GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: motah33 on 27 March 2011, 17:10
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Hi,
I have a VW Golf GTI 8v 1990/H (engine code PB) with the Digifant Fuel Injection system.
When slowing the car down, the battery light flashes or stays on and the car stalls. I can start the car instantly after this happens - several times on a journey. I try to blip the throttle to prevent it from stalling. When the car is driven at normal speeds there are no problems.
Recently, the car had to have its mixture adjusted in order to have its MOT pass. I don't know if this has had an impact as it seems to have run ok since then.
I took the battery out and put it on the charger and the 'full' light came on straight away. I wasn't expecting this as if I constantly have to re-start the engine when it stalls, I would expect the battery to be fairy depleted especially if the journeys are short i.e. not enough time to re-charge the battery. The voltage across the terminals is 12.97v.
What I find is that the when I blip the throttle, as the revs drop, it feels as if it wants to stall but then recovers i.e. it shoots up and then comes back down again. It is a bit erratic during idling. Sometimes it seems to sort itself out when it has been on the move for a while, say 30 minutes. But most of the time, it is only doing runs which are no more than 10 minutes.
Any help would be much appreciated.
Thanks
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Blue temp sender and rjs setting up guide probably wouldn't go amiss
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I'd be looking at the idle valve pal, sounds like yours is approaching the fecked point.
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Does it get better when hot, if so then its idle stabilisation valve probably.
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Thanks for all the replies. I really appreciate it.
Yes, it does seem to improve when it gets hot. In fact, last night, the problem disappeared after 30 minutes of driving. The problem has only occured so I don't know if this is consistent.
"Blue temp sender and rjs setting up guide probably wouldn't go amiss" - how would this temp sender affect things? And what is "rjs". Thanks.
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Thanks for all the replies. I really appreciate it.
Yes, it does seem to improve when it gets hot. In fact, last night, the problem disappeared after 30 minutes of driving. The problem has only occured so I don't know if this is consistent.
"Blue temp sender and rjs setting up guide probably wouldn't go amiss" - how would this temp sender affect things? And what is "rjs". Thanks.
http://www.golfgtiforum.co.uk/index.php?topic=33253.0
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there is a guide by rj - rubjonny - a member who knows his onions on setting up golfs. I think this guide is in the maintenance section, it will take you through everything, right from the cambelt timing onwards etc. The blue temp sender tells the ecu what temp the engine is, and the ecu adjusts things accordingly. If this sensor is unaccurate then the ecu is giving the wrong settings for the engine which causes poor running if you catch my drift... However yeah it could be the isv,or the cam cover pcv bung thing, it could be many things really, best to go for a search on here and see what you find..
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Thanks for all the suggestions/links. I shall go through them and let you know what happens.
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Heel & toe...
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Here's an update:
1. When I switch on the ignition, but don't start the car, I can hear the ISV buzzing.
2. When I open the throttle just a tiny amount I can hear a switch click which I believe is the Idle switch and from what I read this is the correct behaviour.
3. If I blip the throttle and rev the car, the revs come down and the car almost stalls (with the car stationary) but recovers.
4. If I start the engine, let it warm up, then disconnect the blue temperarure sender, it stalls immediately. I can start the car without the sender connected but I have to keep the revs up to stop it from stalling.
5. If I disconnect the ISV (electrical connector), I can start the car but as in the case of the temperature sender, I have to keep the revs up to stop it from stalling.
If this provides any more cluses as to the cause, then please let me know.
Thanks
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Take out all the injectors, including 5th injector and check if they are all working/ spray pattern. This is exactly what my car was doing, I just put in a stand alone ecu so never sold the problem.
You checked your warm up regulator.
When cold the engine needs more fuel, so the 5th injector gives extra fuel whilst cold, if one injector is bit weak I think it can cause these issues. Think resistance across the warm up regulator should be 22-26 ohms.
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no one has suggested the idle screw yet. surely if its wound down so much the idle is set to, say, below 500rpm, the ISV will have to compensate to bring the rpm back up. hence the delay:
3. If I blip the throttle and rev the car, the revs come down and the car almost stalls (with the car stationary) but recovers.
if the CO mixture screw is messed with, the idle screw will also need to be adjusted IIRC
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Thanks for the info. I shall check the idle screw - I've pulled a few bits off it now.
I presume the 5th injector is also know as the Cold Start Valve? Does the Digifant have one because I couldn't find reference to it in any manual. Does it have a warm-up regulator?
This is what I did:
(a) I removed the air inlet hose so that I can see down the inlet manifold and it looked quite clean (I didn't move the flaps to look down the minifold).
(b) I removed the vacuum hose to the brake servo unit and found that the plug on the manifold was gunged up.
(c) I removed the vacuum hoses from the air filter housing to fuel pressure regulator etc (I'll change these hoses when I put them back). I found that the plug (next to the idle screw) in which the vacuum hose from the fuel pressure regulator goes into (through that T-splitter) was also gunged up.
(d) I remove the crankcase ventilation pressure regulator valve, and the hose, to find it was also gunged up.
(e) I removed the ISV completely and it looked ok but I'll give that a soak in some carb cleaner.
(f) I removed the hose from the inlet manifold to the ISV. This plug on the manifold and the hose looked clean.
Do I need to give the inlet manifold a clean out considering the pipes (b) and (c) were gunged-up quite badly. If so, is there a way of doing so using some carb cleaner? I'm thinking if I can I start the engine with the stuff I removed and somehow force the gunge out of the manifold?
Any advice is most welcome.
Thanks
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Could remove the throttle body and give that a good clean before and after flaps.
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with the engine off look in the bay at your throttle body, open and close it manually a few times and listen out for the idle switch clicking. make sure it clicks off and on every time you open and close the throttle no matter how fast or slow you operate the throttle. if its a bit sticky remove the throttle cable and retry, if its better try adjusting the cable, set it so the throttle is just fully open when your foot is to the floor. if that still doesn't help change the cable.
next look at the wiring behind the throttle body, there is a 2 pin connector for both the idle and WOT switches, make sure the wires to this are ok. its common for them to snap back here. if it looks ok, start the engien then go back to the bay, open the throttle by hand slightly so engien revs are at around 1.5-2k rpm, then press the WOT switch on the top of the throttle body. the revs should drop, then rise back up again when released. if not, there is a break in the wiring to the TB, or the switches themselves are damaged.
note this test only confirms the wiring up to the 2 pin plug is ok, and the wot switch works. this doesnt check the idle switch which could still be broken, if you could reach underneath to press it then this would confirm the idle switch is ok, but its a bit tricky. you can use a multimeter to test it though, put it in continuity mode and touch the 2 pins on the tb. it should read an open circuit with the throttle off the stop, go closed at idle and closed at wot