13 replies to this topic

[jhealey1967]

Short version of my (long/somewhat rambling) question below: a) Does anyone have recommendations for a professional rebuilder of Keihin carbs? and, b) Should a 1987 California CRX HF have an air tube on the catalytic converter?

Long version, if you're bored: I have a 1987 CRX HF, California model, that despite being in absolutely cherry condition overall, will not pass smog--hydrocarbons are too high (max allowable at 15 mph is 103 PPM--and my car's exhaust is measuring 135). There seems to be a random misfire, particularly noticeable at idle, and though I haven't yet been able to determine its cause, I am leaning towards a lean misfire condition at this point.

The engine has good compression (210 PSI +/- <5 on all cylinders), pulls a strong vacuum (21" at idle), and has just over 160,000 miles on it. The EGR valve is good, both fuel filters have been replaced, and all major ignition components test to spec. Everything about the vehicle is stock--at least to the best of my knowledge. Additionally, the car runs well at all speeds, save for a rough idle.

Does it sound reasonable to suspect the carburetor at this point?

That said, I cannot find anyone who specializes in rebuilding the carburetors for this vehicle, and am dubious that a "Carbs R' Us" type place would do an adequate job with what sounds like a very difficult carb to rebuild. I have rebuilt carburetors myself before, but everything I've read about the Keihin has scared me away from even attempting it (if anyone has any recommendations for a professional rebuilder, please let me know).

So, at this point, I am strongly considering replacing the catalytic converter. I know I should address the misfire first, but the registration is up at the end of the month, and if a new cat might be sufficient to get the vehicle to eek by the sniffer test, I'd be satisfied--especially since I've spent far too many weekends trying to track down the source of this elusive misfire.

But there's a problem with that, too--the only available California "certified" catalytic converter for this vehicle has an air tube attached to it--and this car, as best I can determine, has no provisions for that. I called the manufacturer of the converter, Magnaflow, and talked to their technical staff about this. They told me that's the only version of that particular converter they sell, and that the certification process for a "California Legal" direct fit catalytic converter is sufficiently costly that it isn't worth it for them to create several permutations of a converter for every different possible application.

 

When asked whether they thought blocking off or welding the air tube shut would be an option, they assured me that no reputable exhaust shop would risk losing their license to do something like that, because it would be illegal, and even if I were to have it done, I'd fail smog when the tech noticed the modification--and possibly even find myself in legal hot water for modifying an emissions control device.

Does anyone have any insight into this? In searching online, it seems that some CRX's of this vintage do indeed have provisions to feed this little air tube on the cat, and in fact many I've looked at have several additional emissions control devices/black boxes under the hood that my vehicle does not have. Being a California car, I would think that this vehicle would be armed to the teeth with every emissions control device of the time, but it appears that the CA versions of the CRX HF are lacking several emissions features found on Federal cars, including an O2 sensor.

 

In fact, the California HF's were EPA rated at 15% less fuel economy than the federal cars (presumably due to the lack of the 02 sensor..? According to fueleconomy.gov, none of the CA models had feedback carbs). That said, I cannot seem to verify whether the air tube to the cat is one of the features omitted in CA cars, or if my vehicle was modified at some point by a previous owner (although it has never failed the visual smog test--assuming the techs know what they're looking for).

Does anyone here have a California CRX HF, and if so, does it have an air tube on the stock cat, and the necessary provisions to feed it? Likewise, I am open to any suggestions, beyond the advice I got from Magnaflow's technical staff to plead my case to a California State Smog "Referee" in Sacramento (which is probably the only 100% legal route)?

I'd hate to think this vehicle is simply obsolete for the above reasons, especially since it runs so well and gets such amazing gas mileage.

On another note, my neighbor brags that his '04 Hummer has never failed a smog test. I'm sure the state's air quality is much better off with his 8 mpg tank terrorizing the roads than my 45 mpg CRX. Sigh…

Any and all ideas or suggestions are welcome.

 

___________________

Also:
Link to the direct-fit CA approved converter for this car:

http://www.magnaflow...directfit=36967

(if the link fails to show up, the p/n is 36967)

[PuddleSkipper]

I've looked into the HF system, it's pretty complex for it's time and doomed to fail. You could do a VX swap to it. It would have to be the california version with the 4 wire O2 sensor instead of the 5 otherwise it won't pass the nitrous oxide test, however you can make a patch harness to put in the 49 state version once your done with DEQ. I have a VX swap for sale, been contacted a couple of times but no takers. It would probably cost you about $1500 total to do, maybe less, $600 of it would be for the Hasport kit, the special axle, and the CMA adapter or something similar. I have a 1988 HF tranny that has the highest final drive for a D series which equals the lowest rpms, if you look at crxmpg.com that is the same tranny he is using. I am thinking the 1G might be lighter too and might do 70 mpgs. Anyway look into it.

