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| Engine starves and ack fires up air box when pedal pressed | |
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| Tweet Topic Started: Thu Jan 1, 2015 9:27 pm (752 Views) | |
| ben190cosworth | Thu Jan 1, 2015 9:27 pm Post #1 |
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NASA, just admit there's aliens
:)
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Hope im in the rite section just a quick question to ask anyone why when I press my pedal down the revs die as if its out of fuel and just as the revs drop to 500rmp if fires and back fires back up the air intake and air box? Also if you tap the pedal the revs seem to drop slightly the die.....any helpful sdvice will be gladly apreciated as wanna get my pride and joy to a garage for MOT ![]() Cheers guys |
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| stwat | Thu Jan 1, 2015 9:49 pm Post #2 |
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Check the rubber boot under the AFM for splits or loose pipes. |
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| ben190cosworth | Fri Jan 2, 2015 12:19 pm Post #3 |
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NASA, just admit there's aliens
:)
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hey, iv checked the boot and all seems good, also went over the whole vacuum system and found a few pipes off headlight, strange motor thing on the heat pipe into the cockpit. but didn't make a difference The only other strange thing i have noticed when the car finally idles, is at idle the economy meter is pulled in to about half way? would that indicate a reverse vacuum? cheers |
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| frankmartin | Fri Jan 2, 2015 12:39 pm Post #4 |
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Part of things
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I experienced a similar thing, when i started the engine from cold, it starved, and if i pressed the throttle, it suddenly die. When the engine was warm, everithing was ok. I discovered that this problem was caused by a faulty ovp relay. |
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| ben190cosworth | Fri Jan 2, 2015 1:07 pm Post #5 |
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NASA, just admit there's aliens
:)
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Ahh great thanks that makes me feel better as i have a brand new one on order from the US ill let you know how it goes when i have installed it
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| eagle3 | Fri Jan 2, 2015 1:52 pm Post #6 |
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Therapy Needed
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Sounds like ignition or valve timing is out
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| balamb37 | Fri Jan 2, 2015 3:19 pm Post #7 |
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Grumpy Old Grampa with Dog
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Yep it sounds like a weak mixture due to the OVP not operating correctly, probably a 'dry joint' inside the relay. And that wouldn't be a 'Backfire' in the induction manifold as backfires are technically because the mixture fires in the exhaust what you heard was technically known as 'Pre-ignition' where the fireing takes place before the mixture enters the cylinders ie. in the inlet manifold and is usually caused by a weak mixture. By the way it could also be a 'dry joint' in the FPR. Hope that helps, good luck. |
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| JustbeCoz | Fri Jan 2, 2015 7:37 pm Post #8 |
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Part of things
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if vac gauge is at halfway to red on idle you have a vacuum leak. most noticeable just off idle as the leaking unmetered air forms a much larger proportion of the air used. |
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| ben190cosworth | Fri Jan 2, 2015 8:50 pm Post #9 |
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NASA, just admit there's aliens
:)
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Great thanks guys some really helpful info, my brand new OVP relay has arrived at my work so gunna have a look and install it tommorow and post the results when finished and probably ask more questions if thats cool
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| Big Ben | Fri Jan 2, 2015 9:48 pm Post #10 |
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Sneaky 2.5-16 Driver!
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+1! Very common problem. You need to check all the vacuum connections. Favourites are the rubber multi connection points especially the one in front of the brake servo that supplies the heater valve! |
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| frankmartin | Fri Jan 2, 2015 10:07 pm Post #11 |
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Part of things
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Indeed i'm checking all of them, because i'm experiencing some uneven idle (and a leak from the rubber hose from the expansion tank). Ovp cured me the starving with cold engine. The garage owner suggest me to use WD-40 on them to discover some leaks. And put a sheath that is used to cover the soldering, to close it, before buying a new hose. Backfiring, also can cause the disconnection af a hose that is under the injection module, under the air box, in the 2 litre. I have written some replies on it, beause it happened to me, after a weak mixture with autogas. |
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| ben190cosworth | Sun Jan 4, 2015 9:03 pm Post #12 |
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NASA, just admit there's aliens
:)
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Great thanks frankmartin, didn't get to check the relay sat morn liked planned as the postman left my new relay with the neighbour who isn't back untill tomorrow so will deff post tomorrow as to its results
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| ben190cosworth | Mon Jan 5, 2015 3:36 pm Post #13 |
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NASA, just admit there's aliens
:)
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Hi guys, just thought id update on my progress new OVP relay is in and engine runs allot better even drivable round my ind estate no longer seems to ignite fuel back up the air intake, also new OVP has cured my vacuum issue and the needle sits where it should do at idle ![]() idles when hot but doesn't idle when cold, the cold start injector squirts for a second or 2 and the idle control valve clicks on ignition so i assume they are working correctly? issues i still have are very flat all up thru the rev range and even with the OVP in on hard kick-down it still seems to starve the engine of fuel for a few seconds then coughs splutters then goes. Cheers |
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| frankmartin | Tue Jan 6, 2015 2:25 pm Post #14 |
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Part of things
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I don't know if youe engine has the same vacuum line as mine, but put a hand under the injection module and check that vacuum line! You are facing the same problem that i had. I discovered that, that hose, was not connected! |
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| ben190cosworth | Thu Jan 8, 2015 10:03 am Post #15 |
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NASA, just admit there's aliens
:)
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I will try that today when it stops raining when you say injection module is that the cold start injector? the pipe that comes out of the Fuel Pressure Reg? that ones connected, and cant see any others off :/cheers |
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| frankmartin | Thu Jan 8, 2015 11:26 pm Post #16 |
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Part of things
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In the 2 litre, i have a hose that goes from a rubber thing in the front of the engine, next to the coolant temperature sensor, under the intake mainfold (maybe mispelled), which is just under the injection module. I don't know exactely where, i just know it. If tomorrow i have some time during the daylight i will try to make a picture of it. this happened to me http://mercedes-190.co.uk/topic/6741512/1/#post8498283 And i think that stwat had a similar problem to your. And if i'm not wrong it's the rubber thing under the AFM. |
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![]](http://z2.ifrm.com/static/1/pip_r.png)
just a quick question to ask anyone why when I press my pedal down the revs die as if its out of fuel and just as the revs drop to 500rmp if fires and back fires back up the air intake and air box? Also if you tap the pedal the revs seem to drop slightly the die.....





9:19 AM Jul 11