Lockjaw

My EX 5 speed has a low speed driveability issue. It seems to surge under 2500 rpms. It doesn't happen all the time, but tends to be worse when the air temp is hot and I have the AC on. Sometimes it bucks pretty good.

This is the main driving range I am in, so it gets old in a hurry.

No CEL's or anything like that.

Car is stock except for a light flywheel. It has E3 plugs.

Any idea's? I checked with a mechanic buddy and he checked with his local contact at a Honda dealership and both are stumped.

ezone

SWAG:

Got EGR valve?

Disconnect the wires from the valve and drive it a few days. See what happens.

Lockjaw

That is the round deal on the passenger end of the head right? Looks sort of like a blow off valve.

I'll give it a shot and see. I'd hate to replace that, I think its a pita to get the bolts loose.

ezone

Don't worry about replacing it yet, I just wondered if unplugging it makes the symptom any better.

Lockjaw

OK well, I think the issue is centered around the AC compressor cycling on and off. If I am going down the road and its jerking and bucking, and turn off the AC it stops.

ezone

Most people can feel the load of the AC compressor pull on the engine when it cycles on and off, that's normal especially with a small 4 cylinder engine. It takes something like 5 horsepower to run the compressor so you can really feel it on a small engine.

The light flywheel might just make it even more noticeable.

kinakoes2

THIS. On an EX, turning on the compressor basically splits the middle (121-122 bhp) between the EX output (127 bhp) and the DX/LX output (115 bhp). Even more so when your engine has over ten years/hundred grand in service... hell, I'm wondering if my 150K EX has even the LX output now...

I don't feel the drop in output as much, when things are healthy on my EX manual, though. Plugs, air filter, oil/filter, good coolant, non-flaky electrical components like sensors, timing belt healthy and not on its last legs, properly-filled tires, good alignment, etc. are essential for good get-up-&-go.

Removing my intake snorkel (on a stock resonator setup), also made the car a little less prone to feeling absolutely sitting-duck in traffic too, without ruining its resonating, torque-preserving qualities.

Lockjaw

It has a low mileage motor in it. I had a blown head gasket a couple years ago, and swapped the motor out at a friends shop. Never noticed an issue until this spring when it started getting hot.

If its power, any idea on how to boost the low rpm power a little?

ezone

Does the AC work well?
Not overcharged? (high side pressure too high)

Ain't gonna happen.

Or maybe.... J swap.

Lockjaw

The ac works well when you are going down the road. However, in town, when its hot (alabama) it takes a while to cool the car down. The main cooling fan wasn't working, so I replaced that a couple months ago.

One of the other things I suspect is that the air temp sensor is pulling the timing way back when its hot. In the summer, the car is very doggy down low if you run 87 octane. 89 is ok, super is better. In the winter, 87 runs fine.

To me, leaving for work in the AM, the car is much more responsive than in the afternoon when temps are up.

Car basically has e3 plugs (which I am about to swap and see if that helps), a K&N panel filter, and royal purple oil in trans and motor.

And the issue is primarily at light throttle. Do these things have a TPS?

ezone

Sounds like that could be normal.

My '12 is the same way...In the summer late afternoon heat I can drive all the way home before it starts getting comfortable inside.



It can take a long damn time to cool down the interior from 190+ degrees. Yes a dark interior can get that hot.


AC system pressure gauge set could help tell if something is outta line.
Yes

Lockjaw

Could the TPS be the issue?

I just don't think its an issue with the HVAC system cycling on and off. It is a low speed low throttle input issue.

ezone

Possible, because the computer watches throttle position and shuts off the AC compressor at somewhere around (SWAG) 70% and higher. I could envision a flaky TPS doing this.

Got any way to watch the input data while driving?

Lockjaw

Yes I have a scan tool, it shows real time data.

I'd have to know what specifically to be watching.

One of the things I am curious about is why it pulls timing out when you give it gas? My old V8 days are showing, we always wanted advance to stay high so you had good throttle response.

I think the tool will show me map pressure, timing, coolant, air intake temp, calculated load timing. The coolant runs between 190 and 200 on a hot day.

Also one of the things I am curious about is what if I have a slow o2 sensor? I have seen how those work with one of those air flow meters, and they adjust the mixture very rapidly, but if one was slow, then I could see it pulling the motor lean and making it buck like it does.

And since its an ULEV, I wonder if that would make it more pronounced.

