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97 Accord LX F22B2 - Missing when Cold


Prothec

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I apologize in advance for the exhaustive post. I'm just running out of ideas.

 

Vehicle:

I have an Accord LX / F22B2 engine.

278,000 miles

No Check Engine lights - The last code was eliminated by cleaning the EGR ports.

 

Problem:

When starting and accelerating while the engine is cold (ie. Start, let engine run about 60 seconds or so), approaching around 2500/3000 rpm the engine feels like it is missing and will not accelerate.

 

If I let the engine warm up until the RPM starts to drop to the ~700 idle, it often starts to stumble and adjust back up a few times before it can finally settle into normal idle. This can take around 5 minutes. At that point, acceleration is normal.

 

What I know is wrong:

- There is an exhaust leak after the catalytic converter

 

- Checked timing - shows 19-20 degrees BTDC instead of the 15 +/- 2 in the manual

> I checked this with and without the service connector jumped with the car fully warmed up

> I tried to move the distributor and the timing doesn't change (service connector jumped)

- Ignition coil resistance check (digital voltmeter) shows 1 ohm A-B instead of the .6 - .8 in the manual - secondary winding @ 20k ohm

 

What I have done:

- Pulled the cover and replaced the seals under the lifter assembly to (finally!) eliminate oil leaking into the plug tubes

- Replaced Autolite spark plugs with stock NGKs

- Replaced the plug wires

- Replaced the EGR valve

- Removed and thoroughly cleaned the completely plugged EGR ports

- Checked the injector screens - were completely clean

- Replaced the fuel filter (not too hard with the right tools!)

- Removed distributor cap and took fine sandpaper to the rotor to eliminate minor rough surface

- Removed and cleaned the IACV (Idle Air Control Valve) and FITV (Fast Idle Thermo Valve) - neither looked too bad, but I removed and cleaned them thoroughly anyway

- Removed and thoroughly cleaned the throttle body (and replaced throttle cable that had a cracked sheathing)

- Topped up coolant and bled the system

 

I don't think I missed anything I did in the list above. Google and searching this forum hasn't given me any new ideas.

 

Hopefully someone can help!

Edited by Prothec
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Well, as long as you bled the cooling system and reset the ECU, which wouldve been how you cleared the stored EGR code, and considering you cleaned the throttle body and associated throttle control devices, the only thing I can point out is that the Ignition Coil may be out of spec. You might need to retest with another meter given you stated finding 1 Ohm rather than 1.00 Ohms. Still, bad coils tend to miss when warm, but at least you'll have a strong spark when you find the problem so change it now.

 

Timing:

You have OBD-2 so rotating the distributor does nothing since the ECU times spark based on trip data collected on each computational cycle; I don't know how often Honda has the OBD-2 type ECUs collect poll data. The advance is actually a floating Target, you can see it change with a data logger connected.

 

Timing check: make sure your timing belt is not off a tooth. Sorry, this is the best I can come up with on timing.

 

Fuel Pressure: make sure fuel pressure is on spec though I don't suspect it being the cause.

 

Make sure the Water Temp sensor, Throttle Position sensor, Heated Oxygen sensor and Intake Air Temp sensor are all giving good data. I've read these can play havoc with an ECU.

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Thanks for the reply.

 

I have since replaced the coil with one testing within spec and the car is still exhibiting the same symptoms. I was reading 1.00 ohms on the old coil. With the replacement coil, the primary winding was 0.6 ohms and about 18k ohms (iirc) on the secondary.

 

I plan to check the timing belt today. I just know it's a real pain to remove/reinstall the lower timing cover so I have been holding off to check other things first.

I'll check out the manual and see how to test the sensors as well.

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It's not as bad as it seems at first once you've changed the timing belt a few times.

 

And double check the functionality of your IACV and FITV even though you cleaned them: I mean take off the Intake Air Tube and plug the holes on the throttle body to see if they're sucking in air when they should.

 

The sensor inspections are all gonna be like "such and such resistance under x condition" a meter and a thermometer pretty much makes it a quick check.

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I verified timing TDC for cam and balancer. I went ahead and pulled the timing cover anyway and aligned the front balance shaft with its mark and adjusted the tension. It was definitely easier than the first time I did it. It took about 3 hours, which is a far cry from a full day just to reassemble (originally had the wrong cover :mad: ).

 

I'll start going through the sensors this week.

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All I have gotten around to so far is checking the coolant temp sensor, which appears to be working appropriately per the manual. I don't know if that sensor only goes to the gauge anyway.

 

If I start cold and hold the throttle at 3000 rpm, as it warms up, suddenly the RPMs drop and it starts struggling. From looking in the manual I'm leaning toward the FITV not opening/closing appropriately. I'll check it out this weekend and make a trip to the junk yard as necessary, thanks for the help.

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Here's what I did this morning:

 

The warm up idle speed is right around 1500-1600 RPM, so that is good.

 

1. Removed the FITV and completely disassembled it and cleaned it per the following link:

When I reassembled, I tightened the plastic donut all the way, then backed it out just until I could blow some air through it.

 

Before the idle got to the point of acting up, I checked that covering the hole in the TB with my finger caused a drop in RPM.

 

While letting the car warm up it exhibited the same symptoms - after about 90 seconds, the idle started dropping and jumping back up. Giving it any throttle makes the problem worse. As soon as I verified the problem still existed, I partially covered the FITV port again with my finger and it was still affecting the RPM while it was acting up.

 

With the car fully warm, there is still suction at the FITV port, however covering it does not affect idle speed. I assume this is right because the manual only addresses whether it affects idle once warm?

 

2. Tested the IACV per the manual

With the car fully warm, I disconnected the 2P connector on the IACV and the RPMs dropped immediately. The manual says this is how it should work and suggests intermittent failure.

 

For the heck of it, once the car cools down completely, I could take some video of the actual symptom.

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The more I read about the FITV, the more I think I could just block off the hole in the TB when it's cold and try a cold start again to see if it exhibits the same symptom part way through warm up. This could help me eliminate the FITV as the cause.

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