new_climber

1998 civic...EX....225K+ miles.

I have been fighting a problem where I get a slight hesitation around 2500 rpm up to about 3000 rpm. I have replaced the plugs, wires, cap/rotor, fuel filter, PCV valve. I used some Seaform into the the vac line to the master brake cylinder...but non of the above have helped. I also have lower then expected gas mileage.

After doing some reading, I was thinking maybe my O2 sensors could be the cause. I have NO CEL lights but the car has 225K miles, and I don't think they have ever been replaced..

Any opinions...or would I just be wasting my money?

new_climber

Nobody?? Surely someone has an opinion about this question?

joey1320

Oxygen sensors could/should help but it may not be your issue.
Do a compression test, a leakdown test and a fuel pressure test - report your results.

delsolpetty

Does it go past 2500?

NotARaCist

iTrader: (1)

Since we're doing basic diagnostics at this point, skip the leakdown test. Compression test, fuel pressure, and if you don't have a voltmeter, get one. You'll want to test your O2 sensor, as well as your TPS.

delsolpetty

X2

new_climber

Thanks for the replys and suggestions...

I am going to the parts store to pick up some tools. I have already checked my TPS and it checks out fine. Also, I suspect that it is OK being if I am in a different gear, where my RPMs is higher or lower, with the throttle at the same place, I don't have this issue...

I am due for a timing belt so if in deed it is my head gasket, I guess I will just do both. I will report back with what I find.

tony_2018

When you seafoamed, did you replace any parts afterwards?

new_climber

After the seafoam, I did the plugs, wires, and cap/rotator. I also replaced the idle air control valve but this was not needed, as I found out later my throttle cable was not allowing my throttle to close all the way, causing a very high idle.

The only parts that I replaced that would be affected by the seafoam was the plugs themselves.

Hondarider995

If you figure out what's making it do that, please share. I've done wires, cap and roter to mine as well and still does it. I'm gonna put a new fuel filter on it, but I'm pretty sure that's not gonna do much.

5EDAN

I got samw problem with my b16 did all the above except seafoam , if any finds out let me know its driving me nuts..

new_climber

I have done my fuel filter also....and you are right, it didn't fix it.

new_climber

I picked up a commpression tester today at Oreily's.

I just want to make sure I do this test correctly:

My plan:

Pull the ECU fuse
Pull the fuel pump fuse
Install commpression tester in cylinder
Complete the remaining 3 cyclinders
Compare between each cyclinder, shoudl be within 10% of each other.

Big question,
Do I need to remove all the spark plugs??
Is removing the ECU fuse and Fuel pump fuse enough? Or do I need to disconnect the coil and wires to the Dizzy?

Thx again for the help..

5EDAN

After inetalling new spark plugs, wires, oil change, new ecu and adjusting the dizzy it helped a little, Its just spitting at approx 2500 and vtecs is not crossing over to its full ability..

I am going to try cleaning map sensor, tb and vtec screen while I install my brand new tps sensor today hopefully this fixes it for my b16.. if not I move onto brand new dizzy o2 sensor injectors and possibly fuel pump, cant think of anything else that could be giving this problem other then maybe vac lines. Any info please

tony_2018

Your o2 sensor must be white as hell.

new_climber

I didn't think about the O2 sensors being affected by the seaform...are you suggesting they might need to be replaced after the seaform??

tony_2018

I always suggest inspecting before replacing.

TomCat39

I didn't see anyone address this.

You just replaced your spark plugs (torqued to 13 ft-lbs I hope) so don't necessarily need to crack them when cold, antisieze them and retorque to 13 ft-lbs. If it's been awhile I do this before I warm the engine.

Warm the engine completely to operating temperature. Turn off and let sit for 35 minutes to an hour (depending on outside temperature). Basically if it's winter 15-20 minutes can be more than enough depending.

Pull all 4 plugs out.

Now for me, I don't know what fuses to pull so I pull both Distributor plugs and I unclip and unplug all 4 injectors.

I then take my reading of each cylinder until the needle doesn't go up anymore and stop cranking (usually about 4-6 cranks typically).

If you see the needle dropping on any cylinder after you stop cranking, you will want to do a leak down test. If it holds pressure in all four, you can skip the leak down.

Hope this info helps.

new_climber

OK thx...I am hoping to get to the compression check this weekend....

I did notice the other day, my problem seems to be only happening after I am up to operating temperature. When she is cold, idling a little higher, I don't get this hesitation at all.

This is leading me back to my O2 sensors. If I am understanding this correctly, before she is warmed up, the ECU is in open loop mode....basically ignoring some sensors like the O2 sensors. After she warms up, it starts getting feedback and adjusting the fuel as needed....but bad readings from the O2 sensors, could cause my problem in closed loop mode.

I will start with the compression test though.

Former User

Did you adjust the ignition timing?

new_climber

Meaning...

I used a timing light and adjusted the dizzy. Then I took it to a shop and had them check it again, they said I adjusted it off, and put it back to the orginal makes. To be honest, I never saw a difference either way, in performance or my problem.

I still need to check the commpression, if that is OK, I picked up an upstream O2 sensor today. Denso for $45....I am hoping to get the commpression tested and this install this weekend (if the compression tests OK)..

One things I have not done is ensure my valves are adjusted correctly...my valve lash I think it is called?

Former User

Describe how you or the mechanic adjusted the ignition timing.

92ehatch

a leakdown test is a better option than a compression test in my opinion. i had an engine with a stalling and low rpm hesitation that tested perfectly with a compression test but leakdown showed the problem. i had slightly bent valves in the head, which would seal during a compression test but would not during the leakdown test, i had 90% leakdown in cylinder 1 40% in 2 and 3 and 60% in 4. i just rebuilt a head on my z6 that had only 150k miles on it and the valve seats were so pitted they didnt seal well, with 200+ miles on your engine it could be that the engine is in need of some TLC

new_climber

When I did it, I put a jumper in the service engine connector on the passenger side floor board. Connected my timing light on cylinder #1, loosened the 3 screws holding down the dizzy and adjusted it as the timing light was lined up with TDC on the crank case.

The mechanic didn't use the jumper, said it was not needed...but like I said, either way didn't help. He said I had move it forward about 6deg...he was able to tell this being he had a more advanced timing light?

Was this done correctly??

new_climber

I will look into doing the leak down. Need to read the How to being I have never done this before. I am going to start today with the compression test though.