Weird VTEC problem.
 

Hi everyone. I have a problem with my VTEC where I can hold it all the way to redline where I can hear the crossover without any problems. However, if I hold the RPM within the VTEC range I would hit the 6500 RPM wall as if the car wasn't warmed up as soon as I shift to the next gear.

This is a bone stock F22 with AP1 ECU since my original F20 died. With the original engine I've never had this problem so I'm thinking that I may have damaged a wire during the swap process but I don't know where to even start at.

What I have done so far:
1. Swapped in a known working VTEC solenoid from the old engine.
2. Changed both VTEC filter and upper gasket.
3. New VTEC oil pressure switch.
4. Repaired a exposed spot of wire on the VTEC solenoid plug (soldered and heat-shrinked.

What I haven't done:
1. P0411 from the missing air-pump. Got the Izze delete.

Thank you for your time an any inputs!

Wait, you're running a 2.2 liter engine on 2.0 liter tuning? That's a thing you can do? You can run an engine with different cams and different displacement without changing the Speed/Density ECU ?? I heard these engines were pretty forgiving of bad AFR's, but I'd expect you're running leaner than stock over most of the rev range, until the rich spike at the top end, right about the same time the AP2 cams are giving up... Then you're probably richer... Anyway, that's not the root of your problem, but it's god damn crazy..

Ok, back on topic... I'm not sure I follow your description...

So, you can run it up to redline, and you hear the VTEC crossover... Good...

Then, during acceleration, you shift from somewhere in VTEC, but not redline... and the revs land below 6500... And you continue accelerating... And then you hit a mystery rev limit at 6500?

Is that correct?

That is a god damn mystery.

Have you checked the coolant temp sensor and its wiring? And taken the throttle position sensor through a sweep to check for dead spots? Do you have the Pre-TSB MAP sensor?

Those are 3 good starting points.

Thank you for your reply.

Yes I am running a 2.2 with 2.0 ECU.

Basically if I were in 3rd and floored it all the way to 8500 I would hear the crossover without any issues reaching 8500-9000. Shift to 4th and as soon as I arrived at 6500 I'd hit the rev limiter as if I didn't warmed up the car. This would only happens if I were to HOLD the revs above 6500 rpm. If I were to just wring it to redline, shift to the next gear then I would still be able to go past 6500 without any problems.

I don't understand your description of what is happening. So in your example if you shift to 4th are your rpms dropping below 6500? And then you are unable to rev up past 6500?

That's correct.

Edit: Sorry for the terrible description. I was going crazy and posting on my phone.

Scenario 1 - I'm in 3rd gear, I've just crossed over in to VTEC at 6500 rpm and moving towards redline. I'm finally near the rev limiter at around 8500 rpm and shifted to 4th. I worked my way towards redline again, without any problem. In this case I can come to a complete stop, gets moving and can still hit VTEC.

Scenario 2 - This is what I am experiencing now. I'm in 3rd gear, I've just crossed over in to VTEC at 6500 rpm and moving towards redline. I'm finally near the rev limiter at around 8500 rpm and stays around there for about 5+ seconds then up shift to 4th. I worked my way towards 6500 rpm. The moment I hit 6500 the rev limiter kicks in. This would stay with the car until I do a restart.

In both scenarios I have completely warmed up the car to three bar on the gauge.

Fried ECU?

Redline on a AP1 ecu is at 9000rpm and it's a really bad idea going that far if you have a F22 engine.
It doesn't sound like your ecu is fried but I suggest you replace it for an AP2 anyways.
Have you checked your oil level by the way?

Well, the VTEC oil pressure switch would throw a DTC and turn on the CEL.

This sounds like either the classic MAP sensor TSB, or the coolant temp sensor being loose / intermittent. either way, vibration from staying at high RPM would cause both of those problems, and issues with either of those sensors would cause mysterious hesitation at high RPM.

It is possible you have a pre-tsb sensor. I have one, and I'm about the throw it away because it's causing hesitation issues.​​​​​

https://www.s2ki.com/public/library/...-073/index.htm
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Read the TSB, and imagine the same scenario happening if you had damaged or stretched the coolant temp sensor plug, and it gets strange resisrance with vibration... all of a sudden the ECU sees an intermittent temp value below the warm threshold and kicks on the rev limiter... Its just a 0-5V analog input.
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Sorry for the ignoramus question... but, will the AP1 ECU allow the AP2 engine to redline at 9K r's?

Thanks!

The AP1 ECU doesnt know the difference. It thinks it's spinning an F20c. Yes, it'll rev the engine like it's an F20.

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I usually don't. It's more of an annoyance than anything.
My paranoia from having an oil burning F20 has resulted with me checking oil on the weekly basis so it's always topped off.

I do have the pre TSB MAP with a ziptie around it. Looks like I will be purchasing a post TSB one soon. As soon as I get the car back from the painter I will check the coolant temp sensor.

What you are saying makes sense. Thank you.

Thanks! Wonder what is the half-life of an AP2 engine rev'ed frequently to 9K?

Ive been running F22 with ap1 ecu for years supercharged and NA. Its a little trickier/harder to read shifting at 8500rpm (safest limit) with a supercharger because the power never signs off, so it begs you to take it to the limiter (which I have done a lot) but NA the motor signs off pretty drastically after 8500 rpm so its not really a problem once you get a feel for it. At my local track there is one turn in particular that is nice having that extra over rev past 8500, but other then that the motor rarely sees it. The connecting rods are really beefy on these motors so its not like your going to throw a rod, the issue is side loading and eventually scuffing the cylinder walls/pistons.

I cant pinpoint the OP issue here, but being experienced running his combo, I can say that the ap1 ecu though rich from factory, will run leaner on the f22, and even more so if its a later 02-03 series ecu, so I would hope that a wideband is being used to monitor afr to rule out an overly lean condition causing break up. I use a adjustable fuel pressure regulator to get the proper fuel I need to run safe in open loop/WOT. I also have some breathing mods like intake, TB/port and cat back w/TP, so thats going to cause my fuel requirements to go up quite a bit over someone running totally stock and with a cat still in place. If thats the case, the fuel is leaner then stock but probably still ok. Guessing when you have a problem though is never much fun, so i always advise having the proper monitoring tools when modifications are made.

Update.

During the process of diagnosing an intermittent starting problem (aftermarket alarm system) I noticed a loose Green/Yellow wire hidden within the bundle of the main harness. Whoever the previous owner before my friend must have spliced into the VTEC Solenoid Valve wire (Pin B12 on the middle plug into the ECU). Instead of soldering the wire back during the uninstall of whatever it was, they just twisted the ends and shrink wrapped over the joint. During my recent engine swap I may have yanked on the harness a little bit while getting the main plugs into the cabin.

I'm going to try to find an empty stretch and just hold it in VTEC for a while to see if it is really fixed.

The alarm that caused the starting problem was a whole different shit show of its own. Thank you all for your inputs.

it's the ghost of vtec here to haunt you. you must repent.

You never got a CEL with the bad wiring? Anyhow, the loom is now correctly repaired?

I did had a P1259 but during initial inspection my focus was at the wrong spot. I was obsessing over the connector, screen, pressure switch and the solenoid. Right when I posted this thread the car shortly got disabled due to the alarm so I couldn't really hit VTEC to replicate the problem.

The engine and the under-dash harness has been properly soldered and shrink wrapped. Any miscellaneous wiring associated with the aftermarket alarm system are gone and all the nasty taps and splices are repaired and wrapped up as well.