Zappo Posted July 19, 2013 Report Posted July 19, 2013 I have been having a minor problem for the past few weeks that has gotten much bigger today. This morning I start up the car, but the car is acting like it has a vacuum leak, and the the vacuum is reading a little low. I pop the hood open and noice that the radiator fan is on even though the car is cold. I shut off the car and the fan continues to run for another 10 minutes, as well as the IAC. I parked the car and drove my spider to work. For the past few weeks I would have an off and on problem of the RPMs hanging when I push in the clutch, and it idles at 1000-1100 RPM. It wouldn't do it all the time though. I thought I had tracked it down to a bad IAC because the problem went away for 5-6 days after I swapped it out. However, it returned yesterday and has obviously gotten worse. Any ideas? I seem to have heard of something similar to this before, but all my searches aren't finding anything. AC is off. I have had no real problems driving normally other than it seems to be idling high and the RPM hang. (until this morning) Throttle is not stuck. MAF has been swapped with a working one, no change.
Zappo Posted July 19, 2013 Author Report Posted July 19, 2013 Gauge reads correct, and it uses the same signal. I tried disconnecting it and it didn't change anything.
gmsgltr Posted July 19, 2013 Report Posted July 19, 2013 fan relay underneath the plastic cover above the fan
Zappo Posted July 19, 2013 Author Report Posted July 19, 2013 Acutally, I do have another temp sender I can just plug in and see if it changes anything. The relay isn't bad though. The IAC is on at the same time, and even if the relay was bad, it wouldn't cause the car to run rough at idle.
ErikS Posted July 19, 2013 Report Posted July 19, 2013 You are on TT, right? I have this problem as well after the car sits forever. It resolved once when I loaded the base/stock map, then reloaded a tuned map.
Zappo Posted July 19, 2013 Author Report Posted July 19, 2013 My car is a daily driver. I can reload the map and see what happens, but I don't think that is the problem. Tried the new temp sensor, same issue.
mercuric Posted July 19, 2013 Report Posted July 19, 2013 Could be some electrical issue where the ECU thinks the AC compressor is on. When the ECU thinks the AC is on, it adds in additional IAC action to compensate for the load of the AC compressor. It will also kick the fan on low speed based on the AC system pressure. If it thinks the AC is on when it's actually not, idle compensation for AC can lead to high idle, and with the AC pressure out of range, the fan running low speed. Haven't experienced this before, just an idea based on what I know about how the ECU handles the fan. ECT and AC pressure are two external inputs it uses to determine cooling fan operation.
Zappo Posted July 19, 2013 Author Report Posted July 19, 2013 Could be some electrical issue where the ECU thinks the AC compressor is on. When the ECU thinks the AC is on, it adds in additional IAC action to compensate for the load of the AC compressor. It will also kick the fan on low speed based on the AC system pressure. If it thinks the AC is on when it's actually not, idle compensation for AC can lead to high idle, and with the AC pressure out of range, the fan running low speed. Haven't experienced this before, just an idea based on what I know about how the ECU handles the fan. ECT and AC pressure are two external inputs it uses to determine cooling fan operation. See, this seems more likely to be the problem, however the AC switch is off and the compressor clutch is not trying to engage. The problem is related to the IAC, which is why I thought it might be an AC issue as well. I tried turning the AC on and back off again, but turning the AC on did cause the RPMs to drop and turning it off didn't solve the issue. I believe the IAC is running BECAUSE the fan is on. The fact that it continues to run more than 30 seconds after the key has been removed is the odd part.
Zappo Posted July 21, 2013 Author Report Posted July 21, 2013 You are on TT, right? I have this problem as well after the car sits forever. It resolved once when I loaded the base/stock map, then reloaded a tuned map. Wasn't TT. I flashed another map, but the fan came on immediately without even starting the car. Any other ideas?
ErikS Posted July 22, 2013 Report Posted July 22, 2013 Wasn't TT. I flashed another map, but the fan came on immediately without even starting the car. Any other ideas? Did you load the stock map, then your tuned map? Is there a way for you to check and see if there are any climate control codes? Do you have another ECU to swap in and see if the problem persists?
Zappo Posted July 22, 2013 Author Report Posted July 22, 2013 I still have an IPD stage 3 ECU. The car won't run right with it because the injector size is wrong, but I don't have to start the car to test the problem.
Zappo Posted July 22, 2013 Author Report Posted July 22, 2013 Did you load the stock map, then your tuned map? Is there a way for you to check and see if there are any climate control codes? Do you have another ECU to swap in and see if the problem persists? Ok, the fan doesn't kick on with the other ECU. Switch back to TT and it does. I will try flashing the stock map and see what happens.
Zappo Posted July 22, 2013 Author Report Posted July 22, 2013 Ok, flashed standard map, fan still comes on. Flashed to base performance map, fan still comes on. Flashed back to my current map, Fan still comes on. Switch to IPD ecu, fan stays off. I have posted a question on the TT forum now.
ErikS Posted July 23, 2013 Report Posted July 23, 2013 Great, let me know what Adam has to say about it. It is an annoying problem!
Recommended Posts
Archived
This topic is now archived and is closed to further replies.