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Honda Accord Losing Power
03-27-2007, 05:25 PM
I have an 87 Accord LX with 309,000 miles on it, and I keep it in mint condition with all the preventive maintenance. It has been a fantastic car over the years with hardly any problems. A few weeks ago, I took 2 other people with me to the city. We had to get on the freeway and just as we were going up a slight incline (at the beginning of the trip), the car lost power and I floored it and it would not go over 50. I thought it was because of the 2 extra people in the car, since it had never done this before. After 15 minutes or so, the problem went away.
The next week, I was alone in my car, and it seemed to lose power again, and again, this was on the freeway. I continued on and it was fine again.
The next week, I lost power in the car on the freeway and this time, the car cut off and I rolled off the freeway onto an exit. Had it towed. The tow driver was able to start it (after 2 hours of waiting for the tow truck).
The first mechanic checked it out and drove it all week and could not get it to cut off or lose power, so I picked the car up and took it to a second mechanic. He ran all the tests and could not find a thing wrong with it, but he did say it could be a bad tank of gas and suggested something called "Heet". He also recommended using better quality gas.
I have a friend who is a car buff (he has several Porsches and Volkswagens and knows a lot about cars). He told me that the catalytic converter should be replaced, as he also has a very old Toyota Corolla that had the same power problem, so he replaced the catalytic converter, and it is now fine! He also said "A catalytic converter, even when new, creates exhaust back pressure,and adversely affects performance AND gas mileage." Is this true? I also heard that it is against the law not to have a catalytic converter on your car as it has something to do with emissions.
I have 309, 000 miles on the car. The fuel pump is 10 years old. The clutch is 10 years old. The catalytic converter is 20 years old and is the orginal part.
Does anyone have any ideas? I decided to replace the catalytic converter with an aftermarket one from NAPA, as the Honda ones are $600. Both mechanics could find nothing wrong with the fuel pump, carburetor, hoses, distributor, cap, rotor, plugs, etc.
Thanks to everyone for their ideas!
03-27-2007, 11:03 PM
Sometimes finding those problems you described are hard especially when they try to diagnose the problem after the car starts working again. Solving your problem may be easier then if you had fuel injection. Cat converters can cause the problem you experienced and after 20 years you might want to inspect it, however, you need to remove the unit so you can see if it is plugged. I would start cheap and replace the inexpensive things first like spark plugs. Then ignition coil and points/igniter.
03-28-2007, 06:51 AM
The monolithic type cats make very little backpressure. Yes, it is against Federal law to remove it, a shop can't legally delete one from a car.
A partially clogged cat could cause the problem if it only manifests itself when the motor is turning high revs, like on the highway or under hard acceleration. This would be a predictable reaction, you'd notice the car beginning to loose power consistantly after X amount of minutes at highway speed, or flattening out and refusing to rev freely when you were running up hard through the gears....
A vacuum gauge would point it out very easily. It's a $25 tool that can save a lot of confusion. It shows the strength of the vacuum developed in the intake.
A car with a restricted cat will show normal levels (18-21hg) at idle, and when the throttle is opened, the level will drop suddenly, then begin to recover to a point as it's held open at a steady rpm.
A car with a cat causing problems will show normal idle vac readings, but when you hold it open steady at say 3500 rpm, after stabilizing, the reading will begin to drop off steadily as backpressure builds ahead of the restriction as the exhaust is produced faster than it can exit the pipe. Engines are just simple volumetric machines, if you can't move air (exhaust) out, you can't suck more intake mix in, so your intake reading begins to fall...as it drops, if you rev it higher, the rate of drop will increase, until at some point the engine will begin to starve from lack of intake volume and begin falling off, this is the point where it would be stalling if under load (moving), but would have lost power and slowed down way before then if moving....
Also at this point, if you were doing this in the dark, you'd likely see the front side of the cat and some length of your lead pipe glowing cherry red from overheating, most likely..sometimes the exhaust manifold will even begin to glow, depends on distance from the clogged cat...
So anyway, a partial clog is a bit perplexing, because the car may run fine as long as the rpms are below the point where backpressure begins to build behind it, but once you cross that threshold and begin quickly building pressure behind it, things start to happen very quickly...
The other likely culprit, fuel delivery, is easy enough to check. What I would do is take the air cleaner apart enough that you can quickly remove the lid and see into the carb. Take it out and drive around until the problem occurs. When you feel it beginning to fall off, fight it to a stop, giving it more and more gas pedal until it stalls. Then get out quickly and pump the acceleratoir linkage and check for presence of a strong shot of fuel from the main jets into the carb's throat. If you get a spitting, broken shot, or nothing at all, the carb has run dry of fuel, the next step is to find out why.
Also a clear fuel filter inline can be very useful if you can put one in it,, then you can just see that the line does or doesn't have fuel in it...I don't know if you can do this on your's, though.
More later...gotta take kids to school...
03-28-2007, 06:09 PM
Thanks to both of you for the information about the loss of power in my 87 Honda Accord LX! I asked the mechanic to replace the catalytic converter, which he did. Also, he recommended putting a product called "Heet" in the gas tank to remove moisture. I had him do that as well. Picked up the car today and tested it on the freeway and locally, revving it up good, and it drives GREAT now. I bought some Chevron gas today. NO loss of power whatsoever. Hopefully, it is now fixed. Ok, do you think it was the "Heet" OR the new catalytic converter or BOTH?
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