afnan

F18 did not came with knock sensor. Not sure about b2 version.

I had same problem and yesterday resolved it. Basically had two problems on my car.

1. Heads and Shoulders in O2 Graph making it look lazy. It was problem of Fuel Pulsation Damper gone bad and hammering effect was causing it.

2. Random bucking, sputtering was resolved when i was looking at MAP values on idle and noticed that MAP is jumpy. Twisted the MAP Wire at some random agnles at one angle it worked out. Was smooth.

by the way All the best with your Swap.......

origamy

origamy

Well, new long block actually solved pretty much nothing. Now compression is 220PSI across the board, and this one consumes much less oil. And that's that. But idle is still rough as it was before. Car jerks/bucks very harsh on acceleration when engine is cold. After a mile when engine gets warmer, jerking/bucking on acceleration becomes less noticeable, buts it's there all the time. When in neutral, idle gets low, almost stalls, then slowly returns up to spec. After few more miles idle becomes normal, doesn't get low and is just rough. Tried a few more things - known good ECT sensor, IACV and PCM/ECM. To no improvement at all. There is no air in coolant, and no CEL. Maybe somebody has any ideas on what to check next?

skhell

I suppose that picture is from your car, right? If so, it's running on LPG, am I correct?
That's funny, because mine is also running on LPG

If your car is really running on LPG, is there any difference while running on petrol or LPG.

I would try the following:

- Switch the car to run on petrol
- Reset the ECU(remove the backup/clock fuse for a few minutes, or leave the battery unplugged during the night)
- Start the engine and let it run at 3000rpm,o until the radiator fan comes on/off twice.
- After that, drive the car only on Petrol during a few days, never switching to LPG, and see how it goes.

If it drives normal, then your LPG system is not properly tuned and is messing up with the Petrol ECU, which in turns propagates to the LPG ECU, then back to the petrol ECU, and so on... getting worse by the time...

I already had a similar issue when my LPG ECU was no properly tuned. A few miles after the a ECU reset, the engine was very rough at idle, either running on petrol or LPG...

Give that a try and let us know.

BTW, which LPG kit do you have installed on your engine?

origamy

BRC sequent 24. Tried that, no luck at all. Runs the same on both fuels

skhell

The kit is the same as mine!

The new engine includes any of the ancillaries, such as sensors, distributor, manifolds, etc, ...?

Is the ignition timing correct?
I noticed that you replaced the timing belt. Are you sure that its properly installed? If it's off by a tooth, it could do that...

origamy

No, just plain long block. Distributor, manifolds, sensors (not all, but most) are from the old engine. Timing belt is properly installed, all marks line up. Timing is 12 degrees BTDC at idle, as it should be

afnan

Strange, All that pain and no result, it might be frustrating. well Have you tried different ECU? My car had same thing, tried changing distributor cap, rotor, ignition coil, wires what it turned out to be injectors. Previous owner had installed D15B injectors in it so that he can save fuel...........

1. What is the valve clearence settings?
2. What sensors or things were used from previous block?

holmesnmanny

Can you describe any and everthing from your old engine that was swapped over to the new one plz.

And I think it might be time for a new ecu. That might just be root cause. You can, at the very least, take it out, open it up, and see if there are any burnt spots in it.

origamy

Yeah, it's kinda frustrating and a liiitle bit expensive Another ECU was tried long before to no positive result. As well as another injector set. From the old block I used pretty much everything except the oil pressure sensor and TDC/CKP sensors. New engine came in just as plain long block without intake/exaust manifolds. So, i've tried to replace so far: MAP, IACV, H2OS (primary lambda sensor), CYP (cylinder position sensor, that is in distributor), TDC/CKP came "new" with "new" engine, ECT sensor. Plugs, wires, coil, cap, rotor are new and OEM. After engine replacement another problem is occuring, in addition to rough idle and bucking on acceleration. When cold engine is started, idle speed is normal, but after a few kilometers, when engine gets hotter, but not fully up to temp, when in neutral idle gets very low, engine almost stalls, and the comes back up to normal (750rpm). (And bucking on cold engine is much worse than at normal operating temp). After few more kilometers, when engine is up to operating temperature, idle speed becomes normal and does not drop when in neutral. Thouh still rough and bucking on acceleration is present on hot engine too. Idle is much more rough if AC is turned on. But when cruising at constant speed - there are no problems at all.

skhell

IIRC, your car is on LPG. I suspect that you have some problem in your LPG system. In order for the kit to be installed, they have to mess with the engine wiring, mess with the injector wires(among some others). If not done properly, there could be some weird problems... I would take the car to a very good reputable LPG shop, tell them what is happening with the car, and let them see what they have to say about that.

