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Zetec startup issue - going lean after closed loop

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dhardison

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Discussion starter · #1 · (Edited)
I just re-installed my stock Zetec and I'm having some idling issues. It starts/idles fine and has good AFR (14.4:1-14:8:1) while in OPEN loop. However, just as soon as it goes in to CLOSED loop it goes extremely lean (17:1-18:1) and starts to sputter, then eventually dies. I can start it right up again (starts in open loop) and the process repeats itself.

The only codes it's intermittently throwing are P0000 and P0443. I'm running a stock tune from FocusSport. Everything is stock with regard to the engine, intake, injectors, throttle body, etc. The only non-stock items are a SVT header & ORP. The primary o2 sensor is installed right after the header flange and the wide band a little farther down stream. The second o2 is not installed or even plugged in.

I've check for vacuum leaks, unmetered air and the usual unplugged sensors, but I don't see anything wrong. Also the EGR and DPFE systems/sensors are long gone.

Any thoughts on what might be the issue or things I should check?
 
Discussion starter · #2 ·
Ok, I found that the vacuum line from the fuel rail was not hooked up. Hooked it up to the intake monifold, but same issue.

Next I swapped out the MAF (had a new one on hand), but still the same issue.

Now when I start it, it goes lean even before going out of OPEN loop. I just don't see any thing wrong....
 
#3 ·
PCV issue.
The breather system is capable of flowing more air than the IACV is capable of handling. The IACV has a minimum duty cycle that is allowed (I think) and the flow from the PCV is enough that at idle the car will go lean.
Only reason I suspect this is I have no PCV right now and at idle I go WAY lean, not sure how lean because it's off the gauge, just reads lean. Car hasn't stalled yet though.

So try this,
Cap the PCV line at the back of the intake manifold and leave both the PCV and VC breather ports open. What happens to the AFR now?
 
Discussion starter · #4 ·
FordFociSHO said:
So try this,
Cap the PCV line at the back of the intake manifold and leave both the PCV and VC breather ports open. What happens to the AFR now?
Click to expand...
Ok thx, gave that a try. I left the breather at the valve cover open and capped off the port on the intake tube. I also pulled the vacuum line from the PCV at the intake and plugged that port. Restarte and same issue.

Basically it starts great, idles at 14.7:1 for 5-10 secs, then about 10 sec before going in to closed loop it goes lean (off the AFR gauge).

Possibly an injector issue?
 
#5 · (Edited)
Now you got me wondering if mine really works like I think or not. I'm gong to go out and look at a few thing, fuel rail pressure sensor may be bad? dunno...


OK. When mine starts idiling goofy it goes into "open loop" idle and out of "closed loop". Digging to find out why.
Lowest IACV duty cycle I see is ~19%.
Lowest injector P/W is 2.7ms.

The thing that does look suspect is my fuel pressure. Labels got screwed up but I think I have the right one, and it looks like when my idle goes screwey my fuel pressure drops to about 20psi give-r-take. Blip the throttle and it jumps back up to about 40. I have no problems WOT with fuel starvation at all, the opposite actually. But maybe some of that will help.

Thinking dirty ground to the FPM, under the rear seat, dirty fuel filter, dirty fuel pump 'sock' filter.

I didn't log the amperage of the FP, but that might give an indication if the pump/lines/filters are dirty.
 
Discussion starter · #6 ·
I broke out the brake cleaner spray and started spraying everything in sight while the engine was idling. It didn't detect any vacuum leaks. When it starts to go lean I can spray the brake cleaner at the air filter and the AFR goes back to normal as expected.

I also hooked up a fuel pressure gauge and it hold 50lbs from startup until it dies. One thing I did notice is that when the AFR goes lean the timing also increases. When I first start it, the timing is around 22*, but when it finally dies it's around 34*. I dunno.......
 
#7 ·
I gotta let the laptop recharge and I'll have another crack at it and try to upload a log so you can compare (in .cvs, Excel format). I'm using a scan tool/software called ScanXL with the Ford Module (which I'd of gone a different path and with a Quarterhorse, nother time).
 
#9 · (Edited)
Spark advance for sure. Do you have something like 'Fuel System Status; open/closed loop'?


