1G Breaking up under boost in cold weather

[mspaintexe]

92 Talon TSI, ETS intercooler, Tial wastegate set to 12PSI stock MAF. In weather above 50F, the car runs and boosts perfect, but once it falls below that the car breaks up badly under boost. No matter how much I let the car warm up, as long as the outside airtemp is below 50 degrees it does this. Can too cold intake air cause this? The intake pipe just before the throttle body is always ice cold if I have been driving at all. Could it be the denser air causing fuel starvation? I thought initially it was spark blowout and I got NGK BPR7ES gapped at .026 but still the same issue.

 

[evil_eagletalon]

Do you have a wideband? If so what is it doing when this occurs? Also pump or ethanol?

 

[mspaintexe]

Do you have a wideband? If so what is it doing when this occurs? Also pump or ethanol?

No wideband. 93 octane. Everything except for the intercooler, piping, and wastegate is stock.

 

[DSMPT]

First things first. Should do a boost leak test and check the IAT sensor.

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[evil_eagletalon]

Wideband readings would paint a huge picture. Sounds like a misfire and usually the wideband would be spiking lean on the “break ups”

I doubt the iat is the issue because it is not reading ambient temperature. But maybe….

 

[mspaintexe]

I doubt the iat is the issue because it is not reading ambient temperature. But maybe….

I'm going to check it tomorrow but even if it is working, because the intake is still in the stock location the IAT is reading the underhood air temps, but once it passes through the intercooler its a lot colder.

 

[DSMPT]

Always do basic and first things first, especially if you run the MAF sensor. This is to narrow down the issue. This will save your time and money in the future.

 

[evil_eagletalon]

Did i miss something? The car is on a MAF? The intercooler has nothing to do with intake temps.

 

[DSMPT]

Did i miss something? The car is on a MAF?

stock MAF

He mentioned that he runs the stock MAF.

the intake is still in the stock location the IAT is reading the underhood air temps, but once it passes through the intercooler its a lot colder.

The intercooler has nothing to do with intake temps.

I don't know why you are mentioning about intercooler but boost leak is the fist thing that you have to check always.

 

[evil_eagletalon]

Because he is talking about the intercooler pipes being cold. Thats why im talking about intercoolers.

 

[DSMPT]

Because he is talking about the intercooler pipes being cold. Thats why im talking about intercoolers.

My bad, that comment was actually to OP, not to you. But it seems he is confused with something.

 

[mspaintexe]

I was thinking that maybe it could be a difference in temp because the IAT is reading the air temp at the MAF but because of the aftermarket intercooler the air actually entering the engine is much colder. If i put my hand on the intake pipe right before the throttle body its freezing cold, no matter how long the cars been running and how warm everything else in the engine bay is. I'm wondering if the IAT is reading a much warmer temp than the air actually entering the engine has anything to do with it. Ideally you would want the IAT to be as close to the throttle body as possible no?

My thinking is the aftermarket intercooler is overkill for the application especially in cold weather and the stock MAF IAT wasn't designed to work with such a large intercooler. Or I could be overthinking this. IF this is the case would it be possible to just wire in a GM IAT, are the resistance values the same? Or is that an ECU piggyback only deal.

Would boost leak be a cause? Because this ONLY happens when its cold outside. Its night and day depending on the temperature.

 

[DSMPT]

Would boost leak be a cause? Because this ONLY happens when its cold outside. Its night and day depending on the temperature.

I really recommend you to start from boost leak test especially if you run the MAF sensor and old rubber couplers/pipings. Then go next after that.
I have seen numerous people keep wasting their money and time to buy new sensors. spark plugs, cables etc etc. Because of the "breaking under boost" issue. Then finally the issue was just a boost leak. I have even seen some boost leak situation that is affected by the under hood temp. That leak only happens when the under hood temp is cold or hot.

 

[mspaintexe]

I really recommend you to start from boost leak test especially if you run the MAF sensor and old rubber couplers/pipings. Then go next after that.
I have seen numerous people keep wasting their money and time to buy new sensors. spark plugs, cables etc etc. Because of the "breaking under boost" issue. Then finally the issue was just a boost leak. I have even seen some boost leak situation that is affected by the under hood temp. That leak only happens when the under hood temp is cold or hot.

Yeah tomorrow if the weather cooperates I'm gonna do a boost leak check and check the IAT with a hairdryer.

 

[DSMPT]

Yeah tomorrow if the weather cooperates I'm gonna do a boost leak check and check the IAT with a hairdryer.

Maybe the cause is not boost leak. But you have to know that boost leak is really crucial if you run a MAF. And some boost leak symptom is very tricky, sometimes it only happens under specific circumstances. Anyways that's a must thing to do at the beginning, even you think it's not the cause.

 

[99dsmer4g63]

The intercooler has nothing to do with intake temps.

Care to elaborate on this? Should we not be running intercoolers?

Step one - BLT

I mean a real one too, air compressor and soapy water. None of this I looked at my hoses and felt around with my hand and it’s good shit or trying to use a bike pump.

-Daniel

 

[evil_eagletalon]

The IAT is reading temps at the MAF housing so the intercooler temps wont matter unless it was on SD.

Understand what i meant?

