OK, I am going to put on my RSR 3" TB this week.
And the DP is a 1 peice cat delete. I knew that the CEL would turn on, but didn't know that it would put the car into limp mode. Well the utec can turn off the light, but not stop the car from going to limp mode and causing timing, fuel and boost.

I want to know is , to compensate for the limp mode, I would need to tune the utec. Well,,,if I tune the utec so that timing, fuel and boost are all correct, Even though the car would be in limp mode, the utec over rides that and uses my set map correct?
And is it true that the only thing the utec wont correct is is I was at idle? fuel, timing and boost wise, using the Stock ECU correct.?

 

why not just simulate the cat or do one of the "tricks" to fool the ecu...

 

That is an option, but I just need to comfirm that the utec can compensate for this with out doing that. BTW the DP dose have an O2 bong for the sensor that goes into the cat. Dono if that would do anything though since there is no catalyst/

 

I didn't think that the test pipe would put it in to limp mode. You may want to make sure that is what is doing it. Not another code hiding behind it. DEpending if you are modifying the settings of the ECU(closed loop) or are running off absolute values you put in(open loop) would detemine if limp mode would affect you.

Ben

 

Thats ture. I wouln'd know untill i see for my self, but from what I read on some site thats the test pipe dose throw off a code. and sends the car into limp mode. Odd cause when I had the s2k and I put in a test tipe it was just a light, now limp mode.

And I'v always thought that with the utec and I have it on so that my absolute values would overide my stock ecu settings. But its only at idle where I would be running rich and timing being pulled. Since the utec dosen't take over unitill I press the gas/

 

If you can't get to a OBD-II device you should take off your negative battery terminal for a minute. This will reset the ECU and take the code out of the ECU so it should be out of limp mode.

Ben

 

I think some cars react different to the Cat defficiency problem. I took my cat off for a testpipe and my car was running great until i threw a check engine light. I bought a o2 simulator from www.o2simulator.com and my headached went away.

 

secondary O2 sensor has no effect on closed loop or open loop.. Its only a emission (catalytic converter) device.. You can completely remove the second O2 sensor after the cat and it will have no effect on the car's operation..

I had suggested to TurboXS at one point that they should put some secondary O2 simulator code into the UTEC so you can run it if you need it.

you generally will not go into limp mode unless there is something wrong with the MAF (but its still functioning) or the primary O2 sensor has a problem..

If you are finding its definitely Limp mode, then check to make sure your O2 sensors are functioning correctly (you need an OBD-II scanner) its possible that for one reason or another your going into a secondary fuel/timing map due to another problem (Bad gas, car is timing sensitive, etc..)

If you mod your car, an OBD-II scanner is almost a prerequisite just as a boost gauge and other instrumentation.

And yes, there's an closed loop to open loop transition that the UTEC is configured for (approximately 30% tps) In closed loop operation, the engine will always attempt to maintain 14.7:1 air fuel ratios, and cruise timing will vary slightly depending on engine load. If you are indeed in limp mode, it runs open loop reference maps, the same maps that are used when the car is first started and the O2 sensors are not up to temp and functioning yet.

 

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Why does the car run a high A/F ratio. Al, with Dynoflash was like thats way too high and got it back down to 11:1?

 

14.7:1 is stoichiometric, and is the (mathematically) correct A/F to run when the engine is under very little load. I expect even Dynoflashed cars run 14.7:1 when in closed loop, as that is part of the core logic of the ECU which operates on O2 feedback. No changing of any maps will alter it.

Now, if he was referring to a car that was running 14.7:1 under boost and heavy load... then I would agree that is WAY too high and should be closer to 11:1.

 

yes that must have been what he was referring to b/c we were on the butt dyno.

 

Thats open loop operation when the car uses throttle position and airflow for reference to the MAP (tables) On a stock car, an evo under load and higher RPM can be off the scale rich, but generally as rich as 10.0..

Closed loop operation isn't something you really "tune" since it will use the primary O2 sensor to maintain a particular (14.7:1) fuel ratio.. However the default fuel trims can be adjusted, and "warm-up, open loop" parameters can be adjusted so the car won't run cruddy until the engine is warmed up, or the ECU is reset.. I'd go into more detail, but I'm a little tired and I feel like I'm not making much sense right now..

 

I am a utec newbie here as I have had mine for about a week. So pardon my ignorance.

So when does the car switch from closed loop to open loop.....a certain tps value?

 

If possible, I would like to see if I can get you on the phone while my UTEC is hooked to the laptop for a few minutes and hash out whatever is mind blocking me so I can do a little of my own tuning. I still need the XS tuner though but not to play with the settings. PM or let me know if thats alright.