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Power FC idle issue

3K views 15 replies 7 participants last post by  MerryFrankster 
#1 ·
My 2ZZ Spyder is having some idling issue and I’m looking for some suggestions. I looked at all the likely causes already and this one seems a little strange.

The car has the basic intake/header/cat/exhaust bolt ons. With the stock ECU, idle is usually around 900-1000rpm. Last week I installed a Power FC with MWR map. Did the idle learn and it settled at 900. So far so good. Next day when I drove it, it idled at something like 1700rpm. Change the idle setting for cutoff to about 300rpm above idle, re-did idle learn, it settled at 900 again. The fan never turned on though, and the A/C kept coming on and off during the last 10 min. Restarted the car and it’s at a nice 900 even after revving the engine. Sou’westers happy. Next day, 1500rpm idle.

The IAC appears to work fine, since it get me down to 900 during the learning process. The previous owner changed it a couple years ago, so it’s not that old. And I found no leaks. Plugs and coil were new last year. The MAF is dirty so I’ll be cleaning that as well as replacing the air filter. While I’m waiting for parts, any other idea what may cause this? It’s completely baffling. Otherwise the car pulls strong.
 
#3 ·
The MWR map is supposed to be pretty close, which is part of the reason why I bought it over other ecu since I don’t have a lot of access to tuners experiences with Vtec or VVTLi. It’ll a shame if it was off by that much. It idles smooth when it does, so I’m guessing the afr is close. No wideband yet. I’ll need to get an extra bung welded on first. Cat pipe only has one bung pre-cat.

How does afr change idle speed?
 
#4 · (Edited)
It sounds like your PFC is forgetting the idle. This could happen if it is not getting a continuous power supply with key off. I would check the BATT pin on the ECU connector harness (connector A pin 1) and make sure it is at 12v with key off.

PS> AC coming on and off by itself is a weird one. If idling for 30 min you do expect the radiator cooling fan to kick on and off at some point as the coolant heats up, but this should not affect a/c.
 
#6 ·
It sure feels like it never remembered the idle learn. I’ll check the pin voltage tomorrow. I do have dome light which runs in the same circuit. So the circuit works. Maybe the connect wasn’t in all the way? That would be too simple.

Yes the A/C thing was a little strange. The radiator fan actually never turned on throughout the 30 min. Just the compressor clicking on and off. This was confirmed by the sensor screen. According to the Japanese manual, it looks like the idle learn is actually 5 min no load, 5 min E/L only, 5 min AC only, and 5 min E/L + A/C.
 
#9 ·
Checked the ecu power pin last night, it has constant 12V, so that was good. Put everything back together and did the idle learn today, and it was behaving about the same. As soon as I gave it a little throttle, it started surging as well as with AC on. The problem turned out to be O2 feedback not working well. As soon as I turned it off, everything was fine. Restarted it twice and it idled good. Of course it did last time too, so I’ll see what happens when I drives it tomorrow.

O2 feedback not working kind of sucks, but it’s a Autox/track car with occasional street used and driving to/from events, so I guess that makes it a little more acceptable. Now I did recall reading somewhere O2 feedback was poorly implemented on the PFC.

Anybody know what temperature the radiator fan is supposed to turn on? I have yet to see the radiator fan turns on during all the idling. Coolant was up to 85C (185F).
 
#10 ·
Hungdy :

The Spyder has well coolant system. On my daily Spyder, the radiator fan turn's on only in summer days or long high load (on track).

To me, your don't have the good PFC idle learning procedure. I tried it too and it didn't work.
My right PFC idle procedure is : 1st step (15min first start with nothing turned on) _ 2nd step (15min with AC/headlights/rear defrost turned on).
If you let the engine learning right, you could hear/see smoother/lower idle during 1st step after 10min.

With PFC tune, my wideband show this :
- 14,2 to 14,9 (good idle learning procedure)
- 13,6 to 15,7 (none/bad learning procedure, and the rpm idle go up slightly after headlight turn on)

On idle, if AFR show 9 (rich>too much fuel), idle will decreasing drasticly at 350rpm with strong gasoline smell.
Maybe my video can help you (show AFR on cold idle/smooth load/high load) : https://www.youtube.com/watch?v=kbe0lsgRmr4
 
#11 ·
According to the repair manual, the cooling fan operating limits are 83°C (181°F) and 93°C (199°F). This means the cooling fan comes on when the temperature reaches 199°F then shuts off when the temperature drops to 181°F. The temperature is measured by the ECT sensor at the engine's water outlet. I don't know whether these operating temps can be re-set in the PFC.

To test the cooling fan at idle, rev the engine to 2500 RPM for as long as needed to reach the fan's operating temp. As suggested in the BGB, if the temp goes above 199°F and the fan does not come one then you should check your fan's motor, its wiring, fuses, relays, and the ECT sensor.

You can also test the system by disconnecting the ECT sensor from the harness. According to the repair manual, with the sensor disconnected, the fan should come on and stay on.
 
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