[kevster]

Hi all
Just wondered if anyone had experienced anything similar? When accelerating, even going gently with boost in lower yellow, I can feel the power come in surges. It is most noticable when the engine is still cold. Without moving my foot at all on the pedal and with the boost in the yellow I go through a series of flat spots that only even out if I floor it (not what I want to do when the engine is cold) and are much less noticible when the engine is warm. I have tried using an injector cleaner...no difference.

Would it be worth doing a resistance/voltage check of the oxygen sensor/MAP sensor/air density meter/air temp meter/whatever else meter....to see if anything is a little out of kilter?

Or could it be related to my sticky idle air control valve which currently gives a rather eratic idle (or I suppose there might be nothing wrong with the IAC valve and the other 'flat spot' problem is causing the eratic idle???)

While on the subject, I can see how to check the resistance of a component at the pins when disconnected, but how do you check the voltage being sent/received at a given sensor? Do you have to strip back a bit of wire and then tape it up afterwards?

Cheers
Kev

 

[Mr. Person]

I have a similiar problem in my CS. I think its a vacuum leak. Where? Don't know. Trying to figure it out, but can't so I think I'm just gonna replace all the vacuum lines.

BTW is there any real advantage to silicone hoses other than the fact that they look cool?

 

[kevster]

I think that silicone may eventually harden but shouldn't deteriorate and fracture the way rubber does....important if you want your hoses to last more than another 11 years . I don't think my problem is a vacuum leak though as I have already replaced al my hoses

 

[slidejules]

Same thing for me here as well, mine has been doing it for about a month now. I haven't replaced my hoses yet so that is first on my agenda... once warm the engine is fine, it's only when cold and at half throttle that the surging is apparent. You say with the boost in the yellow - does your boost gauge move during the surging? Mine does, very clearly, sway from left to right with the surging (exactly as it would if I was pumping the throttle). Let me know if you find the cause (I'll do the same!).

 

[kevster]

Originally posted by slidejules:
[qb]Same thing for me here as well, mine has been doing it for about a month now. I haven't replaced my hoses yet so that is first on my agenda... once warm the engine is fine, it's only when cold and at half throttle that the surging is apparent. You say with the boost in the yellow - does your boost gauge move during the surging? Mine does, very clearly, sway from left to right with the surging (exactly as it would if I was pumping the throttle). Let me know if you find the cause (I'll do the same!). [/qb][/b]

I'm not sure mine is the same thing as I don't get any movement on the boost gauge. I do get a slight pulsing on the boost gauge at full boost, but I think this is due to the way the BPCV works...i.e. the valve moves with a certian frequency. About 3hz (this is off the top of my head so could be complete rubbish

). Your wobbly boost in the yellow sounds like it might be a problem with the BPCV. Is there soemone with a good one you could swap with?
Kev

 

[slidejules]

a ha - thanks for the tip. Is that another name for the APC unit thingy (3 hoses, nr to the top right of the radiator as you look at the front)? I had a problem with that a few months back where I only got base boost - turned out the connector wasn't secured properly. It could be that, although would that only affect it at cold? I don't know any other 2.3 fpt owners in the vicinity, a friend of mine has an lpt, not sure the unit is the same in that one?

thanks again! Jules

 

[kevster]

Hmm..you're right. I don't know whether that sort of thing would go away as the engine heats up. The thing I know as the BPCV is the thingy on the rad' with the wires and three hoses labelled C, W and R. As far as I know any 9000 turbo of that age (MY93/94) onwards has the same BPCV, so swapping it might be worth a try anyway as they are so easy to exchange.
Kev

 

[Derek]

Kevster,

A couple of months ago my car suffered very similar symptoms. Reduced boost, very little guage movement and a surging under acceleration.
Inspection of the vacuum hoses revealed that they had turned into something resembling bendy charcoal and the one from the plastic Y-junction to the boost gauge was leaking badly. The hoses to/from the APC valve however were still in good condition. Replacement of all the other under bonnet rubber vacuum/pressure hoses restored order.

 

[kevster]

Originally posted by Derek:
[qb]Kevster,

A couple of months ago my car suffered very similar symptoms. Reduced boost, very little guage movement and a surging under acceleration.
Inspection of the vacuum hoses revealed that they had turned into something resembling bendy charcoal and the one from the plastic Y-junction to the boost gauge was leaking badly. The hoses to/from the APC valve however were still in good condition. Replacement of all the other under bonnet rubber vacuum/pressure hoses restored order. [/qb][/b]

Hi Derek
Thing is, I've already replaced all the rubber hoses since, as you found yourself, all the original ones had gone hard and fractured easily. The other thing is that I haven't lost any boost. My problem isn't really that big a problem, if you know what I mean. The car drives perfectly well, it is just that it feels lumpy and odd when accelerating gently when cold. I get the impression that either soemthing is about to go wrong or that something is slightly on the wonk and needs looking at.

 

[chris-edinburgh]

hi guys, what are the hoses that you are all replacing as a matter of course? (except apc valve related ones)

 

[kevster]

Hi Chris
The ones I replaced are the small-bore black rubber ones that are attached to the dump valve and the ones that are split by a three-way connector that run to the inlet manifold, boost gauge and somewhere else that I forget. There are two connects on the inlet manifold, but one is capped off (on my car anyway...this is where I've been taking manual boost readings from) and another that attaches to a 'thingy' at the upper engine mount end of the engine.

My larger-bore hoses that attach the BPCV to the wastegate are in perfect condition and appear to be made of black silicone rather than rubber.

 

[chris-edinburgh]

could the thing near the top engine mount that your talking about be the map sensor?

 

[kevster]

Originally posted by chris-edinburgh:
[qb]could the thing near the top engine mount that your talking about be the map sensor? [/qb][/b]

Could be...or was it the fuel pressure regulator??? Hey, I just went for every scabby looking bit of rubber pipe I could find, followed it from where it started to where it finished and replaced it The car definitely feels a lot better with lots of colourful stuff under the bonnet