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All I had was some super small gauge wire so I made due. Though, when I did this the temps normalized.

The intake temp was 62* before the engine warmed up, around 70* when driving with the engine warm, and 90* after sitting at idle for a little while.

The ECT climbed to a normal range as well, I think it was like 160-170.

After I removed the ground, nothing changed though. Everything continued to be normal. So, I wonder maybe if it just needed to be messed with?!? I wiggled all of the wires and tried to see if it made the reading vary, but nothing happened.

Today whenever I hooked it up, with key on and not running, it read like 36% when to the floor. I knew that was wrong, so I manually opened the throttle and it then ready 89.3%. So I went back to the inside of the car and from then on it was 89.3% at WOT... not sure what happened there. Maybe it just needed more time to communicate it to Torque.

I've got nothing else.

No, but I guess that's unnecessary now.

The hesitation persisted even with the ground wire. I'm starting to believe that the hesitation is coming from worn ignition components. Like I said in my first post, the spark plugs are definitely due for a change. There are no receipts for a tune up in the three years that the previous owner has had the car. I checked the gap on the plugs and they are at .70-.75 for all of them. That seems pretty extreme, being that stock is like .44 from what I've seen.

What do you think? I'm by no means an expert...obviously.

 
Rep Power: 518

Sounding "much more gooder".

If you already took the bolt out and cleaned up the bolt and wire ring terminal, and ground off the aluminum behind it to fresh clean metal, then I'd say to just run a more permanent additional ground wire directly to it from a known good ground then (ground cable attachment point on engine or trans, or direct to the ground post clamp). Easier than taking apart all the aluminum parts and grinding oxidation off of everything.

Uh oh. Hard to say, but I'd still run a permanent additional ground wire to it.

Tough to prove that "messing with" had any true effect if it is not in a repeatable situation.

Not sure what to think about this.

Could be your tools, sure. I'd think the time lag/update rate should be consistent though.
I hate not being able to trust my tool. That can lead to all sorts of drama. (My brain just made that really dirty.)
Seriously, when we try to rely on info and data that can't be verified, that leads to trouble for all.
(Code reader gives completely wrong codes, it happens! Aftermarket scanner interprets data bits incorrectly, it happens! And factory tools are not 100% infallible either!)

Could be related to the grounds.
Could be related to flaky electronics too. They do some really weird things sometimes.


But you are the eyes and ears.
And I seem to have a huge reading comprehension problem sometimes.

The plugs are the type that were supposed to be replaced every 30,000 miles.
That's a lot of gap. Put in new plugs, by all means. Those are cheap.
Use proper NGK or DENSO though. (still cheap)
I'm showing NGK ZFR4F-11 or Denso KJ14CR-L11

How's the cap, rotor, and wires?

 
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Cap and rotor both have visible wear, but aren't terrible. The wires APPEAR to be in pretty good shape, but I don't really know what's going on under the insulation.

I guess I'll start with the plugs and see what happens, then move on from there. I was going to do that anyway, but I got caught up in testing everything and never did it. i have a pretty open schedule today, so I have some liberty to work on the car as needed.

I think I'm going to leave the additional ground wire off and just intermittently monitor everything. I'll be using torque for fuel mileage anyway, so that shouldn't be a problem (unless Torque IS the problem).

 
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Plugs are changed, but there wasn't a noticeable difference.

Well, I guess I shouldn't try to do any more work in the dark. The 3rd wire from the right is in pretty bad shape. It looks like a roasted marshmallow. The end of it is kind of crumbling.

Here are some pics for your viewing pleasure.

 
Rep Power: 518

Wire is probably ok, just dirty. Hard to evaluate any other aspect of it though from here.
Plugs look fairly normal ---- with an exception.


The one coated in black carbon was loose. #2?
The gasket was never flattened, it did not have a good seal against the combustion chamber.
Leakage comes up through the threads, leaving carbon deposits in the threads and on top of the plug and on the wire end, and in the sparkplug tube in the head.
A loose plug can overheat, and cause preignition ping/knock/detonation. A loose plug can't properly shed its heat through the threaded area into the surrounding head material.

