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Discussion Starter #1
I've been reading many threads on here but haven't come across any solutions to my issue. What's going on is the rpm is waving around 5k to 6500. It's like the engine is starving for are or fuel. After the rpm fluctuates, it doesn't pull as hard either.

Here's my setup. D16Y7 with Y8 IM, boosted to 14psi, build bottom end, stock fresh rebuilt Y7 head, ARP head studs, commetic head gasket, chipped p28 running on Chrome Pro (P30).

It's not losing any fluids or running too rich. A/F is fairly consistent at 13.0 in non boost maps and 11.8 to 12.2 in boost tuned all the way to 19psi. Thought it was timing so I reduced timing in boost columns by 5 degrees. Didn't make a difference. No detination. Running NGK 9's. Played with fuel up and down. Was so rich it was blowing black smoke. Still did the rpm wave around 5k.

Turned the boost down to 8psi and it wasn't near as noticable but was still there. Turned the boost up to 20psi (engine is built to handle this no problem) and it was very definite. Could a boost leak act this way?

Did a boost leak test and found the injectors were leaking. Fixed that. Did the leak test again and found the IAT was leaking. Fixed that. Did the test again and found that the turbo compressor housing is leaking significantly around the adjusting bolt pattern. Is there a way to seal this up and would this cause the rpm variances I'm seeing?
 

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When you say the RPM fluctuates, does that mean your tach bounces? It's hard to fluctuate actual RPM while you're in gear. If it's bouncing I'm going to guess ignition.

It sounds like you're blowing spark or having some other ignition issues. What are your plugs gapped at?

Old/new ignition components? I had a set of OE honda wires make the tach bounce in full boost because they were bad.
 

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Discussion Starter #6
What is the boost gauge doing at this time? And wot on na should net 12.5:1

Also what turbo and what injectors?
Boost gauge is fairly steady at 11.8. It's an AEM. Same with the wideband. 1000cc ID injectors. Hope it's not them. I've even reset/changed the depth of the injector into the intake manifold hoping the mist flow would change the reaction I'm seeing.

The engine feels kind of like surging which makes the tach bounce about 200 rpm or so. It's not always at the exact same rpm range. In a 3rd gear pull it will bounce around 5500 to 6000 rpm. When in 5th starting at cruise speed and going to WOT, which builds boost at a slower rate than lower gears because of slower rpm increase rate, it will do the bounce around 4500.

It has new plugs, new 10.2mm wires and original dizzy which was cleaned inside before installed. Plugs are gapped at .030" I had regapped the Irridium plugs from stock. Maybe that's what is wrong.
 

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first off you should be running ngk bkr7e's( new part number ngk 4464) start at a .028 gap and work down till needed

when this happens does it still pull hard, or is it breaking up and spuddering? if so your prolly just blowing your spark out.....run a colder plug and close the gap a lil at a time till it stops, then you will know at what gap to set it at......i think im at like a .022 but im running alot more boost
 

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I'm with the close down the gap brigade. At 14 psi I would think 0.022"or thereabouts. If in doubt try 0.018" just to prove the point.
 

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ehh on my gt-17 and my t28 on 12-16psi .025-.028 did the trick on a colder plug

at .028 i was blowing out the spark at 16psi on my hx .25 it was ok @ 22psi im at .022 and so far its ok

heat range of 9 is just to hot on a turbo motor....you want the ngk 4644's (bkr7e)
 

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NGKs go colder with the higher numbers.

I +1 the spark plug gap idea. I was getting spark breakup at .035" plugs with 14psi around 5k. Gapped down to .028" and that solved the issue. Also running bkr7e's.
Damn you beat me to the number range here is some info I found in team-integra from NGK

Whether the spark plugs are fitted in a lawnmower, boat, or a race car, the spark plug tip temperature must remain between 500C-850°C. If the tip temperature is lower than 500°C, the insulator area surrounding the center electrode will not be hot enough to burn off carbon and combustion chamber deposits. These accumulated deposits can result in spark plug fouling leading to misfire. If the tip temperature is higher than 850°C the spark plug will overheat which may cause the ceramic around the center electrode to blister and the electrodes to melt. This may lead to pre-ignition/detonation and expensive engine damage. In identical spark plug types, the difference from one heat range to the next is the ability to remove approximately 70°C to 100°C from the combustion chamber. A projected style spark plug firing tip temperature is increased by 10°C to 20°C.
 

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Discussion Starter #13 (Edited)
Thanks for the input. Took the plugs out and checked the gap. It was actually at .037". So I regapped them down to .022" before even reading everyone's suggestions on here and guess what, problem solved. Never would have guessed the spark was blowing out.

The plugs that are in the engine regapped to .022" are NGK BKR8EIX which is 2 steps colder than stock. I had considered going to 9's (colder) awhile ago and had 'assumed' that they were in there already. My bad.

