Running rich and coolant temp sensor

[95camarslo]

I recently noticed at WOT my AFR is reading around 11:1. I haven't changed the tune in 2 years, and it was running around 12.5:1 at WOT up until I noticed this. Took a log and found that the coolant temp sensor was showing around 240 deg, while the gauge showed around 180. Replaced the sensor and nothing changed. I doubt that the coolant is actually reaching this temp since the car shows no signs of overheating, and haven't seen anything else off that would cause the car to suddenly be that rich. Partial throttle seems to have a normal AFR and there are no codes. Anyone have any ideas?

[Injuneer]

Check the temperature sensor and the harness wiring:

Courtesy of Shoebox

http://shbox.com/1/4th_gen_tech2.html#ect

[95camarslo]

Checked the wiring and got 5V. Couldn't get the leads to read on the sensor before dark. The computer read around 125 deg after sitting for a full day with both the old and new sensor. Going to try to get a resistance off of the new one tomorrow. Kind of doubt that two different ones would read the same wrong reading, but I'm pretty sure that the car isn't running at 245 deg.

[Nostang 96z]

The coolant temp after sitting a few days should be very close to the ambient temp of the area where the car is sitting. Since you have two sensors, keep one under your hood and unplug the sensor on the water pump and scan the reading to see if they are the same temp.

[95camarslo]

I'll have the other sensor this weekend to try that out. Tapped the connector to get resistance of the sensor since I couldn't get leads directly onto the sensor and got 1550 ohms which puts the temp around 100 deg. Car hasn't run since sunday and has been in the shade. The coolant feels like its about 70-80 deg, so I'd expect it to be around 2500 ohms.

I also got about 1550 ohms for the coolant temp sender for the gauge. In the data log there are two coolant temps one C and one F, C is showing 92 deg and F is showing 237.6 deg. These numbers disagree. Converting them from C to F gives 197.6 and from F to C 114.2. Not really sure what to make of this. Has anyone seen anything like that before?

[Injuneer]

You have to measure the resistance of the sensor without the harness circuit connected. If there is a circuit connecting the PCM to the sensor, you may be measuring the combined resistance of two parallel circuits. Even with the key off, who knows what's attached to the circuit inside the PCM.

Did you check the harness pins for damage or corrosion.... that would also increase the total resistance in the circuit.

[95camarslo]

Yeah thats true. I'll try to get it without the connector. The harness pins looked fine. Based on shbox I believe that I'd be seeing too low of a resistance instead of too high. Although if in tunerpro Coolant C is correct and Coolant F is incorrect, then I'd be seeing temperatures that I'd expect.

BLMs at WOT are 138 and 140. GOing to take a look at the MAF and see if its dirty.

BLMs at WOT are 138 and 140 at WOT. Going to take a look at the MAF and see how that goes.

[Injuneer]

When you go to power enrichment (PE = roughly WOT), and the PCM was adding fuel in closed loop, the PCM uses the BLM's from the last cell, which is usually cell 15. But, the PCM sets a richer target A/F ratio in PE mode, which is calculated from tables based on CLT temp and RPM. (And you are probably aware of this, just making sure).

So your problem could be the extra fuel being added by the cell 15 BLM'S, or the faulty CLT sensor reading, or a combination of both. But if those are your cell 15 BLM's, they are the results of the O2 sensors measuring a lean condition in closed loop at high RPM/high MAP condition.

[95camarslo]

Didn't have access to the car for a couple weeks while moving, so I'm back to troubleshooting again.

What would you take it to mean if the WOT pulls are reading BLM cell 17? The TPS output is at 100% (BLM cell 17 would indicate from what I found to be speed>0 and TPS=0). Looking back a couple years to when I believe the car was running right it was running in BLM cell 18 at WOT. Didn't have an AFR gauge then, so don't know exactly what it was at then. I know shortly after the engine was broken in I hooked a friend's gauge up to check the mail order tune from madtuner and saw about 12.7 consistently at WOT. That was in October 2013 and about 11,000 miles ago. I decided since the O2 sensors were stuck in the headers and not looking great it wouldn't hurt to replace them...did that and now WOT reads 10.0-10.3 as RPM climbs.

[Camaro96]

MoeHorsePower

Would be the guy to help you with that. This may get him to chime in.

Sent from my SM-N915V using Tapatalk

[MoeHorsePower]

Im assuming that the O2s you are replacing are the narrow band ones? what type of wide band are you using, does it need to be calibrated?

[95camarslo]

Yeah I replaced the narrowband O2s. The wideband is an AEM and the wideband O2 doesn't require calibration. I'm not really sure if there is a way to be sure that it is reading correctly besides replacing it.

[Injuneer]

Do you have a data log we can review? Cell 17 is usually used for deceleration.

[95camarslo]

Yeah PM me youre email and I can send you a log. Don't think I can attach it on here.

[Injuneer]

BLM Cell in power enrichment mode - It's not running PE mode in Cell 17. It only goes there when you let up on the throttle, as it should. I could only find two 100% throttle events. At record 10865 is enters PE when you hit 100% TPP. It's in Cell 15, left BLM 139; right BLM 138. The left O2 sensor exceeds 1,000mV and the right sensor runs 970 to 1,000+ mV. While the narrow band sensors aren't all that accurate outside of the 14.7:1 range, I'd still trust them to be indicating it's too rich for PE mode. Even with a stock typical PE target A/F ratio of 11.7:1 that you get with stock programming, you don't see 1,000mV O2 readings. Maybe 950 max.

