Here is the story:

I installed a D15b in my 98 civic DX, here are the details, I swaped the intake manifold with injectors of the D16Y7 on the D15b, kept the D16Y7 harness, put a P28 ECU with OBD2A to OBD1 conversion a harness, plugged in the Vtec into the OBD1 harness, kept the crank pulley of the D15B (alternator belt too lose) and everything else is original D16Y7 (oil catch can, dizzy ... well everything except ECT sensors and switches that were already on the D15b). Now the knock sensor on the D15b is not connected since there were none on the D16Y7 and the crankshaft position sensor wire is not connected to the D15B since there was no bracket on the oil pump for it and anyway I was told that there would be no problem leaving it not plugged in (which is true because the engine started on the first crank of the starter and that there is no trouble code coming out).

That being said, here's the problem, the engine started number 1 with idle a little high but nothing alarming for now. First ride, everything is good at first, Vtec kicks in and all. 3-4 minutes after the car has a hard time, at idle the RPMs go up and down non stop. Leaving form a stop, I give it gas but it does not want to go to well, it hesitates (no misfire or bucking or bogging) it goes slowly and suddenly the power comes back and it goes. In higher RPMs the problem seems to disappear, if i floor it in low RPM it doesnt want to go too good but then suddenly it goes and all of a sudden there is less power, then it comes back so basically the power comes in and out. Flooring it at high RPM seems to be less troublesome. On the highway if I keep the pedal steady and keep it at 70 mph in 5th it feels like a roller coaster, power.... low power .... power .... low power ...power. It feels like all of a sudden it pulls, and suddenly it coasts, it pulls, it coasts .... all of this happening at a steady 70 mph (+ or - 2 mph) You see the picture? No check engine light or battery ever flashed. If I recharge the battery and I leave for a ride, the same cycle starts from the beginning, the first 3-4 min are ok but suddenly everything starts over, weird idle ... etc.

Keep in mind that the crankshaft pulley of D15B was too small so the alternator belt is extremely loose and the alternator squeals loudly at idle and occasionally at higher speed (I'll change it tomorrow for smaller one). Also the distributor is form the D16Y7 and I had to drill it to fit it and now because of the tight fit it has no play to adjust the timing. Also the knock sensor and crankshaft position sensor are not connected as previously mentioned. All that still without ever any check engine light or battery light appearing....

Thanks in advance

 

Cliffs?

 

Sounds like the alternator belt is slipping for one.
Get that issue fixed.
If you know that a problem exists I don't understand why people don't fix them.

 

you won't throw a code for the knock or ckf crankshaft fluctuation sensor because the p28 doesn't look for them.

A lot of your problem may reside with the fact that you used y7 injectors. The p28 is for the z6 which uses 240cc injectors like virtually every other d/b-series engine. The y7 however has 190cc injectors. you need to get yourself some 240's and see how things improve.

 

I said the belt is slipping so of course it sounds like its slipping if I said so!! And since the crank pulley is a bit smaller on the D15b and that the alternator is all the way to the max on the adjustment, I had no other choice but to leave that loose belt until I buy a smaller one tomorrow, as previously mentioned!

 

Whats Cliffs?

 

So would any 240cc OBD2A injectors from Honda/Acura fit and plug right into my harness?

 

Just use the D15B injectors they'll fit once you do this

 

So I just yank out the blue thing and they should plug straight in? Is yanking it out really that simple?

 

I'm looking at the same pictures you are. What looks hard?

 

Yep that easy

 

Ok and I heard injectors have various resistances even between the different 240cc injectors and that the wrong one could fry the ECU

 

you said you swapped intake mani's... double check to make absolutely sure that you do not have vacuum leaks... as for the injectors... i would go with the 240's because the number is bigger lol using 190's N/A should work just fine... but you really should match injectors to the harness you're using

 

Yeah I checked for leaks vacuum leaks and there arent any

 

thats basically between OBD0 and OBD1/2 (and some select OBD1 injectors, not in this case however)

 

... this is where the devious resistor box comes in... brum bum bum...

 

oh i forgot to add... did you properly "burp" your cooling system... air in the coolant system can cause your symptoms as well...

 

Yes air has been properly bleed out of the system and I event took apart that little valve at the throttle body that is usually the cause of that symptom... Yet still that problem...

 

I herd that the IACV might be the problem since on the D15b it uses a 2 pin connector and on my old D16Y7 it has a 3 pin connector... I believe that the OBD2A to OBD1 harness took care of all the rewiring issues but someone is telling me that the valves themselves are different and therefore I will have to swap in a 2 pinned one and fit it into my OBD2A harness... Can anyone shed any light on this issue?

 

Uh yeah. You have to use a two wire IACV connector, is your IACV even plugged in?The two wire should look like this



Link to conversion

http://www.d-series.org/forums/diy-f...onversion.html

 

Yes the IACV is plugged in but it is the 3 pined one since im using the D16Y7 intake manifold. So to solve the problem im thinking of just taking the old D15b intake manifold and install that one. My question here is, will all the other sensors plug right up (IAT, TPS, etc...) since it is an OBD1 intake manifold plugging into an OBD2A harness, will there be any other issues? Or should I just get an D16Y8 intake manifold for a manual one (2 pinned) and call it a day?

 

Yeah since you're OBD1 everything will plug right in. You can choose not to use the EVAP purge if you won't since it won't plug in and the OBD1 ECU won't throw a code for it. Your IAT won't plug into the D15's as its a similar plug above and the OBD2 is square. You can just insert it into whatever intake arm you use or swap over plugs to the round style.

EVAP purge, eliminate this


Put this in your intake arm


Or swap plugs and use this one

 

What about the FITV does the D15b's intake manifold have one? What about the intake manifold of the D16Y8? I herd that OBD2 dont use that anymore. Would you know anything about that issue?

Also for the purge solenoid, is it that the OBD1 ECU doesnt even operate it because it doesnt have one and so it isnt even plugged into the ECU anyways? Or is it that even if its not plugged in that it wont throw a code if it cant operate it because I removed it?

 

?

 

FITV isn't electrical so if it has it just connect the coolant lines. Obd1 has evap but won't throw a code if removed like obd2