High engine fan speed in cold weather...a brief story...

[02 LW300]

Iac cannot control the idle speed. Can your code reader give you any readings on the iac position? If it is closing off the idle air bypass port Like it should and there are no vacuum leaks then the throttle plate is letting too much air by. I think 300,000 plus miles things might wear a little. There is a screw probably under a cap that will adjust the throttle plate. I would close the plate some but not enough to get sticky, and see if the idle control will actually work again. You might need to adjust the throttle position sensor also, but I can check. Some readjust with each key cycle.

[pierrot]

Originally Posted by 02 LW300

Iac cannot control the idle speed. Can your code reader give you any readings on the iac position?

I can't say with certainty, but I wouldn't expect that it does. It's an Innova 3030f, not a very high end reader at all although I do like it.

Originally Posted by 02 LW300

If it is closing off the idle air bypass port Like it should and there are no vacuum leaks then the throttle plate is letting too much air by. I think 300,000 plus miles things might wear a little. There is a screw probably under a cap that will adjust the throttle plate. I would close the plate some but not enough to get sticky, and see if the idle control will actually work again. You might need to adjust the throttle position sensor also, but I can check. Some readjust with each key cycle.

I'll be on the look out for an adjustment of the throttle plate. I don't recall seeing anything like that when the throttle body was removed from the intake manifold, but since I wasn't looking for that it could easily have been missed. The other thing about this is just how intermittently the event arises. However, the idea that it may have something to do with the throttle plate has some merit as I see it. More often than not, this problem has occurred after very cold overnight temps. During more average overnight temps this was less common to nil. From about mid-April until last week there had been no irregularities whatsoever. Perhaps the cold temperatures caused some contraction in the metal and allowed for more air to pass by the plate. For the time being, it's just conjecture on my part. We'll see as we go along.

[fdryer]

I think you can determine operating temperatures by creating an artificial error - disconnecting a sensor triggering the OBD II self diagnostics into capturing data. Choose a readily accessible sensor, have the engine fully warmed and disconnect a sensor. The check engine light should turn on and capture freeze frame data including coolant temps. Since you know which sensor (tps, iacv, map, etc) is disconnected, the error code should display the appropriate sensor error code. Download this captured data and see what coolant temps are. Reconnect the sensor and either let the OBD II system reset the check engine light or manually reset the error.

[pierrot]

Ah, fdryer, what a fine idea. The logic seems quite reasonable and the effort to attempt it is minimal. I like it! Thank you, my friend!!

[pierrot]

Believe it or not, I hadn't tried to correct this problem for a very long time. As this issue once again made an appearance in my car during our colder season, I came up with a "work-around" for the extended time of the high curb idle: I'd turned off the engine while waiting for a traffic signal light to change from red to green, and would restart it before I had to move forward. Once the engine idle reaches ~750 RPM the issue is basically over until the next severe cold temp start-up. As for a repair, I've not tried anything other than what I'm about to discuss next.

Last month I visited a Pick Your Part wrecking yard near me and acquired a replacement throttle body from a 2003 L200 with the TPS and IACV attached. I wasn't charged anything extra for the those items, only for the throttle body. I cleaned the replacement throttle body and swapped out the IACV from my unit to the replacement and installed it. (FWIW, the base gasket was also replaced.) Unfortunately, this did not correct the problem although there was some improvement with acceleration. I believe that was due the presence of a "younger," less used TPS on this throttle body. What little this suggests to me is that the problem does not appear to be related to the throttle body. I'm almost tempted to go ahead and replace the TPS to see what will happen.

[jzchen]

Originally Posted by pierrot

[FONT="Palatino Linotype"][SIZE="3"]Believe it or not, I hadn't tried to correct this problem for a very long time. As this issue once again made an appearance in my car during our colder season, I came up with a "work-around" for the extended time of the high curb idle: I'd turned off the engine while waiting for a traffic signal light to change from red to green, and would restart it before I had to move forward. Once the engine idle reaches ~750 RPM the issue is basically over until the next severe cold temp start-up. As for a repair, I've not tried anything other than what I'm about to discuss next.

Last month I visited a Pick Your Part wrecking yard near me and acquired a replacement throttle body from a 2003 L200 with the TPS and IACV attached. I wasn't charged anything extra for the those items, only for the throttle body. I cleaned the replacement throttle body and swapped out the IACV from my unit to the replacement and installed it. (FWIW, the base gasket was also replaced.)

