Are you looking at the correct line?

 

Interesting point. My tach has a line right above 0, the arrow shakes around this line. But if it stands for 500rpm then it is impossible to see the difference between 500 and 300, since the arrow width is similar to the space between 0 and this line
But nevertheless, I assume it is about 200 just because I hear it makes 3-4 rotates per second. Exhaust manifold has a crack on the 4th sleeve, so on each cycle it makes a distinct click.

I've just checked ignition timing, it was wrong. However I could reach the marks on the pulley only in the "earliest" distributor position. By the way, idling got better with this adjustment. Will recheck everything tomorrow.

 

Check engine light on?

 

Nope, CIL only shown missing IACV when I did adjustment.

 

iirc isn't idle supposed to be around 800?

 

It is at 700-800 in normal operation when IACV is plugged in. Manual suggests diconnecting IACV (so it is closed) and set RPM to 500, I believe it is just a base RPM.

 

Oh okay gotcha. Mine does the same thing on my d16z6, I just left it alone since my idle was in the right spot with it plugged in

 

I'm not sure that the engine would actually idle at 200 RPM.

 

Well, I have to recheck it then.

I'm starting to suspect the timing belt is misplaced by a tooth, since ignition is not within a distributor range.

By the way, the mpg is about 12

 

I've taken a video of engine idling with IACV disconnected. The idle screw is almost out, and the tach points to the mark right above 0. As you can see, it clicks in 4th cylinder, I assume it clicks once per single rotate. Is it sound like 500?



I've rechecked the ignition and timing belt position, it seems to be correct.
The problems I observe now is that idle is not that smooth as my d14a4 was, the MPG is frustrating, and also I checked spark plugs - they are black, so it seems that there is too much gas (or not enough air?)

 

In case if anybody interested, I found that a chipped obd1 ECU can be reset to stock just by cutting a J1 jumper.

So I just cut the wire and now I have stock p28. Now I could adjust idle speed (was really too high) and overall engine performance got more stable and smooth.
I'm pretty sure the fuel map was not for 1.6 engine.

 

Hi guys, another question raised with stock d16y8 + stock p28 ecu.

How do I adjust timing? Crankshaft pulley marks are at 10-12-14, would it be the best to adjust it farther than 14 mark by 2 degree to get 16 degree timing which corresponds to p28 base timing?

It was adjusted to 12 before and mpg is still bad, like 16mpg. Better than the chipped p28 but still far from stock mpg.

Now I adjusted it to 16 as I described, mpg is still to be measured, but it seems it became even slower.

Am I doing it right? Any suggestions?

Additional question - is that ok to adjust timing with jumped service connector and IACV disconnected? That is I adjust idle and timing at the same time.

 

Adjust idle, reset ecu. Learn idle and then Adjust Timing.

 

Well, this is just ridiculous. Sorry guys for messing everything up, but it seems that the problem is that ECU is P28-A52, automatic

Converted it into manual (googled the solution, remove 2 resistors, PR17 & PR18, replace PR18 with a jumper). Now idle is stable at 750. Ignition timing is set to 16, will check MPG.

Reached 110mph easily, so it seems all the power is back here. Not much torque though, will also turn the chip back later, just to compare.

Thanks for your support!