Mazda Rotary Club

General => General Technical => Anything Engine/Performance/Tuning related => Topic started by: Dr Gonzo on July 01, 2004, 11:03:24 AM

Title: Performance drop-off
Post by: Dr Gonzo on July 01, 2004, 11:03:24 AM
My Rex used to pull like a train when the turbos kicked in but recently she\'s feeling a little asthmatic. The wastegate whistles & hisses away merrily and the car feels like it\'s holding back. V odd. Being of the zero-mechanical-knowledge-particularly-rotaries school of thought I\'m wondering if any you far-wiser-than-me types might have any ideas....
Title: Performance drop-off
Post by: iaint on July 01, 2004, 12:00:01 PM
Do you have a boooooost gauge?  That\'d help narrow it down some...

Iain
Title: Performance drop-off
Post by: Dr Gonzo on July 01, 2004, 03:24:30 PM
Hi Iain

Yes I do - what do you want me to check for and then I\'ll go take her for a blast, pen n paper in hand...
Title: Performance drop-off
Post by: Andyp on July 01, 2004, 05:16:25 PM
check what boost its reading and check when the hesitation kicks in and if it still boosts / waves about
Title: Performance drop-off
Post by: Dr Gonzo on July 01, 2004, 06:01:25 PM
Ok - starting at 1000rpm straight on to full throttle. Boost pretty steady at 0.5. Just passed 3K boost dips alarmingly then kicks back in going to about 0.6 and staying there pretty much. This is most of the time. The boost gauge on one run was flapping all over the place and the car felt like something was holding it back.
Title: Performance drop-off
Post by: Andyp on July 01, 2004, 06:30:08 PM
right ya underboosting as it should be 0.8

I have the same prob at the mo, think it could be vac loss due to y-pipe / vac hoses / etc

not sure though so i\'m taking mine to have it looked at soon, i\'d do the same, so many things it could be. If it\'s flapping its def not retaining pressure :(
Title: Performance drop-off
Post by: yonner on July 01, 2004, 10:34:22 PM
go non seq!
Title: Performance drop-off
Post by: Dr Gonzo on July 02, 2004, 08:52:55 AM
Ok - thought it didn\'t feel right. Thanks.
Title: Performance drop-off
Post by: iaint on July 02, 2004, 10:19:15 AM
The stock boost pattern is 0.8-dip-0.7 bar (1st then 2ndary tubbies).

It does sound like a leak/collapse - do you notice it more when the car\'s up to temp?  If so then it\'s almost certainly that problem as the hoses/pipes get softer when warm.

Iain
Title: Performance drop-off
Post by: Dr Gonzo on July 02, 2004, 10:29:38 AM
Yes, it definately gets worse as the engine warms up. Ok, better start saving - sounds expensive.

Thanks for your help guys.
Title: Performance drop-off
Post by: iaint on July 02, 2004, 11:50:26 AM
Not really expensive depending on how much you have replaced.

I had the full lot replaced (including all coolant hoses, air, intake, vacuum and solenoids when mine was rebuilt but the main stuff is DIY if you\'re up for it and not to expensive - probably < £200 realistically.

Iain
Title: Performance drop-off
Post by: Dr Gonzo on July 19, 2004, 10:54:50 AM
Iain - diagnosis spot on mate - cheers. Took it to RX Motors - the hose for the boost gauged had perished giving the weird read-outs and one of the hoses on the turbos had split. Easy fix. Plus they changed the oil and sparks, cleaned the filter all for £130 - can\'t grumble. Top blokes (cheers Matt!).

Thanks again for your help Iain!