Question about my new 90 TSI

[Prib9671]

So I recently got a 90 TSI AWD 5 speed and 2 weeks into it the Alternator goes bad so I just replaced it with a 65 AMP unit and it smoked for a while once I first started the car but after it quit I drove it and it ran fine for about a week. Yesterday I drove it about 2 miles I stopped at the light a block from my house and it starts idle surging from about 1500 - 2000 rpms. When I parked it a few seconds later it wasn't surging anymore but just idling at over 2000 rpms. When I turned it off and on it will start at 1500 rpms then slowly creep up to over 2000, I haven't let it go higher to see if it would yet. I have checked the trottle cable for sticking- not it, I have found that the BISS screw doesn't control the idle anymore, and I have checked the resistance between pins on the ISC unit and they tested fine, but haven't got a 6 volt battery to test it. Here is the thing, I pulled out the ECU to check it, and of course the capacitors have leaked a little (I had another ECU leak a lot worse and it wasn't bad so I'm not thinking it's that but I won't rule it out yet). Firstly does anyone think if the Alternator regulator failed it would cause this? Secondly I found this Ford Relay setup right in front of the ECU, can someone explain what this is and if it could be my issue? My 92 TSI AWD Auto does not have this. Sorry for being long winded and Thanks in advance.

 

[g4ebguy90]

i just assume a ford relay on a mitsubishi.... is probaly ### someone put it there for some reason

 

[bomper04]

Can you take pics of which terminals that relay is connected to on the MPI fuse? I'm assuming the relay there is most likely for the fuel pump..

 

[Prib9671]

Ya I will take a picture tonight. Does anyone know if an Alternator regulator would make my idle soo high?

 

[blk91tsiawd]

Check O-ring and adjust that BISS. My car was surging and idling bad til I took care of the biss.

 

[Prib9671]

I took the trottle body off and I am testing the ISC and I think it is bad. I can hear it tick when I put a charge to the pins but it doesn't move at all. The resistance is all within spec. The thing is I am using a 9 volt battery, will this make the test invalid? The writeup says to use 6 volts (not 12v because it will ruin the unit) and I asked someone and they said 9v shouldn't hurt it. Also I can't get the BISS screw out, it will not thread all the way out and I can figure out how to get it out to replace the O-ring. Thanks

 

[gusu]

I took the trottle body off and I am testing the ISC and I think it is bad. I can hear it tick when I put a charge to the pins but it doesn't move at all. The resistance is all within spec. The thing is I am using a 9 volt battery, will this make the test invalid? The writeup says to use 6 volts (not 12v because it will ruin the unit) and I asked someone and they said 9v shouldn't hurt it. Also I can't get the BISS screw out, it will not thread all the way out and I can figure out how to get it out to replace the O-ring. Thanks

There is a thread on how to remove the BISS as well as a VFAQ write up.

A failed BISS o-ring will act the exact same as a failed ISC because the ISC does not function correctly.

When you adjust the BISS you must do it PROPERLY so the ECU will work with the change. There is a full write up on how to do that on VFAQ.

I wouldn't use another voltage to test anything... ever.

 

[Prib9671]

I finally got the BISS screw out and the o-ring doesn't look worn, I didn't leak test for it before I took everything off so I really don't know if it's the culprit. I had found a lantern/flashlight battery in the house but it only read 4.2v but I tried it anyways and the ISC didn't even click. Since I already used the 9v on it I tried it again to see if it would work again. It kind of works, it doesn't move at all it just clicks. In DmTaLoN's write up it says "If there is no movement or vibration from the motor, then it is bad" so does this mean constant movement or vibration? DmTaLoN's Idle Speed Control Test/Fix Page!
When I have the positive hooked to pins 2 and 5 I have to alter touching on pins 3 then to 6 to get the little click/jump of the ISC. When I hold it on 3 and 6 at the same time nothing happens. Are you sure about when BISS screw o-ring fails it will act like a failed ISC? Would that cause my 1500 rpm creeping to 2000 rpm idle? I just don't want to just put everything back together with a new o-ring if that's not the case, and have to tear it apart again. On the 90's you have to remove the feed side of the fuel rail to take off the T.B. and it makes a mess. Thanks for helping everyone!

 

[WizardTSi]

I'm going to second the BISS screw theory. Its cheap and easy. Actually, $15 for a plastic screw, o-ring and cap isnt exactly cheap .

 

[Prib9671]

I guess I will try that tonight if I can find the proper o-ring (I think I read somewhere it was a #5). I don't know if I would want to use a plastic screw though, there is nothing wrong with the steel screw that was in there. Another question I had was, has anyone used a 91-99 ISC on their 90'? I can't find any for the 90' and don't know if the 91-99 will fit because it would have to come out of the front of the T.B. instead of the back and don't know if the wiring will reach around, plus there is a cluster of stuff right there. Thanks for the input.