rudedog9d

We have a 2002 Civic EX with a 1.7L VTEC motor in it. I believe it is a B17A2. The car is raced on asphalt circle track, so it has some modifications.
Every race we go to, the car seems to enter a "limp mode" (2000-3000rpms) after around 5 minutes (5-8 laps) on the track. Some people around the track seem to think it is the car entering VTEC Limp mode.

We have GoPro footage of the problem occuring - pay close attention to the drivers foot. The car becomes completely unresponsive. (car dies around 9:00 - the forum removes my link with the time)


After asking people around the track, they tell us just to get rid of VTEC! There has to be a solution to this problem.

### Things about the car

- It's lacking it's entire interior (including dash - we've been told VTEC might care about the factory dash?)

- Battery has been relocated

- Engine bay fuse box has been relocated

- Several Sensors have been deleted. From the top of my head, I know the downstream 02 and water temp gauge sensor (though the ECU still gets a water temp). It is the one in the thermostat housing

- Inline Fuel shutoff (possible fuel restriction, though unlikely - it runs good when it runs)

- We use a Bluetooth ODB2 sensor to record data on a phone. The app is somewhat meh, and only records some data, but we have data to look back on.

### Things we know

- Car seems to drop to 2000-3000rpms after ~5minutes (5-8 laps) on the track
- The car was kept out after it died once, and it died a second time around 2 laps later

- Always does it, never works for more than 8 laps

- Didn't always do it - here is a video of me driving the car the week before this started happening at practice for 9 laps -
- The car previously had a bad camshaft sensor, causing it to rev limit at 4500rpm.

- ECU is throwing 3 Check Engine Codes:
- P0141: O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2) – Downstream
- P0131: O2 Sensor Signal Low Voltage (Bank 1, Sensor 1)
- P0132: 02 Sensor Circuit High Voltage (Bank 1 Sensor 1)
- I believe it threw an Injector Driver Module code previously, when it had a bad camshaft sensor

- OpenLoop (OL) fault on Fuel System 1

- In one log, we saw a temp spike to 300F *around* the time the car gave out. This wasn't exact, and it hasn't happened again that we've seen.

### Things we've tried

- Thicker oil - 20w50
- We've been told that the oil can sling to the right of the motor, not be picked up, and cause fluxuations in oil pressure.
Vtec will drop out if there is not enough oil pressure. Heavier oil didn't seem to make a difference.

- Jumping VTEC Oil Pressure sensor to VTEC solenoid via toggle switch
- You can see this in the video - it's the switch on the right

----------------------

I suspect our problem is related to something reaching a certain temperature (whether that be overheating, or reaching operating temp and realizing other systems are failing).
We've been told that numerous systems need to be active and working allow VTEC to work correctly, though we can't find a definitive list of what needs to exist for VTEC.


Questions I have:

- Does this sound like it could be caused by VTEC?

- What sensors/systems need to be working properly for VTEC to function?

- What could put the car into limp-mode like this?

ross2004

Is that your ECU just flopping around on the floorboard?

Anyway, you need to un-hack job it. Have all the sensors that feed the ECU in place, including the downstream O2. Thicker oil will not prevent slosh- weld in a baffle and/or use an Accusump.

rudedog9d

...Yes, yes it is. That's since been resolved, we were working on it right before the race

We considered buying a baffle for the pan, and/or shimming the oil pickup, though we've read mixed results on whether it fixes our problem. I'm pretty sure an Accusump would be illegal in our class, unfortunately. It's not certain we ARE losing oil pressure, it's just a suspicion. The data logger we have doesn't seem to record oil pressure - there will be an aftermarket oil pressure gauge hooked up next race.

Adding a downstream O2 sensor might be difficult, considering the only thing downstream of the header is a flex pipe. Do you know explicitly that the downstream 02 can cause a limp condition?

I should mention we got the car already as a hack job - we're doing our best to clean it up.

Thanks for the reply,
Brodie

ross2004

I do not know that it would cause limp mode....but it could by being fully removed. Is the primary O2 in place?

Basically you need to start with a clean slate, as reasonably close to as the car would have been stock. Then you can start removing things and see what any negatives that may cause. The civic sub-forum may have answers.

rudedog9d

Yes, the primary O2 is in place.

I would love to start with the car from a stock state, but that isn't really an option considering how we got the car. We can't dump a bunch of money into trying to make it stock again.

AllMtrRex

How are you monitoring engine coolant temps?

rudedog9d

The Bluetooh ODB2 reader is pulling them from the ECU, which is presumably reading from the head somewhere. There is an aftermarket water temp gauge in the thermostat housing. At the last race, the ECU was reading 190-200F while the gauge was reading around 160F

We've also read from the ECU using a good ODB2 diagnostic scanner with similiar results, so we're pretty confident the cheapo Bluetooth ODB2 reader is working correctly.

AllMtrRex

Questions I have:

- Does this sound like it could be caused by VTEC?
I'm sure you are engaging VTEC before the 5-8 laps. I don't think that is the issue

- What sensors/systems need to be working properly for VTEC to function?
Quite a few, but again, if their is an issue, VTEC will not work from the get go, not 5-8 laps into the race.