Got a good log, labeled right and when my idle goes to open loop from closed my spark advance jumps, from ~20* to ~38* ... blip the throttle and get it back into closed loop and advance is back to normal ... let it idle and it reoccurs.
Also Short Term Fuel Trim ... when the event occurs my STFT drops to zero.

I haven't found what exactly triggers it though. Letting the computer reset right now because I do have some PCM programming code stored, PO604. Figure it's due to my chip but just in case ...


Here is my log file,
http://www.4shared.com/file/1Xh6sgYF/low-idle.html

hate reading these things, the second tab and graph is quicker/easier.


Gonna play more tomorrow ...
 
Discussion starter · #11 ·
FSWerksVP said:
Dumb it down. Flash the car with the same program to reset the KAM and trims. Or better yet, try flashing the car back to stock.
Click to expand...
Unfortunately I can't flash the car back to stock. When I bought the car it had a JRSC and associated tune loaded in the ECU. So, when I first used the SCT it pulled the JRSC as the 'stock' tune. The closest thing I have to a stock tune are the JFA8 tunes I received with the SCT from you guys. Is there any way (other than going to a stealership) to get it back to a factory stock tune?

Thanks,
Dan
 
Discussion starter · #13 ·
FSWerksVP said:
You can order a 100% stock program from us. The flasher will treat it as a performance file and it will be in one of the slots, but it can be made with ZERO changes and just be stock values.
Click to expand...
Sounds good, thx. Can I order that online or will I need to call? If so, are you open Monday?

The tune from you guys that I have loaded now worked perfectly on my old '00 ZX3 (SCCA SSC race car), so I'm not sure why it would be a problem with my current stock combo. :dunno:
 
#16 ·
You don't happen to have a spare primary O2 sensor you can swap in? I suspect that the one on the car is malfunctioning.
 
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Discussion starter · #18 ·
Swapped in a new primary O2 sensor, then disconnected the battery for ~45 mins, then reloaded the stock FS tune. Started up fine, ran for 10-15 secs, then when it went in to closed loop it went dead lean and died. Same issue, no difference. :dunno:
 
#19 · (Edited)
Was waiting to see if the stock tune worked or not. I think I got mine licked, but I'll have to log here to see. The intake gasket nearest the alternator seemed to be leaking, or it might of been the injector O-ring with the chunk missing (but injector wasn't leaking).

back in an hour or so ...


OK. I logged/let the car idle for a good 40 minutes. I couldn't get the car to go lean idle/erratic timing on it's own. So I created a small vacuum leak (pulled the vacuum line off the EVAP canister). O2 voltage went way lean, STFT dropped to 0% and timing rose.

Log --> (when the rain stops, playing hell with my connection right now)

The first few very lean spots are from me pumping the brake peddle. Trying to get the car to stay lean. It wouldn't.
Ignore the EVR/EGR/EVAP stuff. Was just logging them to see if they had any effect, don't seem to far as I can tell. I can't be sure for you though, I don't have EGR ... the voltage changing is me grounding the connector for it (jumper wire).



Basically I'm going to go with a small vacuum leak somewhere. It's the only thing I can replicate and come up with. I know the intake gaskets are a poor design ... if you over-tighten the manifold the gaskets twist a bit, under and they leak, damn balancing act that I just hate. I RTV'd my gaskets just to be sure and it seemed to work. That stupid O-ring on the MAFS could be giving problems or it could be the TB gasket (another stupid O-ring).

Christ I miss the days of METAL that wasn't subject to heat damage, didn't strip at the first sign of over TQing, didn't degrade overtime ... screw you DuPont. LOL
 
Discussion starter · #20 ·
I'm going to be REAL surprised if the stock tune fixes my issue. I'm thinking it's more of an unmetered air issue, I just can't narrow down from where that air might be entering. The only previously untested piece I have installed is a '02 factory plastic intake, so I'm thinking that might be the culprit. As I mentioned, I've sprayed a couple cans of brake cleaner as well as trying propane gas all around the intake/vacuum lines/tb/etc. With both of these sprays I can get the idle/AFR to clear out when spraying in certain areas, but when I try those areas a second time it does nothing, so again, I dunno.... :dunno:
 
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