phils97hx

97 Civic HX, CVT Transmission

This winter this car started to have an RPM fluctuation or surge (approx +-100 rpm, 1 surge/sec) when driving at low engine speeds (1.5 to 3 thou rpm) and low throttle settings until getting all the way warmed up, then it still does it but at slightly higher throttle settings (1/4-1/3 open).

Could this be a problem with the IACV (Idle Air Control Valve)? I'm planning to clean or replace it to see if it helps.

Also: After much searching on this problem, I think I'll take a look at the TPS (Throttle Position Sensor). This I think is an easy check with an Ohmeter. I'll let ya know what I find, or don't find.

Thanks for any suggestions.

SiDNEY99

i have a 99 civic si and ive had a problem similar to this for almost a year now, its been a nightmare my friend let me tell you. ive changed everything from the iac valve to the map sensor, ive brought it to 3 different shops and none of them really had the direct answer to why it was doing this. so far the closest guess was that the vtec was being disengaged due to low oil but i havnt driven it too much since then. i wish i had an answer for you but if you figure out whats wrong with yours or any1 gives you any info it would b greatly appreciated if you forwarded it to me on this page or my email: dustinsmith88@yahoo.com... ill keep you updated on my problem and if any news comes in on it, thanks

phils97hx

Sidney, I fixed mine today. Here's my post from another forum:

By RonJ: First try cleaning the IACV and then bleeding the coolant system of possible air bubbles. Another thing to look into is whether you have a vacuum/air intake leak.

Phils97hx: I got the air bubbles out of the cooling system and now it runs perfecto!

I honestly didn't think this was the problem because the last time I worked on this car was back in August 07 (its Feb 08 now) when I put a new Timing Belt on this engine. I thought surely any air would be out of the system by now! But, then again, this car has not been driven much since then (my daughter got her license suspended so the car has just been sitting). So I figured what the heck, I'll try the coolant bleed deal to see what happens. That did the trick, she runs like new! (I assume the air bubbles were messing with the IACV).

Confession: The problem came back. Intermittent. Great. Maybe I'll be looking at that IACV after all, or the ECT, or the Oxy sensor. Oh boy...

Phils97Hx:
For those who might try this: I let her cool, removed the radiator cap and turned the Heater Control Lever inside the car to full hot (red and to the right). Start engine: As the engine warmed up to operating temp and began circulating, I noticed air bubbles (Yes! air bubbles) coming up to the top of the radiator filler hole opening. Air must have been left in the heater core after the above Timing Belt job. After a couple minutes this stopped. I think I could have stopped here with the Air Bleed procedure accomplished but I went ahead and drained some out of the engine block drain bolt (just above and ahead of the oil filter) which was a pain in the azz and I think probably unnecessary. Remember after the bubbles stop, top off the radiator with coolant, put the cap back on and fill your overflow reservoir with coolant so when the engine cools it will suck coolant back into the radiator keeping it full with no air.

Good luck to anyone else with this Engine RPM Surge when Driving symptom.

maplecivicSi

My RPM was also fluctuating, i changed MAP, TPS and all, in the end it was actually the oxygen sensor that needed to be replaced. Changing O2 sensor fixed everything

phils97hx

I replaced the O2 sensor, no difference, no better.

