I've been trying to get the car to idle for the past week. It cold starts fine and idles around 1300 and slowly lowers as it gets to operating temp with AFs in low 13's. As it nears operating temp it goes into a lumpy idle but not too bad. Then when the fan kicks on it goes the idle becomes erratic and the datalog shows the AFs going back and forth from lean to rich. When the fan shuts off it takes it a while to settle. Now I've been able to get it to idle smoothly at 900 rpms and have it compensate for when the fan comes on as well. The only thing is that it will only idle smoothly richer than 12:1 AF, any leaner and it gets lumpy and feels like it missfires. I tried leaning it out to mid 14s and playing with the timing but it does not help. Any suggestions? Also, would my alternator be going bad if everytime the fan comes on it shocks the system to the point the s300 stops datalogging?

 

It helps when you list the specifics of your set-up. But that's just me.

 

what type of injectors?

low/high impedence

 

83mm 9.8:1 ratio
Ramhorn with 60trim and 3in turbo back
ported head and port matched VictorX and 70mm TB
1000cc precision injectors P/H
S300
PLX M300 with brand new sensor.

Only change from before is the ported head and TB. It used to overheat so I changed the head gasket and swapped the head while I was at it. It was already tuned for WOT but we could not fix the idling problem.

 

Sounds like a bad alternator, since it can't deal with high-current devices starting up. It also sounds like you need to adjust your battery voltage/offset tables, I don't remember if S300 has them.

You might also have a bad injector. Take a look at your plugs when you run it in the 12's. If one is clearly lighter than the others, it may be clogged.

 

Cams?

 

I think the alternator is bad too. I am using the Spal 13in fan off a relay using the stock wiring as the trigger. How can I check to see if the alternator is working fine?

S300 fills in the injector battery offsets when you input the size. I changed the tables to match the ones provided here http://injector-rehab.com/kbse/lag.htm but it did not help. I sent out the injectors for cleaning about 6 months ago so they should be fine. I will check the plugs though.

I forgot to mention that I did install Stage 1 cams. I thought they were the problem so I pulled them and installed the old ones and same thing so I put the Stage 1 back in. The valve lash was adjusted each time.

 

I was thinking battery tables as well..

I have had lots of problems out of the precision 1ks.. Several different sets, with idling issues. Crome seems to require a richer mixture to idle smooth than the ectune tuned cars we have both running the p 1ks.

We had a set that would idle in the 15s at one stop light, then 100ft away the next stop light it would idle in the 9s.

I personally am going to the bosch 1k saturated.

 

I just read Alpha's review on the Bosch's and they sound very tempting but I know I can do something about this.

 

I just remembered something else...last night I was checking the timing with the gun and I accidently pulled the negative cable off the battery and the engine died. This would mean the alternator is not charging, right? If this is the case then would that cause idling problems as well?

 

Most auto parts stores will check your alternator for free.Sounds as if you need a new one.

 

put a volt meter on your battery, turn car on see if volts rise from 12 to 13-15 if they rise and stay steady with the engine reving your alt is most likely good and it doesnt then it is junk

 

I checked the alternator and it is good!