idle surge. hard starts. running rich. low boost fuel cut

[britdog]

the 93 tsi awd has very long cranks and somtimes if i push the gas it starts sooner. Also the car at idle runs rich. it surge from 1k to 1500k or 1500 to 2k. sometimes it will idle at a stop at 500-1k and the oil pressure drops. the car will sometimes fuel cut in 1st around 5 psi and once or twice in 2nd around 7-9 psi. also the wastegate on my 16g was set on my 2g at 15 psi and now its on my 1g and it only boosts around 5-9 psi. the previous owner said it has a walbro 255. and stock injectors. the fpr is not stock and i took the vac line off and there is no gas in it. with the car on it sits at like 41 psi and when shut off it goes straight to 0

 

[dsm'r sk1mp]

Idle surge would come from low coolant, bad thermostat sensor, or bad oil pressure sensor. hard starts would come from many things. Possible vacuum leak would cause your boosting problems. With the hard start it might be a bad cold start sensor which could also cause idle surge.

 

[9!'clipseDOHC]

the 93 tsi awd has very long cranks and somtimes if i push the gas it starts sooner. Also the car at idle runs rich. it surge from 1k to 1500k or 1500 to 2k. sometimes it will idle at a stop at 500-1k and the oil pressure drops. the car will sometimes fuel cut in 1st around 5 psi and once or twice in 2nd around 7-9 psi. also the wastegate on my 16g was set on my 2g at 15 psi and now its on my 1g and it only boosts around 5-9 psi. the previous owner said it has a walbro 255. and stock injectors. the fpr is not stock and i took the vac line off and there is no gas in it. with the car on it sits at like 41 psi and when shut off it goes straight to 0

For the idle surge, do a boost leak test, as this is usually caused by boost leaks in and around the throttle body. It could also be a dirty, throttle body, misadjusted BISS (Base Idle Speed Screw), dead ISC (Idle Speed Controller) or a faulty FIAV (Fast Idle Air Valve).

Check out these links:
http://www.dsmtuners.com/forums/newbie-forum/2198-idle-surge-very-bad-need-help.html
Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)
TB Cleaning
1G BISS Adjustment
http://www.dsmtuners.com/forums/newbie-forum/364030-idle-speed-control-not-good.html
http://www.dsmtuners.com/forums/newbie-forum/259300-fiav.html

Here are two videos which make it very easy to test your ISC (Do both).

YouTube - ‪DSM ISC motor testing & Replacement‬‏

YouTube - ‪DSM ISC‬‏

The "fuel cut" you are describing is probably just the effects of a boost leak (or multiple boost leaks more then likely). Do a boost leak test FIRST. Then go from there. This will also explain your low boost and probably your idle surge as well.

Also you mentioned that there was no fuel in the vacuum line... were you expecting to find any? The fuel is in the fuel lines, not the vacuum line. To measure the fuel pressure, get the car running at normal operating temperature, disconnect the vacuum line from the fuel pressure regulator, cap the end of the line with your thumb, read the gauge. That is your base fuel pressure. Your base fuel pressure should be:
1G MT = 37psi
1G A/T = 43psi
1G NT = 48psi
All 2G cars are 43psi

 

[H@xtGSX]

Yup, time to get friendly with the multimeter and the boost leak tester. You will become a jedi master with them if you want a properly running DSM. T in a sealed psi gauge for the fuel pressure and make sure it is as stated above.

 

[britdog]

Okay so i found a boost leak after i got off work the car was boging bad. Right at the j pipe the gasket was tore in half and it doesnt sit right on the 16g. I also found that there was a hole in a coolant hose. I tested the iac with a multi meter and they were all right around 38 +/- 1. I fixed the coolant leak and ordered a coolant temp sensor. i aslo am ordering a new j pipe because the extra one i have goes toward the stock smic and not the fmic. Is there any good site to get one? I cant find just the j pipe on extreme. Thanks for the help guys.

 

[92AWDHX40]

Stm, extreme psi. EXTREME PSI : Your #1 Source for In Stock Performance Parts

 

[britdog]

Alright fixed the boost leak. I also gave the throttle body a deep clean. I checked the idle air and I took it out and it did move. Also i cleaned that out. So i looked at fuel pressure. On my FPR the gauge when the key is turned to on it stays at 0, then when you try to crank it over the car will start to crank and there is no pressure for a couple seconds, then it starts to go up to around 30 psi and jumps from 30-40 over and over till the car starts.

 

[9!'clipseDOHC]

Alright fixed the boost leak. I also gave the throttle body a deep clean. I checked the idle air and I took it out and it did move. Also i cleaned that out. So i looked at fuel pressure. On my FPR the gauge when the key is turned to on it stays at 0, then when you try to crank it over the car will start to crank and there is no pressure for a couple seconds, then it starts to go up to around 30 psi and jumps from 30-40 over and over till the car starts.

Good job! After fixing a boost leak you need to repeat the test. You will usually find more. It's tedious, but works wonders. On DSM's the fuel pump doesn't turn on until the CAS is actived by the engine cranking over. It doesn't turn on when the key is in the "on" position. Did you check the base fuel pressure the way I described?

 

[britdog]

yes i did and it was right on with the number you gave me. im going to start with replacing the fuel filter.

 

[9!'clipseDOHC]

Sounds good. How is it driving now? Any changes?

 

[britdog]

yeah she is holding like 14 psi. it fuel cuts still so i think im going to lower the boost and see if it still does it

 

[buhay6]

I have a teeny tiny question...
I just found out my ISC was completely broken all connections inside the ISC were shorted.
I found engine oil on the outside of the sensor and in the housing that bolts to the throttle body its self, thinking this maybe what killed it am I right to suspect so?

Issues I've been suffering from:
1.Running rich at idle and even richer at WOT (9-10psi) AFR's were between 9.7-10.8 which I know are way way to rich.
2. Very very hard cold starting, and would die when ever letting off the throttle to say stop at a stop sign.
3. High idle when warm (between 1200-1500 rpm) Biss screw had to be completely tightened down to get the rpms that low.

 

[Type1DSMr]

To start off this is an old thread from 2012 but hey gotta post somewhere . I would replace your isc before messing with the biss screw. Also check all the bolts on and around your tb to get a good seal. When you adjust your biss screw, are you gounding first? I use ecmlink and check the gound the ecu box before adjusting the biss and to make sure my isc position reads at 30 at idle on fully warm up engine.