stuck in open loop

[badandy]

Car is stuck in open loop. It will not no matter how much I drive and how warm the car is or it is outside go into closed loop. I know Bosch O2's are questionable but I put a new one in because it was free. I have never had one cause this kind of problem...in fact the stocker did the same exact thing. I replaced the coolant temp. sensor and all that I can think of is to replace the thermostat. The weird thing is no codes? Autometer gauge is good and will register stoich at start up and creep it's way to the middle of the green bars and just sort of hover in that area. I will get stoich again under decel but any other throttle input send it right back to the greens and stays there...even at idle.

I'll toss in the thermo when I get home...if that doesn't work...any other ideas?

Oh yeah...stock injectors, SMEC, map and press reg.

[Turbodave]

Have you looked at the output of the O2 sensor with something other than the autometer gauge? I would try to verify it with a scan tool or DVM. The fact that it's not looging a code makes me wonder if the computer is seeing something different from your gauge.

How is the gauge grounded? On my A/F gauges I always run the ground right to the battery connection rather than just to the dash or body of the car, this seems to give the gauge a cleaner ground.

[badandy]

Have you looked at the output of the O2 sensor with something other than the autometer gauge? I would try to verify it with a scan tool or DVM. The fact that it's not looging a code makes me wonder if the computer is seeing something different from your gauge.

How is the gauge grounded? On my A/F gauges I always run the ground right to the battery connection rather than just to the dash or body of the car, this seems to give the gauge a cleaner ground.

Yes, I have tapped it with a multimeter...and I have to admit I'm knocking cobwebs out of my head...I did see fluctuation but the numbers were awfully high and didn't "bounce" as much as what I had remembered in the past.

I tried many different grounds and ended up on the intake manifold to firewall ground strap.

The car has a VERY NICE aftermarket aluminum radiator and I'm thinking that maybe that may be causing issues...along with maybe a worn out thermo...but the factory temp gauge sets right about 1/4 which is what I remember from all my other cars.

It's something simple I'm sure...I have just been out of it for so long I'm overlooking the obvious somewhere.

[badandy]

I would be willing to bet that the replacement O2 took a dump.

[GLHSKEN]

LOL then change it!!!

[badandy]

LOL then change it!!!

Easy killer I still think something else is up. I'll swap it out with another and see if I have the same results. It's possible that I spoiled this one as the cam/crank alignment was out of whack when I got the car causing it to run extremely rich.

Maybe I should have bought Whitey back...lol...no, wait...Frank isn't finished re-inventing the wheel yet

[turbovanman²]

Whats your fuel pressure? running stock injectors?

Bosch are known for sticking, OE or NTK are good ones. See if you can borrow a lab scope or Vantage and check it properly. If it was in open loop all the time, it would be using alot more gas.

[badandy]

Whats your fuel pressure? running stock injectors?

Bosch are known for sticking, OE or NTK are good ones. See if you can borrow a lab scope or Vantage and check it properly. If it was in open loop all the time, it would be using alot more gas.

I've owned the car almost 2 weeks and have gone through 60 bux in gas!...and it ain't cause my foots been it it either! She hits overboost before I can say "Vaughn's a loser"...lol...(sorry Spanky)

It's definately using up the go go juice...stock injectors, stock reg.

[turbovanman²]

I would either recheck your multimeter or borrow a labscope, they can tell you if your running rich or if the ox is no good.

Have access to a scanner?

[Aries_Turbo]

you check the TPS voltage?

i had a setup that didnt fluctuate much at idle but then it would bounce at cruise if thats any help.

Brian

[sdac guy]

The car has a VERY NICE aftermarket aluminum radiator and I'm thinking that maybe that may be causing issues...along with maybe a worn out thermo...but the factory temp gauge sets right about 1/4 which is what I remember from all my other cars.

My guess is coolant temp sensor is reading too cold. Note the gauge is off the single wire sensor on the middle front of the head. The coolant temp sensor is the two wire sensor on the thermostat housing. So your gauge can read normal and if the CTS says it is cold, then it will stay in open loop. And if that is the case you may not get a code with it until it is really far off.

Barry

[badandy]

My guess is coolant temp sensor is reading too cold. Note the gauge is off the single wire sensor on the middle front of the head. The coolant temp sensor is the two wire sensor on the thermostat housing. So your gauge can read normal and if the CTS says it is cold, then it will stay in open loop. And if that is the case you may not get a code with it until it is really far off.

Barry

That was my thoughts. I swapped out the CTS with a new one but I'm thinking it's running too cool. I'll check it out tomorrow.