 

[pauleyman]

I was thinking that maybe it could be a difference in temp because the IAT is reading the air temp at the MAF but because of the aftermarket intercooler the air actually entering the engine is much colder. If i put my hand on the intake pipe right before the throttle body its freezing cold, no matter how long the cars been running and how warm everything else in the engine bay is. I'm wondering if the IAT is reading a much warmer temp than the air actually entering the engine has anything to do with it. Ideally you would want the IAT to be as close to the throttle body as possible no?

My thinking is the aftermarket intercooler is overkill for the application especially in cold weather and the stock MAF IAT wasn't designed to work with such a large intercooler. Or I could be overthinking this. IF this is the case would it be possible to just wire in a GM IAT, are the resistance values the same? Or is that an ECU piggyback only deal.

Would boost leak be a cause? Because this ONLY happens when its cold outside. Its night and day depending on the temperature.

This is incorrect. The purpose of the mas is in its name. Calculate the mass. You need temperature, flowerate and pressure (atmospheric not boost) to make this calculation. After that measurement if you subsequently cool the air you do not change the mass flowrate.

 

[FIBA M - EC17PSE]

have you confirmed your coilpack and igniton is good? have you checked your plugs to see how they look?

I would go back to a stock plug, BPR6ES gap .28 vs the 7's as you don't need those in stock form.
once you have confirmed ignition and put the correct plugs in see if this has helped or not.

along with the BLT as suggested above the colder air is likely needing more fuel but i don't think this is related since you have not upped the boost or anything else in that respect

 

[We're on Boost]

In addition to the BLT and checking the 2 sensors per post #4:
Take the spark plug wires out of the coil, one by one so you don't get them mixed up, and take a look at the metal ends that are supposed to be conductive. Sometimes they get really corroded. Look into the wells that they plug into on the coil pack, looking for corrosion. We've been seeing people with that problem sometimes. Look for corrosion at the other end too, where they fit over the spark plugs. Rust Belt you know
Take a picture under the hood showing your Tial Wastegate and how it is hooked up. You say "set to 12 psi". Do you mean it's on wastegate spring pressure only? (Default Tial spring is ~13 psi last I knew). Not using a boost controller? Do you have a boost gauge so you can see what boost it is actually going to?
Showing your MAF, air filter, and piping areas might help too.

 

[mspaintexe]

Just did a boost leak check at 20 PSI, even though the car never sees more than 12-14. Found 2 small leaks, one from the idle adjustment screw, and one where the BOV mounts to the intake pipe. I have an AC O ring set that should work for idle screw. could I use one of those silicone gasket makers for the BOV? I would rather fix it now then order a gasket. About to check the IAT too why not.

I will also check the ignition system. Initially the car had NGK BP6's and I thought it was spark blowout and changed them to the 7's but nothing changed. I will check the plug wires too, and most likely I'm going to order replacements anyways since I don't know the last time they've been changed. Oh and yeah sorry I forgot to mention the wastegate spring is set to 10 PSI but I'm running a NXS manual boost controller. Checked that for leaks too but nothing. I do have a real boost gauge not the shitty OEM one too.

I just realized that the idle screw is supposed to have a cover, mine does not.

 

[pauleyman]

I just realized that the idle screw is supposed to have a cover, mine does not.

It's not needed. It isn't functional towards idle. Just a dirt cover.

Please post a car profile and shown us some underhood pics. Do you have any tuning solution or data logging ability?

 

[We're on Boost]

I will check the plug wires too, and most likely I'm going to order replacements anyways since I don't know the last time they've been changed.

Spark Plug wires, Rock Auto sells the NGK 9634 (ME64) complete wire set for $30. Really good. They are exact OEM fit like it says on the box but improved materials and construction, and made in Japan. I use these on my car.
NGK 9634
To verify the fit of the NGK 9634 wires for your 1992 Tsi, you'll see it here in the "Premium" section:
spark plug wires for 1992 Talon turbo, Rock Auto

Oh and yeah sorry I forgot to mention the wastegate spring is set to 10 PSI but I'm running a NXS manual boost controller. Checked that for leaks too but nothing. I do have a real boost gauge not the shitty OEM one too.

Can you tell us, when it is below 50 degrees and you get this breakup, at what boost psi does the breakup usually start?

 

[mspaintexe]

Spark Plug wires, Rock Auto sells the NGK 9634 (ME64) complete wire set for $30. Really good. They are exact OEM fit like it says on the box but improved materials and construction, and made in Japan. I use these on my car.
NGK 9634
To verify the fit of the NGK 9634 wires for your 1992 Tsi, you'll see it here in the "Premium" section:
spark plug wires for 1992 Talon turbo, Rock Auto


Can you tell us, when it is below 50 degrees and you get this breakup, at what boost psi does the breakup usually start?

Yup just ordered those, I always run NGK. I would say it starts around 8-10 psi somewhere in that range. If I'm giving it more than 70% throttle. I have no way of datalogging, the car is on stock ECU stock sensors, no piggybacks or controllers. My best shot at "datalogging" is pointing a camera at the gauges.

 

[pauleyman]

Look for small white dots on your sparkplug boots. If you find them that's where they leaked.