GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: EvilScotsman on 23 January 2007, 10:49
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Hi,
I just bought a MK3 2L 8v GTi, 1995, and I love it, after driving japs for years.
It has a few minor niggles but one of them I'd like to get some ideas on..
When it starts from cold OR hot, it barely catches, then creeps up to 1000rpm, once its there it revs OK.
When cold it idles smoothly at 1k, but when warm (oil temp 74 on the MFA) it 'hunts' up and down between 900 and 1000, sometimes blipping the throttle will cause it to stall here but not always. It pulls OK, I never abuse it, and it returns 28 - 29mpg ave (MFA 2).
The previous owner fitted plugs, dizzy cap, rotor arm, and timing belt (fitted by a fairly large local garage) so i guess they are out of the loop but what else can it be? I suspect an air leak or idle valve but don't want to dive in without some pointers.
I'm an electronics engineer and confident working on my cars but new to GTi's (or vw's in general)
Thanks in advance for any replies :O)
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Had problem like this with mine - trouble starting, once started is fine.
Guys on here suggested ECU temp sensor. Guy at the garage ran diagnostic on it and it was ECU temp sensor.
The relays only cost ~£12 apparently but of course had to pay for them to run it as well but was getting the timing done at the same time.
Hope this helps
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I would start at the ecu temp sensor as they are cheap and easy to fix (and work the gauge and ecu and cause problem's like you list)..... Next thing to check is all breather hoses as even the slightest air leak here can cause funny starting and running.....There are 2 relay's one for the ecu and another for the fuel pump and these can start to fail
Maybe this will help... it show's my ady simos injection model but most 95 onward are similar
(http://i88.photobucket.com/albums/k165/boneybradley/DSCN3430-1.jpg)
(http://i88.photobucket.com/albums/k165/boneybradley/000544430201.png)
(http://i88.photobucket.com/albums/k165/boneybradley/000544430201-1.png)
On another note don't take your car to a garage for the fault code's to be read as you can buy a reader from ebay etc for about £30 (just make sure it read's and clear's all codes from ecu,abs and airbag)
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Thanks for the quick and excellent replies guys, especially the pics and diagrams.
That gives me good starting point. Someone else suggested cleaning the throttle body and butterfly as the egr valve dumps into the TB before the butterfly and gums it up wi crap?
Cheers again :O)
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yeah the throttle body get's full of crap and sometimes can't fully close making the engine run bad.....again quite an easy job and not only solves idling problem's but also power issue's...I would normally say they idle badly with bad throttle bodie's rather then poor starting but they can also be a fix all!!!! and they are worth doing any how... I clean mine yearly
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BTW, I think it was bradley who diagnosed my problem as ECU sensor :smiley:, so he knows what he is on about
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All the relays can be easily checked.
Warm up the car then turn off and remove ECU and Fuel relays if warm they are fine if cold to touch then replace.
Relays dont show up on fault code checks!
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Cheers, i'll have a look at all that stuff tomorrow. Its bloody cold out at the moment tho an i hate workin outside in the cold but it has to be done!
btw what do you all get on MFA 2 for average fuel consumption? (I dont do long motorway cruising, maybe 15 miles at most but quite a bit of 2 - 6 mile journeys) - mine almost never reaches 30mpg :O( usually hits about 27
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for fuel economy check out this thread http://www.golfgtiforum.co.uk/index.php?topic=51764.0 (http://www.golfgtiforum.co.uk/index.php?topic=51764.0) and please let us know youre finding's with your fault.....
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Cheers Boney, will do.
I'm also going to fit a full set of silicone hoses like samco or similar to get rid of any leaky old rubber problems now and in the future, plus they will make the engine look good! - (its not a very pretty engine anyway lol)
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ok, I cleaned the TB out wi petrol, it wasn't very dirty anyway but did it and the plastic air tube leading to it. It did seem to help but not much.
It still feels like the engine power "pulses" when accelerating up to 3k, it hunts on idle, and sometimes cuts out or won't start for a few secs.
I disconnected the MAF plug and it ran like a bag of nuts, so im assuming its ok. Also disco'd the IAT, that made no difference at all - could be that?
Does the 8v have an idle control valve? if so where is it?
And the silver thing on the rhs end of the fuel rail connected to the TB wi a thin rubber tube - is that the fuel pressure reg and could that be the prob....?
Havent tried the relays yet. :angry:
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Simos engine's don't have an isv..and yes the fuel pressure reg is located where you said in your pm
just a few question's
1. Have you changed the ecu temp sensor???
2. Check the relay's like len say's
3. check all the breather pipe's to make sure there's no leak's (also check valve on the back on the engine breather as they have rubber seal's which can dry up)
4. check the coil is ok as they crack letting in moisture
next thing i would think if all these are ok is the hall sender on the dizzy
please reply if you would like further detail's
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Thanks guys. I will do all of the above tomorrow or monday, as i might not get parts round here over the weekend.
I checked the hoses, the FPR tube was cracked at both ends so i trimmed it and refitted.
It did a funny thing tonight, stopped after a long drive, went to restart and it would fire, idle, then cut out. Revving it didnt help, it still cut out even when revving....switched all off, checked/wiggled all the sensor wires in the engine bay, and finally it fired up. Its never done that before and it didnt want to start for about 5 mins - weird. Will check all the wires in the daylight to see if anythings loose, and im going for relays and an ECU temp sensor asap.
It seems to misfire when accelerating AND has lumpy idling - but its a soft misfire, like dodgy fuelling - not sparks, if that makes sense. Thats why I asked about the FPR. It seems very loose too - for what it does, I would expect it to be a tight-ish fit, but its not (rotates easily even wi clip fitted)
The previous owner changed the dizzy cap, leads, plugs and rotor to cure the fault (which obviously it hasnt) so I know they are ok. Its annoying because my job is electronic fault-finding and I didnt know enough about gti common faults etc to make a good start, but thanks for helping :O)
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btw when it was cutting out continually tonight, like it had run out of petrol, you know - start, fire, idle for a sec then snuff out, made me think of the fuel pump relay maybe dodgy & chattering etc. Will do the relays and the temp sensor first (one at a time tho obvsly so i know what cured it )
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Boney - I found tonight that i have the same 5k rev limit as the other guy whos post you answered about the timing belt being 1 tooth out? weird as my car had its belt changed in oct when the tensioner siezed and broke it.
Does this change your estimation of the fault?
Thanks for all your help mate :O)
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That could be the cause....if the timing is out by 1 tooth on the belt the rev limiter comes in earlier and can cause bad running as the valve's open and close wrongly... best to have the timing checked (which is a pig to do without the correct tester) and to change the timing you will need the belt taking off and resetting but still check the relay's as before as these are one of the worst golf fault's
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Thanks mate will do. Spot on advice btw, I read the BIG post from scooterist lol, so much for VW reliability eh :cool: