sweethatch1866

I'll describe the problem first. Cold, the car will start, idle and rev fine in N. Once it gets a little heat in it or I try to take off, it will start bogging and eventually stall completely. If I get it to start after that I can hold the pedal to the floor and it wont tech over 1k rpm.


now for the car, 92 civic b20 vtec turbo. (b16 head) I built the car and have not had it tuned, it has not even been on the road because of this issue. Im using a civic cx harness, s300, msd ignition system, 1000cc injectors with a resistor wired in, fitec 4 bar map, 44psi fuel pressure, 255 fuel pump, precision 6262 turbo, huge intercooler. I thought at first the turbo and intercooler had something to do with it but I unhooked the charge pipe at the TB and still had the same problem. I changed the iat, and iacv, nothing. I have three concerns but I don't think it would cause it to do what its doing. Its throwing the iacv code but all the wires check out and I have tried three different valves and it still throws the code. I do not have a down pipe, for the time being so the o2 is hanging in front of the turbo exhaust (should do the same purpose sitting still, Right?) The tps is brand new, omni I believe, when I used a volt meter to set it instead of showing 4.5v at full throttle it read 5 something. Matt S. sent me a base map to break the car in with the 1000cc injectors since my fuel rail and wiring was modified to the point stock injectors are out of the question at this point.


any suggestions???

Computer_Nerd

first, get a more descriptive title. everyone that makes a thread in this section needs help.

the purpose of the o2 sensor is to adjust the air/fuel ratio. that may be your issue. have you checked your air/fuel ratios?

sweethatch1866

i dont have any way to check the air fuel ratio but if it was off that much it wouldn't run right cold, correct?

sweethatch1866

wouldn't the o2 get the same reading in front of the exhaust if the car is sitting still?

Computer_Nerd

you are having an issue when you add fuel and when it has been using fuel for awhile. you are trying to use 44psi fuel pressure with 1000cc injectors and a 255 fuel pump. you need to determine how much fuel is needed, given, and used.

Computer_Nerd

http://auto.howstuffworks.com/question257.htm

sweethatch1866

I understand what the o2 does and how it works, as long as the exhaust fumes are blowing on the tip of the sensor it should work. Im pretty sure if I unplug it it will make the computer guess which may make a difference since the reading its getting outside the exhaust pipe may be that far off. I'll try that next

Fabrik8

If you want the thread title changed, don't make a duplicate thread. Don't make a duplicate thread for any other reason either.

Fabrik8

You need to fix the TPS problem, and you need to make sure the base map has been properly set for the 4 bar MAP sensor and the other changes you've made. Also, don't assume that a base map will properly run the engine by itself without actual tuning. You've also made troubleshooting really hard because you've changed a bunch of things at once and so you really aren't able to follow a worthwhile troubleshooting procedure. You don't know whether the problem is related to things you have changed or a problem that was already there, and you don't have an ECU that has been tuned so you have no idea if the problem is completely related to your lack of proper tuning.

You also need to figure out the IACV problem. If the wires check out, and you've replaced the IACV, the only other possibility is that the ECU is bad. The other obvious possibility is that you're not testing things properly.

The O2 sensor hanging in the air is most likely the biggest problem though. Many/most engine management strategies don't use the primary O2 sensor until the engine is warmed up to a certain point, so cold idle is open loop and based on a target RPM. This seems to follow what you're saying about things not working after it gets some heat in the engine.




Soooo basically I wouldn't bother trying to figure anything out until you get a downpipe to install the O2 sensor into.. The IACV won't affect anything except idle, so I don't think the problem is related to that. Check the coolant temp sensor too, the one that the ECU uses and not the one connected to the temp gauge.

sweethatch1866

Fabrik, very helpful. Im going to go ahead and buy/make a down pipe and post the results. I built the engine from scratch, starting with the block up. The s300 is brand new too so I hope thats not bad, but if its storing that code is there anyway to disable it so the check engine light will go out? The car idles fine, the problem is when I push the gas. I have a 75mm TB, would that cause a issue with the tps readings? I will not be running the car at all until its tuned but if I take it to the dyno the way it is I'm either going to get laughed at or have a huge bill. As far as I remember I only have one temp sensor, thats located on the side of the head below the dizzy, I eliminated the fan switch sensor causing my fan to run constant which is fine with me. It probably wont be driven in the winter anyway. The car is obd1, according to my book there is no code 11. earlier it was constantly throwing a code 14 for the iacv but every once in awhile it would show a code 11. Anyone seen that?