Hondata

I am also running a colder plug.. however with a larger gap due to the MSD. As for the fuel question, im running a Bosch monster pump, im sure its up to the task.

My problem began when I solved belt slipping on my ~8.5psi pulley. The belt had been slipping since day one, and unfortunately I tuned with it slipping, indicating about 8psi.

Here is the trick though, and this may be a problem in itself. Since I replaced the belt and tensioned it correctly, its not uncommon for my boost gauge to indicate 10-11 psi. I have 3" exhaust and a relatively new cat, im fairly sure I have good air flow. My mis-fire sound only after the boost creeps up as far as it will go. I thought i may have hit boost cut, so I disabled it, same problem still.

still stumped! and the car is going in the garage for the winter.

This is a little OT, but since private messages are disabled in this forum...

Kannon, what belt size did you use between the SC pulley and the Endyn stepper pulley? I haven't been able to find solid info on this.

-Andy

I've had the similar problem during boost and it was behaving like the MSD rev limiter kicking in at random. I did a datalog and noticed some strange ignition events. I've tried replacing plugs, dist. cap, rotor and plug wires with the same result. I later decided to remove the MSD 6AL and the problem went away immediately! It has been hesitation free for the last 8 months. HTH.

I never found out a sold number either.. however I can tell you its hard to find the right size. Truthfully I dont remember what ended up going on there. I ended up buying a different size belt from every place in town, I think I may have ended up going larger (like 640?!) but I found a trick:

By loosening the tensioner for both the blower and alternator belt, then tightening the alternator belt first, you are able to put a better angle on the blower belt.

That tensioner is such a mind blower I forget how it works every time I go to adjust it.

AndyE: Did you ever track down the problem? I still hear what sounds like a mis-fire at wide open throttle and I'm somewhat at a loss on how to troubleshoot it.

Email me if you have a few spare cycles.

I did finally manage to squash my remaining misfire problems. I was misfiring because the long term fuel trim was causing me to run lean under boost.

This post is a little long, but hopefully the back story can prevent other DIY-ers from making similar mistakes. The moral of the story, for those who don't want to read it all, is tune ALL parts of your fuel map. If you simply aren't able to do that, then be sure to check your fuel pressure when running pre-tuned maps.

When I bought my Hondata system, I knew there was no place nearby that could professionally tune it. So I opted to get my system from a reputable vendor (Payn Technologies) who could provide me with pre-tuned maps for my exact setup.

My initial configuration was a JRSC with the stock pulley, an AEM CAI and adjustable 1:1 FPR, and a DC Sports 4-1 header going in to the stock exhaust. PaynTech's maps ran great in this configuration. I installed the FPR with its out-of-the-box setting, since I didn't have a fuel pressure gauge at the time. I never had a misfire and the thing ran like a rocket.

After a while, I wanted more, so I decided change things a bit. I went for the Endyn stepper pulley to take my JRSC to the 8-10 psi range. At the same time, I picked up a Kamikaze short-runner 4-1 header with a 2.5" collector, and mated that to a custom 2.5" cat and exhaust. I also picked up a set of colder plugs (which are actually OEM S2000 plugs, the ones I didn't screw in tight enough) and a fuel pressure gauge that tees off of the fuel filter canister in the engine bay. I burned a new ROM with the 8-10 psi maps that Phillip Skeete used to get 230 whp from a similar setup. I then set the static fuel pressure to 42 psi (to match the maps) using the "pressurize the system" method, where you turn the ignition on and off several times to let the fuel pump pressurize things (this last step w
as a mistake, which I'll get to later.)

One problem, which I discovered some weeks/months later, is that all of these changes threw my part throttle maps way out of whack. Things were running way too rich, and the ECU was compensating by cutting the long term fuel trim by around 15-20%. Since the LTFT is applied across the ENTIRE fuel map--even during open loop, at WOT--I was running 15-20% less fuel under boost. This lean condition caused things to misfire.

I also later discovered that the method I used to set my fuel pressure resulted in a higher running pressure than I expected. When I used a much better method (disconnect the vacuum hose to the FPR while the engine is running, then set the pressure) I had to back off the FPR setting quite a bit to get down to 42 psi. This was a big part of my over-rich problem.

Next, I set up a custom lambda table in Hondalogger and did some part throttle street tuning using the stock narrow-band O2 sensor. The narrow-band is only good for determining if you're richer or leaner than stoich - it won't tell you by how much. So I simply edged in a little more or a little less fuel until the sensor voltage just started to swing the other way. This process was much slower than using a wideband O2 sensor, but it was free, and worked well enough to smooth out some of the richer and leaner portions of the maps.