All I know is the car runs nice in the morning, and when its cool, when it gets hot, its a slug.

ezone

You were wondering if the TPS could be at fault causing the AC to kick in and out, IIRC?

Timing could be retarded (lack of advance) under acceleration in most carb/dist versions, depending on what the manufacturer wanted and which vacuum source the vac advance used. (A smart hot rodder could make timing do just about whatever he wanted it to do with mix-n-match and creative plumbing....and a distributor machine.
That's so 70s.... Computers have made it so much easier but so far out of reach for the average tinkerer.)

Same is still true today, it all depends on what the manufacturer wanted (PCM programming) and the conditions you are operating in.

Speaking of carbs, if you cranked enough timing into some engines, you could almost completely cover up a bad accelerator pump.


IF your scantool update rate were fast enough you might see it, but I seriously doubt your scanner is that fast. A labscope would be good for watching response time, but then there are also other ways of figuring out some problems.

Does the O2 sensor show lean when it drives like a slug?

Lockjaw

I don't know what it shows. The scan tool does real time monitoring, so you can see the timing move as soon as you touch the gas.

I do not think it shows anything about the 02 except it does tell me if i am in closed or open loop.

I have been looking on the internet, seems the 02 sensor, tps or map could all be culprits. I really think its an electronic issue since it doesn't happen all the time. If it was fuel related, I think I would see it all over the place, not just in an RPM range under a light load.

I may have to drop it off at the dealer and let them sit on it and see. I hate to do that though.

Lockjaw

The scanner I have is an Actron CP9575 if that helps. It is supposed to monitor 02 based upon their website, it think.

ezone

Does it buck (or whatever your complaint is) when the AC is off?

It takes experience to interpret the computer data.
O2 sensor readings should be present in the data list. Fuel starvation issues should show as a lean reading (voltage) on the front sensor.

ezone

This post has pics of some actron scanner https://www.civicforums.com/forums/p...498-post1.html

Lockjaw

No I can't duplicate the issue with the AC compressor off. Only when on. I can be driving down the road and if it acts up turn off the AC and it stops. Either the actual AC button or the fan speed.

I have been watching the 02 sensor voltage moving around, but haven't been able to see it do it when the car starts hesitating.

It seems as though as soon as I disconnect the Actron unit, it starts acting crazy. Leave it plugged in, and not so much. Go figure.

ezone

Ummmmmm..........
SWAG: Losing a ground circuit to the computer and a bunch of sensors and other stuff.

Go fix the dirty/loose/corroded ground connections on the upper hose neck.

Lockjaw

I will try that and see what happens. I did manage to get it to misbehave yesterday with the Actron connected, and the 02 voltage didn't seem to change or so anything it doesn't normally do.



I also pulled the E3 plugs out and put in a set of Bosch plat's, same issue. It is cooler today so it has run fairly normally.

Lockjaw

And what does SWAG mean?

thetut

Scientific Wild-*** Guess

kinakoes2

Just be grateful the ground ezone mentioned, is one of the most accessible in the whole car. Same one on my Escort would've been buried underneath the intake manifold or some other inaccessible location for a home wrench.

If you can't do this ground cleaning in five minutes with normal hand tools and some fine sandpaper... I'll be shocked. Super-breezy-easy. Make sure to treat the contact surfaces with dielectric grease before reinstall -- preferably a hi-temp one, but any one will do.

ezone

Throw them all away and install the correct DENSO (or the correct NGK) plugs.

Lockjaw

I haven't had a chance to clean the ground yet, wifey bailed on me and the boys, and I am kinda swamped during the week.

However, it was much cooler this am, and I had no issues what so ever. So, while I am not ruling out the ground wire problem, I really have to wonder if this isn't an electrical component issue.

What I need is a nice accord ex with a V6 and an automatic. This car is about to wear me down. Of course with my luck, I'd buy one and the timing belt would let go, and lunch the motor.

Lockjaw

OK checked and cleaned the ground, no real improvement.

kinakoes2

Next step is to shirtcan those Bosch plats. They've worked in every other engine of mine but two IME: the Vortec 5.3L in a Chevy Silverado... and the D17.

Denso: PKJ20CRM11. Amazon has them pretty cheap.

Lockjaw

OK I will try the denso's.

I've never had a prob with Bosch plugs. I ran the +4's in my tundra for a long time, now it has iridium plugs though.

I still think its an electronic issue. Some sensor is going bad someplace, and it isn't bad enough to throw a code.