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Cold Start - hard to start and Not revving up

Posted: Tue Aug 15, 2017 1:43 pm
by austskiboy
Have a 3.5 Rover V8 running Haltech Ex6 with supercharger - been running fine for some time (several years) then something changed??

Now hard on cold start - turn over but wont fire. Very hard to get it to fire. When it does it no longer revs up until warm and drop down. It used to then stopped when the cold start problem started. Sometimes when it finally starts now it is hard to get the throttle to rev it up. :(

It did intermittently return to revving up and starting fine for a few days then stopped again. Hot start is normally fine - sometimes takes a few turns but generally starts fine hot.

I have software and computer to connect with RS232 port so can view the computer etc but I just don't know what to look for to work out which part - sensor or the computer - is not working properly.

Experts - where do I start - what maps or screens do you need to see to diagnose.

Thanks in advance for any help
Keith

Re: Cold Start - hard to start and Not revving up

Posted: Wed Aug 16, 2017 12:38 pm
by HaltechMatthew
It could be anything. Check if the throttle is calibrated and reads 0% at idle. If it doesnt the idle control will not work and wont idle up when cold.

Re: Cold Start - hard to start and Not revving up

Posted: Wed Aug 16, 2017 2:50 pm
by austskiboy
Matthew

Thanks - I am a quick learning novice to all this.

What does calibrated mean - getting a signal from the throttle?

Is there are screen I can capture from the software that would help?

Re: Cold Start - hard to start and Not revving up

Posted: Sun Mar 04, 2018 8:27 pm
by austskiboy
Fixed issue ign barrel was failing dropping power to ecu when cranking.

New issue - now running rough when cold.

I accidentally left air temp sensor plug off and it ran really really well. I thought cleaning the air temp sensor and changing the idle control valve had fixed the rough running at start.

New ICV had noticeable impact. Great.

Then I saw air temp sensor plug was off so put it on. Then went for drive tonight - ran like crap again. So stopped and pulled air temp plug off and then drove off and it ran perfectly.

My qu is how does engine run with no signal from air temp sensor and what are the issues if I run it unplugged?

Keith

Re: Cold Start - hard to start and Not revving up

Posted: Tue Mar 13, 2018 3:18 pm
by HaltechMatthew
It will be using the fuel correction data from that table, the Air Temp Correction. It sounds like it needs more tuning.

Re: Cold Start - hard to start and Not revving up

Posted: Fri Jun 15, 2018 5:11 pm
by Danman
A friend with a rover 3.5 v8 had a strange issue and it turned out the distributor had come apart and was allowing massive amounts of free play. If you are still using the distributor open the top and twist the rotor button and make sure it's still secure.