So to follow up (as I just read through all your posts:
IACV is new-ish
Fans- fans are still blowing high when the P0507 shows up? Coolant temp is 100+ in the freeze frame data....

I have a code reader/scanner you can borrow right now not GM enabled but OBDII should read this?....

[pierrot]

Well...silly me. I thought that I'd swapped the IACV from my original throttle body to the one from the donor car, but I did not. I'm rather irritated with myself as I can't remember where I placed the original throttle body. There is, however, a new AC Delco TPS on the donor throttle body. While the problem still exists, the engine is able to idle more quickly to a lower rpm, but not fast enough to prevent the PCM from sending a command to turn on the fan. There have been some other performance improvements, but I will save that information for a later time. Meanwhile, this has led me to believe that I may be closer to finding an answer to my problem.

I don't know what the coolant temp is in degrees when the pusher fan (on condenser) engages at high speed. Interestingly, the puller fan (radiator fan) remains off. I'd previously believed that both fans were engaging, but had never taken the time to view it with the vehicle parked at an idle. For the first time several weeks ago I actually observed the fan operation when this system error occurred again. So what I'd stated earlier was incorrect on that point.

The temperature gauge is almost always above the first hash mark to the right - 1/4 - when the fan engages. I need to find the original throttle body so I can install the IACV from that unit onto the one currently in use. Perhaps a "young" IACV operating in tandem with a new TPS would yield more improvement. At this time, I'm satisfied that the current temperature sensor is functioning correctly as the movement of the gauge seams to behave as it always had.

It's good to hear from you JZ!

[02 LW300]

How fast does your car warm up? My car is blowing hot air in 1/2 mile and up to temp in one mile even on 30 degree days.

[jzchen]

Hmmm. I'm afraid I'm not familiar with the gauges on the Saturn so with "past one mark to the right" I initially thought meant one mark past cold. But anyways either way I'm lost what that means...

But like I noted I can happily lend you a Foxwell NT510 Elite which does data logging. Just let me know. I have a GM vehicle in the household so I could activate/pay for the GM software as well. I don't mind because I can use it myself.

IACVs are a real pain you have to make sure there are no vacuum leaks, and I've read mixed reviews that one can reliably clean them. But you noted you had a new one so I was wondering if you kept it on....

BTW- Good to be back on this forum. I spend a lot of time on TapaTalk but I don't think this forum is supported so I lost track of it! Then it sent me an automated birthday greeting (1 day early), which I found in my inbox which is flooded with advertisements mostly, and tada I'm back!

[pierrot]

Originally Posted by 02 LW300

How fast does your car warm up? My car is blowing hot air in 1/2 mile and up to temp in one mile even on 30 degree days.

Engine warm up is reasonably quick and seems very similar to what you've described. While the engine idle speed is dropping more quickly than it had with the old factory installed TPS it is not quickly enough. It may reach ~800 RPM after about three minutes, but that number is still too high. (BTW, that number would be significantly higher if it was with the older TPS.) If the car is at a standstill long enough and I'm waiting for a traffic signal to change while the engine idles at 800 RPM, then the condenser fan will engage at its highest speed. (Again, the difficulty is that the idle RPM remains too high for too long causing the cooling fan to engage.) After that has happened I sometimes will go through the intersection and quickly find a place to park with the engine on and the transmission in gear. After about a minute or more, the idle RPM usually drops to the "magic number," 750. Once that RPM has been reached for a requisite amount of time the cooling fan will shut off.

Originally Posted by jzchen

...so with "past one mark to the right" I initially thought meant one mark past cold.

Yes, that's exactly what I meant.

Originally Posted by jzchen

But like I noted I can happily lend you a Foxwell NT510 Elite which does data logging. Just let me know. I have a GM vehicle in the household so I could activate/pay for the GM software as well. I don't mind because I can use it myself.

I appreciate the offer and will keep it in mind!

[02 LW300]

I live in the country and when I leave my driveway I accelerate to 45-50 mph. The first stop sign on my commute is 6 miles from home. I come to a complete stop but there is never any traffic so it is a touch and go.

So in reality my car may be behaving the same as yours, I don’t know. I have only had the fan stick on high when I had the thermostat fail to maintain temperature. The rubber in the thermostat had come apart, a thermostat and code clear solved the problem for me.