Hesitation issue - MY99 EJ20 NA Engine

Ben · Post by **Ben** » Sun Apr 02, 2006 7:03 pm

Hi all,

Still having some probs with this engine of mine........

Stats are
MY99 Impreza RX EJ20 with approx 120,000k's on it fitted to a 1992 L series wagon with lift kit.

Problem is
Once the car is warmed up (never when cold) I occaisionally get a hesitation at WOT. The hesitation starts at about 90% throttle and when you back off it goes away. It just feels like it drops a cylinder. After the first time it happens it will happen for a while each time you floor it, but eventually will not happen on WOT - then it is completely random when it happens after that but only after 90% throttle

What I have done
I have replaced leads, ignition coil and plugs. Codes have been checked - all I am getting are Speed Sensor and Neutral Switch...

What else can I do?

Fatz · Post by **Fatz** » Sun Apr 02, 2006 7:44 pm

is there a possibility it could be the cam sensor??
sounds like a problem similar to what i had, and it turned out to be that?
Cheer

Ben · Post by **Ben** » Sun Apr 02, 2006 8:34 pm

Thanks, will try that next!!!

Good thing I have the liberty, I just keep swapping bits from it to see if the problem goes away

Guest · Post by **Guest** » Mon Apr 03, 2006 6:37 am

Are you 'useing' the speed sensor in your set up?

Ben · Post by **Ben** » Mon Apr 03, 2006 7:41 am

bratgeebah wrote:Are you 'useing' the speed sensor in your set up?

No speed sensor is connected.

Guest · Post by **Guest** » Mon Apr 03, 2006 6:38 pm

There is a good chance that this may be your problem. It may be that the ecu is seeing wot or at least a large throttle opening and and no vehicle speed and is 'protecting' the engine from revving hard with no load.
Do you find when you pull the car up quickly eg load on the engine to a sudden stop that it 'hunts' or hesitates as well?
Speed sensors can also give the ecu an indication of load. eg. at high vehicle speed with a large throttle opening in 5th gear the ecu will look up a fuel table that is richer than it would for the same throttle opening in first gear at low vehicle speed. (to allow for wind resistance load)
I don't actually know alot about it but am about to put an 00 2.5 in my Brumby and learnt about it from a mate who is an engineer in the auto. manufacturing industry.
He convinced me that even though the car will run without it, a speed sensor is essential to make the conversion run as smooth and efficient as the donor vehicle.
This may be irrelevant to your problem but its a good place to start.

Ben · Post by **Ben** » Tue Apr 04, 2006 8:38 pm

Thanks for that, makes sense really....

The car occaisionally dies when I pull up quick and have to hit the key to start it again....

Guest · Post by **Guest** » Wed Apr 05, 2006 6:30 pm

A mate of mine with an ej22 in a Brumby used an after market cruise control signal generator mounted on the tail shaft with the pickup on the gear box to replicate the signal. This saves useing the instrument binnacle from the donor car. Another mate who is putting an sr20de in his 1600 found a place that supplies a 'little black box' that rectifies the sine wave generated by his gearbox speed sesor to to a square wave required by the ecu which also saved the hassle of installing the instrument binnacle from his donor car.
I don't know that this is definately your problem but I hope it helps.
Let me know how you go as I still have to start work on my conversion. I don't have a 1/2 cut or the gear box for my engine (useing another) so I have to work out what to do for the speed sensor set up too.

Gee

stamp_licker · Post by **stamp_licker** » Wed Apr 05, 2006 7:31 pm

L series already have a speed sensor in the dash which you can hook into.