[GLHNSLHT2]

make sure all the gauge feed and ground wiring is soldered and ground it directly to the battery. Also a scanner is a good idea. After recent findings I'd ditch the NB gauges and stock sensor and go wideband. The stock NB gauges don't tell you anything about how much fuel you'll really running.

[Aries_Turbo]

^^^^ hes right. if you look at the actual electrical output curve vs AFR, between .87v and .7 v is anywhere from 9:1 to 14:1.... not enough resolution to tune the car precisely to. now as an indication gauge to make sure the car is cycling in closed loop, its ok for that.

Brian

[badandy]

Okay...

For starters...so that nobody misunderstands...I am not looking for tuning right now as I'm just trying to get the car not to swallow more gas than my old ram!

Update:

Brand new O2...still .9 volts constantly
TPS volts OK
All grounds in good shape and verified.
Pulled SMEC plugs, cleaned them and verified all were making good contact.
Swapped out map with two different known good ones
Swapped out coolant temp sensor...even plugged back in the stocker and took a lighter to it to trip the cooling fan
Thermostat is okay
Stock injectors, stock fuel press reg., 255 pump, fuel pressure was verified as stock.
I even swapped in an adjustable fuel press. reg. and set static at 45 psi and STILL get .9 on the multimeter!

Vaughn and I messed around yesterday and we took some pliers to the incoming fuel line...gave it a good squeeze and the O2 sensor voltage did indeed drop...which tells us the O2 is functioning correctly.

I'm leaning towards the SMEC is bad...I can't think of anything else!

[sdac guy]

Swapped out coolant temp sensor...even plugged back in the stocker and took a lighter to it to trip the cooling fan

Does your fan come on when the engine is idling or sitting in traffic after a romp down the freeway?

If not, that would mean the coolant itself is not getting hot enough to trip the fan. Maybe it is not getting hot enough to go into closed loop. Someone before you didn't put in a low temp thermostat did they? Maybe between that and your super radiator, the coolant isn't getting hot enough. A stock one is a 195.

If the fan cycles by itself when idling, then the problem with open loop is not coolant temp related.

Do you have access to a scan tool? BTW, other than bad fuel economy, how do you know the car is running in open loop all the time?


Barry

[badandy]

Does your fan come on when the engine is idling or sitting in traffic after a romp down the freeway?

If not, that would mean the coolant itself is not getting hot enough to trip the fan. Maybe it is not getting hot enough to go into closed loop. Someone before you didn't put in a low temp thermostat did they? Maybe between that and your super radiator, the coolant isn't getting hot enough. A stock one is a 195.

If the fan cycles by itself when idling, then the problem with open loop is not coolant temp related.

Do you have access to a scan tool? BTW, other than bad fuel economy, how do you know the car is running in open loop all the time?


Barry

I tricked the computer into thinking the temp. was up by plugging in another CTS while the car was running and holding a lighter to the sensor until the cooling fan came on...then I checked the O2 as well as checked the a/f gauge. The multimeter read .9 and the a/f gauge was pegged.

I do not have access to a scan tool at this time. I know that the car is running open loop all of the time due to the multimeter readings and the a/f gauge which I have verified as being accurate enough to use to diagnose the problem.

[sdac guy]

I tricked the computer into thinking the temp. was up by plugging in another CTS while the car was running and holding a lighter to the sensor until the cooling fan came on...then I checked the O2 as well as checked the a/f gauge. The multimeter read .9 and the a/f gauge was pegged.

I do not have access to a scan tool at this time. I know that the car is running open loop all of the time due to the multimeter readings and the a/f gauge which I have verified as being accurate enough to use to diagnose the problem.

So does the fan cycle when the engine is hot & idling for a while?

Barry

[badandy]

So does the fan cycle when the engine is hot & idling for a while?

Barry

Yes it does cycle. I previously simulated this test by using a spare coolant temp sensor and holding a lighter to it to get it hot. Nothing changes the O2 voltage which leads me to believe the computer is driving the injector duty cycle to too high of a pulse width

[skunkwork]

Hey guys, I am the previous owner of the csxt in question here. I did put in a lower temp thermostat when I first got the car cause the one in it was stuck open, @ the time it was the only one I could find. I do have a scan tool for the car, if you want to bring it back I can put it on it, the last time I checked it the only code that came up was for overboost. The car did have a adj fuel pressure reg. from foward motion on it, never really liked it all that much though. I NEVER had it over heat in traffic or after a hard run, an the electric fan always came on an cooled it down in a hurry.