Narrowing down cold start issue before winter

[tarheels23]

So I have a 90 tsi awd and last winter I had to hold my foot on the gas for about a minture to keep the rpm's up. I just check my isc and all the coils read to 28.
Last winter the coolant lines were just looped and bypassed the fiav but hooked them back up a couple months ago. Now when it's cold I still need to hold my foot on the gas for a few mins to keep the car from dying then after that its fine.

I set the bass idle like vfaq said and then after I pull the negative terminal off the battery to reset the ecu it will run right, idle around 1500 and then slower lower down 750-800 and that only works like that once. Ay other time after I start the car cold its back to holding my foot on the gas till it can stay running on its own.

 

[DSM1G90]

Didn't think about checking the TEMP SENSOR, did yas?

When a TS goes bad, it's telling the ECU that the coolant temp is 77 degrees, thus no FIAV is needed. Now, when it's cold the FIAV is open causing that lean mixture to try to start up a cold motor and it can't keep an idle until things start to get warmed up, then the idle is okey with the lean mixture.

Put a VOM across the TS before starting it and you'll have high resistance. When the coolant warms up, the resistance should be dropping until coolant is fully hot when you should have the lowest resistance. If no change, need to replace the TS - no getting around that.

Did you reset the ISC before messing with the BISS ? Otherwise, you could mess things up pretty bad. Do the resetting (listed in VFAQ) of the ISC, then do your BISS screw settings.

And keep the FIAV connected in the coolant loop at all times. It's done like that for a reason.

Good luck - DSM

 

[xxShaneOmac]

This sounds very similar to a problem that I have. Tell me if this sounds right.

Turning the key gives the car a nice normal strong cranking that sounds like the car is starting but the second you let go of the key the car dies or does not start.


It will only start if while cranking you are giving it gas and if you let off the gas quickly the car dies.

I have never held the gas down or got the car to warm up so I have no clue how it acts at that point, its always been cold.

Thats my current problem.

 

[tarheels23]

yup you turn the key and it will start, the engine will rev up then die, and have to keep your foot on the gas till it will stay running on its own for about a minute or two.

Also I cant find anything on vfaq about resetting the isc

 

[DSM1G90]

Yep, both examples above sounds like TS failure. Do the VOM test and see what happens. Good luck.

Also I cant find anything on vfaq about resetting the isc

"Seek, and ye shall find...."


1G BISS Adjustment

DSM

 

[tarheels23]

Oh I already knew about that and I did that, after that and I reset my ecu it will work once and any other cold start up after that I have to keep my foot on the gas for a minute

 

[DSM1G90]

Do the TS and you should be good afterwards.

 

[tarheels23]

are part store ones okay or should I buy an oem? I would test mine but its on jackstands right now waiting on a clutch and flywheel. When I replace it will coolant pour out?

 

[DSM1G90]

Not all coolant has to be removed since the TS is located in the neck of the filler.

It's the two pronged - with the two prongs at right angles to each other - device next to the EGR vacuum sensor on the filler neck.

Carquest, NAPA and similar carries the sensor and not at all pricey .. about 20 bucks.

 

[tarheels23]

Alright just thout id ask because the price of oem ones online is a little crazy being 45+

 

[turbo4awd]

I'm have the same issues with my car now. I had a 0021 code and found that the wires to the icoolant temp sensor broke off I repaired the wires and now just waiting for the car to get completely cold to see if it fixed the. Problem.

 

[xxShaneOmac]

Did you ever fix this?

 

[tarheels23]

Not yet, im going to test my coolant temp sensor tomorrow since.I just finished up putting my back together

 

[2gjlc]

Any updates on this? Im having the same issue.

 

[tarheels23]

Haven't found any answers yet, and I checked my isc, changed my coolant temp sensor, replaced my rad fan mpi fuse, and adjusted the bass idle. Still no luck

 

[travisgoldkuhl]

have you checked to see if your egr valve is stuck open or need to be cleaned?

 

[tarheels23]

I have a block off plate

 

[travisgoldkuhl]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge) hopefully this might help you out some. I know you dont have idle surge but shows you what could effect idle.

 

[2gjlc]

Just in case anyone stumbles across this thread I figured out the issue. It was my mechanical timing. Belt jumped like one or two teeth and caused all the issues. Thankfully no bent valves or anything serious.