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Discussion Starter #1
I have an eg4 1992 civic,
I have put a d16y6 (head code p2j, intake code p2k) into the rig, with a p08 ecu. I have a stock jdm d15b obd1 distributor. Stock transmission,
The swap was all fairly straight forward.. most of everything was fine, worked sweet, timing dialed in no hard start no driving issues all was well.

I am however experiencing a couple minor issues.

Idling (after an IACV reset procedure) is low and lumpy and intermittently will search (jumps up to approx 1.5 holds for couple seconds then drops back down).
I have replaced intake gasket and i'm pretty sure there are no leaks- stalling the engine with my hand over the TB it has awesome vacuum however there is a little whistle coming from the PCV valve (have replaced) pinching the hose though will make it hold vacuum for ages.

Vtec, Now when i first start the car and drive for a little bit and then hit vtec the first time it will hit ~4800rpm really nicely and rev throughout to 7200rpm and works how it should.. Then if i hit vtec again straight after it lacks power and falls over almost feeling lean. The cams do change over (audibly) however the power is lacking.
if i park up (20~30mins not allowing it to fully cool down) it still has this issue. It has to get properly cold before it works well again (for the 1st vtec)..
 

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mm p08 and y6 never came together .

might need some time to get to know each other...

what is the dizzy set at?
 

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Heya yeah has been in there for quite some time few ecu resets here n there but like I say runs strong n hard first time I hit vtec.. I believe it somewhere between 12 n 16 degree marks probably the 12 degree
 

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Have replaced distributor with good second hand & double checked timing at operating temperature - problem persists..

at operating temperature coolant temp & iat resistances were within spec..
IAT, MAP, TPS, ECT, IACV, distributor sensors all trace back to ecu with continuity tests..
TPS has no spikes and is 0.5V- 4.48V..
Grounds have been checked & cleaned no issue there..
Battery is near new - and oversized if anything (500cca)..
No vacuum leaks present (put hand over TB and it slurped me in only slowly purging through PCV valve which is near new)..
O2 sensor has been replaced and fresh wire ran..
IACV has been replaced with a known-good from d15b intake manifold..


closing the gap of spark plugs has seemed to help slightly in terms of power..

Gonna do a set of spark plugs, dizzy cap & rotor, oil & filter and put an injector cleaner through her.. will keep posted - i doubt it will be anything of this nature especially because once its hot the problem arises..

Any thoughts?
 

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check valve lash.

P08 is supposed to run the JDM d15b I beleive.

Check oil pressure somehow, either by swapping in a gauge kit that runs in place of the factory sensor (factory sensor only runs the idiot light in dash cluster), or by screwing in a T adapter in the vtec solenoid and running a gauge from there.

Remove and clean the vtec solenoid screen. If it has debris in it, figure out WHAT debris it is, and if metal, stop driving the car hard.

Crappy idle can be a simple fix, remove the IACV and clean it out. even when pulled from a good car, the moving around can loosen up some garbage and cause a clog or stickyness. Use carb cleaner. NO BRAKE CLEANER!

Another idle helper is to follow factory idle setup. the USDM manuals are easier to find, and they are floating around for free somewhere. Whoever uploaded them is awesome.

Else go for a short drive, dont beat on it. Just put an ear to the car, so to speak, and see if it shows any odd behaviours.


Ive seen dozens and dozens of honda motors with the exhaust valve lash set too tight, and when the engine warms up, it basically bleeds compression off constantly.

Do a compression check both warm and cold. Ignore the actual numbers, pay more attention to how each cylinder stacks up against one another. a healthy motor will make within 5-15 psi or so of each cylinder. a hurt cylinder (or simply a bad headgasket or lash adjsutment) would be more like 20-25psi or more of a difference.


Kinda throwing those numbers out willy nilly, but you get the idea. That tech manual you can find online has the actual data you want.
 

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Discussion Starter #7
Hey thank you very much for the reply..
I have done valve lash twice now initially I set it too loose and got valve chatter & so have set to intake 0.15mm and exhaust 0.22mm I believe, too tight? what would you recommend?..

Will get onto checking oil pressure & compression, cleaning IACV, & sh** yeah even the JDM workshop manuals are up there.. set idle to 500RPM with IACV unplugged via idle set screw then plug back in seems to be the key

It seems to be running even worse as of late with less audible vtec crossover (double checked it with a test light it was that unnoticable)..
Other recent stuff ; oil and filter, distributor cap & new gapped plugs to 0.7-0.8mm round there(can you read spark plugs? got about 10 WOT runs on it then checked, white as ceramic, yellowish on the electrode, black as timing strap), currently running some injector cleaner through it, cleaned vtec solenoid gasket/filter screen, cleaned all grounds, tried manually engaging vtec via switch and honestly think it runs better without engaging vtec vs engaging vtec...

some weird stuff that happens with it is that when dead cold anything >15% throttle will cause brutal misfire/hesitation and cause me to clutch in, back off revs and ride out the clutch basically and then couple minutes down the road upon acceleration it will pop/backfire during the accel process but still run quite nicely... (untill its hot)

My thoughts are leaning towards fuel pump - runs fine cold then once i put some load on it doesn't cut the mustard,
perhaps compression when hot falls off and thats why itll lose power after a good pull (i can bang first and second and have it feel mean and then the next corner itll feel crap and cant hear the crossover)
perhaps it is the ecu im to understand p28 is a better match to the d16 then a p08?
 

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.007 to .009 inches for intake, 9 and 11 for exhaust.

so intake probably around 0.18mm intake and 0.23mm for exhaust.

