Zip

A year or so ago a number of threads floated around discussing a sudden cut in power at highish revs in a high gear which was variously attributable to the ECU cutting power as the boost limit was reached, coil packs breaking down and failing under load, and various other non-specific causes. Well I have sold my car as you know, and the dealer has called me telling me that it is happening again:

4500-5000rpm, 110ish in 5th gear, sudden drop in power, check engine light comes on, pull to the side of the road, light goes off, engine appears fine, then same again in same circumstances. Now I have very rarely experienced this since replacing the coil packs (I'm not often accelerating hard at 110...), but since all the original threads, has anyone diagnosed and cured this one for good, short of bleed valves and fiddling around with restrictors for an eternity.

My best answers came from Bob Rawle originally - any ideas, Bob? Thanks in anticipation.

Zip

Bob Rawle

As the check engine is coming on then its definately something the ecu knows about, coil packs etc are not "seen" by the ecu. So this is still boost cut but this time it is probably due to the mass air flow meter. its possibly not generally known that there are in fact two boost cuts, one initiated from the map sensor reading and one initiated by the mass air flow meter. If the maf is faulty this could be the problem. the other option is that the car is detting so much for some reason that the ecu is putting itself into limp home mode which effectively cuts boost and flags the check engine as well as limiting revs. Any known info on the boost level when this happens ?

Bob

Zip

Thanks for the rapid response. Not sure about exact boost level - must be near maximum, due to the circumstances under which it occurs, but if I recall when it was last occuring regularly, PTS in St Albans, replaced a turbo hose, and had to fiddle around with restrictor diameters to prevent it happening after the coil packs were replaced (which I suppose is effectively restricting boost) Would oil from a Ramair filter effect the MAF sensor? I have had one fitted for about 15 months. In which case, could this be causing it? As I said, it happens only under specific circumstances (high gear, high revs, heavy load - foot to floor). It has never happened when I have been *****-out in 1st, 2nd or 3rd gear.

Regards,
Zip

Trout

iTrader: (1)

Zip,

if the check engine light is coming on then the ECU should have stored an Error Code in memory. This can be read with expensive Scoob diag equipe - try MRTRALLY website - top tips sections. Or search as there are lots of 'diagnostic' threads.

R

Bob Rawle

You have described boost cut ... this is exactly the circumstances under which it occurs, possible causes are a sticky/gummed solenoid, this can be cleaned through with brake cleaner or gummed up restrictor. You dont mention MY of car and I can't remember but if it has the two port solenoid things can be improved by fitting a three port and moving the restrictor from the turbo to actuator pipe to the vent pipe.

richbay

Hi i am the new owner of Marks wrx, firstly i would like to thank him for all the information he has given me about the car, its a great help.
The dealer from which i brought the car from, has taken the car to PTS in Luton, they have examined it, but could find no fault on a rolling road, but they did turn the boost back, in the hope of a cure,
does any one have any reports (good or bad) on a mongoose back box for the car, i would perfer a scoobysport box, however funds are a little limited at the moment and i can get a good price on mongoose
thanks
Richard

Blow Dog

try someone other than pts.

richbay

the problems seems to have gone at high revs/boost, but has now appeared at lower revs with no boost, the check engine light comes on very intermittantly even at 30 mph,
any ideas, i agree with the PTS statement, has anyone else had problems with PTS, (they did charge £175 for the rolling road and to turn back the boost)

Blow Dog

richbay,

maill me offline and I will tell you what I know of PTS.

cem

jwhitton

MY00 turbo UK spec 1500miles:

My car has done this twice at around the same revs, 4500 to 5000rpm is second gear full throttle. Both times on bends. Feels like the engine has completely been cut then comes back. The engine light does not come on. Maybe nothing to do with level of the engine oil but have checked and this is 3/4 full. I read somewhere not to have it on the max.

I am going to see if it does it again then will have it into the dealer.

jon

Zip

Rich,
The reason I took the car to Power Engineering was because I was not completely convinced with PTS...

Blow Dog - drop me a line and give me the detail. Were you the guy they tried the chargecooler on...?

Hope the rest of the car is still good...!!
Zip