Civicnationdot

Guys im in exactly the same situation as you two phils97hx and maplecivicSi and alot other Civic owners. I have a 97 civic was problem free for almost 5 yrs. I parked it for like 6months and then started driving recent and then my headaches start. When the engine is cold i get RPM surges that is very annoying.......it would get worst if i am driving on the hwy. sometimes i have to pull off on the side of the road till it stops so i dont **** off other drivers. But when the surges stops this car (97 civic) is like a rocket.
Anyways i have brought the car to two mechanics and they cant really figure out what the problem is. See i dont blame them because by the time i got to those shops then the car is warmed up and running fine.
So far i have: (1) cleaned my throttle body
(2)Replaced my IAC valve
(3) Bled my radiator successfullly (and it stopped for a bit and then came bad)
(4)checked for vaccum leaked by have found none
(5) checked the spark cable and cap for damage (and they OK)
(6) i have replaced my coolant turn sensor
(7) Scanned my computer module system and it says the "Engine Speed (RPM) fluctuation sensor---sensor--no signal"
(i have cleared the code ECM code and it came back. So i guess that is the culprit of my problem................So i am going to work on that.....
As well when my buddy readjusted my distributor it stoped for a bit for 1 whole day and then the same thing came back the next day.....So this could also mean the coil pack in the distributor is probably stressed out......so i will check too. I will keep you all informed if i solve my problem first.
But yall do find the answer then dont forget to share it. Thanks greatly. Vinny

PS
My suggestion to you all.....get your car ECM scoped out or get the codes read by a pro or just buy the code reader or the software from ebay price ranges from 50 dollars and up.
Good luck

imtek9

ppl always have problems with the idle on hondas, i being one of them. i have done all the above mentioned things in civicnationdot's post and problem persists. please post if anybody finds a cure

Cleft_Asunder

iTrader: (1)

Check to see if your exhaust manifold is cracked. Check for air leaks in intake using a stethascope. Make sure IAC vale is clean. Don't touch idle rpm adjustment screw(s). See if you've got air bubbles in your coolant.

Cleft_Asunder

iTrader: (1)

Thanks for the info but dude, you don't "check the distributor." I mean you do, but you don't. If you've got miles and miles on it you'l find fouling on the electrodes. Also, the rotor will look like it's fried somewhat. Those 2 need to be replaced period. Don't clean them it's a waste of time, replace them. It's standard maintenence. Get new wires too, and plugs if needed. Napa sells distributor/rotor (get the good one) that is made in japan. Or buy everything from majestic.

Distributor cap.
Rotor.
Wires.
Plugs.

Other than that, replace fuel filter. Doubt it has anything to do with it, but still. And check for coolant leaks!

Cleft_Asunder

iTrader: (1)

I had a similar problem, but not to the extent that you guys are describing. At it's most severe, the car would throw an "idle air control system" error and power in relation to RPM would go down hill. In other words, very little power. Also, my idle surged.

The first problem was that the previous owner ran water which rusted out the system. The barb on the intake manifold got so rusted that a hole developed. I had to remove the intake manifold, punch out the barb using a custom punch I made on the lathe, weld it. Had I been smart, I wouldn't have just bought a new intake manifold on ebay which run like 20 bucks(!). I assumbed it would be expensive. Stupid me.

Okay, so that helped at least I thought it did for a day. Then it threw the code again. Wtf? I check my head gasket and notice that it has squirted out some coolant. For some reason, my HG has always leaked a tiny amount on the passenger sid. I attributed the code to the HG leak, causing air bubbles. Maybe, maybe. The thing is, currently mg HG is NOT leaking to any degree. Maybe it's because it turned cold causing less engine expansion.

So I live with it for a while, but the problem does not go away. I get the code, clear it, do an idle relearn, and then it happends again the next day or so. Eventually, I start having problems with my car starting. Throws a code (don't know which one, never got a reading). I notice that the 4th coil isn't plugged into the socket properly. This fixes the problem for a day, then next day I'm having issues with the car dying randomly while accelerating. I go to napa to replace my distributor/rotor. Problem still there, but the next day it got better and eventually the problem disappeared. The problem was that distributor wasn't providing sufficent energy to plugs, then they got fauled up due to lack of proper ignition (and probably misfires). Before I changed the distrib/rotor, the car only got 35mpg and power was lacking severly. Now, I'm getting 38 like I should and I've got normal power.