I'd be surprised if the plug was not difficult to remove due to threads binding (known as "carbon lock").

Kinda looks like the others weren't fully tightened either, judging by the look of the gaskets.

Were they super easy to break loose? Little or no resistance? Felt like you didn't even need the ratchet for the initial pop?

No matter now.
Just make sure the new ones are properly tightened.

 
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You are right about the loosening. They didn't give much of a fight at all. Usually when I change plugs there is a creaking sound for about the first quarter turn, then the plug will break loose. That didn't happen this time.

What should the plan of action be from here? I'm thinking of ordering a tune-up kit, which I'm sure it is due for. I'd like to fix the hesitation before anything, but I'm just not sure if the tune-up kit will have any effect.

 
Rep Power: 518

Is your hesitation a misfire-- random misfire or single cylinder misfire, or is it fuel control related?

See, I can't answer that and I can't feel what your car is acting like.

 
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It may be a single cylinder misfire. It feels rhythmic in nature and is pretty consistent. I guess it could be a dirty injector or something of that nature too.

I hate these kinds of problems. I guess I'm learning something new though.

 
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Alright it has been over a week and I just wanted to give some updates and a short synopsis of the journey since this is getting pretty lengthy.

The problem: car has hesitation (surge) in the lower RPM range and seems to be mainly under light load and can sometimes be felt at idle. It is erratic and doesn't follow an observable rhythm (contrary to what I previously thought) but generally appears under the same conditions. EDIT (8 Nov): It is dependent on engine temperature. It is worse when the engine is hot.

Diagnostics:
(Test was after driving for about 5-10 minutes)
Ambient Air Temp: 60*
65mph 2500 rpm
Timing: 12* (varies from around 10.5-13*)
Engine load: 60ish%
Coolant temp: 140*
STFT -3.9%
LTFT -3.1%
F/T 1x1: -0.8% (was at 0.0% but jumps around a bit)
F/T 1x2: -0.8%
O2 1x1: 0.5V
O2 1x2: .08V
Mpg 31 (Estimated by Torque)

Troubleshooting:
Checked TPS & MAP sensors: good
Unplugged O2: after running several test it was inconclusive. Seemed to be about the same
Unplugged EGR: no change
ECT sensor: good
Changed spark plugs: no change
Changed thermostat (4 Nov): engine now reaches normal operating temp, but hesitation still present
Cleaned EGR passages (8 Nov): may be a slight improvement, but not fixed
Added redundant ground from t-stat housing to negative battery terminal ground wire (Nov 9): no change

Today I cleaned the IACV, as it was looking pretty dirty (pic below). My car idles a little lower now, but it didn't have any effect on the sumbling/hesitation problem. I also sprayed the MAP with cleaner just in case, but it didn't change anything either. I took a peak into the intake manifold from the throttle body and it was coated in an oily residue, but it wasn't like caked up super thick or anything.

I'm not sure if you see something in this info that might stick out to you, but I just thought I would give an update. Thanks for all of your help thus far.

Oh and just an FYI for anyone who is viewing this, here is a good little article about fuel trims http://www.aa1car.com/library/fuel_trim_wellsmfg.pdf

 
Rep Power: 518

This one still stands out: Not hot enough.

I'd like to think that 10 minutes driving in 60* ambient temp at highway speed 2500RPM is sufficient to get that engine up to 180*F when all is well.

How hot DOES that reading get:
While driving?
When stopped long enough to let the radiator fan run?


Either the reading is wrong, somebody is lying, or the engine really is that cold. You said you have an infrared temp gun? Check it.

 
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140-150* It seems like it will slowly approach 150* if I am not driving at highway speed. It takes a while for it to get there.

As soon as I stop it starts to go up. The fan is spot on with what the ECM is reading, kicking on at 200*

 
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So....seems like the accuracy is there now, at least those 2 sensors are agreeing.

