Changed Plugs, Now Seems Sluggish

[cpt_impossible]

S13 240sx

RB20det

Stock Turbo

Stock Injectors

3" Downpipe back, no cat

255 pump

Nismo AFPR

Stock intake pipe

M's K&N Filter

FMIC

Stock BOV (plumbed) and HKS Super Sound (open vent)

MBC

I had my car dynod, made 170rwhp on 12psi and 191 on 15psi (accidentally went too high on MBC). Around 6,200 the power would drop and the AFR would drop into 10:1. There was some concern as to the dyno calibrations but I figured new plugs wouldn't hurt. Switched the plugs from NGK 5's gapped at 1.1 (tips looked OK) to NGK bcpr6es-11 which I gapped down to 0.86mm. While I was doing this, I swapped out the engine covers for some painted and modified ones I had and remembered that long ago, I had removed the Crank Angle Sensor without realizing the implications and I had no idea what timing was set to. So I got the plugs, in, swapped engine covers, and set timing to 15 degrees btdc using the black loop. Had to turn the CAS almost all the way to achieve 15 though, if it was in the middle, it was around 25. I have heard that 15 should be right about the middle of its range of motion so I thought that this was odd, but timing belt shouldn't have skipped or anything, It is a Greddy super strong put in only like 5 thousand miles ago (assuming the tuner installed it correctly). All of the coil packs looked great, didn't notice any cracks after inspecting each.

So I get all of this done and notice that the car has a slight miss occasionally at idle (a lot better when timing was set to 15). And after driving it today it seemed slow. It revs fine at a stop and can hold any rev fine without missing, but when in motion, it seems to take longer for the tach to climb than previously. Inspected for any vac leaks and couldn't find any, even sprayed vac connections with carb cleaner, and idle didn't change at all. Inspected the open vent BOV by putting my hand in front of it while I rev and it doesn't seem to push any air until it gets vac signal to release.

Maybe because timing was set so advanced before, so before it would climb rapidly and then have knock issues up top and go into R&R? Car runs great, but just seems to lack the power it had before I did the plugs and set timing. I would think if all it was screwing me up on the dyno was plugs and timing that I should see 40whp or around that in gains from correcting it, but the car seems slower still.

Any suggestions?

Edited March 31, 2008 by cpt_impossible

[cpt_impossible]

While I'm at it, here are the covers I put on... I didn't think out the location of the lettering very well though lol, but the venting seemed like a good idea.

Edited March 31, 2008 by cpt_impossible

[cpt_impossible]

A friend suggested that instead of using the black loop by the igniter to set timing, I use the lead to coil pack #1. Is that correct? Maybe I am getting the wrong signal and set timing too far back, that would explain why the car is sluggish and the CAS is almost all the way turned down.

[cpt_impossible]

So I changed out the spark plugs for the V power ones in a 6 heat range pregapped and double checked to be at 0.8mm. Didn't change idle at all, still seems to have slight misses. The NGK BCPR6ES plugs that I pulled which were only 3 days old were flat white on the grounding arm though. Not sure if I was actually running super lean or if it was just because most of the time the car was running during those 3 days was at idle and adjusting timing where the engine runs leaner rather than driving it.

I read on NICO club (US forum) that timing using the black loop for timing would read higher than it actually was and that using the black loop, you wanted 25 btdc. I tried that and drove it around and it seemed to drive as it had before the spark plug change after the ECU got used to everything. Was a little sluggish, but after a few minutes of "spirited" driving, the car seemed to run fine again.

Still though, if normal for me is 170whp, then my problem is not fixed as, I should be running over 200whp and this was certainly not 30hp faster than what I consider normal...

Anyone have any thoughts?

[cpt_impossible]

Come on, someone has to know what I am doing wrong...

[Dose Pipe Sutututu]

Why are you running 2 BOVs? LOL... remove the atmo one

[cpt_impossible]

Why are you running 2 BOVs? LOL... remove the atmo one

Engine came that way, doesnt choke on decel or anything so I have just left it, sounds wicked at night on an empty street though with the two bov's echoing at slightly different times.

I don't see how the BOV would affect the performance under load as long as it isn't leaking. All the vac lines on it look good and If I cup my hand over it and rev the engine, it doesnt push out any air until I release the throttle. I have considered buying a stock unmodified cold pipe to rule it out, but I don't see how it would be causing any problems other than after a shift (which it doesn't). Car doesn't feel like it has a vac leak at all, and If I take the hose off the bov the car tries to die, so if it was leaking, I would guess it would do the same.

