VTEC-E question, help!

[theholycow]

Clogged cat, in this case, would be intermittent with something loose that sometimes blocks it and sometimes doesn't (probably related to thermal expansion)...no idea how you'd diagnose it.

[pgfpro]

Originally Posted by benfrogg

Okay, so plot thickens.
On the drive tonight (40 miles each way) it was snowing heavily on the way there. It was also very windy (gusty, not one direction). The extra torque was there, no doubt. I used the block heater to bring the car up to operating temp beforehand. The traffic was heavy and traveling slowly then fast, etc. This trip was 63.3mpg.
On the way home, the car had to warm up on it's own. There was zero traffic. The speeds were about 5 mph faster overall. No snow coming down, the roads were clear as well. The new found torque, however, was absent until the last 3 miles of the drive. This pushed the FE down to 55mpg for the same trip in the opposite direction. No, there was no significant change in elevation from point at to point b.

So, I don't know what is different, but something sure is.
It's possible it has nothing to do with vtec but I really don't know. I have not yet looked in the valve cover and found two valves opening at idle. I've been checking consistently. I'll check it tomorrow at stone cold when oil pressures are likely highest.

What the heck else could cause this?
Maybe a cylinder not firing (or getting adequate fuel) during lean burn?
I'm totally out of ideas. Whatever it is, it is the cause of my less than stellar FE after all these mods and driving changes.
B

The only other thing I can think of is a bad CTS. It could be dropping down drastically from a warm up point to a cold point. You could monitor the 5 volt output back to the ECU to see if it drops a ton all at once.


The other thing it could be is a bad injector that is not flowing due to internal issues. This would make all the other three run extremely rich to make up for the bad injector because the O2 is reading all four as a whole and not each.

[benfrogg]

Forgive me, what does the acronym CTS stand for? I'd be happy to monitor it if I knew what it was!

The injector idea is certainly possible. I have now have 8 spare injectors. I'm going to clean them with a syringe and carb cleaner and see which ones flow best when done. I'll swap them in and verify there's no problems there.
It could still be the harness, I suppose, as well.

I've been reading around on the web and this issue appears common. Other people document the same symptoms; you can barely hold 55-60mph in lean burn and every once in a while on a long drive it all of a sudden is easy to. I'm going to recheck my EGR ports/valve tomorrow for grins.
I swapped a spare ECU (I now have two spares) and the same thing is happening.... interestingly, the idle is smoother with the new ECU. I don't know why that is.

I picked up a VX motor and tranny complete - the exhaust mani today. Best $100 I ever spent!

I am not ruling out clogged cat. I want to rule out all other possibilities first as that will be big money to replace.

I've got a host of testing I'm going to do tomorrow, I'll update.
Thanks!
Ben

[pgfpro]

Originally Posted by benfrogg

Forgive me, what does the acronym CTS stand for? I'd be happy to monitor it if I knew what it was!

The injector idea is certainly possible. I have now have 8 spare injectors. I'm going to clean them with a syringe and carb cleaner and see which ones flow best when done. I'll swap them in and verify there's no problems there.
It could still be the harness, I suppose, as well.

I've been reading around on the web and this issue appears common. Other people document the same symptoms; you can barely hold 55-60mph in lean burn and every once in a while on a long drive it all of a sudden is easy to. I'm going to recheck my EGR ports/valve tomorrow for grins.
I swapped a spare ECU (I now have two spares) and the same thing is happening.... interestingly, the idle is smoother with the new ECU. I don't know why that is.

I picked up a VX motor and tranny complete - the exhaust mani today. Best $100 I ever spent!

I am not ruling out clogged cat. I want to rule out all other possibilities first as that will be big money to replace.

I've got a host of testing I'm going to do tomorrow, I'll update.
Thanks!
Ben

(CTS) Coolant Temperature Sensor Also know as a ECT Engine Coolant Temperature sensor.
See in my Neptune pic how the correction table works?

