Sudden drops and surges in rpm
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From: Texas
Sudden drops and surges in rpm
I have a 98 Honda Accord, and I have replaced the distributor, cpu, and map sensor. I have also had a complete tune up done in which metal was found in my brake fluid so that was flushed as well. Originally, my car would die will driving or idling and after a 15mins or a jump start it would come back on. It would continue to do this all the way home, and after sitting over night it would be fine for about a week.
After replacing said various parts over the last 2 months, now my car has sudden shifts in rpm. While driving on the hwy and trying to maintain speed, my car would slow and the rpm would drop. Then the rpms would suddenly jump and my car would shoot forward. Also, when accelerating from a stop my car will crawl, then suddenly shoot forward with the rpms jumping as well. It continues with the sudden peaks and valleys until I stop and cut it off.
I had it scanned and no error codes come up.
After replacing said various parts over the last 2 months, now my car has sudden shifts in rpm. While driving on the hwy and trying to maintain speed, my car would slow and the rpm would drop. Then the rpms would suddenly jump and my car would shoot forward. Also, when accelerating from a stop my car will crawl, then suddenly shoot forward with the rpms jumping as well. It continues with the sudden peaks and valleys until I stop and cut it off.
I had it scanned and no error codes come up.
Last edited by AMCooper; May 25, 2013 at 07:23 PM. Reason: forgot information
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Re: Sudden drops and surges in rpm
Your first paragraph would appear to be symptoms of the main relay. The second paragraph I'm not so sure. My first thought would be possible TPS. When you say the rpms drops, is proportional to the actual speed of the car, or is it simply just the tach that moves ?
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From: Texas
Re: Sudden drops and surges in rpm
I(the husband) hunted out the main relay after it started acting up today and following up with some heavy searching online to find a lot of similar issues lead to the relay... good call... once i found it I found I could turn the key and when it would keep turning over i could knock on it a couple of times and it would fire... then I knocked on it a couple of more times and it died promptly... great call... my big hefty self had a heckuva time contorting to get to it but I got it done. Thank you... we shall see if it cancels the rpm issue or not... last time it did that the Check Engine Light came on and that was what led to the replacement of the MAP sensor(code indicated).
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Re: Sudden drops and surges in rpm
a jump start would not revive a main relay *clear* hahaha map sensor sounds like you did right on the idle issue it could also be iacv. air in the system. even fitv or cold start valve, i don't know if the 98 has a cold start valve, that's not the name just can't remember right now.
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Re: Sudden drops and surges in rpm
When the main relay starts to go, it will die and then restart only after a passage of time as the solder in the main relay has time to cool. Assuming it takes a few minutes to set up a car for a jump start, this could be just the time needed for the solder in the main relay to cool, hence allowing the main relay to run again.
Your apparent tach issue, may not be an issue at all, it could just be the relay trying to die but not completely killing the car all the way.
So there is a chance these two issues could be fixed now. We will wait and see, if it does fix it, feel free to update this thread.
Your apparent tach issue, may not be an issue at all, it could just be the relay trying to die but not completely killing the car all the way.
So there is a chance these two issues could be fixed now. We will wait and see, if it does fix it, feel free to update this thread.
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Re: Sudden drops and surges in rpm
a jump start would not revive a main relay *clear* hahaha map sensor sounds like you did right on the idle issue it could also be iacv. air in the system. even fitv or cold start valve, i don't know if the 98 has a cold start valve, that's not the name just can't remember right now.
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From: Texas
Re: Sudden drops and surges in rpm
Well the car hasn't died, thankfully; however the rpms are still a problem. Thinking it is something in the fuel system? No check engine light, no code. . . attempting to clean the catalytic converter to see if this helps since the fuel injectors were just cleaned. I hope this works otherwise I am looking at trying to replace the car, because I have already put more into it than it is worth!
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From: Texas
Re: Sudden drops and surges in rpm
I replaced the main relay and it worked for a week and now it does the same thing. The engine cuts off and won't come back in for about half an hour. It is also still doing the rpm surges, but when I rev my engine for a minute or will be fine for about ten minutes until I have to punch the accelerator again. I can't find anyone that knows what is wrong and I have already put a lot of money into. At this point I just want to get it running enough to trade it in on a new car!
