1998 Honda Accord rpm drops on highway

[ShreddedWheat]

1998 Honda Accord with 202k mileage.

Old Thread: See bottom for Update

Pre info: A year ago I was on highway doing about 70+ mph gave the car gas to pass a car and it just died (almost got creamed by 18 wheeler). Problem was distributor cap....replaced.

When distributor cap replaced also had tune up, air filter is clean, not sure about fuel filter? Just recently had a new catalytic converter installed. No major tranny problems though using Lucas Transmission fluid fix which has made tranny drive/shift smoother.

A week ago was on highway and doing about 70+ mph and rpms dropped from 3000 to about 500....scared me based on past experience...gave it a little gas and it came back up. Drove back home on side streets and car drove fine?

Any ideas what it could be?

Thanks in advance for responses. Want to get fixed soon gas driving my Jeep Wrangler is killing me

Thread closed because it's old, the OP gave us an update, but it's still getting bumped.

Zenmervolt - AnandTech Moderator

 

[onza]

Obvious answer is transmission seems to act up.

Do you know what Lucas did during the transmission work? Drain / refill? or Fluid flush?

 

[ShreddedWheat]

No transmission work....sorry if my sentence was confusing. Added lucas just to help tranny run smoother. Only work done was catalytic converter and distributor cap.

Car shifts good....

 

[phucheneh]

Lucas is sometimes a marginally effective bandaid for a failing transmission. But I would never put that crap in a good trans. There are very specific requirements for the fluid, and you should not modify any of its characteristics.

It sounds like the trans went into neutral. Which sounds like a valve and/or solenoid problem. Or maybe the seal for the piston that engages the fourth gear clutch pack is smoked....dunno why you would lose gear intermittently, though.

 

[Zenmervolt]

If you've never changed the fuel filter, I'd do that just on the basis that by this mileage it should be changed anyway.

I'm not sure that it would be the transmission since you'd have really felt a clunk if it dropped out of gear and then back in at freeway speeds. And if the transmission dropped to neutral the engine would have raced rather than dropped to 500 RPM because the sudden lack of a load would have let the RPM jump up, not fall. It's still possible if there's electronic control of the throttle to prevent revving in neutral, but it's not the first place I'd look.

To me this sounds more like an engine issue.

OP, when you changed the distributor cap, did you also change the rotor, plugs, and plug wires? Those are usually included in a "tune up" but you didn't specify and I'd want to make sure there.

If all these parts are still original, this is what I'd look change first and go from there:
- Fuel Filter
- Spark Plugs
- Plug Wires
- Distributor Rotor

At the mileage you have, these are parts that probably need replaced just as routine maintenance anyway.

ZV

 

[phucheneh]

If you've never changed the fuel filter, I'd do that just on the basis that by this mileage it should be changed anyway.

I'm not sure that it would be the transmission since you'd have really felt a clunk if it dropped out of gear and then back in at freeway speeds. And if the transmission dropped to neutral the engine would have raced rather than dropped to 500 RPM because the sudden lack of a load would have let the RPM jump up, not fall. It's still possible if there's electronic control of the throttle to prevent revving in neutral, but it's not the first place I'd look.

To me this sounds more like an engine issue.

OP, when you changed the distributor cap, did you also change the rotor, plugs, and plug wires? Those are usually included in a "tune up" but you didn't specify and I'd want to make sure there.

If all these parts are still original, this is what I'd look change first and go from there:
- Fuel Filter
- Spark Plugs
- Plug Wires
- Distributor Rotor

At the mileage you have, these are parts that probably need replaced just as routine maintenance anyway.

ZV

That's a good point about the engine revving. If his foot was on the gas at all, the engine speed wouldn't drop like he's describing.

How could a properly-functioning trans allow that kind of RPM drop while in gear, though? Especially at 70mph, when the converter should be locked up.

OP, were you trying to pass or otherwise accelerate when this happened? Or was it under decel (foot off gas)?

 

[radioouman]

I suspect the idle air control solenoid in the throttle body. Just a hunch.

 

[Zenmervolt]

How could a properly-functioning trans allow that kind of RPM drop while in gear, though? Especially at 70mph, when the converter should be locked up.

If he was holding speed and the engine stumbled, my best guess would be that the sudden drop in engine power would make the transmission controls think that he'd lifted off the throttle, which would disengage the lockup clutch. Most automatics I've driven will try to let you coast without much engine braking if you're in the higher gears and lift off the throttle. Basically, when input torque drops, they'll release the lockup clutch in most cases.

