Opinions on a boost fault?

[ryanaj79]

Hi all, before I spend alot of cash on a trial and error, wondered if anyone has an idea with a small boost problem.

Had diagnostics done and rolling road to see whats happening, as over last month or 2 my turbo aint boosting fully. Gets to about 3/4 boost then drops off, no knocking, bucking or massive drop in power,
just turbo kinda backs down at about 4,500rpm. Feels a bit lackluster compared to before, when it was fully boosting. Knock sensor is fine, no error codes and no leaks anywhere, engine is stock and healthy otherwise.

anyways, I was told it could be either actuator or recurc/blow off valve maybe sticking, as dyno print out shows something makin it drop off,
so wondered if anyone has had a similar problem? im considering gettin a de-cat, in case the cat is clogged...



best run it did was 233hp so not bad from 245hp 18 years ago.
Any ideas would be great ta its a rev4 turbo btw

[androo007]

If it has an aftermarket bov then look to pop a standard one on first, nice and cheap.

Actuators rarely go unless you stick on the eBay decay pipes which then catch on the actuator. Otherwise v unlikely to fail.

[robbie_742003]

Got exactly the same problem, down on power, rolling road said running rich at higher revs. They suggested either actuator or vac leak, neither of which have I managed to sort

[ryanaj79]

Hi, its got stock recirc bov atm, but that could be sticking i suppose. What does actuator look like?

I know where the boost solenoid is, as someone suggested they can stick, as my defi boost gauge sometimes stops at 0.5bar.
Sounds similar to mine Robbie, but ive not got any leaks and not running rich

[jimGTS]

its not unheard of for the boost to drop if being controlled by the standard boost solenoid/controller, aka the tvsv.

i would look at your timing and for any leaks.

[ryanaj79]

cheers, will have garage look at timing as well.. tho was set up last summer when I had new cam belt put on.
Theres no leaks atm, but looking at the age of the car, could it be the solenoid or actuator just not doing the job anymore?
Also is the wastegate and actuator the same thing?

Another thing I forgot to mention, is someone I know who works for Honda asked me how I drive it, as if turbos not driven hard sometimes, parts stick lol,
I drive it conservatively, as had a N/A celica before, plus it was stood for a good 6 months before I got it, as was imported. I didnt boost it much last year, so my driving style doesnt help lol

Also worth mentioning, it started losing boost after I got it back from having full service and mot.. tho might be coincidence?

[mr2magic]

its not unheard of for the boost to drop if being controlled by the standard boost solenoid/controller, aka the tvsv.

i would look at your timing and for any leaks.

This!

[androo007]

what was in the service? bet its a boost leak....

Start at one end (exhaust or intake) and trace back every pipe... trough intercooler....turbo... etc check that all boots are on and tight.

[sinjen]

its not unheard of for the boost to drop if being controlled by the standard boost solenoid/controller, aka the tvsv.

i would look at your timing and for any leaks.

As I suggested on FB

[ryanaj79]

its not unheard of for the boost to drop if being controlled by the standard boost solenoid/controller, aka the tvsv.

i would look at your timing and for any leaks.

As I suggested on FB

aye, cheers for ideas folks, has helped me whittle it down a bit while ive been reading up. I don't hav tools to do jobs myself,
but will look to gettin it back to the place i had it other day, will hav each thing checked..

Also am I right in thinkin, if it was the dizzy cap being at fault, the car would buck at high boost? if it wasnt gettin right sparks?

[ryanaj79]

Also is there anyone near Nottinghamshire who has a smoke machine for diagnostics? My mate had one at his workshop,
used it for finding leaking bov on my old rev2, but he's not working currently due to an injury..

theres some beers in it for anyone nearby could take a peek who knows their stuff?

[ryanaj79]

its not unheard of for the boost to drop if being controlled by the standard boost solenoid/controller, aka the tvsv.

i would look at your timing and for any leaks.

This!

Hi again all, left it a while before I got the 2 booked in.
but had it checked over again by same place with rolling road and diagnostics checks.
No boost leaks and timing spot on, they also checked the cat to see if blocked and it isnt. Turbo and recirc bov good, and fuel pump fine, and isnt running rich or lean, so they puzzled too.
So theres a ghost in the machine lol as its running perfect otherwise.

Only thing I can add is it boosts better thru lower gears, if ive accelerated hard from 1st to 3rd it does around 0.7 or 0.8 bar sometimes, then starts to drop off.
Any one else with similar problem found solution? I'm tempted to source another solenoid just to try, if oem one going?

[Martin F]

Why don't you just buy and fit an electronic boost controller then try raising the boost ?

[jakeymears]

Is the fault consistent or is it more apparent after a short spell of spirited driving/or take a little time through the course of a journey to become apparent ?

If so I would have the down pipe off and check that the cat hasn't shifted or collapsed internally. We had this on the R56 mini's we used to run and would get a similar effect to the boost curves on the dyno due to the massive back pressure in the exhaust stalling out the turbine.

I wouldn't put a decat down pipe on as that would in itself bump the boost up a smidge and may mask the actual problem.

[ryanaj79]

I thought about a boost controller other month, but wanted to make sure I can eliminate any faults first without faffing with engine

And its a constant thing, tis same on a short or long run. Already had cat looked at an they said it didnt look blocked.

Will just put up with it for now, tis fast enough atm, prob gonna get boost controller and new intercooler, decat maybe next year tho!

cheers for advice