All codes have disappeared, so take that for whatever it's worth. I still don't feel like idle is 100% normal, but I haven't hooked up an rpm guage after the parts swap, so I wonder if I'm getting rpm fluctuation/oscillation.

muchas

Hi,
i havea 98 civic hx with 130000 miles on it. the car will surge pretty badly when accelerating for the first 5 minutes of driving, then it's fine for the rest of the trip. it doesn't matter if you warm up the motor or not so i think it's the tranny, not the motor. if you sotp and put it in park, it idles smoothly. if you rev it up, it's smooth, no pulsating, but when you drive it, it pulsates and you can really feel it surging. the tach shows the motor revving and slowing in about 1 second intervals. does this sound familiar to anyone? thanks in advance for any help.

EMC

I had to pull off my IACV and clean it with some carb cleaner and a brass bristle brush. You don't want to scratch up the internals, but you need to get the deposits out of it. Connect power and see if it works. It will stick and cause an erratic / surging idle.

There is a simple way to check if it's the fast idle valve or the IACV. Pull off the air cleaner or intake tube, depending on your setup. Start the car and plug the throttle body holes one at a time with your fingers. If the IACV is stuck in the closed position, it won't make a difference when you place your finger over the hole. If it's stuck wide open, then you can change the idle by covering only part of that hole with your finger. Either way, it's simple to see if that's the problem or if you have something else to chase down.

When I installed a newer motor in my 2000 civic, the bouncing / surging idle problem came back. I cleaned the IACV on the newer motor, but it didn't help. So...I swapped in the older throttle body and IACV, etc and the problem was gone. Apparently I didn't clean the newer IACV well enough. Oh well, problem solved again.

shadymechanic

Get some electrical cleaner from Autozone and spray the throttle sensor plug. Also, Sometimes the O2 sensor is on it's way out and will cause the car to run rough/erratic on idle. The oxygen sensor that is most common is the one above the manifold - go to junkyard save some $$ these parts are usually good.

Save your money for a new car and buy used parts for your old one :^)

Shehzad Qureshi

I have the CVT like the OP.

I used to have the surging problem until I dropped the transmission pan and replaced the filter, cleaned out the strainer, and refilled with new CVT fluid. I also added a Magnefine inline filter.

I still have the fluctuating idle, which I believe is also a transmission issue on these CVTs. It only happens in D, S, L, and R but not Park or Neutral. It seems to go away after the transmission is thoroughly warmed up [which btw seems to take much longer than the engine].

Roslina

Hi Guys.
I am newbee over here, so hi5 to all of you. I got the similar problem with my 97 civic. See the short movie:
[autostream]http://autostream.com/ibcivicforums/?page_type=firebirdplayerthumbnail&framepage=1197& transactionid=1329829765-95160122108&posted_by=Roslina_www.civicforums.com& youtube_video_id=O2DKqaKpjs4[/autostream]
What I already did:
- scanned with computer twice (knock sensor damaged, o2 sensor damaged - both replaced), no other errors displayed
- all injectors, throttle body with gasket and all sensors attached to it (twice), spark plugs with cables, air intake temp. sensor, ignition coil cap and after that -whole ignition coil set, egr valve with additional flow sensor (dedicated to this engine), air intake mainfold gasket and coolant temp. sensors (both), alternator.
Already checked: timing belt, valves adjustation. Cleaned: throttle, mainfold, egr valve with chamber. I changed transmission fluid with filters. I belive this is no tranny problem. I just had to replace old one. Problems did not dissapear. Also, the engine looses stable rpms on idle also. I don't know if you noticed if you push gas pedal to the floor, and then release, the rpms don't stabilize instantly. The indicator goes to 800rpms, then to 1200rpms, and after that stands on 1000.
Seems that fluctuation is harder on cold weather.
I am going to check out coolant bubles, but I wonder how air gaps can cause such problem.
As I read your posts, I noticed all of you had similar situation but totaly diferent solutions.

gseattle

____

fletuitus

http://www.ecomodder.com/.../1999-civic-hx-mystery-surge-solved-21529.html

http://hondaswap.com/blogs/fletuitus...ge-solved-622/

The info supplied in the page links above will answer your question and solve the surging issue, weather it is an idle surge or at a rpm range.