Running fully lean at idle after warmed up

[GsxMan98]

First off the its a 92 talon tsi mods list is up to date but if i start the car completely cold it will start right up but after like 2 or 3 mins it will sound like its missing then go completely lean. Its not a boost leak because thats what i thought and fixed every single one. Not an exhaust leak because thats also what i thought it was because it had a huge crack in a tubular manifold i had and replaced that and still didnt fix the problem. So if somebody could just help me out it would make my day ive had this car for almost a year and ive drove it 50 miles

 

[1gAWD92]

Havent found much out. im thinking it might have something to do with the fuel pump or filter, then again there are alot of things it could be. the hard part is figuring out what it is...... when i get some days off work ill properly go through all that could cause it and get back to you.....

 

[420a dsm kid]

It couldn't be the fuel pump because I replace mine with a255 walbro and its still running lean...

 

[1gAWD92]

check for leaking injectors, injector voltage, and fuel filter for clogs.

 

[1gAWD92]

update I started the laser up this morning and let it warm up a little bit, and it seemed to run fine! I didn't do anything to the engine other then fixing the lower rad hose leak. I'm going to take it up to a shop and have them look at it and pull some codes.

 

[420a dsm kid]

Hey you haven't found nothing yet

 

[GsxMan98]

The problem with my car was the wiring harness was all hacked up. I changed the wiring harness and it runs good now.

 

[1gAWD92]

the shop guy said it has bin running fine!? i think i might have made a huge noob mistake. i dont think i had enough fuel in the tank! but the laser is still at the shop and im waiting for a phone call so i can have them do a couple things that i havent got around to doing yet. sorry if i wasted anybodys time on this.

Hey you haven't found nothing yet

^^^

The problem with my car was the wiring harness was all hacked up. I changed the wiring harness and it runs good now.

yeah i bet thats another problem too. the last guy that owned the car hacked that crap out of it too.

 

[1gAWD92]

got the car back a few days ago, and it crapped out on me again! had to leave it over night on the side of a parkway. came back the next morning and it started up fine and started to drive the thing back to my house....... and no farther the a mile from my house, the engine cut out on me again!. still siting there. going to tow it home tomorrow and d a fuel pressure test on it......just so i know the stock fuel pressure at the rail should be 42-45psi? is that right?

 

[GsxMan98]

Stock fuel pressure on a manual is 37psi. I could be wrong though.

 

[erkitner]

Gentlemen, (All of you)

Please realize that when you start your car cold the ECU is in "Open Loop Mode". What this means is that the ECU does not take the sensor readings into account until the engine has at least reached operating temperature. What it does is just ASSUME settings and run those until your engine reaches proper op temp. Then the ECU switches to "Closed Loop Mode". Closed Loop is when the engine warms up and THEN starts reading sensors such as coolant temp, timing settings made to the ECU, previously set idle RPMs and such. One of the BIGGEST factors in op temp, idle, smooth operation is AFRs. These are drastically effected if the fuel settings are not perfect. Fuel pressure may be good for your generation of DSM, but the ECU controls the injectors. This needs to be dialed in perfect for the size of injectors applied. A proper tuning program with this ability alleviates this issue.

SIMPLE FIX. Injector deadtime seems to be the main culprit in this situation, as you all describe. So here's what you do. Start the car and let it warm up. Then when your car starts to chug or whatever the hell it's doing, make sure to look at the wideband. Does it read 18s? 17s? Or is it dead by then? If dead, program your ECU to run 450cc injectors. Save to ECU. Then start the engine again. Then increase injector deadtime, save as you go and watch the AFRs get the levels you need. Target 14.7 pump gas. After you run this at 450cc setting and stabilize with this, set your injectors for your applied injector size. Repeat the same steps as before and you fuel issues at idle should be cured.

Starting issues to simply get it fired up are usually coolant temp related. There are much better write-ups on this than I can say. Search them. They're amazing.

I speak from my experience of DSMLink v3. If you have the same control ability with your program, more power to you.

Remember, though, Gents, you cant just bolt on parts and hope they work. The brain of your car (the ECU) must make sense in the overall "equation" of what you want to accomplish...FIRST. THEN the "Holy ****" pull will follow.

I hope this helps.

Cheers, happy tuning and DSM4Life.

 

[1gAWD92]

thanks for your input my man. im running stock 450s with a basically stock engine. the ecu is in mint condition and no tuning of any kind...... but like you said in your post, when it starts to chug and try and cut off, my wideband IS reading 16s and 17s. at that time. ill get you some pics of the ecu and maybe you can tell me what you think.