Operating temp is WAY too low.
I'd say to get a factory thermostat.

 
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Thermostat changed with a Honda OEM that I had sitting around. Temperature now floats around 176* when driving.

Unfortunately my car is still having issues. It's been going nuts over the past couple of days. When I hold the throttle steady at any speed if feels like I'm pumping the gas and letting off repeatedly. The tempo is like someone is hitting the front hydros on their low rider, bouncing the front end off the ground (weird description I know).

No check engine lights or anything. One thing I did notice, not sure if this is normal, but when driving tonight I noticed that my timing advance was 12* at idle, but while driving at a constant speed it is in the 20-25* range. Everything otherwise seems normal.

 
Rep Power: 518

Much mo' gooder. LOL
I've never really looked or cared ever since cars went away from mechanical/centrifugal/vacuum advances. If the initial setting is right, the computer is supposed to take care of the rest.
But it sounds ok.


Would that be like one-second intervals?
IDK.....
Are you still ignoring the grounds on the thermostat housing?
IDK.


Too bad your app is so slow on its update rates. It would be good to view data in real time as the surges are happening, see if you can pinpoint anything going wild.

This would give nearly instant live data: Can you backprobe a voltmeter into the ECM wiring connectors? Long and drawn out though, probe something and drive it until it acts up.....
TPS?

 
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Yes, about one second.

I guess you could say that. I got sidetracked and forgot about it. I need to run a more substantial ground than the one that I was running, it was pretty pathetic.

I'm on an Air Force base and we have an "Auto Hobby" shop--the mechanics that work there are pretty good. It's free to get stuff diagnosed, so I'm thinking of dumping it off there and letting them have their way with it. Life has been increasingly busy lately. I have several types of training happening in tandem, along with being in charge of my section, managing millions of dollars worth of projects and learning an entirely new job. I'm also in college and have a 4 year old and am in the process of moving...so yeah.

 
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You don't need an battery or welding cable size wire there, look at the size of the wires that are already there.
I'd think a 14-16 ga ground wire would be plenty.
I still have no idea what to think with the surges....I'd want to see live engine data first (preferably on my own equipment that I'm familiar with), see if I can discern anything unusual. Maybe do some snapshots of the data.

Damn, man! You a busy ****. Best of luck!

 
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Well, there is a link between this and the new thermostat; the problem is worse at normal operating temps.

I remember reading about the EGR causing issues, especially when the car is hot. I figured the system has probably never been cleaned, so I gave it a shot. The passages into the intake runners were completely blocked and the cover that has the grooves in it was dirty but not blocked. I had high hopes, but when I went for a test drive I didn't notice any considerable difference. I unplugged the EGR and drove around, but it didn't seem to hurt or help.

I didn't take it to the shop yet. I feel like I'm on the brink of solving this thing, lol. I've still not done the ground, but I will.

 
Rep Power: 518

That's why earlier I was telling you to disconnect the EGR valve, to eliminate it from the picture as a possible cause.

 
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I cleaned the EGR because I was pretty sure that it needed it anyway--and it did. I did disconnect the EGR before, I was just documenting it after cleaning the EGR.

So, today I re-ran the redundant ground wire from the t-stat housing to the negative battery ground wire. There wasn't any improvement though.

 
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Alright, so it's been a while. I'm out of training and had a little time to post, so I'll give an update.

-The redundant ground is still in place, with no positive results.
-I inspected the fuel filter, because it looked pretty old. I replaced it with OEM because the old was fulll of nasty slime. No positive results (Really?!).
-Tested the spark plug wires. They seemed to be in spec, ranging from 7,000-11,000 Ohms depending on length. At least from what I've been told, that is in spec.
-Tested vacuum from brake booster line with cheesy looking AutoZone gauge. It was 17 Hg at idle. This seems a little low, but not sure how low is acceptable.
-Tested the ignition coil (not sure I did this totally correct), but it registered 1.7 when on 200 Ohm scale. I read that spec is 0.6-0.8, but it wasn't for an HX. I'm not sure if that matters or not.