[Dose Pipe Sutututu]

I'm not too sure what you mean by black loop?

use a timing gun to set it to 15 degrees, and try disabling the SAFC see how your car runs then...

i.e. D/C it and connect all the wires back to the ECU

[cpt_impossible]

I'm not too sure what you mean by black loop?

use a timing gun to set it to 15 degrees, and try disabling the SAFC see how your car runs then...

i.e. D/C it and connect all the wires back to the ECU

-By black loop I mean the wire loop toward the intake mani side of the ignittor chip built into the harness for diagnostic purposes.

-I don't have an SAFC...

If the black loop is not appropriate, then is there something that I can use that doesnt require dissasembly before and after? I read that what some people do is take off the coil and coil pack boot on #1 and run a normal spark plug wire between the coil pack and spark plug for timing, but that would require taking everything apart, setting it up, reassembly, timing, take it all apart once timing is set, and reassemble everything to make it driveable.

Seems like there must be a simpler way.

[cpt_impossible]

Ok, so I was searching all morning and found that many of them were reporting that if you use the black loop with a cheap timing light, the reading will be cut in half on some guns. therefore, when I set it to 15, I am really only getting 7.5 and what I need to do is set it to 30btdc.So I decided to give it a shot. Set it to 30 once the idle came down and car was up to temp, 30 was right in the smack center of the CAS adjustment range which would seem to confirm this.

The popping int he exhaust at idle is accelerated though which I guess it to be expected when you double the timing. Maybe I have a bad coil pack? It is odd that if I did it wouldn't give me any problems before changing the spark plugs to a smaller gap. If anything it should have caused problems on the large factory gap of 1mm.

Have not tried to drive on it yet though. Other than the miss at idle, the idle sounds smooth and it revs quickly.

Edited April 2, 2008 by cpt_impossible

[Dose Pipe Sutututu]

If you buy BCPR6ES without any numbers at the end is already gapped at 0.8mm no need to regap.

Sounds like your timing is out, a dropped coil will cause your car to idle weird and splutter, in short producing no power.

Readjust your CAS & try resetting your ECU

[cpt_impossible]

If you buy BCPR6ES without any numbers at the end is already gapped at 0.8mm no need to regap.

Sounds like your timing is out, a dropped coil will cause your car to idle weird and splutter, in short producing no power.

Readjust your CAS & try resetting your ECU

The 1st set of plugs I tried when replacing the 5's that were in there were:

NGK BCPR6ES-11

I gapped them down to 0.86mm and that is when all this began. Since then I tried NGK V Power 6's that were factory gapped to 0.8mm. I verified the gap and left them that way. They still miss at idle (maybe a little worse than the BCPR).

Today, I tried doubling the timing to 30 based on the info by some that cheap timing lights can read double what is really going on in the RB when you use the timing loop. It idled and revved fine, but I didn't want to risk the motor by driving hard on it, so I broke down and did it the annoying way, stealing a plug wire from my bro's civic and putting it on cyl #1 spark plug and ran that to the #1 coil and used that wire for the inductive timing light. If my research is correct, the double timing issue with cheap lights doesnt happen when you do this and it read at 30 still. Based on this I am thinking the timing light is reading correctly so I set it back down to 15. (where it felt absolutely gutless on the street.)

[**RB2530**]

Come on, someone has to know what I am doing wrong...

I am not 100% (but 99%) on this but using the black loop does not work properly with a timing light. The timing light will fire ok but at the wrong time...This is why,

The way ignition modules and ignition coils etc work is you have two windings...primary and secondary..what happens is the ecu energises the primary coil and as a result a magnetic flux builds the primary coil. The secondary (high voltage coil due to larger number of windings) is also wound in the same magnetic field ..as soon as the primary field has been developed the ecu then drops the current instantly and the magnetic field collapses...The sudden change in field induces a high voltage in the secondary and this fires the sparkplug... simple so far??

The time taken to build the magnetic field in the primary is known as the dwell...if you have ever worked on distributors and point you would undertsand this already...ie dwell angle

The black loop is actually the connected to the primary winding on cyl number 1...BUT when you connect a timing light to it you are measuring when primary coil is energised and NOT when the spark is produced. The spark is delayed by the dwell time which in an EFI engine is hard coded in the software...So if you use a std inductive timing light on the black loop, you will always be wrong...You retard the CAS as a result..Let me guess?? the CAS is rotated fully clockwise....

The solution is pull coil pack no 1 off and use a short high tension lead between it and the plug. Connect your inductive timing light to thsi and you will then be measuring the actual spark...

