So... last year I had a zetec turbo built using St 170 bottom end blacktop head, using boost monkeys new system had it mapped was great for 500 miles or so then it developed a idle problem. It won't tick over at all but drives fine and when u give it a touch of throttle it hunts. then the cam belt tensioner came loose. So I fitted a new one and it ran fine ect but this idle problem has just got worse and worse.

So I re done all the vacuum hoses, changed all the gaskets went to change the exhaust gasket and one of the threads in the head pulled out so I stripped it down had all the tapped holes helicoiled bought a brand new stage 3 turbo had all the head rebuilt valves all ground down n lapped in ect so I have put it all together thinking right that engine bay is brand new and it's doing exactly the same thing now I'm totally stuck any pointers would be great .

 

Who mapped it. Is it sequential?

 

Sounds like you might have an air leak, do you have an AFR gauge? If the map sensor line has a small leak it will be rich on idle.

Have you spoken to your mapper Rikki as really this should be your first port of call rather than a forum.

There are a lot of issues which can cause this. For example, the closed loop idle strategy looks to see if the throttle is closed before entering idle mode. If your TPS is faulty your ecu will not enter idle mode.

- Map line air leak as said,
- Faulty idle valve
- TPS etc.

And don't rule out mechanical issues such as a head gasket etc.

And to answer Jano's question, no it is totally as per the original ford EEC-IV so is not sequential. Sequential injection doesn't magically = good idle.

Rob,

 

I have done but without getting it170 miles there bit stuck so just trying to get it drivable safely mechanicly it's brand new with everything it's gotta be map or something electrical just seeing if anyone had the same problem it just hunts if I hold a tiny bit of throttle on dunno just at the end of my tether with this car.

 

i had the same problem with my zt when i first got it up and running. hunting really badly at idle. as it turns out, it was a very small air leak at the throttle body. a real bastard to find but once i sorted it it ticked over mint

 

I'm sure Rob can check all the sensors and idle valve are working if you can get it to him Rikki?
There's so many things that can cause unstable idle... Idle control valve, vacuum leak, faulty injector/s, fuel pump on it's way out or low voltage to the pump (25 year old pump wiring degrading is a common problem), faulty throttle position sensor, coolant sensor, air temperature sensor, etc.
Need to eliminate everything one at a time until the problem is found.
Assuming no one has played with the ECU since it was running fine all the tables and setting will still be correct, but Rob can double check this too.

 

Trouble is that if it ran and idled, and the map hasn't be touched... and spec hasn't changed then the map and ecu settings will not be at fault.

Something must have changed for the problem to have occurred. Do you have a boost leak tester?

Have you taken the idle valve off and looked at it whilst you cycle the ignition, you should see it moving when you do. If it doesn't there may be an issue with the valve its self or the wiring.

Also, the car should idle with the idle valve unplugged, adjust the idle speed screw in the side of the throttle body, set the idle speed to 5-700rpm with the valve unplugged and see if that helps.



Rob,

 

If I unplug the idle valve the fuel pump will not prime. I fitted a new one and same thing I know I need to get it looked at but I have spent a fortune so far just hoping it's something simple so it will atlas idle the ecu has not been touched at all so in theory It should just work but as you say it could be anything which is expensive.

 

Forgot to add it was a gradual thing that's just got worse and worse over 100 miles

 

A gradual degrading sounds like something mechanical to me mate, Ie a small air leak which has gotten worse perhaps. (injector Orings are common, but the map vac line will play a huge part in idle mixture control).

Also the idle valve should have nothing at all to do with the fuel pump so there may be a wiring fault somewhere for this to happen. Start by checking the main relays, wiring from both the ignition (for the main relay) and wiring to the ecu for the fuel relay.

Your not going to fix this unless you start inspecting things properly, I can give you some help and tell you what to test with a multi meter, but first I would suggest double checking the map sensor line to make doubly sure there are no air leaks here.

You have four options:
Sell it
Break it
Take it to someone
Fix it your self

Unfortunately all of these things are hard to help with via the internet.

 

Well I replaced every vac line and gasket I can get to.

So that's that ruled out.

I tried a different icvs and the valve moves on ignition cycle.

I tried a different coil pack.

I'm gunna try take a look at the tps and see if that's ok.

I have ordered a throttle body gasket so ill see if that makes a difference.

I have spent so much money on this car and I just need to get it drivable to get it somewhere .

It's probably something so simple.

 

Replacing them doesn't mean they don't leak Rikki, they can still leak at the joint.

Did you change the vac line which goes to the ecu?

You changing things is wasting money and a bad way to fault find as it can cost you so much money and time.

Have you at any point removed the throttle body or TPS sensor?