My 1990 TSi fwd dosent idle smooth *HELP*

[99 gst 420a dsm]

My 1990 TSi fwd with no mods runs like crap! it dont idle and feels like it skips, i changed the spark plugs, wires, fuel filter, and air filter, nothing helped im out of options, its sounds normal at like 1500 rpms but at idle it skips and runs like crap, and under a load its even worse, no check engine light either

 

[94EclipseGST]

Check your BISS.
Check your ISC.
Check your timing.

Adjusting all of the above fixed that problem for me.

 

[H.A.R.T 4G63DSM]

Check your BISS.
Check your ISC.
Check your timing.

Adjusting all of the above fixed that problem for me.

Wut is a BISS??

 

[BlackbirdOfPrey]

BISS = Base Idle set screw. On top of your throttle body is a screw used to change your idle speeds, however your ecu will act weird unless its grounded when you change the speeds. (well in my experience anyways others haven't run into that problem).

One question though, this may seem dumb, but when did you change your oil last, and what did you use? I had idle problems, and I changed my oil to some good oil, and problems went away. especially if its cheap oil, or has sludge/particles whatever. Other than that

Check o2. (very small chance it is your o2)
Check ISC/motor
Check timing.

Sound advice.

 

[99 gst 420a dsm]

BISS = Base Idle set screw. On top of your throttle body is a screw used to change your idle speeds, however your ecu will act weird unless its grounded when you change the speeds. (well in my experience anyways others haven't run into that problem).

One question though, this may seem dumb, but when did you change your oil last, and what did you use? I had idle problems, and I changed my oil to some good oil, and problems went away. especially if its cheap oil, or has sludge/particles whatever. Other than that

Check o2. (very small chance it is your o2)
Check ISC/motor
Check timing.

Sound advice.

the oil is good, the o2 sensor is good, mas is good, will a non-turbo ISC motor work (im not even sure which that is on the motor)

 

[realitytb]

BISS isnt your problem. But if you check that, YES ground your ecu or else it will "fight" to maintain the idle you had before. Also check for vacuum leak. That is a very likely possibility for your problem, and alot of people over look that.

 

[realitytb]

go to http://www.vfaq.com/mods/BISS-1G.html if you want to adjust your BISS. Although im pretty sure that isnt your problem, but who knows.

 

[99 gst 420a dsm]

BISS isnt your problem. But if you check that, YES ground your ecu or else it will "fight" to maintain the idle you had before. Also check for vacuum leak. That is a very likely possibility for your problem, and alot of people over look that.

I deffinetly checked for a vaccum leak

its just idles like crap and i dont get a CEL

idle is at around 1000rpms but acts like its 200rpms, and the engine just rocks from it skipping or what not

 

[94EclipseGST]

Check your timing. My timing was retarded too much --- it was at 3 degrees --- and the minute I adjusted the CAS and checked it with the light (now set at 8 degrees) the idle problem disappeared immediately. The car runs stronger than ever, and even under load it runs strong.

Obviously, you cannot adjust the timing by hand at the CAS because you don't have one, but check it. If you have a datalogger you can get some idea where your timing is. Then if you need to make adjustments, use a timing light. There are instructions on the vfaq website.

 

[realitytb]

So it idles at 1000RPM but feels like 200? See if it is your balancing rods. They obviously balance your engine so it doesnt wobble. That might be a possibility. Also, ive seen a talon who's engine wobbled bad, because an engine mount was busted. Just a thought But, timing is your most likely problem at this point. But never hurts to check other things.

 

[99 gst 420a dsm]

The timing is correct and always has been, the motor mounts are good, it seems to idle at 200 rpms even tho it is at 1000, but when driven it dosent have any power what-so ever, when adj. the cam angle sensor it did change the way ther engine ran obviously but nothing made it better, i think right now i have no choice but to perform a compression test, also could someone tell me what the orientation of the spark plug wires is supposed to be, i dont that thats the problem, i would like to know 100% though

 

[Twizzle]

being that its an older car...i would put a bottle of injector cleaner in the tank. that and lucas oil stabilizer with your next oil change do WONDERS to your car's smoothness. i put lucas fuel injector cleaner in a full tank, as soon as i turned the car on, it idled alot smoother. then when my oil change came around, i added lucas oil stabilizer and my engine is running SO much better than when i first got it. it actually idles within 50rpm now!

