Making Boost but slowing down ?????

Shannon · Post by **Shannon** » Sun May 23, 2004 6:08 pm

Hi Guys,

I've just purchased another Starion and I am having problems. Everything on the car works, it starts easy, idles nice, free rev's great but as soon as I put my foot down and the turbo starts to build pressure the car slows down. It's like I'm applying the brake at the same time as opening the throttle.

The boost gauge show about 7 - 8psi and it remains stable there until the engine starts to slow down. There is no pinging or knocking, it just slows down until I lift me foot. It drives fine on light throttle, it's more responsive and accelerates better before the turbo builds any pressure.

Has anyone experienced anything similar and if so what was the cause.

Thanks,

SH.

Defective · Post by **Defective** » Sun May 23, 2004 6:18 pm

thats what my old sigma was doing... i think the turbo was rooted... actually the whole car was rooted but i think the turbo caused that problem.

Shannon · Post by **Shannon** » Sun May 23, 2004 6:43 pm

thanks for the info, but mine is a fresh rebuild. my turbo works fine.

Chris 83JA · Post by **Chris 83JA** » Sun May 23, 2004 7:13 pm

do you mean the car actually slows down, or that the rate of acceleration slows down?

Will · Post by **Will** » Sun May 23, 2004 7:45 pm

Check your boost retard mechanism on your distributor - it might be retarding too much. Check your base ignition timing too. If ignition is too retarded, then it can be a bit lean too and still not ping, so check the MAP sensor too.

Shannon · Post by **Shannon** » Sun May 23, 2004 10:50 pm

thanks, the ingnition timing is spot on 5deg at idle. the car actually slows down as the revs drop while under boost this will continue until i lift my foot.

Is there anyway checking the boost retard ? and fixing it if there is a problem ?

The boost gauge is working fine.

androoz · Post by **androoz** » Sun May 23, 2004 11:09 pm

maybe your turbo is connected backwards...

rofl

hehe

SpidersWeb · Post by **SpidersWeb** » Mon May 24, 2004 12:51 am

Check your turbo compressor out to throttle body pipes (including intercooler and any BOV).

Reason I say this, is if there is a hole along here, the MAF will read more air than is actually going in, thereby causing the car to run too rich.

Just an idea, its the only thing that sprung to mind. If I am correct, then your car would be blowing black smoke out the rear when its on boost. You would also hear a rather loud air leak noise from under the engine.

There are many other weird things I can think of, but check that first, costs nothing to check. Some include the already suggested idea of the boost retard, and maybe spark plugs are worth a try. Ive noticed a lot of performance sites selling plugs with different 'temperature settings' for different boost levels.

This is the first case I heard of where the rpm drops under boost without spluttering or coughing about, so really got no idea, just sharing thoughts.

decoy · Post by **decoy** » Mon May 24, 2004 2:43 am

im guessing your timing is out as well

Shannon · Post by **Shannon** » Mon May 24, 2004 5:15 pm

Does anyone have a diagram of how the vacuum hoses are setup, also does anyone have a copy of the voltage outputs for the sensors or ECU fault code descriptions ?

Thanks,

SH.

Paradoxx · Post by **Paradoxx** » Mon May 24, 2004 10:22 pm

All that info is in the starion manuals available for download, I cant remember the url but it's on some previous topics.
Does the engine actually die when it comes on boost, or is it a case of losing spark or enrichment or what? You can usually tell what the cause is by the sound it makes and if it makes smoke or whatever. If it runs like poo when it is slowing down (ie under boost) then its spark/timing and its out by like 30 - 40 degrees. If its more subtle like just bogging down and losing revvs then its fuel related. If its a smooth loss of power then it seems like an air flow problem or turbo problem. Check the wastegate actuator if this is the case, and that this hose is connected to.

Hope this helps
Steve.

Will · Post by **Will** » Mon May 24, 2004 11:36 pm

I thought base timing at idle was supposed to be about 8 deg, but 3 deg shouldn't make a car slow down. If you can establish if mixtures are too rich, too lean or about right - that would be a good place to start. Beg/borrow a wideband A/F meter or go to a workshop with one.

Shannon · Post by **Shannon** » Wed May 26, 2004 11:49 am

can anyone remember the URL for the manuals mentioned above.

Black JA · Post by **Black JA** » Wed May 26, 2004 12:01 pm

http://www.camotec.net ?

logik · Post by **logik** » Wed May 26, 2004 1:39 pm

Yeah ive been meaning to post about this, i have a similar situation.

If i go from the lights, not launching, just a normal take off and i put my foot all the way down, the turbo spools to 7psi (as normal) but it feels like
the car isnt going as fast as it should.

Its quite hard to describe but i'll try. If i take off and gradually apply the pedal (controlling my boost), judging by the boost gauge it will actually go
faster if i hold it at half throttle, then when im around 4500rpm i can put my foot all the way down and it goes fine.

If i just take off from the lights and hold my foot right down, it feels like the engine is choking or something, no pinging or noises though, but the exhaust
suddenly gets a lot louder .. so i know the turbo is making boost.

Its weird, ive never seen it in any turbo car before. In the case of a silvia you can apply it gradually or just hold ya foot down and the thing just goes
(and smokes the tyres if your lucky). It doesnt matter if your on full boost at 3000rpm, theres no 'clogging' effect.

I havent checked my fuel mixtures as i *THINK* this could be the prob.

Oh well :)

(Just read shannons post again that time, sounds pretty much exactly whats happening to me)

Austarion

Making Boost but slowing down ?????

Making Boost but slowing down ?????

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