Wont start when cold, starts perfectly once started

[Fu Manchu]

If you look at the start circuit a speedo sensor will not produce results like that.

Let’s not guess at stuff because you will replace the car bit by bit until you have a new car.
Get all connections cleaned. Dont just look at them. Get them undone and cleaned as mentioned earlier and then snugged back up.

Already looking at spending money on a battery. What if doing something that costs only some of your time and a $25 can of CO Contact cleaner fixes it. You find a major cable with corroded terminal or an earth bolt connected to a harness earth showing minor corrosion. There’s your gremlin.

To solve this without parts swapping will require some mad skills with the picoscope (or oscilloscope.) You will also need a bidirectional scan tool, which I suspect might be able to see a few things already.

You also need to download the VZ factory manual from links posted here in order to better understand the car.

This is a computer network. Seeing wave form data on starting from various inputs will start the long process of finding what is playing up.

I know what needs to be done but have training wheels when it comes to it. It’s really hard stuff.

 

[Fu Manchu]

Also, remove the cam sensors. Clean them with paper towel and throttle body cleaner.

Remove the cam actuators. Clean them with Carby cleaner. Get the screens clean. Get their insides clean.
Get some oil into them and reinstall.

You will need to move the ECM bracket out of the way on some models. If so, disconnect the negative battery terminal first. Clean the 7mm bolt and earth for ECM while you are at it.

Clean the throttle body. I prefer removing the throttle body so I can clean it without moving the butterfly. Not a great idea to move the butterfly on drive by wire systems. Use your wife’s toothbrush and throttle body cleaner and paper towel. Go easy on the throttle body cleaner. You don’t want it going down the shaft and into the motor and electrical bits.

This all makes sure that you have done the best you can to ensure timing is ok at start, and that engine vacuum is ok with a clean throttle body.

So if still no joy, I’d be looking at vacuum leaks, and on old Alloytecs, PCV and brake vacuum hoses will have hardened. A smoke test is the go to method for definitely finding every tiny vacuum leak. You can make a smoke tester or have a proper one.

Replace or modify with new hoses.

Do the PCV mod. There’s a thread in the How To section. Make sure that it’s not blocked and then the mod makes sure it works better than new.

 

[lout]

i must say this post is concerning me
seems very common to the vz wont crank, but starts after bridging starter relay

 

[Fu Manchu]

i must say this post is concerning me
seems very common to the vz wont crank, but starts after bridging starter relay

Yep and I now know a guy who could have solved the puzzle but we no longer have the sedan.