Stevey629

Symptom: Surging between 800 up to 2500. The idle goes up to 2500, then back down to 800 consistently. It drives perfectly otherwise. The bizarre thing is that once I turn on the A/C, the idle balances out and is rock solid stable. The moment I turn the A/C off, it surges again. Check sig for mod list, I had fuel work done recently, if that makes any difference. Oh I have also lost my rear defroster for some reason. Clicking the button does nothing, when I used to see the little yellow light turn on and it actually functioned, now it's dead. I have a feeling that possibly both of these problems are something electrical and not mechanical, but who knows.

spoolage

iTrader: (2)

Hey... I will put $10.00 down that your AFR's are off and if that is not the case you might have a compression issue. Just hope it is your air fuel ratio tho.

The reason why your idle is solid with the A/C on is likely due to the fact that the engine is running at a higher load due to the compressor kicking in to pressurize the A/C system.

Stevey629

So, fixing this issue is going to require a retune. It seems my power FC is locked, meaning I can't get in there and probably for good reason because I would undoubtedly make a mistake because I have no F'ing clue what I'm doing when it comes to tuning of any kind. In either case however, the shop I took it to most likely would have been able to fix it but because of the lock that XS engineering put on the computer, I have to go back up to them to fix the problem unless some of you know how to otherwise. I don't have a commander, so I can't tell whats happening or whats wrong with the idle and its associated components either.

Sr20fd3st

thats weird that they would lock your pfc. check the idle speed controller as well as check for vacuum leaks.

CantGoStraight

There's a procedure in the FSM for setting up the idle so it's the same without heavey engine electrical load and stays the same with the electrical load. Just follow the procedure for setting the TB idle for both conditions.

Sr20fd3st

just jump the ten and ground in the diagnostic and while it's running it will disable the idle speed controller so you can lock in your idle with the isc turned off. then just pull the jumper wire and the ecu will figure thigns out from there..or atleast it's supposed to

Stevey629

Huh? I'm terrible with electronics. jump the 10? and wheres the diagnostic? Are these both in the fuse box? I don't have access to the FSM either, and I'm wondering if the idle adjustment is mechanical or computer related. Of course this may depend on whether or not I have a vacuum leak as well. Sigh. What to do. I'm so lost, but you guys sound like you know what you're talking about. I'm just having a hard time comprehending.

Sr20fd3st

eh...theres a black box about 1 inch by 1 inch under the hood, just left of the strut tower when looking from the drivers side. it sits next to 2 gray boxes which are harness plugs. It saiy Diagnostic on it open it up. it shoudl have a chart under it. there are little holes in the connector with metal pins in them. the one you are looking for is marked TEN not 10. then there should be another (theres 2 of these actually) marked GRD or GRND or similar for GROUND. take a piece of wire and stick in in the TEN hole and the other end of it into the GROUND hole. this si what you use to pull codes as well as deactivate the idle speed controller while the car's running. idle adjustment is both mechaniclly set and ecu controlled. once you have it set correctly mechanically, you can pull the wire out of the diagnostic connector and the ISC will take over and take care of adjusting idle under loads like A/C and steering, cold weather, all that. make sure to adjust your idle when the engine is at full operating temp. take the FSM from there.

Sr20fd3st

buy Carb Cleaner at a parts store and if you can, set you idle to around 1000 rpm with the set screw at the bottom of the throttle body. spray the carb cleaner around the manifold, around vac hoses, uim flange, injectors, wherever. if the motor starts to stumble and almost die for a moment then you sprayed it on a spot that is leaking vacuum, since the vacuum would have sucked in the carb cleaner.

Milwgearhead

This is clearly a PFC problem. They all do that, ESPECIALLY if you just had some fuel adjustments made on the map. My PFC has done this SEVERAL times, and it's totally normal, my friends' have done it as well. Just drive the car for a while, it should drive itself out.

Of course, if your sh*t blows up, I guess I was wrong. But if the car runs fine other than your pulsing idle, 9 times out of 10 that's what it is.

Stevey629

So, drive the car...and it fixes itself? Why does that seem too easy?

Sr20fd3st

happens to alot of us i think..these problems sometimes drive themselves out..somehow..perhaps you had a vac leak that sealed itself somehow, maybe a gasket sealed itself finally, maybe the injector nozzle seat had crap on it making it run rich since it may not have been closing all the way making the idle surge like that, and the crapcould have worked itself off or w/e...

TT_Rotary

iTrader: (3)

mine did the same problem, i just set the idle sensor myself and it fixed. somebody has ur idle sensor outta whack. maybe when some1 rebuilt ur engine, or someone trying to tune it up to put out more power than it can handle, just tune it back down.. idle should be at 720.. thats factory idle.

rynberg

It's likely a combination of the PFC and the bleed-air screw fighting each other. Given how much XS charges to tune PFCs, I wonder why you aren't bugging THEM to fix it. They cannot lock the programming on the PFC. But they do jack with the base map so you have to have a Datalogit to see what they really did. Them jacking with the base map could be responsible for the idle instability.