- What could put the car into limp-mode like this?
Several things. But I do believe its engine temp related. That is the only thing that is time sensitive in your equation. Possibly oil slosh, but if that's the case just go out hard as you can in the 1-2 laps and try and make it happen.

rudedog9d

I read/heard somewhere that VTEC won't engage until the motor is up to temp - is it possible we enter VTEC limp after 5-8 laps because that is when the engine reaches temp?

I would say the car is being pushed equally hard from the green flag to failure. (I agree that if it were an oil slosh problem, one would expect it to happen sooner).

We can get the track to open up for practice, but they are an hour away, so I'd like to have a list of things to test if/when we do that. One idea I had was to tape the radiator up and see how many laps it takes to cause the condition - if it happens quickly, that confirms it is related to high heat in the motor, right? Does any one have any other tests to suggest we try?

AllMtrRex

Just start the car and let it idle for few minutes until your bluetooth logger shows 180 or so degrees. Then take it down a side road and see if you go into limp mode. No need for taping radiator up.

rudedog9d

Unfortunately I live close enough to town, I can't use the road. I could take it to my buddies house, but it's halfway to the track, so we may as well just head up there.

Kaan

iTrader: (3)

its one of the temperature sensors (water/oil) and/or the harness going to it. any spike to 300 will cause a limp mode to kick in.

your blue tooth and external gauge wont "ping" fast enough for you to see it happen. you said you saw it in the data log... you need to figure that issue out.

rudedog9d

We've only seen that in ONE of the 3 data logs. The data logging is via the Bluetooth adapter, and I'm not sure how it works - it's possible that the BT adapter takes a snapshot every 5 seconds and we just missed the spike in the other two logs.

Kaan

iTrader: (3)

I think a cheap solution would be to go to the junk yard and pull all the sensors off a motor and replace them on yours and see if that fixes it. while you are replacing the sensors check the harness side with an Ohm meter.

dirty19

iTrader: (1)

Dirty is gonna side with Kaan on this one.^^^^^^^^
Too many pieces removed that make it all go.
You don't have to take it back to stock, but you need to find the culprit.
Also look back on the other post about looking at the sub civic forums for more information.
There aren't a lot of D17's used in road courses. Its either the D16Z6, B Series,or K's so refer to the above forums for more detailed data for your application.

You have to start someplace and not jump all over the place.
You mention Bluetooth ODB2 reader and ecu What kind of reader is it and how is it incorporated in your ecu?
The ECU is also very very important in how the engine runs. Check the wiring harness leading into each pin... are they tight or loose.
Have you tried a different ECU?
One pin loose makes the go not go.
I've had electrical demons before, and they aren't easy to chase if you have no clue.
This is a rats nest indeed. I would not take the car to the track again until you know you have it ironed out.
Your inability to maintain speed on track is also a danger.
An hour to the track, gas, food,entry fee all for it to hobble around the track in 8 laps. I don't see the value in it.
Summer isn't here yet you have time to get this straight.

dirty19

iTrader: (1)

Ok i just looked at your vids....
I never heard Vtec kick in... if it is its very very subtle.
What were those two switch flips in the first vid?
You said you hard mounted the ecu... that's good. Check those wires each and every one.
If one is loose you'll find it.
Loose that lowrider steering wheel its too damn small.
Yes i do have circle track experience... you guys aren't using enough track.
The shortest distance around the track isnt the fastest.
Dont lose the vtec its VTEC Yo!

rudedog9d

It's just a BT adapter that plugs into the ODB2 port and connects to a phone. Driver uses an Android app to record data.

https://smile.amazon.com/dp/B005NLQAHS

I'll double check the connections on the ECU side. We don't have an extra ECU around to try, although I don't believe that is the problem. Up here in NY, it's pretty hard to find donor cars in junk yards because everything has already melted into the ground because of salt

This isn't my first time dealing with electrical demons - the trouble I'm having is that I don't understand how the system is supposed to work. (Particularly the stuff around VTEC)

Although the whole team here agrees that it isn't worth the time and effort to go race, we also have no where else to test changes. I've been also racing an S10 pickup, so typically the civic comes with for testing and more diagnosis at the track.

Lol that's what I said! The driver likes it though, and it's not my car - just my headache

rudedog9d

Oh, I forgot one more reply:

We have read a couple of places that jumping the VTEC Oil Pressure Sensor wire to the VTEC solenoid wire would force the car to stay in VTEC if we were infact losing oil pressure. Pretty sure that didn't work. The switch all the way on the right is the jumper - when up, VTEC Oil Press == VTEC Solenoid Voltage.

A thought we had last night was to add a light to the VTEC solenoid wire - since the solenoid should be getting 10-12v when VTEC is activated, we should be able to add a light for when VTEC is on. Correct?

We're going to the track Monday for a few hours to try some things. I'll also post in the Honda subforum, as recommended (I really wasn't sure if I should have posted here or there in the first place).