My brother came and visited over Christmas and he had Dash Command on his phone. He had it hooked up while driving and when holding steady at 60 mph on flat road I was getting around 28 mpg. At 40 mph I can manage 35-36 mpg if holding the accelerator steady. It looks like it never enters lean burn at highway speed.

Anyway, hope Christmas/New Years was good for you (and everyone else reading). Hopefully this info will shed some light on the situation.

 
Rep Power: 518

Wow, I about forgot all about what's been in this thread.

A rule of thumb I learned long ago was approx. 10k ohms per foot max.
If it isn't misfiring, they probably aren't an issue.
Ignition coil is either good or bad. If it makes spark of sufficient length, it's good. If it was bad, it would either run horribly or not at all.
See a spark air gap to kV chart to evaluate spark length.

If you backprobe the MAP sensor with the engine fully warmed up, in neutral, no electric loads, it should be around (ideally) 0.80-0.90v.

Have you done a valve adjustment?

Is the STFT still hanging in the double digit negative numbers?
Do the temperature sensors (ECT and IAT) reflect actual temps?


I think it has to see a very low load situation to enter that mode. Aerodynamics and rolling resistance come into play for that.

Do you have good quality tires on it? Low rolling resistance? Aired up?
(My fat tires killed all sorts of gas mileage on my car, seems like close to 20%. It does not roll easily, and it was very apparent the day I installed them.)

=-=-=-=

Hey, a new person in the shop just got a 99 HX and is currently fighting a surge and low gas mileage too. Over 200k miles on it.
It had a cat code, he bought a header and an under car cat from a completely different car, modded the O2 wiring to install them.

I'm watching to see if he comes up with any answers on his.

 
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Yeah, I tested the MAP a while back and everything checked out. I don't remember the reading, but it was within the acceptable range.

Nope. I've never done a valve adjustment on any car, haha.

It never really was. I did see is spike once or twice, but it was only when coming off of heavy acceleration or something like that. Under normal driving conditions it never exceeds +/- 3% or 4%

Temperatures read correctly.

Yes it does. That is when I am getting 28 mpg; at 60 mph under very light load on flat pavement.

My tires are terrible, but they are low rolling resistance (according to deceleration tests). They are 185/65/14 compared to the stock 185/60s, so theoretically at 60 mph I should get a little better mpg from being at a lower RPM. Oh, and I keep them inflated to 38 psi. Not that I would expect to see higher mpgs from these things, but I wouldn't expect a decrease either.

Hmm. I'm interested to see what happens here. I was thinking the other day that maybe my cheap 5 wire O2 might be responsible for the low mpg; like maybe it's not a wide-band or maybe it's just crappy. I need to pull it out and get a part number off of it.

 
Rep Power: 518

Might be a good idea. Tight valves cause manifold vacuum to drop, and make the system go rich with additional fuel through the MAP sensor input. Plus, tight valves burn.


Problem: Your RPM does not change for any given indicated speedometer reading.

Your real speed did change though. You now go about 62 MPH when your speedo says 60.

That's a little under 4% change, and you should expect a calculated gas mileage difference of roughly the same.

I bet this could be part of your additional load on the engine (it IS, but I don't know how much effect this has on it).

This does not explain the surging in your complaint (in my mind).

Your CALCULATED gas mileage will be lower, simply due to the taller tire.
Mechanical disadvantage.

Conversely, if you switched to a shorter than stock tire, your calculated gas mileage should be higher.
Mechanical advantage.

The speedometer and odometer operate off of differential/axle/tire revolutions, not actual distance traveled. You changing the tire diameter throws that off by a percentage of a little under 4%.
If you could consistently calculate distance by GPS or something (real miles traveled), the gas mileage calculations might be more accurate.