[jhealey1967]

PuddleSkipper,

 

Thank you for your insights. I agree that the HF's emissions and fuel delivery setup is ridiculously complex. I'd not yet considered an engine swap, though have read up a bit on Weber carb conversions (although they wouldn't pass muster with CA smog laws). That said, I'm not sure I'm quite ready for a major surgery as such yet--the car is almost completely original, which seems pretty increasingly rare for these old CRX's, although it may be quixotic attempting to keep it that way. As for the '88 tranny having the highest available final drive ratios, I was unaware of that--good info. If my transmission ever kicks the bucket, I suspect an '88 trans might be my best bet, fuel economy wise at least, especially if I've already by that point given up on keeping everything all original.

 

…on another note, I've just picked up an A/F meter in hopes of licking this lean misfire at idle. 

 

Any more ideas or suggestions--especially in regards to that mysterious air tube on the aftermarket cats--are of course greatly appreciated. 

[cbstdscott]

Honda made these cars run lean to pass CA emissions tests and get high mileage. With lean running comes high heat, head gasket failures are common.

Your misfire may not be lean related. Have you replaced your plug wires lately? If not, try replacing them.

The catalytic converter on the HF is right at the exhaust manifold, right? The OEM part is not available so a generic should be acceptable to the BAR. Contact them for specific information.

The stock carb is a pain to deal with. There is a rebuilder in the SF bay area that works on them. I think they are in the East Bay area. I will get the info and post back here.

Scott

[GLHS988]

The carb rebuilder Scott is referring to is Recarbco in Pittsburg, CA.  I contacted many carburetor rebuilders all over the country.  There are very, very few rebuilders who will touch a Keihin carb.  Another member tried the Carburetor Exchange out of El Monte - the carb they mailed back to him was not his original and it leaks fuel (I know - I borrowed his carb while mine was out for rebuild).  I don't know much about National Carburetor out of Florida, but decided it was not worth dealing with an outfit 3000 miles away.  So I stayed local and drove my carburetor to Recarbco, a reputable rebuilder I have known about for many years.  They are not cheap - cost $500 to rebuild my carb - but it came back looking like a brand new carburetor.  As I am still dealing with other issues on my car and Recarbco already did some warranty work on the carb to fix a vacuum leak.  I can't give you the full verdict on the rebuild they did on my carburetor yet.  I should hopefully know more about the rebuild in the next week or two.

 

http://www.recarbco.com/

 

Good luck with your carb. 

 

GLHS988

 

 

The stock carb is a pain to deal with. There is a rebuilder in the SF bay area that works on them. I think they are in the East Bay area. I will get the info and post back here.

Scott

[jhealey1967]

Scott--

 

You could be correct, my lean condition may not be carb related, although the plug wires test to spec and aren't particularly old. I just hate to throw parts at it, although I certainly wish I could pin it down as being spark related as opposed to fuel related. As for contacting BAR, it looks like there are a few smog referees in the Bay Area, so I may just have to do that, explaining (pleading?) that an identical replacement is not available and that a universal cat should be suitable. My one concern is that I have read that the reason Honda used a manifold mounted cat on these cars, as opposed to a downstream cat like on the SI, is that the low-horsepower HF engine didn't produce enough heat to adequately heat up a downstream cat. Any idea if that is accurate? 

 

GLHS988--

 

Thanks a bunch for the carb rebuilder info. Pittsburg is less than an hour from my location, and though $500 is a bit steep for a rebuild, I'd gladly pay it if Recarbco can properly rebuild a Keihin. I had previously looked into Carburetor Exchange a bit because their prices are good, but their reviews online are atrocious, and it looks like your experience with one of their rebuilds confirms that. I definitely look forward to hearing about your experiences with the Recarbco carb. 

[cbstdscott]

The HF engine was so lean that it made almost nothing but heat. The location at the manifold was to allow the cat to get hot faster and pass the cold start test. 

 

When you have the car ready for testing, but the highest octane fuel you can find and then add octane booster to that. On the day of testing get the engine as hot as you possibly can, you want the cat to be glowing with heat to pass that test.

 

Good luck!

[GLHS988]

I probably won't have further update on my carburetor until sometime mid next week.  With the rains moving in, I've covered up the car with a tarp and won't be uncovering it until after the weather clears. 

 

FYI.  Several mechanics warned me about rebuilding a Keihin carburetor, stating that they just won't run right after being taken apart.  For me, the carburetor appears to be what stands between getting my car running again after rebuilding the top end of the engine.  It came down to doing what I could to get my carb working again or starting over again with an engine swap.  I am hopeful, but have no idea if I will pass smog yet. 

 

I feel your pain about the exhaust manifold mounted cat.  My ineffective cat is still there, but I also have another cat mounted in-line downstream.  It has worked effectively on my 1.5, but probably restricts the exhaust flow a bit.

