Technical HELP - Urgent!! Problem with throttle and cooling fan!! Urgent, please HELP!!

[Georgpap85]

I bought a fiat stilo 1.6/ 2003 model, two months ago, when I bought it the car wouldn't idle properly, and the problem was becoming worse when hot.. I get to a garage to get the throttle cleaned. after the cleaning it was ok but check engine light came on occasionally and throttle died. when switching off the car and on again it was fine. I went back to garage and they said that it was a throttle error message and that I was going to need a new throttle if the problem persisted. Well I left it as it was, but now the weather became hotter and the problem became worse... I read a few threats here and read about the throttle relearn procedure, I tried to do the throttle relearn, but when the cooling fan supposed to cut in, something strange happened. The throttle died and the car rev went about 1500~2000 rpm, as it does when it does the problem, I left it a few more minutes but the cooling fan never turned on. So I started to notice that the problem with the throttle comes when the car it is supposed to turn on the cooling fan, e.g when in traffic and it is hot outside, and I could notice it now because the weather got more hot and the problem started to come on almost on every day when the car is hot and I am in traffic. Cooling fan never goes on!!! I wantted to get sure if the problem is related so I repeated the test, with the engine running and with the car stopped the thottle dies and car revs goes 1500~2000 every time car reaches 90C and the cooling fan is supposed to turn on. I also noticed that when switching off and on again a red dot at the temp reading comes on, displaying high temp? for a few seconds, but cooling fan does not come on. Before the throttle cleaning the car had idle issues but never engine fault. Also I remember a few times that the cooling fan did turn on before the throttle cleaning. I hadn't connected the throttle problem before because the weather was more cold and I also use to drive more on the highway, I also need to mention that the problem never happens on the highway when the car runs fast and it doesen't get hot. It always happens with the car on traffic or stopped. Please any help or suggestions where to look would help. Could it be a bad ECU? and how can I know for sure? I have the car for two months and almost want to give it away really cheap just to get rid of it and it will be a pitty because I will loose both a lot of money and time... Thank you a lot!

 

[Ralf S.]

I'm not sure... but if the fan is supposed to come on and doesn't, the ECU might be compensating for the extra electrical load it is expecting on the engine by giving the engine a few more rpm.

If the fan isn't coming on, then that extra bit of juice will increase the engine speed.

Does the fan come on at all, ever? If you have never seen the fan running then you need to check whether it works (assuming it has a current) or whether it has a current but doesn't work. If you can rig the fan up directly to a battery then it should come on.

If the fan is good but the ECU is not activating it then that might be an ECU or temperature sender problem. I don't know if the ECU takes a signal from the same sensor that feeds the temperature gauge. Some cars have a separate temperature sender for the ECU.

Ralf S.

 

[bri1232]

Check this Guide.

https://www.fiatforum.com/stilo-guides/104106-testing-radiator-fan-engine-temp-sensor-circuits.html

 

[Georgpap85]

thank you for your answers. Yesterday, while the car was hot and the fan didn't come on, I pushed a little the plugs from the ECU and the fan started to work, then I removed the ECU, opened it and checked for bad solders, it had a lot of bad solders on the plugs pins. I soldered all of them, then the car worked fine for a day and a half, until today afternoon that the problem came back, now the fan starts but the throttle keeps dying when the car is hot... I am thinking if there is any point on trying to solder again the pins of the plugs or it might be a bad chip, or maybe the main processor need reballing or something... I wonder why on earth fiat put the ECU on that point.... does anyone have experience of ECU problems and repairing? I also thought that I could move the ECU somewhere away from the motor to keep it a little cooler... does anyone had done this before?

 

[corcai]

thank you for your answers. Yesterday, while the car was hot and the fan didn't come on, I pushed a little the plugs from the ECU and the fan started to work, then I removed the ECU, opened it and checked for bad solders, it had a lot of bad solders on the plugs pins. I soldered all of them, then the car worked fine for a day and a half, until today afternoon that the problem came back, now the fan starts but the throttle keeps dying when the car is hot... I am thinking if there is any point on trying to solder again the pins of the plugs or it might be a bad chip, or maybe the main processor need reballing or something... I wonder why on earth fiat put the ECU on that point.... does anyone have experience of ECU problems and repairing? I also thought that I could move the ECU somewhere away from the motor to keep it a little cooler... does anyone had done this before?

Well the fuse box tends to get drenched if you hit a flood so that may be why they located the ecu there, or just to simplify assembly at the plant.

Its definitely worth checking the connectors under the fusebox:
https://www.fiatforum.com/stilo-guides/99828-d4-connector.html

 

[stilomies]

What's the exact fault code you're getting?

My Stilo (2004 1.6) has throttle problems too, code P1121 and sometimes P1221 P1220 and 0105. It started with P1221 and throttle pedal not working. When I released pedal fully usually started working again.

But now idle is not constant, when clutch is pressed then engine sometimes almost dies and wobbles between 200-1000 for a while until settles to normal idle. And sometimes revs stay up in about 1500rpm for no reason and noticed that if ECU connectors are touched, then usually settles to normal idle. Also jumpy ride when warmer conditions. I moved ECU to different place (left side of the battery compartment) and it helped for a while but not a permanent fix. Then I was almost sure that it was ECU fault and a local electric shop checked it out but they fu**t it up :bang: and I was forced to purchase a refurb'd ECU.. but guess what, it didn't make any difference! Throttle body was also changed when I purchased the car (and the early symptoms started before that) so pretty much what's left is the wiring. I am pretty sure fault is inside the engine side ECU connector since when it is touched the revs come back to normal. Too bad the engine side ECU wiring costs 800€ new or 200€ used at least here in Finland... I even opened the ECU connector and managed to take single wires/connectors apart. They looked OK but I think the contact surfaces inside the single connector are tired/bent. but if I want to get to them I need to use some violence and not sure if I can get it back together. But I think that is still my next step, I don't want to spend any more in this car.

BTW, have you tried contact spray to the ecu connectors?

Good luck!