3.4L stumbles under load

[cardana24]

I have been having an issue with my 3.4L swap. When I am cruising on the highway, and I come to a hill I will push the gas pedal down more to continue at the same rate of speed, but pushing the pedal down does not seem to add any more power, so once the pedal is pushed down to the floor if I let off a little bit, it feels like I released the emergency brake and the vehicle lurches forward, so I am wondering what would cause that? To me it feels like it is running rich and is stumbling. I have a supercharged maxima that acted this way before I got it tuned. As far as I can tell I am getting pretty bad gas mileage though i am not sure what I should be getting since the 3.4 is not in a camaro. Also when I floor it I blow smoke out of the tail pipe which leads me to believe it is running rich. THe idle is pretty smooth. My O2 sensors are new, and my check engine light is not on. I have check my injectors with noid lights so I know they are all getting power, but out side of that I have not check the resistance (what should the resistance be?). Could it be an injector is stuck open? MAP sensor? Does anyone have any ideas? Thanks for any help.

[geoffinbc]

yea it sounds rich to me from what you describe. What injectors are you using and what size throttle body?

[cardana24]

yea it sounds rich to me from what you describe. What injectors are you using and what size throttle body?

I am running the stock 3.4L injectors. The engine was from a 94 camaro. The throttle body is also the stock throttle body that was on the 3.4 camaro.

If it is the injectors is there an easy way for me to pin point which one/s is/are the problem?

Also something else that leads me to believe that it's running rich is the fact that my exhaust will smell like eggs some times.

[geoffinbc]

Oh you kept the SFI. Well in that case a rich condition would most likely be caused by a bad ECT sensor. It will be difficult to tell if the injectors are leaking causing a rich condition. but you can check the pressure and see if it is bleeding off pressure with the key off.

[cardana24]

Oh you kept the SFI. Well in that case a rich condition would most likely be caused by a bad ECT sensor. It will be difficult to tell if the injectors are leaking causing a rich condition. but you can check the pressure and see if it is bleeding off pressure with the key off.

I am running fuel injected, but I installed a cam that does not have the sensor lobe on it, so the SFI is not functioning properly.

[geoffinbc]

Well shit then all bets are out the window. I know it runs without the sensor but I have no idea if it will run as designed. From what I have herd the engine will run in batch fire mode (obviously with no cam sensor) but will also run in limp mode and never go into closed loop and uses a very conservative timing curve. I would be willing to bet you will need to get a chip burned in order to get it to run properly.

hopefully one of the EMC programming geniuses on this site can confirm whether or not the ECM will be running in limp mode or not.

[cardana24]

Well shit then all bets are out the window. I know it runs without the sensor but I have no idea if it will run as designed. From what I have herd the engine will run in batch fire mode (obviously with no cam sensor) but will also run in limp mode and never go into closed loop and uses a very conservative timing curve. I would be willing to bet you will need to get a chip burned in order to get it to run properly.

hopefully one of the EMC programming geniuses on this site can confirm whether or not the ECM will be running in limp mode or not.

I would like to know that too, but I figured the RPM's would be limited in limp home mode, I know you cannot exceed 2.5k rpm in my maxima's if they enter limp mode. Also I did not think you could tune the 1.5 ecm at all?

[IsaacHayes]

You can't.... I would look into megasquirt if I were you. http://www.turbocamaroproject.com/me...tallGuide.html that should help.

That or get an OBDI harness and burn a chip. But since you have the obd1.5 harness, might as well just $150 build your own MS and go..

What is this swap in?

[cardana24]

You can't.... I would look into megasquirt if I were you. http://www.turbocamaroproject.com/me...tallGuide.html that should help.

That or get an OBDI harness and burn a chip. But since you have the obd1.5 harness, might as well just $150 build your own MS and go..

What is this swap in?

I would rather not run megasquirt, because I am not trying to achieve any mega power goals with this vehicle. I would just like my current set up to run smoothly. My set up is not that much different than stock. I have a mild cam, comp cam lifters, chevy performance valve springs, and an air intake. I have other vehicles that I am concerned with getting maximum power out of, I would rather not spend money on this one doing the same.

[IsaacHayes]

Then you'll need to swap to OBD1 setup that runs the ECM like the 93 3.1L had, and tune that for the 3.4. Either way you'll have to tune to get it to run well since you cant tune the obd1.5 and it's not running well without the SFI it seems. If you can hook up an ALDL cable if you have one and datalog with tunerpro (the info is out there to write a definition , or try my 3100 one, dunno if it will work, but the ECM's are teh same hardware/pinout wise) then you could see what timing its running and if it's ever goign into closed loop or not.

Check the FPR for leaks is the only other thing I can think of, and make sure it's giving the right pressures with and without vacuum. Other than that it might be in open loop....