JDM H22 - TERRIBLE gas mileage, smells rich, black soot.

[deevergote]

The title is pretty detailed, I must say!

Anyway, I've been getting terrible gas mileage (down by nearly 25%!). I haven't been flooring it very much, and it's still bad.

It definitely smells like it is burning rich. It has that familiar tang to it...

Lately, I noticed black soot all over the rear of my car... the muffler is black.



Now, until 2 days ago, I was running Bosch Platinum 4 plugs. I have a feeling that they might have been the cause. However, I might as well ask now, just in case there could be something else!
2 days ago I changed out the Bosch plugs (ran them for a couple months, they were covered in black carbon) and installed some NGK Irridium IXs. It's really too soon to tell if they're helping, though acceleration seems a little less laborious. I reset the ECU immediately after installing the plugs, and kept it around 35mph (under 3000 RPM) for about a half hour afterwards.

I plan on changing the wires soon, for something good (like NGK) since one of my old wires has a small gash in the casing. I also hope to change the cap and rotor. Is there anything else that could be screwy that I can fix?

[phatdoughnut]

So are you getting any CEL? it sounds like its running uber rich.

[deevergote]

Yeah, it DEFINITELY feels and smells rich...

Any way to adjust that (safely)?

[ACCORDinglynice]

Bosch are know for that and blowing honda motors i had that same problem on my f22 i took them out and put soem other ones and like 3 days later it was normal

[aero]

This makes 2 of us. I had mine in the garage, and there was soot on the floor, and the back is getting just noticeably darker. Someone said that jdm motors run a bit rich, and vafc is the only way to help. mine has everything tune up related done, so i was guessing distributor timing. I set it at 15, and it has hesitation. So im prolly gonna try to advance it, see how it does, and retard it.

[cp[mike]]

dont ppl have problems with the bosch platinum 4's in hondas? i believe it was TheInfamous whos h22 wasnt running very smooth and he pulled the platinum 4's out and it ran great? lemme search a bit...

[deevergote]

Yeah, I have heard that before... a number of people told me they were shite... AFTER I bought and installed them. I guess I can add myself to that list!

[NutBucket]

Always go with OEM plugs! I had regular bosch plats. in my F for a while. When I switched back to regular NGKs there was definitely a difference.

[br0nx finest]

Originally posted by NutBucket
Always go with OEM plugs! I had regular bosch plats. in my F for a while. When I switched back to regular NGKs there was definitely a difference.

yes, you are teh truth. i use oe plugs, as well as plug wires. it is honestly the best. made specifically for our application, and is approved by honda of america. how much better than that can it get?

the only way i'd run other plugs was if, i needed colder sparks because i had forced induction or nitrous or something. which i won't be getting into anytime soon, so no worries here. ngk 5f-11 ownz all.

[aero]

yeah, im using the stock plugs.. ngk. they helped a little i think.

[rebels]

Which octane gas are you running? I get better gas milage with my H22 than I did with my F22. When I was doing highway driving with the F22, I would get about 315 miles, and with the H22 I get about 375.

City driving I get almost 300 with a full tank of 93.. I never use anything else.

So your plugs and wires are new? I changed mine and it gave me a little better gas milage. Have you had the engine tuned on a dyno yet?

[Kurobei]

Nope that makes the 3 of us

Ever since I got my H22a it drinks gas like there's no 2maro! Ok Ok so I was v-tec happy for awhile but gas prices are sky high right now so I've been laying off it.

I have a v-afc though I have yet to get it professionally tuned.
My car runs super super rich as well. If I were to clean my exhaust of deposits, One day of driving will make it black all over again. I really notice the the gas fumes when I go 110+ on freeway battles.


One thing to take notice though is the octane rating effects the engine as well. In japan 95 octane is the base for super unleaded.....over here in california 91 is the highest octane we can get at regular pumps. So you guys that live out of state or can get 93octane thats even better for a jdm engine.