I've only tested at 8psi and have had positive results with the .022" gap. No rpm fluctuation anywhere through acceleration and it pulls nice once boost is fully engaged. Had to touch up the fuel maps since the A/F went into the low 13's in boost after regapping. Will test at higher boost when I get time to work on the car again, hopefully before Monday.

Plugs looked good when initially pulled out. The electrode had nearly no build up on it and the insulator was fairly clean (clear if you will) at the top and gradually went to dark gray or black at the bottom, going away from the tip. I'd say the A/F is about right for that plug. It's a touch on the rich side maybe from start up as the outside ring is black with a thin layer of soot. I cleaned them up before putting them back in. Will take a look at them again soon.

On a side note. When pulling out the spark plugs, #4 had oil around it and the rubber boot on the end of the wire was torn off, still around the plug. Had fun getting that out! Looks like a valve cover seal is leaking into the spark plug hole. Doesn't seem to be any discolouration in the cylinder side of the plug. It looks just like the other 3 at the electrode.
 

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Discussion Starter #14
Excellent information. Got some boost leaks fixed while trouble shooting as well. :)

Still bothers me that the compressor housing at the adjusting flange leaks significantly. Maybe it's normal. Maybe I'm too fussy over air leaks. It's a Turbonetics T3T4B ball bearing by the way.
 

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Discussion Starter #15
Been adjusting the gap on the plugs and even trying different plugs. I've used a 9 NGK (cold) with a .016" gap and it still gives rev limit like symptoms and actually will not hit the rev limit set at 7000rpm. Goes to about 6200 and won't go any higher. Thought it might be too lean since the A/F gauge was reading a little lean in the higher boost region. Richened it up and it helped with the cutting out or backfire like symptoms but will not reach the rev limiter in 3rd gear. Could the distributor be weak? Just replaced the coil with a heavy duty. Still same thing.
 

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I'm starting to think weak valve springs or sticky valve stems.
 

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Wait a miniute, I just read where there was oil on the porcelain of the plug and the boot on the lead was damaged.

Fix the gasket where it seals oil out of the plug well and replace the damaged leads.

The reason we close the gap is because the electrical resistance of the air in the cylinder increases with pressure and fuel content. The increased resistance across the plug gap causes more volts to build up before it will jump a spark across the gap. IF THERE IS AN EASIER ROUTE TO GROUND, THE SPARK WILL TAKE THE EASIER ROUTE. A torn boot and oil on the external insulator provides the easier route.

I don't believe heat range has a lot to do with this problem. To hot causes detonation or even pre-ignition and glazed type deposits on the internal insulator and they have heat blister spots on them or cracks forming. To cold and they load up with carbon deposits and misfire from fouling of the internal insulator with conductive carbon deposits. You would see these on the plug in either case.

Having said that, the higher the cylinder pressure, the colder the plug should be, BUT, compression ratio, inlet valve closing point, inter cooler efficiency and therefore intake air temperature in the manifold all play their part, so what works for one guy does not necessarily work for the next.
 

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Discussion Starter #18 (Edited)
Thank you for the response. The seal has been fixed in the valve cover and oil does not leak into the spark plug tube any longer.

I've read that the stock head is good for upwards of 400hp or even more. This head has new valves, springs, retainers, guides, seals and has been planed for flatness back to stock specs. But I wonder if a modified head with intake ports that have been opened up for better flow and a larger valve would deliver more volume would be beneficial in this case. The stock head may generate the same HP but the velocity at which the charge is entering into the cylinder is greater. With a high velocity and turbulance I'm thinking that the spark is being blown out. I'm going to adjust valve timing slightly to try and get the intake to close earlier before the spark. I may also try adjusting the ignition timing to see if it makes a difference.

Thanks for the help. It has really made me thing of things I wouldn't have come up with on my own.

Here is a pic of the plugs that have been in the engine for the past 2 months of DD. These are the NGK BKR9EIX (2669 #9 cold). It's page 4 of this link, near the bottom.

http://www.d-series.org/forums/engine-building/141332-vinces-d16y7-build-4.html

Makes sense that a cold plug will look this way and misfire occasionally. I really notice it just after startup.
 

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Discussion Starter #19
Well, it turns out that the spark was being blown out. After replacing the coil and nothing changed, I decided to purchase a new distributor comlete. This one has 389,000km on it and has never been rebuilt accept for the new coil about a month ago. Installed the new distributor and problem has vertually gone away. No more cutting out or backfire symptoms when going into boost. I'm very pleased with the outcome and relieved.

I'm currently running 22psi up to 7,000 rpm. This SOHC non-Vtec pulls real nice from 4,500 up to 6,000 rpm. After that it doesn't seem to pull as hard. Haven't been on a dyno to see what's really going on yet. Some day. :doh:
 
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