Without the lockup clutch, the torque converter is only efficient in one direction (engine to transmission); there's a shit-ton of slip if you try to apply power in the other direction (transmission to engine). For example, in my S70 if I'm going down a moderately steep hill at 70 and lift completely off the throttle, the RPM will drop to ~1,000 RPM even though the car will continue to pick up speed because the transmission is programmed to let you coast longer with less engine braking (better fuel economy) when you're just leaving the lever in "D."

I can see it being possible that if the engine truly stumbled or stalled that the RPM could drop into the 500 RPM range before the engine caught again if the car were running at freeway speeds when the hiccough happened.

ZV

 

[SearchMaster]

If you've never changed the fuel filter, I'd do that just on the basis that by this mileage it should be changed anyway.

The 6G Accord has an unusual setup where the filter is integrated with the fuel pump in the tank and is not really serviceable.

 

[sontakke]

It is a Honda Accord. Of course, it needs the ignition key switch replaced. There was safety recall on it. 99.99% this is your problem.

 

[SearchMaster]

It is a Honda Accord. Of course, it needs the ignition key switch replaced. There was safety recall on it. 99.99% this is your problem.

Good thought but the bad ignition switch causes random shutoffs (and difficulty in restarting). That really doesn't match the OPs symptoms. It matches his original symptom (car dying on the interstate) but that was supposedly fixed with the distributor cap replacement. The new symptom was different.

 

[Thegonagle]

It is a Honda Accord. Of course, it needs the ignition key switch replaced. There was safety recall on it. 99.99% this is your problem.

I was thinking this.

It's most likely that your RPMs didn't actually drop to 500, which is below normal idle speed. As others point out, that's pretty much a mechanical impossibility.

I'd guess that the power to the gauge and/or the ignition system was interrupted due to the switch failing.

I had a 99 Accord for a few years and the ignition switch really was a weak point. I went through 2, one from a U-Pull, and one brand new.

 

[phucheneh]

Ignition switch sounds like a good fit to me. It doesn't take long for the tach to drop off once it loses power, and that amount of time may not be long enough to notice any 'my car died' type of symptoms. I would think the dash lights would also blink on, though. As in, CEL, oil light, ect. Things that self-test when you first turn the key on.

ZV - I know an auto is not like a manual and that the converter's main purpose is to work one way. But I still don't think that much of a drop should be possible...hard to say; I think it may be dependent on trans design. IIRC the biggest limiter of engine braking is usually a one-way (sprag) clutch inside the trans itself. I don't know if honda even uses any of those. Basically, though, I think you'd have to know the powerflow of the trans to see if it could turn the engine at interstate speeds without lockup.

I'm definitely not a tranny guy (...harhar). Gimme internal engine any day...

But in general, I dunno how 'standardized' trans operation has become in comparison to engines. I know some auto trans designs will engine-brake like a mofo. Infinitis with the paddles were fun...not for upshifting, but for gearing down before entering a corner.

 

[sontakke]

the car will restart as if nothing was wrong but before you can start it, it needs to be in neutral or park. DONT TRY TO PUT IT IN NEUTRAL WHILE IN MOTION BECAUSE IF YOU ACCIDENTALLY HIT THE REVERSE, YOU WILL NEED NEW TRANSMISSION. Do not ask me how I know :-(

 

[CA19100]

It shouldn't be able to go into reverse if you don't push the button/lever on the transmission selector. D and N are in the same gate on every auto I've ever driven.

 

[Mermaidman]

I had a GM car that displayed the similar symptoms. Turned out to be a bad crank position sensor. Of course, different make and model, but who knows . . .

Hopefully the OP returns and posts an update.

 

[Zenmervolt]

Ignition switch sounds like a good fit to me. It doesn't take long for the tach to drop off once it loses power, and that amount of time may not be long enough to notice any 'my car died' type of symptoms. I would think the dash lights would also blink on, though. As in, CEL, oil light, ect. Things that self-test when you first turn the key on.

True, but I've never seen an ignition switch fail in that manner before. It's certainly technically possible, but I've always seen them fail in ways that make the car die pretty completely for a while, not just a single isolated stutter like that. Other engine electronics (main relay for the ECU, etc.), sure, but that doesn't match what I've seen with ignition switches. If the OP were also having trouble starting the car sometimes or if the engine actually died completely and wouldn't re-start without jiggling the keys in the ignition or something, then I'd be inclined to suggest looking at the ignition switch. Additionally, if the issue were the ignition switch, he'd be seeing the speedometer needle fall just as the tach did.

But as it is, I think that Mermaidman is on the right track since most ECUs will shut down if they stop getting a proper timing signal (crank or cam position sensors usuall) and that would also kill the tach (since most tachs today get their signal from the ECU) without necessarily killing every other gauge at the same time.