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From: on the south side of dixie, 1986 Accord Hatch
Re: Sudden drops and surges in rpm
I replaced the main relay and it worked for a week and now it does the same thing. The engine cuts off and won't come back in for about half an hour. It is also still doing the rpm surges, but when I rev my engine for a minute or will be fine for about ten minutes until I have to punch the accelerator again. I can't find anyone that knows what is wrong and I have already put a lot of money into. At this point I just want to get it running enough to trade it in on a new car!
longest project ever
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From: on the south side of dixie, 1986 Accord Hatch
Re: Sudden drops and surges in rpm
usually the ignition switch issue will just cause the car to suddenly quit, but I could see a bad contact causing all kinds of issues
Summer 2002
Important Safety Recall: Ignition Switch
Dear Accord, Civic, CR-V, Odyssey or Prelude Owner:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act.
What is the reason for this notice?
Honda Motor Co., Ltd., has determined that a defect relating to motor vehicle safety exists in the ignition switch on certain 1997 thru 2000 Honda automobiles. Electrical contacts in the ignition switch can wear prematurely due to high electrical current passing through the switch. Worn out ignition contacts could cause the engine to stall without warning. Although the engine will restart in most cases, if your engine stalls while driving in traffic or at highway speeds, you're at risk of being involved in a crash. Difficulties starting the engine (for example, hard-to-start, stalls immediately after starting, etc.) may indicate that the ignition switch is failing.
Important Safety Recall: Ignition Switch
Dear Accord, Civic, CR-V, Odyssey or Prelude Owner:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act.
What is the reason for this notice?
Honda Motor Co., Ltd., has determined that a defect relating to motor vehicle safety exists in the ignition switch on certain 1997 thru 2000 Honda automobiles. Electrical contacts in the ignition switch can wear prematurely due to high electrical current passing through the switch. Worn out ignition contacts could cause the engine to stall without warning. Although the engine will restart in most cases, if your engine stalls while driving in traffic or at highway speeds, you're at risk of being involved in a crash. Difficulties starting the engine (for example, hard-to-start, stalls immediately after starting, etc.) may indicate that the ignition switch is failing.
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From: Texas
Re: Sudden drops and surges in rpm
The ignition switch was changed a long time ago. I think it's a fuel problem; just don't know where to start. . . it fires, just doesn't follow through. Thanks though!
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From: Texas
Re: Sudden drops and surges in rpm
Someone told me I needed to replace the fuel pump relay, but when I search for the part, the part #is the same as the main relay. . . is the main relay and the fuel pump relay the same part?
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Re: Sudden drops and surges in rpm
Yes, some places call them that...main relay/fuel pump relay.
When the car dies, you really need to find out what is missing. Spark or fuel. There are some ways to test for spark. For fuel, you can try spraying carb cleaner into the TB - open the butterfly.
When the car dies, you really need to find out what is missing. Spark or fuel. There are some ways to test for spark. For fuel, you can try spraying carb cleaner into the TB - open the butterfly.
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Re: Sudden drops and surges in rpm
To the OP, what was the final diagnosis of the problem? My 2000 Accord would have a momentary dip in RPM while cruising and then recovers within a split second, sometimes that was too quick even to turn to see the RPM change on the dashboard, but can feel the car jerk.
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From: Tampa, FL, USA or Somewhere in the Caribbean
Re: Sudden drops and surges in rpm
Honestly, sounds like a the symptoms I had of a bad igniter (within the distributor) some years back. Vehicle would run eratically including a jumping tach, then when you shut it off, you couldnt get it to start back when it was warm. I would have to run the fans for about 20 mins or so to get the dizzy cool enough to start it back.
Changed the igniter (i had a spare dizzy) and everything was fine after that. I had far less mechanical experience then and I was able to do it with a friend in about 30 mins using a basic socket set and screwdrivers. Great tip from my dad, if you are opening the fine screws inside of the distributor to get at the igniter, use a locking pliers to crack them open if they have never been opened before, if not, super easy to strip the philips head.
Changed the igniter (i had a spare dizzy) and everything was fine after that. I had far less mechanical experience then and I was able to do it with a friend in about 30 mins using a basic socket set and screwdrivers. Great tip from my dad, if you are opening the fine screws inside of the distributor to get at the igniter, use a locking pliers to crack them open if they have never been opened before, if not, super easy to strip the philips head.
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