colin c

I'm helping out a friend of a friend who has a problem with his 94 WRX.

Apparentley the engine started pinking going down the motorway, after that it didn't run as nicely as it used to. So he took it to a garage in Southampton which supposedly had Subaru knowlegde. They diagnosed a knackerd engine. The owner purchased a replacement secondhand lump and got the garage to fit it. The replacement engine has now been fitted for 3 months and it still doesn't run. The garage now say the replacement engine has no oil pressure and a missfire on No 1 cylinder. The owner has now given up with the garage and I now have the job of fixing it thanks to my friend.

The Scooby is now dumped on my drive at home. It was recoverd by recovery truck due to the oil pressure problem.

1st thing I checked was the oil level, I noticed the oil looked like new, i.e the engine has never run since it has been fitted.

Tried starting it, cranks over but does not attempt to fire. Checked the coil packs and noticed No 1 & 3 were connected back to front. Reconnected the correct coil pack to the right wire and checked No 2 & 4 which were connected correctley.
Still doesn't start up. Removed spark plugs which were wet, so I have fuel getting into cylinders. While the plugs were out I carried out a compression check and all cylinders were between 105 psi and 120 psi. Slightly low than I would of expected, but it is a turbo so a lower compression ratio would account for this. Also while the plugs were out I thought I would test the spark from the coil packs, had a good spark on No 1,2 & 4, but no spark on No 3 coil pack. I had a spare new coil pack in the garage so I connected that to No 3 and still I have no spark. Checked the feed to the coil pack which is 12 volts, but appears to be no earth, which must be the trigger wire. Traced the wire back to the multi plug by the fuse box in the engine compartment and I have continuity, removed the engine ECU and can not find the wire at the multi plugs on the ECU.

Does this wire go to any other units before the ECU ?

I know this is not going to make the engine run but it is a problem that has to be overcome at some point.

Just spoken to the owner and he said the garage that fitted the engine had to swap something over on the cambelt as it was fitted back to front. This is going to be the next place to check for the non running.

Any suggestions other than a gallon of petrol and a box of matches.

Cheers Colin, from the house of 2 dead Scooby's

jonny gav

iTrader: (1)

check the crank and cam position sensors, this the best place to start looking for the non-running(common fault for non-starting)!

not sure about the coil packs though.

name and shame the garage so no other scoobynet members fall foul of these cowboys

colin c

Cheers Jonny,

I have now tried the camshaft and crankshaft sensors off my Scooby on it which I know are good and off the same model year. It still didn't start. Tested continuity of wires for the sensors and found the wires to the crankshaft sensors were open circiut. I traced the wires back and found a break in the wires under the inlet manifold. The wires are now repaired and it still doesn't attempt to fire.

Any more sugestions.

Colin.

jonny gav

iTrader: (1)

the ecu could have gone into limp mode after the fault,have you left the battery disconnected for 15 mins before trying to start it?

if the ecu IS in limp mode it thinks the temp is at 80deg therefore not engaging the cold start.

jonny

David_Wallis

got access to a scope?? check for a square wave on crank and cam position sensors at the ecu connectors whilst cranking..

possibly check the block has an earth (clutching at straws)

Ignition module thing behind boost control solenoid?

Possibly something to do with it on chassis leg... dodgy alarm / immobiliser installation?

You've done a diagnostic check I assume?

David

David_Wallis

Also try your ecu..

David

colin c

Hi David,

Tried a different ECU already with no luck.

I can borrow a scope from work at the weekend to test the sensors.

Going to give the earth mod a try also, a set of jump leads from the engine to the battery earth should be ample earthing.

I still think that the crankshaft sensor is telling the ECU that the engine is the wrong stroke, it sounds as though it's trying to fire on induction stoke not the power stroke because if you give it full throttle while cranking you can hear it trying to fire in the intake system with the air filter off.

Hopefully I will be able to have a better look this weekend if it ever stops raining.

Cheers Colin.

David_Wallis

Whats the engine out of, did whatever spins on the crank / cam for the pickup change design??

Wind it by hand to tdc and do the same on yours and compare?

Good Luck.

David

ustolemyname??stevieturbo

iTrader: (1)

Perhaps jumped a tooth on the belt? There is an ignition amplifier mounted on the drivers side strut tower. I once connected 2 coils the wrong way ( ie 2+4 swapped ) and for some strange reason, after I discovered the problem, the coil packs only lasted a few minutes after this before failing.

colin c

Been playing with the Scooby today again. Tried the ingnition amplifier, still no go. Stripped the cambelt covers off and it was all timed up correctley, no water in the rad so it saved me draining the cooling system.

Tracing the wireing back to the ECU I found that the sensor on the crankshaft pulley is an engine position sensor, is there another crankshaft sensor as there is a provision for it in the ECU harness ?

I took the TMIC off to get to the multiplug under it. When cranking the engine with full throttle there is not a vacum at the throttle body but pressure, it try's to blow my hand away from the intake. At this point I thought there must be a blockage in the exhaust system not allowing the gasess to escape. I got the girlfriend to crank it over while I checked the exit of the exhaust, there appears to be no blockage and it smelt quite fume.

Would this engine have hydraulic tappets, if there was insufficient oil pressure would it cause the valves not to correctly open and also back pressure in the inlet manifold.

I need to get this soughted soon so I can get some spare time to put a new gearbox in my own Scooby.

Cheers for everones help, Colin.

tweenierob

Pressure from the throttle body would suggest to me that timing is out somehow and that the engine is on compression stroke whilst an inlet valve is open???
If the engine was not changed then my next suggestion would possibly be a stuck open inlet valve..
Not much help...
Rob

UkLegacyT

i would agree with the suggestions of stevie and rob. as you mentioned, you have sparks, and fuel, so in theory if all correctly timed, it should start?

also, there must be inlet valves open on the compression stroke to get the pressure you describe.

i would put it down to the cambelt setup. if theyve messed with it at all, it could be all over the gaff if they are cowboys.
i know you say youve checked it, and im not by any means saying you dont know what you are doing, but i would have another look just to make certain.

keep us informed

ian

UkLegacyT

as for the tappets, im sure it would still start anyway without oil pressure, as an amount of oil stays in the tappets anyway, would just sound like a tractor.
i reckon theyve probably just told you its oil pressure as they havent a clue what it really is

colin c

Just got back from the pub ( I sound like David ) and had a brain wave while cleaning my teeth.

The camelt is definately timed up correctly, I'm a qualified motor vehicle technican and have done loads of cambelts including a few Impreza's. But I just realised even though it is timed up correctly it could still be that the crankshaft is 360 degrees out, making the ECU think that the camshaft with the sensor on it is 180 degrees out, which would cause it to try and fire on the induction stroke, hense the back pressure in the inlet manifold.

If it is not raining tommorrow night I will try my theory out.

Colin.

David_Wallis

See if you sounded like me, you'd have fixed it by now.

David

colin c

Sorry that was a beer induced idea that is not going to make any difference.

Better idea is has anyone got a picture of a 94 WRX cambelt crankshaft pulley so that I can check if the sensor positions are the same.

Cheers Colin

David_Wallis

LOL..

David