[hounter90]

Before you crack open that carb check for vac leaks. Its very simple and easy and can save you alot of ass pain.(those carbs are not fun to rebuild) spray starting fluid at vacuum lines and if the engine rpms increase or it shuts off the engine you have found a leak and need to replace the hose

[hounter90]

And btw the air tube that comes off your cat is for egr, if its not hooked up that may be why you cant pass smog. Not 100% sure on cali smog rules I just know its a whole lot of nope I will never deal with. Move to a state with less retarded laws and you wont have to deal with it. In NC our inspections pretty much consist of making sure that there is nothing that would cause your car to be a road hazard (bald tires, bad wheel bearings, ect) and if you have a car newer than 96 it cant have a check engine light on.

[GLHS988]

If you haven't read the other thread on my car, I passed Cali smog yesterday (27 HC value at 15mph with a max 162 ppm allowed).  My Recarbco rebuilt Keihin carb seems to be doing well enough.  I'm not completely out of the woods though.  There is still a miss when my engine is cold and I have a flat spot in the throttle on occasion (step on the throttle to accelerate in 2nd/3rd/4th/5th and nothing happens).  I'm not sure what the problems are about yet, but I'm not going to worry about those issues yet until I get all the old fuel burned off and I've driven the car for a few weeks.  I'm just be happy that my car is running again after 2-1/2 years of deteriorating in the fog and salt air. 

 

BTW.  I did not notice that you had posted up a link to a direct fit CA legal catalytic converter until now.  Great find!  I had no idea that any kind of replacement was available until now.

 

As of this moment, I will give a thumbs up on the Recarbco rebuild.  Good luck with your car. 

[jhealey1967]

Sorry for the delayed response (I've been traveling) and thanks to all for the additional input. 

 

GLHS988--I am glad to hear you were finally able to pass smog--27 PPM HC is very good! In the few weeks since you passed, were you able to work out the quirks that you mentioned, i.e. flat spots, miss, etc.? And as for the link to the direct fit cat--it took a good deal of searching to find, but alas, it appears that air tube makes it a no go for this application. I am however making progress on the A/F tuning front with an Innovate O2 meter--I will post updates in the future in this regard in case it may be of help to anyone else. If it doesn't solve my problem, then it looks like a rebuilt carb from Recarbco is my next best bet--and thank you again for keeping me updated regarding your experiences with them. 

 

Hounter90--The EGR valve on my vehicle appears to draw exhaust gases through a port in the head. I have had the EGR looked at by two smog shops and both have found it to be functional and hooked up properly. I am almost certain at this point that the air tube on the aftermarket "direct fit" cats for this car is for an air injection set-up not found on all models--with the Calif. HF evidently being one of those models excluded. I have not yet been able to find any evidence to the contrary, unfortunately. As for vac leaks, I've not been able to find any indication of one using a vacuum gauge, nor with propane/carb cleaner, though I am tempted to take it to a shop to have it hooked up to a smoke machine just in case. 

[GLHS988]

jhealey1967,

 

On the good side and unlike any other time in the last two years, my car is starting reliably.  It is a hit or miss whether the electric choke engages, so starting can be a little rough - not a Recarbco related issue.  On the bad side, I haven't had much time for driving my car.  I have been surveying the body and found some bad rust.  Thus, I have been spending my little available time scraping the rust out and applying POR-15 to try to stop what is there.  Lots more rust work to be done since Straman did not rust proof any of their custom coachwork body parts.

 

I did drive my car earlier this evening.  The flat spot was absent and the miss was only there when the car was cold.  It disappeared after driving the car a couple of blocks.  I don't think my throttle response is quite the same as before the rebuild, but all in all the carburetor seems to be doing okay.  I'll have to wait until after this weekend's rain before thinking of driving it again.

 

GLHS988

[letank]

You can get a cat without the air tube. Contact the BAR (check their website) and they will give you a list of approved manufacturers by the state of California. Been there done it... And it was not the cat... But because I already had spent $500, I got a 2 year waiver... But the spent $$$ have to have been recommended by a smog certified tech, your smog station tech, and checked by the smog referee, usually at a community college.

As for lean misfire... Plugs, the one listed in your owner's manual, not a cross reference. Plug wires... Oem work best... Distributor up to specs, for air gap, cap and rotor, oem are best.

As said those carbs are a pain because they are more air delivery control system than gas!

In my case I had high nox, but the egr worked fine... Just a giant untraceable vacuum leak from under the intake manifold, that spraying wd40 from above could not detect. I found it when the alternator gave up, and when pulling the alternator from under the vehicle, spotted a big rotten hose. Passed smog a year later... Same 150kmiles.

What are the other numbers, co2, o2, hc, co, nox for 15 and 25mph.

You can lower HC bit by lowering your timing by the max allowed number which is 3 degrees...

The obvious, Is your choke fully opened? Pop the air filter cover, and the little mesh cover... You can always wedge something made w 10 gauge electrical wire to keep it opened.

One more, what were the last smog check values?