Strange RPM Dropping Problem
#1
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Strange RPM Dropping Problem
I need some suggestions on what this problem could be. I have an EH with an ITR swap (bolt ons, NA) with a dyno tune on Hondata. The car has been running flawlessly for almost two years after my tune and haven't changed a thing. Out of no where yesterday when I was in 3rd or 4th gear and dropped to neutral to coast to a stop, my RPMs dropped to WAY below idle. So it did it the whole ride consistently, with or without pressing the brakes, with or without shifting to neutral (holding the clutch in), every time. Sometimes the RPMs would drop so low it felt like my car was about to shut off. I was going to the grocery store so I went in for about 30 minutes. When I came back out, my car actually started up very weak (never ever felt like this before), then all of sudden that problem never occurred the whole ride home. I don't even feel like seeing what it will do today. But what the hell does this mean?
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Re: Strange RPM Dropping Problem
has the dizzy come loose at all? the map still plugged in? do you have a fuel pressure regulator/guage? What have you checked so far?
#3
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Re: Strange RPM Dropping Problem
So yesterday I took out the car, and at first it was acting fine. It was doing as normal, when I coast the RPM stays a little above idle, like maybe 1200 RPM like most cars. Then 10 minutes into the ride it started doing it again. This time when I would coast it would drop to about 600 or so, still low and not normal, but never as low as that first day.
I checked my starter, battery, alternator, all with the Advance Auto testing thing and they call checked out great. Everything is plugged in, I need to go check the distributor but I doubt it loosened itself up. Last month I did have to take off the distributor to replace a leaking o-ring , but other then that the car has ran fine since then. Everything is plugged in as always, and no I do not have a fuel pressure regular or gauge, but I can datalog with my Hondata S300 on SManager.
I have a feeling this is some sort of fuel problem. I don't know what though. I know with my tune that my stock injectors are almost maxed out in terms of duty cycle percentages and I have the stock fuel pump. Maybe soon I will get a Walbro 255 lph pump, but I am not sure that this will fix the problem.
I checked my starter, battery, alternator, all with the Advance Auto testing thing and they call checked out great. Everything is plugged in, I need to go check the distributor but I doubt it loosened itself up. Last month I did have to take off the distributor to replace a leaking o-ring , but other then that the car has ran fine since then. Everything is plugged in as always, and no I do not have a fuel pressure regular or gauge, but I can datalog with my Hondata S300 on SManager.
I have a feeling this is some sort of fuel problem. I don't know what though. I know with my tune that my stock injectors are almost maxed out in terms of duty cycle percentages and I have the stock fuel pump. Maybe soon I will get a Walbro 255 lph pump, but I am not sure that this will fix the problem.
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Re: Strange RPM Dropping Problem
double check your work on the dizzy work. check for bad vaccum lines/connections. usually my prob on idle issues. I doubt it might be it but just a suggestion.
Worse comes to worst. try a compress test..
Worse comes to worst. try a compress test..
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Re: Strange RPM Dropping Problem
I had somewhat of the similar problem as what vtechjunkie stated for you to check. I replaced my dizzy and it still would do it. So, I check my spark plugs and they seemed fine. I still had the issue and decided to just replace my plugs and double check my IACV (idle air control valve). After that, everything was "A" okay.
#7
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Re: Strange RPM Dropping Problem
Hmm. I don't see anything in here that I am thinking. I am thinking it is fuel related.
If by "cells" you mean check engine lights, no I don't throw any.
I don't believe I have any vacuum leaks because losing air usually makes your idle go up if any. This is not really an idle problem. If I sit still and rev up the car, it will drop back down to idle perfectly. I am pretty sure its not my distributor but its possible. It's the one that came on the swap when I got it from HMO and I have not yet replaced the rotor or cap, but thats usually not the problem.
The plugs were replaced when I got the swap in less than two years ago, for OEM Platinum plugs (ITR), so they shouldn't need to be replaced any time soon (if ever).
If by "cells" you mean check engine lights, no I don't throw any.
I don't believe I have any vacuum leaks because losing air usually makes your idle go up if any. This is not really an idle problem. If I sit still and rev up the car, it will drop back down to idle perfectly. I am pretty sure its not my distributor but its possible. It's the one that came on the swap when I got it from HMO and I have not yet replaced the rotor or cap, but thats usually not the problem.
The plugs were replaced when I got the swap in less than two years ago, for OEM Platinum plugs (ITR), so they shouldn't need to be replaced any time soon (if ever).
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Re: Strange RPM Dropping Problem
On my boosted set-ups, there are sometimes a problem similar to this. It is usually fixed by adjusting the IACV, as that adjusts the idle. Try cleaning the IACV, and make sure all the parameters are correct. Not that I could think of a way they would go askew. LOL!
#11
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Re: Strange RPM Dropping Problem
I never found the problem but now I am almost certain that it only happens on days that are pretty humid and fairly over 80 degrees.
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