You may be a hair tight on intake, and may be worth looking at.

I would not suspect fuel pump unless you can confirm it via a fuel pressure gauge. Generally, fuel demand is higher when cold.

VTEC also tends to cross over higher in rpm range when cold, if at all. There are throttle position, rpm, and coolant temp requirements that need to be made, apart from teh obvious oil pressure.


Change the fuel filter after running cleaner through the engine. And do it AFTER running the fuel tank very low. lots of crap can be loosened up with cleaner, and use the old filter to soak up the garbage first, rather than a shiny new filter.

Worth a check, yank teh vacuum hose off the fuel pressure regulator after a drive, make sure it does not smell strongly of fuel. SOME fuel vapor smell is acceptable.

I vote to stay away from tossing too many parts at it until you can get a proper baseline for how things are operating.

Just make sure the spark plugs were original to the engine. aka, if they were NGK ZRF5-11"s, make sure the new ones were a match, for example.

Just about ALL honda's (and most other cars) perform best with plugs that match the factory. colder heat range plugs are for high compression or turbo builds.

NGK or Denso. check out an online honda parts dealership, they will list the proper plug

0.044 is the general baseline gap in inches. With NGK V-Power plugs, that middle groove is 0.004 inches, so the actual measurable gap would be 0.039 inches.

I personally have ran a much larger gap and been fine, so if a smaller gap seemed to help smooth out how it runs, you may be dealing with something that is going bad, such as ignition module or ignition coil. But again, I would vote against tossing parts at it until you can run a few diagnostic tests.


Plus it is an excuse to buy more tools!!!!
 

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Discussion Starter #9
Heya thanks for the quick reply,
I will once the motor has cooled down set intake 0.18mm and exhaust 0.23mm, just to rule that stuff out.
Yep brand new zrf5-11s will set the gap to the 1.1mm/0.044in honda recommendation and do valve lash and see how i get on.

I am a mechanic just off work atm, i can go into the shop and test compression, fuel & oil pressures when i get a chance and hopefully tests are indicative of a fault (hopefully :'( )
Removing a spark plug and grounding it to the head it has an ok blue spark upto gap of 1.5mm , have swapped the dizzy for a supposedly good one and got a new cap (no new ignition leads, as theyre quite expensive) to no avail really,
Yanking fuel pressure reg vac hose and then plugging it has seemed to make an improvement in power and vtec crossover..
my understanding would be that with more fuel spark would not need to work as hard, being it either a lack-of-fuel problem or a lack-of-strong spark problem..
& with cold enrichment and with the fuel pressure vac reference off both instances would be dumping more fuel?

So next ill grab a fuel filter hopefully having had tested pressure before and after, rotor and ignition leads?,

Im all for spending less money cause the list of what ive replaced is ridiculous; o2, ignition relay, spark plugs, distributor, distributor cap, fuel pressure regulator, pod filter kit, intake/exhaust gasket, tb gasket

Got the car for $500 nz and motor/gearbox package for 150 it kills me to spend this much on it just to get vtec back haha
 

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Have you checked for any stored fault codes that might be intermittently setting and not turning on the CEL? The way you describe the issue sounds like the ECU is reacting to something out of whack on a consistent enough basis that you seem to have determined a failure pattern.

The P08 should run the Y6 fine as long as the Y6 injectors are still used. The only reason I say this is I'm not sure if Y6 injectors are the same size as the D15B's, but if the injectors that are meant for that engine are present, then the ECU should still drive the injectors appropriately for their flow rate. I can't imagine the OEM injectors between the Y6 and the D15B are all that different.

I would get the car to mess up again following your determined pattern, then check for flash codes BEFORE turning the key off. Remember OBD1 type ECUs reset fault memory after a key cycle, so you have to check for them before cutting the key off.

If nothing, then continue as you were lol
 

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Discussion Starter #11
Thanks drtalon123, am just waiting on the rain to let up before doing valve lash and spark gap adjustments and will report back,
Cheers
 

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Set intake to 0.08in / 0.20mm and exhaust to 0.10in / 0.25mm, spark plug gap to 1.1mm /0.4 inch roughly... Didnt see too much improvement however lil bit. still improves with fuel pressure reg vacuum line removed & blocked

Yes it did have pending codes 1 o2 - which i have replaced recently and will undergo the workshop manual tests for it tomorrow,
and 21 vtec solenoid - which in my great luck is now leaking so this may be the cause of the fault code. however manual actuation makes a click and test light shows 12v getting to the solenoid at ~4800rpm. Perhaps get a junkyard one?
 

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Reset ecu and did another hot limi bash around and it did seem to pick up some more power however not the same as how it behaves when cold..
parked up still running jumped service connector and it was without codes..
 

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Went out for the weekend ~ 50km drive and about half way while climbing a hill in 4th the CEL code came on for o2 sensor - almost immediately i felt it pick up power so smashed vtec next opportunity and it was running heaps better...From my understanding active cEL code sends ecu into closed loop that runs quite rich? so my issue is too lean? is there anyway to run open loop constantly?
Problem is i think ive replaced the 4-wire obd1o2 sensor with a p28s 1 wire o2 sensor and it is a little further down the pipe now ... 1 wire o2 was ~80nzd and the 4 wire was ~200-300nzd so i had thought the 1 wire would be fine
Doing the 4th gear 1.6k revs WOT for 5 seconds then closed throttle for 5 seconds doesnt make it throw the CEL..
Unplugging the o2 causes a pending code but no active CEL light in dash however did improve power a bit...
 
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