Hesitation

[JoKO]

Hi guys, got a 92 Liberty RS. Everything is stock on the car. Just a couple of days ago while cruising, it started hesitating out of the blue. The engine runs rough at idle too. I'm thinking the coil on plugs might be at fault (I read that they often need to be replaced) since my turbo is giving out boost and my fuel pump primes healthily, but I may be wrong. Any ideas? Thanks!

[mike-tracy]

Hi JoKO, i'd recommend starting with the simpliest stuff, such as brand new copper NGK spark plugs, running fuel system cleaner and then changing the fuel filter. Then go on to check for vacuum leaks.

I have an ej20g, and with my old home-made intake setup, I was having the same issues as you, rough idle and running with hesitation. Turned out the intake manifold gaskets were bad - letting unmetered air escape, as well as a couple other spots in the intake were leaking. But she would still boost.

If you haven't yet, I recommend resetting the ECU and checking what codes come back. Here is the procedure for that: http://legacycentral.org/library/literature/codes.htm

And lastly, if you are able to diagnose it down to the coil on plugs, here is a write up on how to convert from the fragile ej20g style ones to the much improved 2nd generation Impreza ones. Couple of my friends have done this to good success.

http://forums.nasioc.com/forums/showthr ... ?t=1192028

[JoKO]

Hey MT, thanks for your response.

I was able to diagnose the fault down to ignition coilover on Cyl #1. Replaced it, plus used 2 upper cylinder spray cans, now car runs smoother than before BUT now I'm not sure that my boost gauge is giving out the correct reading. I have tried setting my boost to 15psi (abt 1 bar) and while road-testing on 2nd and 3rd gears, the peak boost would vary between 11-15psi. Does not seem normal to me... Shouldn't it be fixed at a given pressure on WOT?

Also, a couple of times, at around 3-4k rpm, the engine would lock abruptly (like a hiccup) for a brief moment (less than a second) and would then keep accelerating.

P.S: Can't be turbo related as the latter has just been rebuilt.

Nybody help pls!

Thx.

[Legacy777]

Maybe you ended up with some of the upper engine cleaner in your boost gauge line. That may be the same for the MAP sensor. You may want to remove the vacuum lines that come off the intake manifold and blow them out with compressed air to make sure there's no residual cleaner in the line that could be causing issues with the gauge/sensors.