Often overlooked FI fix

[zachmac]

First, I couldn't decide if this belongs under engine or electrical so I put it here. We really do need a FI section!

I just wanted to share will all FI owners the importance of the temp. sensor connector at the thermostat housing. My car would occasionally stumble or not run worth a crap, never would idle all the way down, and ran rich. I have already done just about all you can do to "fix" known problems with the FI system. Then one day while the car was running and I was doing an unrelated task under the hood I bumped the connector on the temp sensor. The car immediately went into the run like crap mode. Sure enough if I wiggled the connector I could make it run great or like crap.

I ordered a new Bosch style connector from Mr. Allison and waited for the mail. In the meantime I mentioned this to my local European car mechanic expert and he said "Oh yeah, very few people understand how critical that connection is for Bosch FI systems. All of the power for everything important passes through that connector. If it is loose or has any high resistance the car won't run worth a damn!"

Well I got the connector in the mail and spliced it in with a couple of screw type inline cconnectors, heat shrink wrapped it all up nice and prettey and made the connection and the difference is amazing. The car idles 300rpm lower, runs smooth and performs better than it ever has since I've owned it. Apparently the bad connection was adding a fixed resistance to the variable one the temp sensor itself is supposed to supply and it was throwing the whole system out of whack. Plus as an added bonus the newer Bosch style connector uses a spring release that makes connecting / disconnecting painless versus the OEM PITAs. I think I'll add changing them all out to the "to do" list.

I highly recommend all FI owners check this connection point and change it out if at all suspect.

[wikkid]

Thanks - I'll add it to my list of stuff to check as I go through the FI components.

It's a bit confusing sometimes on what section to post in, but in general, if you follow where the issue is dealt with in the Fiat shop manual, then maybe that would provide enough consistency. F'rinstance, FI system is in the engine section of the shop book, so I post FI issues there, even if it has to do with the relays or ECU or connectors.

[zachmac]

wikkid,

Your logic for posting makes sense. While electrical it is indeed engine mananagement so I will post FI issues there in the future.

[Specialk]

Hi,

Where exactly is the temp sensor located? Is this the same as the lambda sensor or something completly different?

Rgds

[azruss]

It is located on the coolant T coming thru the timing belt cover. one side goes to the top of the radiator and the other to the stadt. Many FI guys carry a resistor that they can jerry-rig into the connector in as part of their emergency kit. Dont remember exactly, but around 200 ohms. Also needs to handle a watt or more, as i recall.

[wikkid]

Specialk, the lambda sensor is totally different: it's located in the exhaust header, and it is also called an oxygen sensor, since it measures the amount of oxygen in the exhaust mix, and tells the electronic control module (the FI computer) how rich/lean the exhaust is, so it can make corrections to the fuel/air mix.