90 jetta gli intermittent problem

[kaloko]

I have a 90 jetta gli 16 v with an intermittent problem , it loses power and hardly runs . I found that by disconecting the coolant temperature sensor the car runs at about 90 percent with no intermittent problem .
I replaced the CTS and checked it back to the control unit and it's good , so I replaced the control unit , didn't help . It's not the cold start valve and I've replaced the coil . Any Ideas --- What else does the CTS influence . Thanks

[boschmann]

Disconnecting the CTS is just throwing the ECM into default settings to run, that's why it runs somewhat better. The car does have the capability of giving trouble codes. Unfortunately they can only be read by a VAG scanner or someone who has a VAG-COM and the 2x2 adapter. Troubleshooting CIS systems can be very difficult w/o the proper gauges, test harnesses, etc.... I don't suppose you have a California car with a check engine light?

[kaloko]

boschmann , thanks for your response , The 90 Jetta does not have a check egine light and the guys down at the VW dealer laughed at me when I asked for the VAG test , they said that a car that old (120,000 miles) shows everything being bad . What do you think , should I have them check it any how , I'm still thinking If I could find out what exactly the control unit does with the information it recieves from the CTS , What other functions that information influenes , we might be able to figure this thing out . If you have anything technical , lay it on me . Thanks

[boschmann]

Most dealers will want to avoid these cars as they are a pain to work on when the system gets a problem. It's not that the ECT is causing anything except that when you disconnect it the ECM will go to default settings. Then, whatever sensor or component that is causing the actual problem is ignored. An alternative to the dealer would be to find someone with a VAG-COM & the 2x2 adapter, the guys at http://www.dub-tech.com keep a list of people who have one & will help. Is there a local independent shop that knows VW? More than likely there are no codes in there (aside from the ECT you set by disconnecting it) as it is a very basic self-diagnostic system. After that you have to fall back to the mechanical/electrical checks of the various components; fuel pressure, bleed down rate, fuel distributor, differential pressure regulator, potentiometer....

[kaloko]

Thanks again for your reply boschmann , O.K. so default setting causes the ECM to ignore not only the disconneted sensor but other if not all sensors and components across the board , Wow , that might make things tuff . You might want to say a prayer for me , I live on one of the less populated hawaiian islands (I know , poor me ) and no one here can figure this thing out , it's been over a year . I'll have the dealer do the VAG and go from there , I have to much money into this car to drive it over a clift and wouldn't feel right selling it with this type of problem , Keep forgeing ahead I guess .I will keep you posted on any progress , It might be a week or two .