"But it's less than 4%."
Yeah, but it still matters.....Let's take that to extremes:
------

Hot rodders used to swap tire sizes, it's like a super cheap set of differential gears. Short tires are like artificially changing the gear ratio, therefore quicker acceleration. But top speed will be lower. Speedo is off because it input comes from driveshaft revolutions.

Other extreme, big tall off road tires. Acceleration is slower, gas mileage goes to hell. Mechanical disadvantage. Speedo is off because it input comes from driveshaft revolutions.
If you have enough power to overcome the inefficiencies and drag, your top speed is faster.
To restore somewhat normal operation with the big tires, you would have to re-gear the differentials with a "taller" ratio ring and pinion set.
Brake efficiency goes to hell no matter what, because of the big diameter tires. Time to go to bigger brakes.

------

I had a customer with a '93 ish twin-turbo RX-7 complain that his car was slow. Checked it out, drove it, took readings, everything checks out fine but it FEELS SLOW. It wasn't until I stood back about 30 feet away and stared at the car that I realized the rear tires were bigger than the fronts. He had scored a pair of tires off of a Corvette, and they were a couple inches taller than the stock tires. Swapped them to the front and had the owner drive it, now it accelerated like it should.


Damn, this was unnecessarily long.

 
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Hmmm. yeah that doesn't sound like a bad idea.

As far as the tires, I understand how mechanical advantage works, but I'm not relying on the car's measurements for my calculation. I guess I am assuming that Torque and Dash Command are calculating off of actual distance traveled through GPS while calculating fuel consumption at the injector. I'm not really sure how it does it.

Even if the mechanical disadvantage were 10%, it doesn't account for my car's loss in fuel economy. I'm losing roughly 37% on the highway. I'm kind of a hyper-miler so I would expect to be getting even better than the EPA rating. I've always done far better than EPA ratings in my cars due to my driving habits.

Hopefully we can figure this out soon. It's pretty annoying, lol.

 
Rep Power: 518

Oooh, you should check that out more and find out for sure.
I had no idea they could do that (I've never used either).
Post a link? I'd like to read a little more about it.



Are you calculating your gas mileage only from the Torque + Dash Command, or are you calculating mileage by hand at each gas tank fill up (gallons/miles)?

 
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I saw somewhere, on their wiki I believe, that explained how it does it. I know that the program measures fuel flow and also that it uses GPS to measure distance traveled. I just can't find where it says that it puts the two together to calculate mpg.

I do both. Torque Pro does average mpg, trip mpg, and instant mpg. Although, I've never used Torque for the duration of an entire tank of fuel. Manual calculations, at the pump, show like 31-32 mpg for mixed driving. **UPDATE: Today at fill-up I averaged 26.7 mpg. Not sure if things are getting worse, or if I just wasn't as conservative this go around. I never rev over 2500 RPM and always coast to stop lights and whatnot though.

 
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Alright, so I got some interesting news tonight. I got an O2 socket and took the sensor out and it is actually an OEM NTK LZA09-E1 factory Honda part. How the shop was able to only charge $70 for it is beyond me, but it's cool with me.

 
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That's too cheap?
Must be aftermarket sourced. No way anyone can get them from a dealer for that price.

Did you cross reference your sensor numbers on the NGK (NTK) website to see if they match Hondas part numbers?




98 HX
2 door
5 speed
US market
D16Y5

Front AFR sensor 36531-P2M-A01, MSRP USD 550.07
Rear O2 sensor 36532-P2E-A01, MSRP USD 282.65

Front (upper) sensor has 7 wires, right?

Both sensors show different part numbers depending on CVT or MT.



EDIT: NTK and DENSO are both (OEM) suppliers for Honda.
I have no way of telling you which one would have supplied the original sensors on that car without ordering new from Honda.

 
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This is the cross reference that I was using http://www.oxygensensor.net/widebandsensors.php

It's a 5 wire.

 
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Nope, not unless your dealer likes to keep $500 sensors on hand for a pretty dang rare version of a 15+ year old car.


The dealer parts catalog does not tell who the manufacturer is.