dsm lean at idle and surging

[Laggg]

Alright i got my dsm to finally run and drive but i have a extended crank time of maybe 15-25 seconds. Then it barelys starts and fires up to normal and runs super lean


adjusted tps
changed the isc
brand new stock o2
ecu is good
did a boost leak test no leaks anywhere
temp sensor is good
no CEL light
fuel pump is on and not spraying back down into the tank.
battery relocation to the trunk with proper cables and all grounded.
fuel pump rewire
plugs are good
coil is good
i got fuel to the rail
injectors have correct voltage




i have no tuning device is this car is mostly stock. anyone got any ideas? Ive tried just about everything to get it to start properly and run normal. Thanks

 

[WES_393]

When you say not spraying back into the tank, do you mean the return isn't flowing any fuel? Or that the fuel pump is sealing well against the hanger?

 

[Laggg]

sorry about not being clear on that, its sealed up well against the hanger

 

[WES_393]

When you did the boost leak test, did you spray soapy water everywhere including the throttle body? Have you tried adjusting the BISS according to VFAQ to get the idle under control?

1G BISS Adjustment

 

[Laggg]

yes, i did the soapy water all over the air intake system(turbo piping,cooler,couplers,vac lines,intake to throttlebody) nothing produced out of it. and my BISS screw was removed and filled with red silicone i believe( previous owner did it) but i would run rich i assume from it being filled.

 

[WES_393]

Well the BISS is supposed to have a cap, but over time they got lost/broken and shows that the BISS O-ring leaks during BLT's. Quick fix: Fill it with silicone. It doesn't draw in unmetered air so it wouldn't affect A/F ratio so long as it doesn't leak. If the BISS screw truly is missing, it could be the exact reason your idle is surging. It is what sets the base idle speed (hence the name Base Idle Speed Set Screw). If it's missing or adjusted too far out, it will bypass enough air to let the RPM's raise to the point of surging.

The reason behind idle surge is that the RPM's raise past ~1500rpm without the TPS moving. The ECU sees this as an issue and cuts fuel until the RPM's drop to the point that the engine almost dies. The ECU kicks the fuel back on to keep the engine running, the RPM's raise without being "told" to do so, and the cycle repeats. For this reason you can't really rely on your A/F ratio when your surging. It will constantly fluctuate as the ECU struggles to keep the idle under control.

I would suggest taking a screw driver or razor blade to all that silicone to find out the condition of the BISS. Then attempt the VFAQ idle adjustment in hopes of getting the idle under control. Once the car idles at even a fairly decent rate (at least not surging), you should be able to get a much more accurate reading of the A/F ratio. But typically running lean and surging is a sign of a vacuum leak, most likely after the throttle body. So if playing with the BISS won't help the idle surge, I'd give the intake manifold area another look.

Also, are you using a narrowband or wideband?

 

[xxNocturnalxx]

Get this stuff, biss screw (if needed), o-ring, cap, they can be had from extremepsi for cheap. You'll need to fix the previous owners hack job first. Also I have never seen a stock dsm throttle body pass a BLT. I recommend going to throttlebodys.com if you decide to get a re-built TB all together.

EXTREME PSI : Your #1 Source for In Stock Performance Parts

 

[toppertopper]

Are you sure the silicone isn't over top of the bliss screw ..I have seen people do that

 

[Marceldsm]

i have the same exact problem right new

running super lean at idle surging and sometimes stalling

let me know if you find out the problem

cose i did everyting

tps ajustment
boost leak test
idle speed control test and changed
biss ajustment


its a stupid problem to have

 

[xxNocturnalxx]

Have you tried adjusting the idle stop switch? The one with the single wire on the firewall side?

 

[Laggg]

idle stop switch has been set, still idle surge and super lean



ive also driven it and it runs great when in gear but not when idling. my cheapo autometer hooked my narrowband is showing lean off the charts at idle. gonna change the gauge to a different not so cheap one to see if its any different. could it be the stock fuel regulator not working right? it has pressure through two ports and one is capped. its also off my buddies old 90 gst which ran good.

 

[nlg4021]

Ive been running into some of the same issues with my 1g talon. This may not be the case for you but I stumbled across my issue randomly when I notice my throttle plate wasn't closing all the way. At first by the naked eye I couldnt tell but it had maybe another 1/32" to close. My idle would sometimes be high, low, or it wouldnt idle at all. I adjusted the throttle and cruise cables and havent had another issue. The bracket on the intake manifold is what made the difference for me since it was the primary cause of not letting the plate close completely.

 

[Laggg]

im gonna head to my car shortly and check out the throttlecable, i was thinking the same but never looked into it. im starting to think maybe a faulty FPR.

 

[fonzi90Tsi]

My cars having similar issues but its rich. Ended up finding out my o2 sensor is bad.

 

[Laggg]

i wish it was my sensor, i just bought a brand new one

 

[Abe'sGST]

I would check into the fpr and also replace the fuel filter.

 

[Laggg]

im really thinking its the fpr. my car started today, first try. a little bit of a 5-10 second crank and it fired up. no misses, wasnt lean, no surge. odd. well i turn it off and suddenly it wont start and my cabin reaks of raw fuel. fuel filter is new btw.

 

[xxNocturnalxx]

Nice, at least you know it's fuel related. You didn't mention a fuel smell before though.

 

[Laggg]

that didnt occur till i finally started the car that day and it ran. it was weird. im gonna replace the fpr as soon as i locate one

 

[Laggg]

alright turns out it was the coolant temp sensor was bad and wouldnt let my car restart. disconnected and turn it over and it started. but died out, got a new one and no issues. thanks guys