Hi,

Looking at an issue with a 97 classic Impreza that wont rev beyond 5k (video attached). I was originally told the code (video attached) suggested injectors but since a further look at the car and the code its linked to the spark plugs. They are new but 2 look like they aren't sparking, burning the fuel properly. As these are new i have been told it is likely coil pack and / or leads. My main concern is replacing them and then still not being resolved and chasing it on and on. The engine had a basic rebuild with new head gaskets, spark plugs etc (some photos attached). Any thoughts or suggestions would be greatly appreciated.

Many Thanks

Michael

 

looks to be error code 45 from the long/short flashing.

 

Hi Gambit,

Apologies for being a bit daft but what does error code 45 relate to on a 97 impreza turbo?

Kind Regardsh

Michael

 

watching back again - need someone else to watch your video to double check it - but looks to be multiple error codes

but im sure its

code 23
code 24
code 44
code 45

some of those could be historic also so youd need to reset the ecu to clear all codes then try again to see whats actually fresh error codes

 

there are NO fault codes for Spark Plugs or Coils as such simply generic "misfire codes" of which those listed aren't.......
likely the reason it won't rev past 5K is because of the faults!! its probably in "safe mode"
code 23 Knock Sensor
code 24 MAF Sensor
code 44 Wastegate Solenoid
code 45 Pressure Exchange Solenoid

 

i see the same watching the video
23 Mass air flow sensor
24 Idle air control sensor
44 Turbo wastegate regulator malfunction
45 MAP sensor

to me that would suggest maybe a boost leak, wiring problem, dodgy MAF sensor all as possibilities. If the speedo has stopped working as well you'll also get low limiter.

Start with the codes as clues, check idle valve, check wiring back to the ECU, look for hoses hanging off the map sensor/boost solenoid or perhaps someones put the hoses in the wrong place.

Once you've made repairs then reset the ECU and go for another drive to see what comes back and repeat the whole process again until all codes are solved and the cars driving how it should be.

 

I suppose my main fear is that it could be something big and therefore potentially expensive. The car is solid after having welding etc and generally looks solid for the age but dont want a knackered engine. If it is likely just that these things that need tracing and replacing i am hoping that wouldnt be too expensive but havent priced all of these components up yet to be fair. Anyone have some rough ballpark figures if all the components in question require replacing?

 

best to do some diagnostic work as it could be a wiring loom issue rather than a bunch of sensors all magically giving up the ghost at the same time. import car parts website should let you price up the cost of the new parts

 

Nearly be sure thats a broken wire.

 

@1509joe Have you had something like this before? where would the broken wire likely be with these faults showing up?

 

Clear those codes first then see have you any hard faults and let us know check earth strap from body to battery.

 

So after an ECU reset there was no flashing code but the car still doesn't rev over 5k. Pease see attached videos. One is a cold start to show no smoke. One is the engine management light and one is revving engine. Any thoughts???

 

doesn't rev over 5K stationary or when under boost?

 

is it just me or do the vids make it sound like it has a misfire - whens last time you had all the plugs out for a nosey?

 

when stationary mate

 

I thought it sounded weird on this vid but I’ve been told it sounds ok.
the spark plugs are definitely not sparking right as they are new and two are already a bit black. Could it be leads or coils pack?

 

yeah if you've already fouled the plugs ticking over then leads and coil would be worth a shout

 

Last video sounds like a large air leak never heard a dump valve sound like that.
Which two plugs are black? Remember it's wasted spark being a V3/4 so could be ignitor to and or coilpack.
Also check under air box there's a round plug that gives bother sometimes.

 

I have uploaded two videos i got last night to see if it helps at all. Apparently there is only 1 cylinder (unsure of number) sparking correctly. Is definitely misfiring quite badly and smells extremely strong of fuel, almost like its pumping pure fuel through due to not combusting correctly i guess.
One video is the engine running from cold and one is the exhaust and the fuel / smoke.

 

if its missing on 3 cylinders then yeah it would be pumping raw fuel out the back. stop trying to drive it out of it though and start diagnosing, make sure fuel and spark on all cylinders, make sure firing in the right order, check ECU outputs.

Just letting it run and revving it is only going to end up with a shopping list of parts like pistons/block etc.

 

Sorry if i wasnt clear, this is a car in possibly going to own hence trying to work out if it could be something big as that would be a killer as a new owner. I am not overly technical when it comes to Imprezas or these type of issues in general i guess but enjoy learning and have learnt and carried out various jobs on previous cars i have owned. I am happy to go through processes etc to diagnose issues but dont have access to lots of equipment other than a decent amount of sockets, spanners etc but not fault readers etc.
I suppose one of my concerns is having to purchase lots of items to try to find the issue, i.e. MAP sensor, MAF, Coilpacks, leads, spark plugs if it doesnt actually need all / any of them. I would love to know someone locally who could not only help me learn and test things but maybe interchange parts with another Impreza (if they owned one, club member etc) to rule out certain things one at a time.

 

Have you got a spark at all 4 plugs?

Are the leads on the right order?

You clearly have fuel - do you have an air leak causing the ECU to over-fuel?

Have you replaced the injectors?

 

If its not your car yet then I'd say walk away and find another - there are still plenty about for sale and without spending on a mechanic to diagnose it or buying the tools to do it yourself its only going to end up draining your wallet.


If you want to keep diagbosing then try and work out if it actually has spark on all 4 cylinders, it could be sticky injectors too if its been sitting up a while maybe one or more are stuck open with old dried in fuel

 

I mean it could be as 1509 Joe said a couple of posts ago that it sounded like an air leak or that the dump valve sounded weird at least.

 

Smoke test

 

I get that mate and i appreciate your feedback. Its a tricky one as i am usually very risk adverse and i have thought more than once to walk away but it is tidy for the price having had sills, arches and turrets welded which is what is keeping me interested. The slightly more adventurous side of me is thinking that it could be a fun winter project to try to diagnose and learn a bit but im not sure how quickly that will wear off if i am struggling with it!

My main worry is that it is something larger and turns into a massive problem which requires a huge amount of work or new engine etc, if it turns out to be a sensor and just needs lots of time thats ok but this is where it is so hard to know what to do and how to roll the dice.

 

This is all hard when its not mine though as i can spend money on doing it whilst he still owns it and potentially not buy it, i ask for it to be done by the owner who is likely to say no as he wants the space back in his garage or i gamble and do these things once i have it at home but it could be a bit late if there is something major.

 

Could the boost leak be on the dumpvalve itself? if he has the OEM one should i ask him to put it back on and test? Is there a common point that these like to leak?

 

Can someone kindly confirm which lead should go to which plug on the attached?

 

The plugs correspond to the cylinder layout. So top right goes to top right cylinder (closest to passenger firewall, cylinder 4) Bottom right goes to passenger side closest to rad (cylinder 2)
And so on.