I have fitted a single throttle body to me engine, works fine when warm but will not tick over when cold. If i hold about 1000rpm on from cold for
about 2mis it runs great, have tried playing with cold start enrichments but no change.
Have lifted tick over up runs fine but when engine has warmed up it runs at 1400rpm.
I think i have got to fit a slow running valve but this will mean changing the throttle body for one with a stepper motor. Any ideas Welcome.
If the butterfly is closed (and it only takes a tiny amount of opening to increase revs), then it's an air leak somewhere. an engine simply will
not run if it can't suck in air irrespective of how much fuel you have.
I would check the butterfly angle first, then look to gaskets, seals, etc.......
It ticks over fine when warm its only when cold i have this problem. Have checked for air leaks and very confident there is none.
Have a look at the after start enrichment's too
There are three to play with if you are using MS
Cranking
Cold Start
and ASE
Are you using the throttle stop to control the idle speed, or do you have an Idle Control Valve? If youve increased the size of the TB, then you might be letting too much air in for the cold settings, which will be near on impossible to resolve without an idle valve.
I am using the throttle stop to control the idle speed i have no stepper motor or control valve.
I am looking for something to solve the problem, i do not want to change the throttle body as just had on rolling road and very happy with results.
Kev.
quote:
Originally posted by madteg
I am using the throttle stop to control the idle speed i have no stepper motor or control valve.
I am looking for something to solve the problem, i do not want to change the throttle body as just had on rolling road and very happy with results. Kev.
could you add a bit more advance for idle when cold?
Does it have to be electronic? Can you fashion a 'choke' cable that pulls on the throttle slightly raising the idle slightly while it warms
up.. Alternatively, tickle the throttle while you do up harness, check mirrors, listen for rattles etc.
Electronic could be servo with little cam on end that pushes on accelerator pedal linkage. Label it fast idle and leave it on when sitting at traffic
lights next to the boy racers.
The simplest solution is to add an electric on/off idle control valve. This just lets more air into the manifold downstream of the throttle so is similar in effect to having the throttle partly open. I have a megasquirted injection Pinto using the standard Sierra inlet manifold. With the water temperature below 75 deg C the valve is open letting air past the throttle. On start-up idle is approx 1200rpm. This gradually increases as the engine warms to about 1700rpm before the valve snaps shut and idle settles down to 900rpm or as set on the throttle stop. The valve could be controlled by a simple on/off switch if you don't have an ECU that will do it. As it just bolts onto the side of the manifold it could easily be adapted and used as a standalone unit. There are stepper motor controlled idle valves too. These can be driven by a map in megasquirt so the idle speed is kept constant as the engine warms up, but overkill on a kit car in my view. Take a look on EBay at the Ford ones. They look similar to one I have. Not sure which of these other than the Sierra ones are the on / off type.
Simple 12v solenoid valve put a restrictor in the line and a filter on the end to stop crap jamming the valve
For a restrictor try a MIG welder tip you can drill it out as required, for a filter just just a cheap in-line fuel filter.
For valve see ebay item 161025989122