RPM Surge or Jump at Highway Speeds (3000-4000rpm)

[jakeg1984]

Hello All

Car:

1988 Civic LX Sedan
1.5L fuel injected
100000 miles
no cruise
code 10, 14

Problem:

My RPM meter surges (allways drops never increases) rapidly when my pedal is at a certain position. The surging mainly occurs when driving with the engine at about 3000 to 4000 rpm but also occurs when in neutral and engine is brought to 3000 to 4000 rpm. I have observed that when the RPM gage drops the engine also looses power. But here is the thing, when I am at a stand still and have the engine reved and then completely release the accelerator I can see the normal engine drop speed is quite slow compared to how quickley the RPM meter drops when the surging occurs. So this means that there is some electrical problem that is causeing my RPM to drop faster than the engine is actually droping. Again, the surging only occurs at certain pedal positions and i can reduce the amount of surging by rapidly pushing and releasing the pedal. When i do this, the surging isn't as severe but still occurs. This behavior sounds like that of a ditry potentiometer. Is the throttle position sensor a potentiometer. If so is the throttle position sensors readings directly related to the distributor cap and could this be causing the RPM gauge to drop. Please reply with any opinions or technical know how. I am at a loss and can't just start rapidly replacing parts as I am poor so I need to know where to start. Thank You.

[90civicracer]

Sounds like your distributor to me...i had the same problem with the surges around 3-4k rpm and shit and it turned out to be the distributor. I know its happened to some other on this site also.

[jakeg1984]

OK here is some more specific information on the car.

Yes it is a fuel injected Honda Civic LX

These following things are what have been done or replaced on the car:

New:
Distributor cap
Rotor
I gutted out the cat
Has stock mufler
New fuel filter
New injector seals
New fuel pressur regulator
New Fuel Pump
Swaped ECU module with no change in engine codes below.

I have the following engine codes:

10 - Air Tempurature Sensor
14 - EACV (electronic air control valve)

I did an engine swap about 15,000 miles ago (no upgrade just a newer engine with 100,000 miles) and replaced the clutch, timing belt was fine.

The distributor and wires are from the original engine which had 195,000 miles on it.

AS far as those engine codes go. I have tried everything besides buying new parts.

I tried several different EACV from the junk yard but all gave the engine code 14. I tried several different air temp sensors but all gave the same engine code 10.

I tested the EACV with 7 volts and the sollenoid kicked in imediatly.
I tested the EACV wire harness under normal opperation and it gives out 5 volts to the EACV. Is this the correct voltage? I cannot feel the solenoid kicking in and the engine speed does not change upon removal of 2 pt plug to EACV. I even lubed the EACV. I have heard of using carb cleaner on the interoir of the EACV when removed but haven't tried this.

Another thing about the air temp sensor, when I turn the key to the ON position after I reset the ECU memory I get code 10 immediatly, like the check engine light turns on the instant I turn the key, no delay!! I check to the best of my ability for continuity from the location of the sensor plug to the location of the wires at the ECU and I have continuity and the sensors seem to be in spec.

Dispite these 2 minor engine codes, 10 and 14, my major problem is this engine surging at 3000 rpm WHAT IS THE CAUSE. I have a new rotor and cap, but old wires that are in spec and they don't have any cracks in them. If my wires were shorting out to the engine block it would make my engine miss but as far as I know it wouldn't make my RPM meter go eratic as that is what the spark is suposed to do. It is supposed to leave the wires and disperse to the block but instead of doing it at the plugs it may be doing it midway down the wire. Either way spark is going in the general correct path and that should not cause my RPM to fall so erraticly. But then agian if the spark was jumping from wire to wire, would that cause this problem. I don't know about that. Any opinions.

Possobilities for problem:

1: whole distributor is shot
2: wires are shot
3: primary or secondary coil is shot
4: EACV is shot (unlikely becuase that is an idle mechanism correct?)
5: wire harness to EACV is shot
6: Air Temp Sensor is shot
7: wire harness to temp sensor is shot

As far as I can tell this problem is not fuel related as a fuel related issue would not cause erratic RPM behavior such as this.

I hope this information helps with some of your diagnosis. Thank You and quick replies are appreciated as I would like to fix this soon before I give up and bring it to a MECHANIC!!!!!!!
Jacob German
Honda Forever

[90civicracer]

When it happened with me it was the same type of thing and we replaced the whole distributor. I am not sure if this is it for you considering I am not a mechanic by any means but I am kind of leaning toward that because that is what happened to me. Anyone else know?

[jakeg1984]

Ladies and Gentlemen,

The Honda Civic is FIXED and working correctly. All I need to do now is set the timing and valve gaps and I will have a new purring little kitten at my disposal.

What I Did:

I took the advice "90civicracer" gave me and I replaced my distributor with a $35 used one from the junk yard as I didn't want to pay 350 bucks for one from Checker (complete rip off!!!!!!!!!!). So I swapped the distributor on site and she started right up. I tuned the timing by ear and tightened her down. Running perfectly!!!!!!

I Hope this post helps some people in the future. Good Luck.

[90civicracer]

Yeah junkyard shoppin is the best if you can actually find what you want. Glad i could be of some help.

[Santas90Si]

Out of hand...

[90civicracer]

What do u mean "out of hand..."

[outofstep]

no no no outofstep

[90civicracer]

Damn, im so lost, lol.

[Santas90Si]

the new ppl are out of hand.

[90civicracer]

Shit im still lost, o well.