[benfrogg]

Does the coolant temp sensor also feed the dash? Or is it a separate sensor like many cars have?
I'll run the tests on it tomorrow and verity it's operation. I may actually just swap it out with one of my spares.
Thanks
B

[benfrogg]

So, I did some things today to the car:
Pulled and cleaned all 4 injectors. Swapped in one different injector because one of the ones on the car wasn't flowing well. It was almost not noticeable, and may well be in my head, but I figured it couldn't hurt to swap it with a known good one.
Pulled, tested, and cleaned the EGR valve.
Cleaned EGR ports again. No noticeable clogging to begin with.
Tested TPS cold and warm. Right at spec.
Tested CTS. It was -2df when I started and my book only had readings for 50-70df. My ohms were very high, but that corresponds with what the book says is right. Higher the temp, lower the resistance. I tested it while warming it against my garage heater. It's resistance lowered. I swapped it with one from the new parts motor; they both had exactly the same readings.
Checked CKP, CYP, and the other sensor in the same harness. All were supposed to be between 350 and 700 ohms. Mine all tested at about 330-340. I ran the same test on both of my spare dizzy's. All had about the same results. I'm thinking it was due to the lower starting temperature. Should I be concerned about that?

I also finished my underbody paneling. Came out looking pretty good. I'll have to do some highway driving to see how effective it will be.

I drove about 20 miles around town/short highway doing some testing. Prior to that, I let the block heater run 2 hours. After the drive, the radiator hose feeding the thermostat was still very cold. It was obvious that the thermostat had not opened during the drive. I wonder if that is normal? Am I not making enough heat to keep the car at operating temp? My grill opening is only about 3"x4" right now.

Anyway, so, nothing really to explain my sudden torque/FE gains yet. Still open for suggestions. Looks like I may need to pull that cat at some point.
I'll also try to start documenting under what conditions the gains happen. Maybe that will lead to a cause.
B

[imzjustplayin]

Originally Posted by pgfpro

The only other thing I can think of is a bad CTS. It could be dropping down drastically from a warm up point to a cold point. You could monitor the 5 volt output back to the ECU to see if it drops a ton all at once.


The other thing it could be is a bad injector that is not flowing due to internal issues. This would make all the other three run extremely rich to make up for the bad injector because the O2 is reading all four as a whole and not each.

which would then let the computer calculate the MPG as being very high since it uses the pulse width of the injector in order to calculate fuel economy. Maybe he has a sticky injector(s) and that is giving him more power while giving the perception of better fuel economy when in actuality it's no better. I mean to get 104mpg at a steady cruise makes no sense but due to the information given to the computer, that'd be the only conclusion it could come to.

OP, I'd just check every ground inside of the car and remove them, sand them down, clean them up and reattach them. Just did this with my portable phone today and not only do the keys work better (used q-tip+rubbing alcohol) but I also get a bit better signal (did it to where the antenna mounts).

[theholycow]

A sticky injector would not affect the pulse width of the signal that operates it, and therefore would not affect the FE reading. Nothing measures mechanical open time, just the signal that's used to operate the injector.

I can't imagine doing all that work in my snowy yard at -2?F.

[GasSavers_Erik]

Originally Posted by benfrogg

I drove about 20 miles around town/short highway doing some testing. Prior to that, I let the block heater run 2 hours. After the drive, the radiator hose feeding the thermostat was still very cold. It was obvious that the thermostat had not opened during the drive. I wonder if that is normal? Am I not making enough heat to keep the car at operating temp? My grill opening is only about 3"x4" right now.

B

Since you drove for 20 miles, I think that you thermostat is coming open slightly- just enough to keep the engine at the proper temp. If you had your heater set on high and "hot" for the entire drive, then it was likely doing quite a bit of the engine cooling.

Even with the small grill opening, the radiator area is drafty and the high surface area of the rad does a great job at letting the coolant give off heat. So- it is very possible that the thermostat was open a small amount and the radiator was just getting rid of all of the heat so the small flow of coolant entering the engine was very cold.

[pgfpro]

Originally Posted by *************

which would then let the computer calculate the MPG as being very high since it uses the pulse width of the injector in order to calculate fuel economy. Maybe he has a sticky injector(s) and that is giving him more power while giving the perception of better fuel economy when in actuality it's no better. I mean to get 104mpg at a steady cruise makes no sense but due to the information given to the computer, that'd be the only conclusion it could come to.

OP, I'd just check every ground inside of the car and remove them, sand them down, clean them up and reattach them. Just did this with my portable phone today and not only do the keys work better (used q-tip+rubbing alcohol) but I also get a bit better signal (did it to where the antenna mounts).

I agree with this statement. Also I would like to add is check your injector wires back to the ecu. I ran into a problem with my sons civic last summer and it took me a week to diagnose it. It turned out to be an injector wire that was almost broke in half. It was at the kick panel where the wire harness does a 180 to the ecu.