I noticed when mixing 100octane with regular 91, my car accelerated with less drag like it finally woke up 4real for the first time. 91 Octane is just borderline for a jdm engine.

Gas will have an effect on the engine and mileage too I assume coz when I drove my car back for the first time after the H22 install, I had a 3/4 mix of regular 87 octane gas and '91 premium in my tank. I found it really hard to get into v-tec but it still engaged but not as strong. My car didn't idle weird or anything with this mix but I assumed it was running in the "retard" mode. My friend made a mistake one time and put a full tank of regular unleaded in his 2k civic si. He told me he couldn't engage v-tec at all and his car was running like $hit because the ECU fine tuned itself to accept the lower rating octane gas he gave it.

So therefore I'm trying to say the lower the octane, the less quick it will burn. The higher the octane rating you use 91,91+ it's going to burn faster no matter what. (anything close to 95 for jdm engines) your engine will perform how it really should but again the higher octane u put it it's going to burn much quicker.

I drove on a 3/4 full tank of 100 octane once from the track......hahaha my trip from Sacramento to Fairfield (55miles), my h22 was already about to light up Mr. Gas icon.

The mileage on that tank of gas I drove on 89/91 however was really good....hence the lower the octane made it burn slower.

I'm not recommending doing a 89/91 combo but I had no choice because I had a near full tank of regular gas for the f22a.

After that tank of gas however, my gas mileage has been really crappy but I thought that was the price I had to pay to go faster. With my car regular commuting from work to school, I have to fill my tank up every 4days almost. With my old f22a6 even when I beat the hell out of it, I still got almost a whole weeks worth out of a full tank!

About bosch 4+ plugs, I have the bosch 4+ sparkplug wires (going to get rid of) and I used to run the sparkplugs as well
I bought this setup coz I believed that the more expensive the better right??? and at the Kragen store these were the top of the line they sold at the counter.

My mechanic replaced them with NGK iridums and that was a major difference like night and day. Bosch I'm going to say I 3rd that....... they are crap. Let Bosch products stay on German and European cars. For hondas, Denso or NGK only in my opinion. I'm thinking of running Spoon spark plug wires later.

[NutBucket]

BTW, you guys should recognize that there's two systems for measuring octane. The one that we have in the US is the average of the two. In Japan they use one of the two (which is higher then our average).

That isn't to say we don't get piss gas in CA though. I haven't had any problems mileage wise with my H. I get about 27 highway and maybe 22-24 around town. Its stock with a USDM P13.

[aero]

Well, i have not yet tried to see what kind of mileage i am getting. I will next fill up. But I am using 93. I havent had the car tuned, and prolly wont unless its really needed. I do get on it quite a bit more than i did w/an f22. It just feels nice. Although I try not to hit vtec but only on occasion.

[Kurobei]

Originally posted by NutBucket
BTW, you guys should recognize that there's two systems for measuring octane. The one that we have in the US is the average of the two. In Japan they use one of the two (which is higher then our average).

That isn't to say we don't get piss gas in CA though. I haven't had any problems mileage wise with my H. I get about 27 highway and maybe 22-24 around town. Its stock with a USDM P13.

But you are running a US P13 ecu. I'm pretty sure if I were to run a US p13 ecu (which i can't) i'd get a slightly better gas mileage. The jdm p13 is asking for the higher octane gas and people like running the jdm's coz of the extra hp bump. (unoticed but it's there) Thats the main reason why B.A.R. wants any jdm swapped vehicle to run the US counterpart ecu because it will detune your car slightly to emit lower emissions.

If you were running a US p13 on a jdm engine it would almost be like running a US-spec h22a motor but with jdm spec internal boltons. I'm unfortanate because I have a J-spec auto P13 which made it so I couldn't pass B.A.R. I wish I could swap in a OBD-2 h22a auto ecu but then I would have to change a whole lot more on my engine and it wouldn't even be worth it!