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Join Date: May 2004
Location: uk
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Smile 951 cutting out on acceration

hello
my 951 suffer from a bad dme relay(no start)and since i have changed it and now have another problem when i accerate hard the car cuts out and then will cut out after at the slightest acceration.i have changed the ignition switch and have tried running car with fuel pump on constantly(by-passed the relay)and its still cuts out mainly in 3rd and 4th gear under load.
what can i do next to fix this problem??????????

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Old 08-01-2004, 08:49 AM
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It could be a bad cycling valve. When it falis, it usually sticks closed and prevents boost pressure from getting to the control port on the wastegate, so you end up with an overboost condition under hard acceleration. The computer then shuts off the fuel to prevent blowing up the engine, resulting in a rather violent sudden deceleration.
Old 08-01-2004, 09:25 AM
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thanks so much for that i will get that changed,is this a common problem.also in the past ive noticed when i change gear i loose so much boost and was told you fit a dump valve
what do you think to these aftermarket bits

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Old 08-01-2004, 01:45 PM
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helo 951 keeps cutting out still

hello
ive ran car and once it cuts out ive wired a switch to fuel pump(in case dme telling fuel pump to shut off) so i can switch power to fuel pump when it cuts out but still the same ????????????????
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Old 08-06-2004, 03:57 PM
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hello
the engine cuts out violently as if the engine died,then the car will not come back on until i stop and turn the key off and wait 5 seconds.i have tried to continue driving keeping it in gear but it wont cum back on.once ive turned the key off and started again it will cut out at the slightest acceleration but if i drive it very slowly and dnt take car above 3000 revs it will get me home.as this happens mainly in 3rd and 4th its as if its only when the engine/turbos being used to its fullest


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Old 08-06-2004, 04:54 PM
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no i dont know anybody here thats how a car like mine.do you think that could be at fault?is there any way of testing it?ive not tested the cyling valve yet as not sure what it looks like and how to test it and my mechanic has no idea and just wants to make money.what do you think to testing blink codes?
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Old 08-06-2004, 06:20 PM
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cant the blink codes determine this ??
is the only way to test this by trying another dme?
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Old 08-07-2004, 11:16 AM
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Does this only happen after going full blast? If you are overboosting (wastegate shim or the like) and don't have aftermarket chips, the boost controller will make the engine 'stop'. You are going really fast and then the power cuts out and it feels like you hit a ton of bricks? You can keep going but if you push the throddle it feels the same?

If so you are hitting the overboost protection.
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Old 08-07-2004, 12:33 PM
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I had a similar problem a while back, it was a broken wire at the fuel pump within the insulation; contact most of the time but if using revs to pull out of junctions etc the extra load was too much and it cut out. Took a long while to find this! Waggle the wires about with ign on, listen for pump stopping.
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Old 08-07-2004, 01:08 PM
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no this happens during full blast.
i will try checking fuel connections though this only happens in 3rd and 4th when cars under full load making me think fuel pump is ok.think its it may think its over boosting or fr wilk says maybe a bad dme unit?????
really do apreicate all this help as no1 can help me on this without charging silly money only to say its fixed or it didnt happen when at garage
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Old 08-07-2004, 04:52 PM
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Quote:
Originally posted by FR Wilk
todd951,
Does the engine still run when this happens?
Yes, it only takes a fraction of a second for the boost to drop, and the engine will continue running once the boost comes down. It's like hitting the rev limiter, but more violent. Knowing now that the ignition has to be switched off before the car will run again, I would agree that it's most likely a problem with the electronics.
Old 08-08-2004, 06:32 PM
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You are hitting the overboost protection....You should go into 'Limp mode' which will then limit boost to 1.2 bar on the factory gauge. At this point there should be a fault code present
You need to check for codes BEFORE you turn off the engine as they are reset.
Check here for fault codes and how to build a tester.



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Old 08-09-2004, 03:25 AM
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