origamy

I know that, and I'm going to check wiring by myself. But car ran fine after LPG installation for about a month. And conversion was done at reputable shop, which, after problems started, checked everything and said that LPG kit has nothing to do with all this. I've even tried to fully disconnect LPG computer and put jumper wires into LPG computer's connector where gasoline injector signals are cut, and nothing got better.

origamy

Aside from jerking/bucking on acceleration and a bit rough idle, thing that annoys me most of all is, that when I start up completely cold engine after sitting over nigh, it fires up ok, idle is a bit higher as it shoud be, say 1500rpm, and after a hundred meters of driving, when I switch it to neutral, idle drops to 400rpm or lower, but never stalls. This happens until engine gets fully up to temp, for a few kilometers or so. Then idle gets normal and does not drop lower than 750rpm. There is no FITV, IACV only. IACV is clean, throttle body also. Another IACV was tried, to no improvement. I suppose there migh be some vacuum leak, that kinda seals with higher engine temperature? Or there are other posibilities? I guess all my problems are interconnected

origamy

Did emissions check, passed with no problems. CO = 0, CH = 140. (Two years ago, when bucking problem wasn't there, emissions were: CO = 0,1 CH = 160). Still no resolution to bucking on acceleration problem, still waiting for any suggestions on what to check..

Dennis Zarin

That yellow/blue reservoir near power steering,what do you put there?I have the exact same one and I have no idea what it is.Answer,please!

origamy

Valve saver fluid "JLM"

jollyhonda

Did you ever get your car running properly?

origamy

Nope, issue is still present, but I'm driving it on a daily basis still. If anyone has any ideas about the issue, let me know

user456101

I apologize if I am covering old ground but I just watched a Scotty Kilmer YouTube video "Replacing a bad O2 sensor on your car" and he said using non-OEM O2 sensor can cause lots of problems. Are you sure the O2 sensor is the same as the original manufacturer and part number? you may be able to get the part some place other than the dealer - just make sure it is the same as the original. The reason is, if the O2 sensor doesn't communicate to the computer in exactly the way that is expected, it will throw off the calculations driven by the algorithms, and then fuel trims will be wrong and.... Also, if it is helpful, Schrodingers Box on YouTube is a good place in my humble opinion to learn about diagnosis and analysis of engine problems, including O2 sensors and fuel trims. Scanner Danner is another one. Diagnostic equipment is much more expensive than a code reader, but it can be much less expensive than trying to solve problems without it.

origamy

Well, new pre-cat O2 sensor is NTK OEM, part number is the same, so no doubts here. Long time fan of Schrodingers Box youtube channel, it's sad that guy rarely posts anything now - has no time I guess. Scanner Danner is a really nice source of info too. Kilmer... well. "Is your car hesitating? Well maybe it's your TPS!!! Let's change it and see if it helps". Not my style of doing things I'm considering buying a scope, but still not sure if it's worth the effort and money, a decent one costs more that this car is worth now

kslavek

Origamy, I have exactly the same issue with my F20B6 (and one of my friends with F18B2 too) which is widely discussed on Polish Honda Accord Club forum and still no one has found any solution. You did a great work by describing what you have replaced and checked (very similar list to mine), especially about the engine, which I also suspected. Fortunately I can exclude it now.
It seems that there is some strange electrical or mechanical problem which is not connected directly to the engine.
This weekend I am going to check the whole electrical system, including relays, ground points, cables, connectors, ignition switch, alternator and every possible sensor for anomalies with oscilloscope and multimeter. If this also fails, I will check the "rear" engine mount and look at the transmission - differential mechanism (clutch is almost new) and right axle. If I dont find anything, I will consider... changing the car.
I have been struggling with this for about 20 000km. Got slightly worse recently.

holmesnmanny

OP, did you ever replace the crank sensor ?

origamy

"New" crank sensors (CKP and TDC) came with replacement engine. Resistance of old and "new" engine's sensors was within limits, stated in dealer's manual. You think they may be dirty?

holmesnmanny

obviously since it's doing the same thing with the new engine it's clear something not associated with the engine is bad, it really sucks it's not throwing a code, you need to start plugging off evap things by unplugging the sensors and seeing if it runs better after throwing a code, which turns off that system

holmesnmanny

did you ever get a hold of a $20 fuel pressure tester kit from Harbor Freight, hook it up, lay the hood on it with the gauge facing you in the driver seat at the windshield, drive around and see if the fuel pressure is steady ?