thewird

iTrader: (8)

I'm wondering how the FPR solenoid works. More specifically under what conditions does it close off vacuum to the regulator. Does it activate every time the car is started or only during hot starts? I'm considering putting mine back in.

The reason I'm asking is I seem to be having an issue where to car will die when its cold in about 5 seconds after it has started. When I start the car again, it idles fine after that. I've let the wideband warm up before to see what its doing and it seems to get slightly leaner before it instantly shuts off without the vacuum changing at all.

If I hold the throttle up at say 2600 rpm, it won't die but it will drop a few hundred rpm and then come up and be fine. It only happens on the first 5-10 seconds of a cold engine so I think it has to do with all the internals warming up.

I've tried resetting the tps and adjusting the idle screw, air bleeder, and the thermowax screw but it seems the problem is always there.

thewird

thewird

iTrader: (8)

I tried to make a video of it happening but it didn't happen. Figures >_>. I'll try tomorrow morning again, maybe it wasn't cold enough.

thewird

arghx

iTrader: (3)

The solenoid only comes on when fuel temps are really high. See the workshop manual. I know about the problem yhou are experiencing. Try increasing the water temp correction.

thewird

iTrader: (8)

I've tried that but that just makes the car run rich after it passes that initial warmup point. It's literally the first 5-20 seconds of a completely cold engine (it varies depending on how cold it actually is). Once it passes that point, it idles fine even if its -10*C water temps (yes, i've started my car that cold ).

Since I have my fuel temp sensor unplugged, it reads 5 volts. Would that mean its always triggering the FPR solenoid? How long is the solenoid triggered for anyway? I have this idea in my mind that its 30 seconds but not sure if I read that somewhere or I imagined it.

Anyway, here is my fail video of trying to replicate it... Wasn't gonna post it but since I made it, might as well haha. Excuse the dirtyness of my car, I haven't had a chance to clean it since I got back from the DGRR >.<

http://www.youtube.com/watch?v=4S1ZXFnYn90

thewird

Double_J

iTrader: (28)

Can you explain the purpose of the solenoid and its impact on fuel pressure?

thewird

iTrader: (8)

The purpose of the FPR solenoid is to take away vacuum during hot starts for easier starting. I just wasn't sure if it was also active during cold starts. It does nothing after the car is running (or at least a properly functioning one should do nothing).

thewird

arghx

iTrader: (3)

The FPR solenoid is to prevent vapor lock or rough idle on hot starts only. On the FD it's only active when fuel temp is over 50 C, water temp is over 70 C, throttle position is less than 30% and the shifter is in neutral. There is a 90 second timer for it to remain active. It's all right there in the diagram of the AND gate logic. FYI the FC's didn't have a fuel temp sensor so it was based on IAT.

I recommend you go into diagnostic mode (INJ/IGL/IGT screen) on the Commander and experiment with adding fuel and timing to see if the engine will stay alive. I have run into this problem before and it was solved with more water temp enrichment. I'm not sure if there is some quirk in the PFC's logic or what.

What idle setup is on this vehicle--what is used to control idle?

Double_J

iTrader: (28)

Bah I was hoping this solenoid was causing my issue, the fuel pressure to dropping when the car gets hot.

If it's only impact it has is when the car is in neutral with small throttle response then that rules out my problem.

thewird

iTrader: (8)

Currently I have it setup with the computer controlling the idle (ignition) as I found thats the way it runs best in all conditions. The ACV is removed along with pretty much everything else lol. I used to run manual idle control which works well since you can pull the highest vacuum by increasing the timing but say on hot days with all the lights and accessories on, the idle would drop too much for my liking. With the computer controlling the ignition its a lot closer to my target in all conditions.

I had the problem last year (although it was much worse before) and just assumed it was from the one piece ceramic apex seals and the large 750cc primaries. This year I switched to 2 piece ceramic seals and 650cc primaries and its a lot better where I can idle the car how I want. And even seemed to fix the issue somewhat since it doesn't happen every cold start now.

Really the issue isn't that big of a deal. It seems I've gone from the point of taking everything off to start putting stuff back on to make the car run more like stock lol. I had the thermowax removed until recently when I put it back on so I don't have to push the accelerator in when I start the car cold.

You know though, you might be right about the water temp corrections. I've been taking % out from my previous settings so the car idles lean under all conditions as you can see from my short video it idles steady 13's even though its cold. I'll play with it some more. It's one of those tuning things that takes a while since you can only do it during cold starts which basically limits it to once a day and you have a very short time to test things hehe.

thewird

arghx

iTrader: (3)

I ran into this exact problem on an FD with 3mm RA classic seals. I had been leaning out the water temp correction just as you described, to keep the idle just lean enough. But I guess I went too far.

And I hear you about the manual idle control etc. I think manual idle control is a good setup but it's not for everyone. One thing I noticed though is that the engine will run in manual idle control (in terms of the timing) until it is warmed up to around 60 C. That is with Idle IG control on, O2 feedback off. Another thing you should do is datalog your ISC duty cycle. It is erroneously listed as "Advance ??? (2)" . the values are from 0-1000, where 1000 is 100% duty and 0 is 0% duty.

thewird

iTrader: (8)

I don't have the ISC installed. I noticed the same about when the IGN control actually kicks in at 60*C but the car usually idles high when cold (even without the thermowax) so its not a big deal. I also have higher timing set on the idle section then the IGN controll normally does anyway.

thewird

arghx

iTrader: (3)

I've recently been doing some experiments with warmup timing. I've found that less timing during warmup seems to help the popping and missing that some engines seem to have. The higher advance also results in a higher idle, as you'd expect. Then when you get to around 60C the PFC will take over idle timing and probably run less advance. That usually makes the idle drop down and smooth out.