At record 12484 it enters PE again at 100% TPP, and it uses Cell 15 with the left BLM 160; right BLM 138. CLT temp is 238*F. It stays in Cell 15 until you let up on the throttle for 0.2 seconds(0% TPP) and it moves to the decel Cell 17 for that brief period. At record 12496 you reach 100% TPP again, and this time it moves to Cell 18. That cell is used in open loop TPP>0%, and is a weighted average of the other cells. I see it used in PE mode, perhaps because you came from cell 17, and it doesn't want to use the BLM's from the decel cell (last cell you were in). Now left BLM is 140; right 134. I don't see anything wrong with the cells it's using.

The CLT temp is a problem. It continues to increase at a uniform rate, until it reaches 250*F at record 8979. The data log has 3 columns labeled Fan 1, and 3 columns labeled Fan 2. I would expect at least one of those columns for each fan to confirm that the PCM has commanded the fans on... low speed at 226*F, high speed at 235*F. That doesn't happen. Maybe its just my lack of familiarity with TunerPro format, but I don't think your fans are coming on. But there is no codes set for the fan control circuits.

The BLM's are high on the left side, at least for the Cells you drove in (5, 6, 9 thru 18), typically in the 140 range (adding 9.4% extra fuel), but as high as 145 in Cell 16 (idle). The right side isn't as bad. Only Cell 5 and 16 are high (~145). The others are in the range of 127-132, generally not a problem. The Cell 15 values seem to jump around a bit both left and right.

I'll look some more when I get a chance.

[95camarslo]

Ok, I see now looking at the data in a .csv that the BLM cells are correct. I believe the fans do kick on, although I notice when I stop in traffic that it will climb up on the gauge from 180 to around 210 or so, but never really goes past that.

As for the coolant temp I'm not sure what to make of that. In the file there is a coolant temp F and a coolant temp C. These values don't agree throughout the entire data log and in past ones that I have taken. Coolant temp C is about what I would expect, while F is showing very high. The car doesn't show any signs of the coolant being at 245 or so deg F. Looking back to my first traces from when the engine was built I had similar readings from the two values.

I guess the fans may not be getting turned on based on the log, but it still doesn't explain the differences in the two coolant readouts. Going let the car warm up and see if the fans are turning on or not.

[Injuneer]

As for the coolant temp I'm not sure what to make of that. In the file there is a coolant temp F and a coolant temp C. These values don't agree throughout the entire data log and in past ones that I have taken. Coolant temp C is about what I would expect, while F is showing very high. The car doesn't show any signs of the coolant being at 245 or so deg F. Looking back to my first traces from when the engine was built I had similar readings from the two values.



You are correct.... the coolant temp reported in degrees-C appears to be the correct one. If you convert it to degrees-F, it always 40*F lower than what is reported in degrees-F. Serious error in the program. I checked the two values for the inlet air temp, and the same error does not appear there. Your coolant temp appears to be maxing out at 208*F, based on converting the degrees-C column.

I normally hide the degrees-C columns, and for many sensors the voltage columns, to make the file easier to review and manipulate.

You might want to consider running Scan9495. Far superior to anything else out there... I prefer it to DataMaster, freescan, etc. Free download, your cable may work, and the author is a member on this site if there are any problems. He responds rapidly to questions.

[95camarslo]

I got a few traces with Scan9495 today. Wasn't able to see anything different. Going to put the old O2s back in since they ran at about 11:1, and since I put in the new ones it has been running at 10:1 (WOT). Want to see if it was that change that caused it or if it was something else. Scan9495 showed normal temps so I think I can rule out a coolant temp issue. Having trouble making sense why this would be happening. Over the past few thousand miles it has gone from 12.3:1 and gone down. Not sure if it went down all at once or not since I was dailying it and not going WOT/paying attention to AFR at WOT that often.

Going to check the FPR tomorrow to make sure that isn't messed up. A quick check tonight it seemed ok.

[Injuneer]

Where is the wide-band located..... on one side, or in the combined exhaust from both sides?

Just looking at it mathematically, adding 10% extra fuel, which is what the BLM's are doing, particularly on the left side would knock 12.3:1 down to 11.2:1. Do you have BLM's from when it was running 12.3:1?

Do the plugs indicate it's running rich?

[95camarslo]

The wideband is just after the Y pipe comes together. The plugs show that its rich but the ones I pulled didn't look too bad. I don't have BLM's from when it was at 12.3:1. I have some from when I was at 12.7:1 a couple years ago. It was showing 129 and then after a shift it went to 132 on the left side and 137 on the right.

[95camarslo]

Found that the MAP sensor seal was torn up, got a better one on it and it reads almost 10 kpa higher than before (around 54-55 kpa at idle). Also replaced a burnt spark plug wire. Car is running a bit better usually around 11.5:1 but its inconsistent. Definitely doesn't hold or repeat itself on different pulls. Have had pulls as high as 12.3 and as low as 10.8. It changes after shifts too. Will go from mid 11s down to high 10s going 2-3. The inconsistency is confusing. Could it be the opti going bad? I don't think it should be but not really sure at this point. Maybe a bad injector? It has sat for 9 months each of the past two years.