Engine revs high when clutch pressed

OK, Apologies in advance if this has been dealt with before - I couldn't find it and the all powerful Google has failed me.

1989 Honda Accord LXi 2.0L Manual Transmission

This all started when I bought the car (yay!!). I will start here in case anything I've done to the car could be an issue. Bought it at an auction and it ran well there, just at idle since I couldn't drive it around anywhere. Smooth idle, no check engine light. Bought it Cheap.

Get it home, get the engine warmed up and the check engine light comes on. Also it starts running badly.

Changed the oil, oil filter, air filter, and fuel filter (standard for me when I buy a car) - Not really expecting a change, and none happened

Checked the codes, says it's the Engine Coolant Temperature Sensor. Changed that - CEL goes away. Car Still not running great.


A few Days Later, the car becomes undrivable (apparently undrivable is not a word according to Google Chrome - just FYI). It bogs down when trying to accelerate.

Changed the Fuel Pump Relay (Bought it by mistake when trying to get a Main Relay) - No Change

Changed Main Relay (Seemed to be the most common problem for this issue I saw on most forums - Figured if they went out that often then at 220,000 miles mine was due for a replacement anyway.) - No Change

Changed Plugs, Wires and Distributer cap (probably needed it anyway, plus one wire was definitely bad - not sure if or how that cylinder was firing) - No Change

Checked fuel pressure and it's low (25PSI instead of 33-39 as recommended). Check the fuel pump and it is not an OEM fuel pump (Much Smaller - possibly not able to pump at the correct pressure) and the screen is pretty clogged. Changed the pump and Screen - Worked Flawlessly...

For 1 Day

Then it goes back to it's old ways - Then an epiphany :idea: - I had to buy a Gas cap when I got the car...How long did the guy who had it before me run it without a gas Cap?

Well, Judging from the 3 pounds of dirt and grime I pulled out of the gas tank, I'd say a long time.

Success!! - Except for one Lingering issue...

When I press the clutch to coast to a stop the engine revs to about 2700, until I come to a complete stop. Then it comes back down to normal. Doesn't matter whether I'm in gear, out of gear, out of gear with the clutch released, it stays at 2700 until I come to a complete stop. If I'm stopped on a downhill slope (idle down to normal) and release the brake (so that I start moving forward again - I haven't tried this in reverse as that prospect terrifies me) the engine will rev back up to 2700.

What?!?! I am at a complete loss.

Sorry for the long post, and thanks for your help.

That's some nice sleuthing. The crud in the tank is an especially good find. Couple things I would look at. First, check the condition of your throttle cable. If it's kinked, or simply worn out, it can cause a sticky throttle. If it is bad, don't try to lube it. Instead, replace it with a new one. The cable moves inside a plastic sleeve and once the sleeve is worn through, it will be sticky, no matter how much lube you use. Also, check the butterfly valve on the throttle body. It can get notchy. Repairing that is a little more involved. Remove the throttle body, remove the plates and extract the pivot. Clean everything thoroughly and oil the pivot points well before reassembling. That will probably get it. If not, then report back and we'll see what else we can figure out.

sounds like a vacuum leak. but you say it goes to normal after awhile. i would check your fast idle valve and clean it. be careful thou . they have a oring and if you try to adjust it sometimes it dont move if you force it you may have a leak afterwords.

Thanks for the amazingly quick responses guys.


Dr_Snooz

I had thought about both of those but sort of ruled them out (I'm not going to ignore a suggestion though - these will be part of my Saturday Tinkering) for two reasons.

1. It's not a certain amount of time until it revs down. The RPM's only drop when I come to a complete stop. If I'm moving even just a little it still revs high.

2. It always revs at the same RPM (around 2700). If one of those was stuck I would assume (we all know where that tends to get a person) that the car would rev at different RPMs depending on how far the pedal was pushed. Though as I think about it, they could be sticking in the exact same spot each time.

I should probably just delete reason two, but I put so much effort into typing it I just can't bring myself to do it.

Rendon

I have Checked for vacuum leaks, though that doesn't mean I didn't miss anything.

I'll check with as much of that as I can and get back on here with the results. Thanks again guys.

Oh - and it's not happening all the time (apparently - had up until now). On my drive home from work tonight it didn't happen a single time. Certainly lends credence to the sticky something theory.

Dr_Snooz - Your sig line features the car I have in my garage - I dearly wish mine looked as good as yours though. Someone beat mine nearly to death.

Thanks.

Fast idle valve located at the throttle body unscrew the cap and snug the valve all the way to the bottom.

Book indicates looking at: 1) Hoses and connections 2) fast idle valve 3) Electronic air control valve.

I would suspect that the idle has been screwed with so look to adjust that after doing the above.

A good thorough throttle body cleaning is in order as well. Throttle cable return spring could be sticking as well.

Good luck, keep us posted.

I've had a faulty cruise control actuator cause similar problems.

I would pull the hose that goes from the intake manifold to the cruise control off and block it, then see what happens

So, I made a discovery...I am an idiot.

During all the process I adjusted the throttle cable so that the low idle speed was back in factory spec (I imagine that the previous owner was having trouble with the car and had increased the idle speed to try and help with it.)

Well, there are the two nuts there that you tighten on either side of the bracket. I forgot to tighten the one on the left. I've only driven it a few times since then but it seems to be doing just fine now.

Thanks for all of your help.

There should be slack in the cable at idle. TEchnically the screw on the throttle body is for idle adjustment.

Wp

Glad that you resolved the issue. These are great reliable little cars.

Thanks OldBlue,

I only messed with the throttle cable at all because I could tell it had been fiddled with, just to try and get it back where it was supposed to be.

Nice work! Excellent post on how good detective work should be done! Glad to hear she's running tip top. Sounds like with you keeping an eye on her, she should run great for a long time!