That said, there are other possible causes, such as an electrical issue. You really should have a Commander or the Datalogit so you could monitor the sensor readouts.

rxcited2

Sounds like typical PFC ISC learning. Have you tried just letting it idle for 10 minutes when it starts surging? I think the "driving the problem out" observations are just that - the PFC learning. The initial installation calls for 10 minutes of idle with no electrical load, 10 minutes with rear defroster and 10 with A/C. I have found that when you change things (either settings or maps) it some times needs to learn again. Just drive around and when it happens take it out of gear, foot off accelerator, coast to the side of the road and let it do its thing until it evens out, or 10 minutes, whichever is longer!! If it doesn't even out, then there may be a problem: call XS!!

Sr20fd3st

i want a PFC so badly..if only they were only 200 bucks

rxcited2

Dunno if this applies when you have a PFC. Remember it is replacing the entire stock ECU. The PFC certainly does not behave identically in many respects - for example controlling the Check Engine Light. I don't know whether the jumper procedure works with the PFC or not, but I doubt it. When I want stock behavior, I stick the stock ECU back in there!

Your point about adjusting the idle without ISC is right on though. If the mechanical adjustments are whacked, it could be what is causing the PFC to have problems learning.

Sr20fd3st

yea the isc has to be blanked or zero'd while the idle is mechanically set at the proper value, so the ISC can make it's corrections based on the correct idle to begin with and so it can make +/- idle adjustments from that point...if it's already maxxed out at the lowest of its adjustibility when you set your idle mechanically, then it cant electronically decrease idle. cant you override the isc by jumpin TEN and Ground while it's running?

Sr20fd3st

make sure your not running rich, maybe the a/c is putting just enough load on it to where the load is actually needing the extra fuel and balancing out. could be just a few points over on your idle. check your idle map and maybe drop a few percentage points down and see what happens, do it till it flattens out a bit. lean idle mixture makes it slowly stumble and die usually, and rich makes it surge. see what happens...also make sure your fuel pressure gauge is working, or that the vac line to it is not blocked and flowing. idle vac is what decreases the Fuel pressure, and it increases from there. if therse no vac i will up the pressure to that of what it would be if you were drivign around with partial throttle at 0 vac... maybe use some injector cleaner in the fuel tank to make sure your injectors are clean...

Stevey629

This is impossible to do without the commander. Even if I had one though, I still am too scared to mess with one. Is anyone around here locally that knows how to fix this problem and has a commander/datalogit? I'd appreciate the help before I go up to XS engineering and pay a fortune to have them do this. Beer and lunch is on me if you do. I also noticed my rear defroster just doesn't even turn on anymore ever since having the fuel work done. I noticed that RXCITED mentioned something about 10 mins with different devices on while the car idles. I'm wondering if my rear defroster being broken might have something to do with it. Or, is the defroster broken (not turning on more correctly) because of the PFC. *Scratches head*

rxcited2

The PFC does not break the defroster. That procedure I mentioned is in the PFC installation manual. The point of the defroster is to activate an electrical load. This closes a particular relay which the PFC notices and uses a separate idle speed and learning curve for this situation. Then with the A/C on, another relay closes, again notifying the PFC which has a separate idle speed and learning curve for this.

If your defroster is not working, check the connections and fuses. But you can also cause the electrical load condition by turning on your fan (interior air without A/C) to speed 3 or 4. You mentioned turning on the A/C quieted it down. Turn it all off, let it go whacko, then try speed 3 or 4 on your fan. What happens?

This is all just out of curiousity. Even if it works with E/L, this only means it is able to learn for E/L and for A/C, but still is having difficulty with no loads. Personally I think XS ought to fix this without charge. Clearly they did the work which is causing the problem. I suppose the increased fuel delivery could be part of the problem. Do you know if they checked your fuel pressure to ensure it is still correct after upgrading the pump?

Finally if you were going to try to fix this blind (no Commander and no Datalogit), I would try adjusting the wax rod out of the way. I think this means turn the adjustment screw in all the way. The fast idle cam ought to just not touch the wax rod at all, cold or not, after you do this. I was having the fast idle problem too until I did this. It might be that I could have adjusted it "correctly" so it worked properly and did a mild fast idle while cold. But in my case, I just didn't want the fast idle at all, even when cold. It is a stab in the dark, but I would lay money on this being your problem.

Stevey629

OK, with the fan on, no A/C, the same result of the surging idle is apparent. The idle is no different with the fan running at 4 v.s. off. Once the A/C is on, it runs fine again.

rxcited2

So it idles OK with AC, but not with EL and not with no loads. You have a problem. Duh.

Take it back to XS and make them fix it for free, or...

Take it back to XS and pay through the nose to have them fix it, or...

Try my suggestion and adjust the wax rod out of the way...

Your choice!

Sr20fd3st

or, remove the wax rod and cold start system all together with the uim butterflies.

rxcited2

There isn't any reason not to remove the uim butterflies (AKA double throttle) provided you can control yourself and let her warm up before boosting. Same goes for the accelerated warmup system (AWS) - just fire her up and let her come up to temperature in her own sweet time. The wax rod system actually makes a little more sense to me: adjust the idle speed upwards when its cold. But it seems with lots of mods and with the PFC, often this needs to be either readjusted or disabled. With lots of mods, the car is louder and I would just rather disable this too. I have been very happy with it out of the way.

Now I am seriously looking into a keyless entry/remote start system! It would really make my morning routine easy if I could just fire her up a few minutes before I walk out there in the mornings...