The black loop is meant to be used with a full engine diagnostic computer that triggers on the negative edge of the ecu ignition output...

Hope this helps

[cpt_impossible]

I am not 100% (but 99%) on this but using the black loop does not work properly with a timing light. The timing light will fire ok but at the wrong time...This is why,

The way ignition modules and ignition coils etc work is you have two windings...primary and secondary..what happens is the ecu energises the primary coil and as a result a magnetic flux builds the primary coil. The secondary (high voltage coil due to larger number of windings) is also wound in the same magnetic field ..as soon as the primary field has been developed the ecu then drops the current instantly and the magnetic field collapses...The sudden change in field induces a high voltage in the secondary and this fires the sparkplug... simple so far??

The time taken to build the magnetic field in the primary is known as the dwell...if you have ever worked on distributors and point you would undertsand this already...ie dwell angle

The black loop is actually the connected to the primary winding on cyl number 1...BUT when you connect a timing light to it you are measuring when primary coil is energised and NOT when the spark is produced. The spark is delayed by the dwell time which in an EFI engine is hard coded in the software...So if you use a std inductive timing light on the black loop, you will always be wrong...You retard the CAS as a result..Let me guess?? the CAS is rotated fully clockwise....

The solution is pull coil pack no 1 off and use a short high tension lead between it and the plug. Connect your inductive timing light to thsi and you will then be measuring the actual spark...

The black loop is meant to be used with a full engine diagnostic computer that triggers on the negative edge of the ecu ignition output...

Hope this helps

Thanks for the reply:

Today I tried measuring timing by taking coil one off and running a normal spark plug wire between it and the plug. I clamped the inductive lead around that and it read identical to using the black loop. I used this reading to adjust it back down to 15btdc, which as you suggested, is almost fully clockwide. 30 seems to be the dead center.

Basically I am still stuck.

[**RB2530**]

Thanks for the reply:

Today I tried measuring timing by taking coil one off and running a normal spark plug wire between it and the plug. I clamped the inductive lead around that and it read identical to using the black loop. I used this reading to adjust it back down to 15btdc, which as you suggested, is almost fully clockwide. 30 seems to be the dead center.

Basically I am still stuck.

Do you have adjustable cam pulleys?? If so the exhaust one may have moved but it would fully retard and therefore CAS woule be more anti-clockwise to achieve 15degbtdc...

Also if you have stock ECU you need to ensure that idle is around 700 rpm when setting base timing...the stock ECU pulls 10 deg of timing out just above idle for some reason even at no load...i think it is an emmisions thing....

[cpt_impossible]

Do you have adjustable cam pulleys?? If so the exhaust one may have moved but it would fully retard and therefore CAS woule be more anti-clockwise to achieve 15degbtdc...

Also if you have stock ECU you need to ensure that idle is around 700 rpm when setting base timing...the stock ECU pulls 10 deg of timing out just above idle for some reason even at no load...i think it is an emmisions thing....

Stock cam pulleys, stock ecu, set idle to 650 before doing timing.

[cpt_impossible]

I am starting to wonder if my engine installer was off by a tooth or something when he installed the Greddy timing belt before the engine went in.

[**RB2530**]

I am starting to wonder if my engine installer was off by a tooth or something when he installed the Greddy timing belt before the engine went in.

Its well worth checking and would explain a couple of things you mentioned...One tooth off makes a huge difference..

[cpt_impossible]

Its well worth checking and would explain a couple of things you mentioned...One tooth off makes a huge difference..

Can I do this just by takign the CAS cover off and looking?

[**RB2530**]

Can I do this just by takign the CAS cover off and looking?

Not sure about the RB20?? If it is like the RB25 it is CAS off, then the pulley cover off...The timing marks for the pulleys are on the pulley cover backing plate. There is one just to the right of the exhaust and one just to the left of the inlet pulley..there is also a mark on the crankshaft pulley and it is real bitch to see without taking the harmonic balancer off..It should line up with TDC and 0deg TDC timing mark on the harmonic balancer so start with engine harmonic balancer at TDC. NB that the camshafts rotate at half crank speed so there will be one TDC where the marks on the cam pulleys line up and another where they dont..If your engine starts you can assume that there will be only 1 or 2 tooth error.

Now if the timing is out you need to undo the idler tensioner to put slack in the belt so you can move it...If you haven't done this before or you are not confident get someone else to do it...The consequence of getting it wrong is potentially piston into valves due to the belt coming off via broken tensioner...not good!!

If you find the timing is out I would be incline to take it back to the engine builder and get him to fix it for free...

Anyway hope this helps...