help...just had a second hand engine fitted to me zed but its running like crap. seems fine when cold but gets bad detonation when hot, Also boost gauge reads 0 to 0.5 psi when at idle,drops to -2when slowly accelerating and goes on up to 10 when hard accelerating.is this an air leak or something worse/wrongly connected. Bloke who did the work is a "jap specialist" but then admitted to have never worked on a zed after job was done.

Is it jap or uk? Does the boost gauge go from 0 to 14psi or -7 to +7?

Sounds just like a boost leak to me. 10 psi means it's only in safety boost, but must be quite large if you still have detonation at that level.

At idle your boost gauge should read about -1 bar or about -14psi.

 

With your foot to the floor over 3600rpm you should have 0.62 bar or 9psi boost.

 

Stuart

Originally posted by Devil

Sounds just like a boost leak to me. 10 psi means it's only in safety boost, but must be quite large if you still have detonation at that level.

 

No Safty boost is 7psi normal boost is 9psi or 9.5psi.

 

Stuart

its a uk spec with -14 to +14 boost gauge. also runs very hot but this could just be due to the det.

think my brain had a relapse there for moment. Still think it has leak somewhere as it shouldn't be idling with any boost.

Yeah if it showing 0 at idle check the boost gauge tube see if its out.

 

But something is not right if you are getting o at idle.

 

What fuel do you use?

 

Stuart

Why do the gauges run from -14 to +14? Not from 0 to 14?

using optimax, gauge does go to anywhere between 10 and 7 psi when turbos come in depending on whether safety boost comes in .(not giving it any sort of use as detonation is bad!!!)

Originally posted by Devil

Why do the gauges run from -14 to +14? Not from 0 to 14?

 

 

Because turbos cause a vacume when they are not spinning. That's what Turbo lag is. It's the time it takes for the turbos to be spinning quick enough to actually blow air.

 

As for the det sensor, I think it only works at below 3000 or 4000 rpm or something like that.

 

 

Leon, you said that the engine runs fine when its cold. The engine runs in safety boost while it is cold and when it reaches a certain temperature it allows full boost, so it shouldnt really run any different from cold to hot.

 

I am a little consernied about the running hot though. You say it could be running hot because of the detonation but really it could be detonating because of the heat.

 

Flush your engine rad out. If you have has a new engine put in, there could be an air lock in there some where. Flush all the water out and refill it, but this time put more coolent in. I flushed mine a few weeks ago and put about 50/50 mixture of water and coolent in.

 

Have you got an after market water gauge? If not it may be handy as the stock gauge doesnt really tell you anything. My temp ranges from 60C to 95C and the stock gauge doesnt move.

 

Stuart

Originally posted by SRRAE

Because turbos cause a vacume when they are not spinning. That's what Turbo lag is. It's the time it takes for the turbos to be spinning quick enough to actually blow air.

 

 

Stuart

 

[pedant]

the vacuum is created within the engine, not by the turbo's. ;)

[/pedant]

Originally posted by SRRAE

 

Have you got an after market water gauge? If not it may be handy as the stock gauge doesnt really tell you anything. My temp ranges from 60C to 95C and the stock gauge doesnt move.

 

Stuart

 

Syuart, this sounds like a damn fine idea, have you got any details on the gauge you have fitted?

Any hissing sounds from the engine bay ?

 

I suspect one or both big plastic hoses running from the intake to the turbo is either not connected or has split.

These hoses are real bitches to get back when reinstalling the engine and since you say the guy that did the work had no experience with Zeds I suspect he didn't know how to get these hoses back (in one piece)

 

The detonation + heat is probably a result of a far too lean mixture, since the turbos are able to "suck" up a lot of extra air that isn't registered by the AFM..

 

-Eric

Originally posted by NigelBoyd

Syuart, this sounds like a damn fine idea, have you got any details on the gauge you have fitted?

 

 

Yeah it tells the temp and plugs into the stock sensor ;)

 

 

I bought them from these.

http://www.sca-racerally.co.uk/

 

 

 

I think http://www.speeding.co.uk sell them too. Its under interior or Engine section.

 

Stuart

no obvious hissing sounds from the engine but i'm going to block off the intake and use an air line to pressurise the inlet manifold and listen for any leaks on saturday.