If you have installed a conversion and are having problems with the engine not running correctly, everybody always assumes they have an engine management problem. They rarely do. Over 90% of the problems people phone us about are simple mistakes they ought to have checked for themselves. Before suspecting engine management components, all the usual checks which apply to any engine should be made. An injected engine still requires all the same mechanical checks as a carburetted one! Very briefly, these include:
- All connectors connected to the right things! - leaving something disconnected is probably the most common mistakeIf you have a problem, check all the connectors are connected NOW, don’t rely on knowing that you plugged them all together in the past. If the latch on the connectors does not click shut or is damaged, it is possible for them to come out.
- A supply of clean, unrestricted fuel at the correct pressure
- Sparks going to all the cylinders, and not escaping the ignition system and going elsewhere
- No vacuum leaks into the induction system. This is a very common cause of missfires / backfires, and is almost always caused by forgetting to connect a hose, or one which has come off. If you have missfires / backfires which are worse at idle, check the induction plumbing. As with they electrics, please check that all hoses are connected NOW, not that you knew / thought they were at some point in the past. A very common hose for people to forget / miss out is the brake servo, especially on VW’s with no servo. Block the servo fitting if you have no servo, otherwise you will get a lean backfire which is worse at idle.
- Is the compression ratio of each cylinder within specification?
Before contacting us:
Before contacting us to ask questions about diagnosing any problems, please be sure to have checked out all of the above first. If you do get in touch with details of a problem, the details are critical. E-mails and phone calls saying little more than ‘my engine is not running right’ are a waste of both your time and ours. As much information as possible is needed. Most problems with a new installation prove to be something very simple:
1. What is the history of the engine? Do you know with 100% certainty that it was running OK before being removed from the Subaru? If not, pay particular attention to the above.
2. If your engine is not running right, and you have checked all of the above, details of what is wrong are needed. You can’t provide too many! Specifically, is your engine:
- not running on all cylinders
- stalling at idle
- cutting out
- lacking power
- idling unstably
- rev limited
.....and under what conditions:
- constant speed driving
- wet weather only
.....are there any error codes, and if so which ones?
......how repeatable is the problem (i.e does it occur at the same throttle position, revs, etc)
- never (random)
Problems with engines not running properly immediately after installation usually prove to be something simple - usually very simple. Examples include:
- · Not connecting a sensor on the engine (the cam, crank, temperature and knock sensors are all easily missed).
- · Getting connectors mixed up - note this is difficult, if not impossible on most Subaru engines, but not all. Some which can be mixed up on certain engines include:
injector and cam position sensor
air flow meter and ignition module (engine won't run at all)
- · Air leaks into the induction system (hose missing or manifold gasket leaks)
- Vacuum pipe to fuel pressure regulator disconnected
- · Blocked fuel filter
- · Restrictive fuel plumbing (pipes too small a diameter, unsuitable fuel filter, etc)