GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: Whaleshark on 14 July 2009, 17:04
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Sadly my trusty '89 8V passed away(prohibitive to fix for MOT) last month.
Was rather gutted as it had lasted me 75,000 miles(3 years) without so much as an oil change. Infact when it failed the MOT there was nothing wrong with the engine(low emissions too) and I was still averaging around 38mpg a tank - worked out through odomotor and pump readings, not MFA.
The second Golf is a newer model, a '90 8V ! I picked it up for a reasonable price, but knew there was several things wrong with it.
The main one is that it lacks power. I adjusted the timing and checked obvious things but couldn't find much improvement. I had resigned myself to wasting a few days to try and sort the problem, albeit sometime in the near future when I am not working quite so hard.
Now here is where it gets strange. A few days ago, the power returned and it was like I was back in the '89 again. It was like the proverbial off a shovel for the rest of the day and the beginning of the next, where upon the power disappeared and it was like driving a 1.3 again.
I am baffled as to what this could be. Something electrical perhaps? I really have no idea, but am hoping one of you might.
Cheers, Ed
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bad ECU? :undecided: You still have the ECU from the '89 ?
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75k without an oil change :shocked:, you're a cruel and heartless bas**rd........ :laugh:
It might be a knackered knock sensor retarding the timing.......they tend to split and fall apart and the wiring shreds, much more expensive than an oil change though.......? Inermittent vac leak?
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75k without an oil change, was there any left in the sump.
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hi ive had similar probs before turned out to be exhaust blockage
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It sounds like an intermittent sensor to me, or as someone else said, the ecu. You have another car full of spares, so start swapping one thing at a time. Also look at the vacuum tubes for a split.
Then give it an oil change.
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75k without an oil change :shocked:, you're a cruel and heartless bas**rd........ :laugh:
It might be a knackered knock sensor retarding the timing.......they tend to split and fall apart and the wiring shreds, much more expensive than an oil change though.......? Inermittent vac leak?
I know, I know. It started off as something I just never got around to and I never expected it('89) to last beyond it's first MOT so there seemed little point.
Then it became a cross between fascination and superstition. I felt that if I changed the oil, then it would surely die the very next day.
It did have fresh oil going in every so often - probably around 1l every 8,000 miles - not a huge burn I understand, certainly well within VWs limits.
I think that it is a testament to VWs engineering and modern Oils. As I mentioned before, on it's final MOT, the hydrocarbon readings were still really low.
Infact the only problem that I ever had with the engine was when the ECU once failed.
That brings me on to the other('90). Funnily enough last night driving to see the missus, it was particularly gutless, with a bit of a stutter. However, this morning it was back to full power for only the 2nd time in the month or so that I've had it.
I think the ECU is the first thing that I'll try. When the ECU failed before(in the '89), it really failed. I couldn't even get a spark. So the ECU is already out of the Gti I had before('88)! The vacuum tubes I have already checked and I don't know where the intermittent and knock sensors are. If I get a chance I will try the swap today or tomorrow and report back.
Also, I promise to change the oil a bit more regularly. :laugh:
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1 litre of oil per 8000mls. :shocked:..800 is probably more normal for one of these......I want that engine. :grin:.......why not just drop it into the '90 model and be done with it?
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Check all the eraths first, including the fuel pump.
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1 litre of oil per 8000mls. :shocked:..800 is probably more normal for one of these......I want that engine. :grin:.......why not just drop it into the '90 model and be done with it?
You made me think, and I've just realised I made a mistake with my maths. 75,000 miles has taken me 3 cans of oil(not 2 as i originally thought) 75,000/15 = 5000miles/litre. A lot of motorway miles though, which I don't need to do any more.
I have often thought about dropping one engine in t'other and if ('90) dies I might take the plunge. Otherwise, I find the idea a bit intimidating.
Cheers, Ed
ps. Organysis - Will have a search around for earths. presumably fuel pump earth is one of the terminals of the connector that plugs into the pump/filter unit under the car?
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would a knackered blue temp sender have the same effect? or does that just upset the idle when warm?
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Sounds like a loose wire/dodgy earth. Best way through this is to think about what exactly could be causing the behaviour you describe, and work from there...
Don't think it will be a vac pipe, because I can't see how that would be intermittent? A pipe is either split or it's not - it doesn't keep switching from okay to split!
A fuel pump problem is a possibility, but would this cause the car to cut out altogether?
I would suspect that it's ECU related - either the ECU itself, a frayed wire to one of the sensors or a faulty sensor. The engine still runs, albeit retarded, so I'd hazard a guess that something is feeding the ECU duff (or rather no) information. Without information from all of its sensors, the ECU goes into safe (sluggish) mode and retards the timing becuase it doesn't know what's going on!
I would check the operation and wiring to the following components:
Blue Temp sender (as already mentioned...) - allows the ECU to adjust the fuel mix if the engine is cold. Note that the timing will be retarded if this isn't working, regardless of the actual engine temp (as the ECU doesn't know what the temp is!). This is on the coolant hose entering the front of the head (there's a blue one and a black one - the blue one is for the ECU, the black one is for the temp gauge in the dash). When it's working okay, there's usually an audible difference in the idle when you disconnect it with the car running. Clean the plug contacts, and check the condition of the wiring all the way back to the ECU. Replacing the blue sensor itself is always a good idea anyway.