As for the transmission discussion, I think you're probably right. I re-checked it the other day in my S70 and while the RPM does fall significantly when I lift throttle at freeway speeds without noticeable engine braking, RPM only drops to something like 1,800 RPM (from 2,500 rpm) and I'd been mis-remembering in my earlier post. Even with the engine off and not just at idle fuel trim (deceleration cutoff in the S70 doesn't happen with the automatic unless the RPM is above ~2,500 and the throttle is closed, so when I lift at 70 and the RPM drops to 1,800, the engine is still getting some fuel) I doubt that actual engine RPM would fall as low as 500.

ZV

 

[thomsbrain]

The auto on my Accord does NOT un-lock the converter when you lift off the gas except under very low-RPM conditions (like under 1500 RPM before you lift off) or when the grade logic is doing weird stuff. But I have a newer model with a completely different drivetrain.

I do still have an ignition-switch recall, though.

 

[ShreddedWheat]

Yes, Digging up this old thread but first off Thanks to everyone's input! I started putting in nothing but premium gas and had no problems at all after that (aka 7k+ miles ). The other day I thought I would put in a bottle of Lucas Fuel Treatment as a "treat" to the car. WTF? About half a tank into it the rpms started dropping like before and the car seemed sluggish which I thought might be the tranny....though when picking up speed on the ramp to the highway it shifts like a butter? Stop and go traffic the tranny is finicky.......stop light to stop light traffic the car is fine....Houston "life sucks" afternoon traffic tranny is "pissed too". I'm starting to think it is the fuel filter and will have it most likely replaced soon. From what I read about the Lucas treatment is that it will basically clean out the fuel system but I'm thinking that more debris is getting trapped in the fuel filter that is 208k miles old? Looking for suggestions, etc...

 

[CraigRT]

the car will restart as if nothing was wrong but before you can start it, it needs to be in neutral or park. DONT TRY TO PUT IT IN NEUTRAL WHILE IN MOTION BECAUSE IF YOU ACCIDENTALLY HIT THE REVERSE, YOU WILL NEED NEW TRANSMISSION. Do not ask me how I know :-(

haha.. Neutral is fine. You only have to push the gear selector to get it to N, it WILL NOT go into reverse unless you push the button, which you are not supposed to do. It is designed that way for a reason.

 

[LTC8K6]

Surprising that a 1998 MY car will go into reverse at all while driving forwards. Most electronically controlled transmissions will just ignore you if you select reverse while driving down the road. They will not go into reverse above a certain speed, and they will wait if they are above that speed until the car slows down enough.

 

[EricSinCT]

1998 Honda Accord with 202k mileage.

It seems I am having the same problem with my 98 accord also. I have a V6 coupe with 300,000 + miles. I am the original owner and have done only the necessary maintenance requirements. I did change the recalled ignition switch.

My problem (seems same as yours) Randomly my car will lose acceleration and the RPMs drop. Usually it occurs on highways too, but I have had it occur on smaller roads and lower speeds. RPMs tend to drop from 2500 to same 1500 then it kicks in and starts to accelerate again. Sometimes I can goose the gas pedal and it come back quicker. I find it does not usually happen when i fist start driving. It usually occurs after I am driving for 30 minutes or so.

I do not lose all power to the car, radio, AC, lights all continue to work fine during this loss of engine power.

Did you ever find out what the problem was with your car? I love my car to death and it has treated me well over the years and i am not ready to take on another car payment yet. Please help. ericsinct@aol.com

 

[EricSinCT]

1998 Honda Accord with 202k mileage.

It seems I am having the same problem with my 98 accord also. I have a V6 coupe with 300,000 + miles. I am the original owner and have done only the necessary maintenance requirements. I did change the recalled ignition switch.

My problem (seems same as yours) Randomly my car will lose acceleration and the RPMs drop. Usually it occurs on highways too, but I have had it occur on smaller roads and lower speeds. RPMs tend to drop from 2500 to same 1500 then it kicks in and starts to accelerate again. Sometimes I can goose the gas pedal and it come back quicker. I find it does not usually happen when i fist start driving. It usually occurs after I am driving for 30 minutes or so.

I do not lose all power to the car, radio, AC, lights all continue to work fine during this loss of engine power.

Did you ever find out what the problem was with your car? I love my car to death and it has treated me well over the years and i am not ready to take on another car payment yet. please help ericsinct@aol.com

 

[EricSinCT]

I have a V6 coupe with 300,000 + miles. I am the original owner and have done only the necessary maintenance requirements. I did change the recalled ignition switch. I have a random loss of power every few days. Any suggestions?

 

[EricSinCT]

any ideas?

You received replies in the thread you started on your own. http://forums.anandtech.com/showthread.php?t=2340859&highlight=

Any useful responses are almost infinitely more likely to show up there than in an old thread you're randomly bumping.

Zenmervolt - AnandTech Moderator