 

[99 gst 420a dsm]

being that its an older car...i would put a bottle of injector cleaner in the tank. that and lucas oil stabilizer with your next oil change do WONDERS to your car's smoothness. i put lucas fuel injector cleaner in a full tank, as soon as i turned the car on, it idled alot smoother. then when my oil change came around, i added lucas oil stabilizer and my engine is running SO much better than when i first got it. it actually idles within 50rpm now!

but that dosent explain the huge loss of power, i used STP fuel inj. cleaner

 

[crankbender]

First off if you are idling at 1k then you have something adjusted incorrectly. Don't cover up a problem by cranking up the idle.

Do the simple stuff and make sure you don't have a serious problem. Spark timing, cam timing, make sure the car is running on all 4 cylinders (older cars don't diagnose misses for crap....I idled mine with the spark plugs on wrong for 30 mins and it never threw a code), and compression test it.

Once you do those things you should have an idea on the problem.

One of the harder causes to find for a bad idle is a stuck open EGR...this will recirc "dirty" air when you don't want it to and cause some idle problems. Easily checked with a tuna can block off plate.

 

[99 gst 420a dsm]

i have done all of those things accept the egr block off and comp test

 

[99 gst 420a dsm]

Car still runs like complete crap, i pulled the plugs and they all look like the car is running rich, and the car will absolutly not produce boost, and the turbo is fine!!!

EDIT:

today i checked the plug wires while the car was running and i held them real close to the valve cover and two out of the 4 had very shitty sparking power (i had to hold them real close to ground to junp a spark) and two had real nice spark (i could hold the wire an inch-1.5 inchs away from ground and it would still jump a spark

( ) = good spark
(O) = bad spark


( ) (O) ( ) (O)

One bad one is on one side of the coil, the other bad one is on the opposit side, changed, coil pack, wires, plugs, fpr, and two vaccum solonoids....

NO CHANGE!! still runs like crap!!!

 

[kyle h.]

i having the same problems with my 93 tsi.

i've narrowed it down too:

-EGR VALVE
-vacuum leaks

if its not one of those, i dont think i will ever fix it.

 

[99 gst 420a dsm]

Im about fed up with it, its going on ebay moday afternoon.... i'll let the next owner figure it out, on the plus side... the 6.8inch fold down TV works great!!

 

[anubis]

it's been a while since anyone has posted on this thread... hopefully you guys are still wathcing. it's been my experience that whenever you've exhausted your possibilities for idle problems, check your ecu. the capacitors tend to leak on the circuit board and begin to short things out. this is especially a problem with the older cars. there are pages at vfaq.com regarding ecu stuff under the electrical section (read up - it's very useful info). if your caps leaked, there is no doubt you'll need a new one. you can tell by looking for a gooey substance under the capacitors. there will only be a little bit, so you need to look closely. also, if it smells like anything besides silicon and solder, they've probably leaked.
if you check your ecu and find that you need to replace it, i suggest going to either a bone yard or ebay to get a used one. brand new they'll cost you around $900 and remanufactured ones range from $250-$400. make sure that you get all the numbers off your old ecu so you can match one up correctly. and before you put in a used one from the yard or from ebay, replace the capacitors so they don't leak on your nice clean board.
good luck.

 

[99 gst 420a dsm]

unless i can find a junk yard ecu im not going to get one, i dont think it will work but i have a 1990 n/t computer that i was going to try, since 1990 dsm's can only use 1990 computers, i doubt it will work but its worth a shot for me..

 

[anubis]

it won't work. you need an ecu from a turbo. the year of the ecu doesn't matter as long as it's a 1g. the things that matter are: engine (1.8, 2.0, 2.0T), transmition (manual, auto), transaxle (fwd, awd), and brakes (non abs, abs). here is a link from vfaq if you want to read more about it:

http://www.tmo.com/howto/ecu1g/checkeprom.htm

if anything, you should at least pull your ecu and check it. if you don't want to buy one and you the right kind of friends, find someone that has a car similar to yours in the areas of importance and try there's to see if it makes your problems go away. you'll be pretty lucky if you know someone who has an ecu you can try.

just go pick one up from a boneyard. from what i've read on your thread you're running out of options. it'll be worth the $$ if it fixes your problem, and if it doesn't... so you lost a day or so worth of work. it's just money, you'll make more . you could always take it back and tell them it wasn't the right one or something and try to get your money back.

 

[4G63 GST]

.. all dsm's idle funny ..

each car will do different things .. sucks

Luke

 

[99 gst 420a dsm]

.. all dsm's idle funny ..

each car will do different things .. sucks

Luke

My 91 tsi awd idles great.....

 

[99 gst 420a dsm]

the car is on ebay now... PM/e-mail for link

 

[anubis]

My 91 tsi awd idles great.....

so what was the problem? what did you do to fix it?