Knock Sensor - allows the ECU to adjust the timing to account for knocking. This is on the left-side as you look at the engine, on the front - can't remember if it's at the top of the block, or the bottom of the cylinder head :embarassed: Again, the engine will run retarded if no signal is received from the knock sensor, so check the wiring.
Airflow Sensor (AFM/MAF) - informs the ECU of how much air is being let into the engine (by measuring the position of the intake flap). Check the wiring is okay, and there's a procedure of how to test the AFM itself in Haynes. Don't think it will be this will be at fault, unless there's an intermittent fault from within the unit.
If it's none of these, check the earths for the ECU, and as a last resort, swap your ECU. When you've found and fixed the problem, it probably wouldn't hurt to get your CO set and work through rubjohnny's tuning guide.
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Sounds like a loose wire/dodgy earth. Best way through this is to think about what exactly could be causing the behaviour you describe, and work from there...
Don't think it will be a vac pipe, because I can't see how that would be intermittent? A pipe is either split or it's not - it doesn't keep switching from okay to split!
A fuel pump problem is a possibility, but would this cause the car to cut out altogether?
I would suspect that it's ECU related - either the ECU itself, a frayed wire to one of the sensors or a faulty sensor. The engine still runs, albeit retarded, so I'd hazard a guess that something is feeding the ECU duff (or rather no) information. Without information from all of its sensors, the ECU goes into safe (sluggish) mode and retards the timing becuase it doesn't know what's going on!
I would check the operation and wiring to the following components:
Blue Temp sender (as already mentioned...) - allows the ECU to adjust the fuel mix if the engine is cold. Note that the timing will be retarded if this isn't working, regardless of the actual engine temp (as the ECU doesn't know what the temp is!). This is on the coolant hose entering the front of the head (there's a blue one and a black one - the blue one is for the ECU, the black one is for the temp gauge in the dash). When it's working okay, there's usually an audible difference in the idle when you disconnect it with the car running. Clean the plug contacts, and check the condition of the wiring all the way back to the ECU. Replacing the blue sensor itself is always a good idea anyway.
Knock Sensor - allows the ECU to adjust the timing to account for knocking. This is on the left-side as you look at the engine, on the front - can't remember if it's at the top of the block, or the bottom of the cylinder head :embarassed: Again, the engine will run retarded if no signal is received from the knock sensor, so check the wiring.
Airflow Sensor (AFM/MAF) - informs the ECU of how much air is being let into the engine (by measuring the position of the intake flap). Check the wiring is okay, and there's a procedure of how to test the AFM itself in Haynes. Don't think it will be this will be at fault, unless there's an intermittent fault from within the unit.
If it's none of these, check the earths for the ECU, and as a last resort, swap your ECU. When you've found and fixed the problem, it probably wouldn't hurt to get your CO set and work through rubjohnny's tuning guide.
Wow. Thanks Tony, that is a massive source of information. I bet quite a few searches in the forum would be answered in just that one post.
In fact, I wonder if a forum glossary would be a good idea? Much as Tony has done above?
Anyway......
Yesterday evening I had 30 mins spare so I cleaned up the earths from gearbox and rocker cover. I presume that these are the main two?
I also intended to swap over the ECU. However, when I opened the wiring connection that is mounted on a bracket on the front of the ECU(not the one that goes to the ignition module) and found that there was a lot of corrosion inside. I cleaned this up. When i ran the car, I found that the power had been restored. Sorted!!
I'm not sure if it was cleaning the earths or the the contacts by the ECU that that has fixed it. It could even just be in the good phase of the intermittent problem. I will find out soon enough if this is the case.
I would say that it is now 90% of the power of my previous Gti. This is good as it had been about 50%.
I will tune it to Rubjohnny's guide. I have previously done the best i can using timing light and ear, but really need to get hold of an CO meter. I also need to replace my MFA screen as the one that I have has cracked. To that end, if anyone has a MFA screen and circuit board for sale, please let me know. It is the one off the single pin clocks. Perhaps someone whose clocks are knackered or very high mileage? I just need the IC board and display.
Thanks again to all who have taken the time to provide advice and help. WTF did we all do before forums like these?
Cheers, Ed
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Don't thank me - thank all the others who have posted advice on this forum! I also had problems with the running of my digi recently, so I guess you're benefitting from the fruits of my research :smiley:
Also, a lot of info comes from here:
http://www.vanagonparts.com/digifant.html
A bit heavy for bedtime reading, but a good wealth of information.
There's also an earth strap from the bonnet to the bodywork, on the right hand side as you look at the engine.
When you get your new clocks, try them out first by removing the lower parcel shelf on the driver's side under the dash, unplugging your clocks, then plugging the new clocks in. Obviously the speedo and mpg readouts won't work like this, but at least you'll know everything else works before you start taking the dash out. Also, once the repaired clocks are in, dont put the dash back together until you've tested everything, including the dash lights! There's nothing more frustrating than put it back together and realising a bulb is out...
And yes...i have done my clocks recently too!