During this tuning process, I was going over captured logs of the short term fuel trim vs. MAP and RPM (looking for MAP/RPM values where the ECU was adjusting fuel more than it should) and I came across another source of my LTFT problems. In the Phillip Skeete maps, the part-throttle columns were set up for a gradual increase in richness as the manifold pressure approached 0 psi (the last two or three columns before boost are usually set up for low 14s/high 13s A/F ratio in an NA setup for maximum power), but the ECU was configured to stay in closed loop for some of these columns. So the maps were intentionally made r
icher in these regions for more power, but the ECU was still running in closed loop and trying to lean things out to bring it back to stoich, bringing down the LTFT in the process. The solution here was to lower the closed-loop cutoff value in ROM editor, to prevent closed-loop operation in the richer portions of the map.

Recently, I've switched to the Hondata JRSC Big Boost pre-tuned maps. These maps have pretty good part throttle tuning, and they went the extra step of setting all the fuel maps to stoich for anything below about 1 psi, and adjusting the closed loop cutoff and VTEC engagement appropriately. This makes a lot of sense for a supercharged application, since you spend a lot more time in the just-below-boost columns in part throttle driving than you would for an NA setup.

So in conclusion, running too rich in the closed-loop columns of the fuel map can cause the boost columns to run lean due to LTFT adjustment, which in turn can cause misfiring.

Kannon--I don't know if this is your problem, but a simple way to tell is to pull up Hondalogger and see what your LTFT value is. If the LTFT value is more negative than about -10%, chances are you need to do some tuning. You can test this hypothesis by doing an ECU reset (kill power to the ECU for a few minutes), which will reset the LTFT to zero. Then go do a few WOT runs and see if your misfire goes away, before the ECU has a chance to readjust the LTFT.

-Andy

AndyE, thanks for the lengthy response. I think that tuning is my problem, but unfortunately I don't think its the same precise problem as what you had. As a matter of fact, I captured some WOT runs yesterday, and just took a look at the LTFT. Its 3.2%.

I have a similar setup to you. 99 Civic Si. Jackson kit running a stepper pully (MAP and boost gauge indicate 10psi). Kamikaze header into a 3" cat, and 3" thermal exhaust. 440cc injectors.

I also don't have access to a tuner nearby (that I trust, at least). I picked up my Hondata Stage 4 from Tom Payn also. I actually drove out to Michigan to have him take a stab at tuning my car in April 2002. He didn't do any on road, partial throttle tuning. He based the tune off of one of his maps.

Unfortunatley, I found out at a later time, that when Tom did the tuning, my SC belt was slipping, and only generating 8psi. The exhaust is so damn loud I had no idea. Another interesting problem that developed immediately after the tuning is a squealing sound as I cross from vacuum into boost at partial throttle...more on that another time (IT DRIVES ME NUTS).

So I need to tune the maps... I don't want to upgrade to a S200 if I can help it. I just dont have the funds to play like I used to (bought a house, getting married, blah, blah).

Do you know where I can track down a map for a stage 4 that would be a good starting point?

Should I just spring for a wide-band (I really dont want to, although I have a second bung ready to go for it)... or do you have any tips for tuning with what I have?

thanks for the input... i'm technically savvy, just feeling a bit overwhelmed by the situation.

Well, it's been almost a year since I last visited this thread, but I thought I'd chime in with an update. I began having misfire problems once again with my setup, and again I checked the usual things like spark plugs seated correctly, LTFT within good limits, etc. This time, all of those things were fine.

After checking out some online resources regarding spark plug gaps (and reading the comment from "20lb.teg"), I decided to try reducing my spark plug gap. Now, something to keep in mind here is that the stock B16A plugs are gapped at .052". I'd purchased OEM S2000 plugs which come gapped at .044", which is already quite a bit lower. However, I decided to gap it even closer.

At .035", I noticed a small reduction in the misfiring under boost, but not enough to convince me. However, gapping the plugs was easy enough to do, so I figured "what the hell" and gapped it all the way down to .030".

My car has run absolutely perfect since then. I can't get it to misfire no matter how much I try. I can start in 4th gear at 3krpm and peg the throttle and it will pull 6-12psi all the way up to 8400rpm without a single hiccup.

I just wanted to share how incredibly stupid I feel for being pissed off about my misfires for nearly a year and not trying something as simple as reducing the gap on a spark plug. It worked. If you're having problems, try it - and don't be afraid to gap it insanely close before you give up.

I was never able to trace the root cause of the problem i was having... but i can tell you that it was solved by switching to a s200 with a new, well tuned map.

Mine are currently gapped to 0.028"