I'll try to keep it short.
93 Accord with 215,000 miles. Failed the emissions test. NOx blew 4.43. (2.5 is limit) Took it to a registered shop to fix. Estimate for $460 for a good tune up. Plugs, Wires, Dist. Cap & rotor, Air and fuel filters, oil and filter. I asked if I could do the things I can, and then bring it back...sure. When I took it back the shop said I had to take it and have it retested. Did that, failed again. The shop says it may take 3-4 hours to diagnose and so far they want to clean the EGR estimate (2-3 hours), latest update, says well over $1500 to replace the entire intake manifold do to plugs inside.
Any advise would be greatly appreciated.

Considering taking car off-island to a Honda Dealer

back story...i live on an island with speed limits of 35-45, so carbon builds up. the car is driven only about 6,000 miles a year. Mistakenly thought synthetic oil would be better and have been using it for several years. Also used RXP Kicker (gas additive) after tune-up to clean system. After the tune-up the car is running very well, no lag, seems better MPG...140 miles on 1/4 tank.

 

have you taken it on a beater run to blow all the carbon build up out? if not, take it out on the highway, and just beat on it for at least 15 minutes. you don't have any engine codes showing do you? With the new tune up and a beater run, your car should pass. have you also though about taking it to another shop? I take my car to a shop I know is pretty friendly mod wise and as long as I pass emmissions they don't care what is on my car. where in Mass are you? north shore, or south shore?

 

No engine codes or lights (93 is pre OBD) Temperature seems normal, No engine light, coolant, oil light, nothin. Actually I am on the Vineyard (Cape and Islands) so highway is not an easy option. I can only go 45-50 for about 5-6 miles and then turn around. "Beater Run"??? don't follow...high and low revs or just flat out. Is running the engine in D3 with higher RPMs an option? I may not have allowed time for the additive to work properly, they do warn that emissions can spike during the cleaning process.
http://www.rxp.com/gaskicker.htm

The second shop mentioned a possible leak in the header or "A" pipe. The inspection shop has not mentioned it.

thanks for the quick reply

 

for a beater run I mean you should get the revs up high for an extended period of time. maybe take a trip onto Rt.3 and get the revs up. if you can get away with it, I'd say take it up to 75-80mph. I think if you were to drive it in D3 and you get the revs up that might help, you just want to push the car and clean out all the built up crap. after you get thru one tank of gas with the additive and a little romp on the car that should help a little. if that doesn't work, the header issue the 2nd shop mentioned might have some merit. let us know how the car runs after you get to clean the exhaust out.

 

After I got the car back, post retest failure, the NOx went up from first test. 4.4 to 5.3. Shop said I need to replace the EGR valve and the Intake manifold...$1600 plus to 2 hours of shop time to diagnose. No one has suggested the O2 sensor. I was told the possible leak in the A pipe wouldn't be the probable cause for failure.
At no time since I have owned the car (4 years) has the engine light come on...but after I got it back today the engine light came on before I made it home. Is this a case of something put back together incorrectly or connecting the computer for diagnosis reset something???
The car is still running great, but hesitate to take it on a "beater run" with the engine light on. Will keep posting updates

 

typically if an engine light goes off its due to the oxygen sensor, so your car should be fine to take out on a beater run. heck the ligh might go out after you beat on the car. I have had a check engine light on for just about a year, its for my secondary O2 sensor and the car runs great. Just last week I got 420 miles on one tank of gas. I'd be sketched out to spend that kind of money to for the ERG valve and intake manifold. you should be able to replace the erg valve yourself. got to a local auto parts store to get the part, and you could run a search on how to install the erg valve. it shouldn't be that tough, and it might save you a ton of cash.

 

Check engine lights go off anytime you have an open/short on an OBD1 car.
The only reason your car runs "great" is because the secondary O2 sensor isn't used for fuel control. This guy doesn't have a secondary o2 anyways and even if he did that won't cause a Nox problem generally speaking. Nox is formed when the combustion temp. exceeds 2500 f. You need to look at the egr system first. These CB7 models of accord get clogged EGR ports all the time. You can clean them without replacing the manifold. You need to go to a Honda specific shop and stop listening to ppl on HAN who think they know everything. Chances are the manifold is clogged.

 

this link helped me..

http://www.cordclub.com/forums/showt...?threadid=4059

take care and good luck
dirt diggler

 

I don't know everything, and never claimed to. I'm just trying to help the guy out.

 

Thanks to everyone for the feedback. Without an engine light on and not knowing that the 93 Accords are EGR Port challenged, a carbon blowoff may not help but wouldn't hurt to try. I have found a couple of other forums that discuss cleaning the EGR ports. I have an appointment with a shop I trust to clean the ports and replace the EGR valve if necessary.

I spent enough money to get the emissions waiver and keep the car on the street while I sort out the problem. Not that I want to contribute to the smog level but I need wheels. The car does have have 216,000 miles on it.

I had hoped that testing the EGR valve tripped the Engine light and that pulling the backup fuse for 30 seconds might have solved the engine light problem but it didn't. As I said in my last post, the engine light has never come on until after the shop diagnosed it when it failed the retest.

Hopefully I will get things fixed soon and leave one final update post.

thaks again