Hello all, Can anybody help with information about the timing on a 1990 1.8 Gti 8v please ? The car has Digifant and Transistorised ignition i.e. Distributor has no points, no vacuum advance, no weights. From my Haynes, I think it should be 6 deg BTDC @ 2300 rpm with the temperature sender disconnected. It seems to have been timed at 6 deg BTDC at idle (temp disconnected) which I think is for the 16v. Problem is it runs fine when timed at 2300 rpm, pulls cleanly but sluggish. When timed at idle, starts and idles OK, stutters under mid-range acceleration, backfires on overrun ! I'm experienced with older cars but this is our first Golf GTi. Finally, Haynes seems to indicate that having timed it, reconnection the temp sensor should advance the timing - is this correct please ? as mine doesn't. Many Thanks Andy
it needs to be put into timing mode, cant remember how but a search should show it up, something to do with reving it a number of times.
Warm the car up to operating temperature (fan cuts in). Remove the blue temperature sender wiring and rev engine over 3000rpm 3 times. This puts the ECU into setup mode.
no need to put it into setup mode to set the ignition timing, it just needs to be hot. You put it into setup mode when setting the idle & CO. If the throttle responce is sluggish, first double, double check the static timing is ok, then replace all the vacuum hoses. The hose to the FPR is very important, if its gone pourus the FPY will be slow to react when you put your foot down! Also the ebay ECU chips are said to help with the so called 'digi lag'. Check the above 1st tho, when I 1st got my GTI it was a slug due to the ignition timing, then gradually the throttle responce got worse again which turned out to be a badly cracked & degraded vacuum connection to the FPR
Thanks guys, especially rubjonny, I was a bit perplexed about how the setup mode would help the ignition timing. Simple question but what's the FPR ? Can anyone confirm what he ignition timing should be please; My Haynes suggets 6 deg BTDC at 2000 - 2500 rpm with Temp sensor disconnected (see my earlier post) car is 1990 1.8 8v GTi with Digifant and Transistorised ignition. Again it suggests the timing should advance when the temp sensor is reconnected, is this correct please ? Many Thanks Andy
Yep mr haynes is correct for a change, 6 degrees at about 2.25k rpm, and the timing should be seen to advance when the blue sender is reconnected I always replace the blue temp sender with a new one from VW as a matter of course on a digifant MK2, its essential for the ECU to manage the fuel & ignition correctly. In addition NO additional advance should be dialed in, set it to EXACTLY 6 degrees. The ECU will advance the timing automatically based on the signal from the knock sensor, temp sender etc, advancing it further will just mess things up. The FPR is the Fuel Pressure Regulator, which is attached to the driver side of the fuel rail. This is what regulates the fuel pressure (surprisingly ) based on inlet vacuum, and is why a bad vacuum lines makes a digifant MK2 run badly
Thanks again rubjonny, My car (well my son's) has two temp sender/switches in a plastic 'flange' between plugs 2 & 3. The one nearest the head is black 2-pin with a black connector. The one furthest away from the head is blue 2-pin with a blue connector. I've been disconnecting the black one (as shown in the manual, no colour specified) - are these in the correct place ? It seems to me from this site that the blue one is the one to disconnect (they both measure the coolant teperature so perhaps position does not matter). Anybody have a part number for the blue sender please as my local VW didn't really seem to know what I was talking about ! Many Thanks Andy
the blue sender is the one you disconnect, the black sender is for the temperature guage, I think now we've found out why its not running properly
Right, up to temperature. Blue Temp Sender diconnected. Up to 2,500 rpm. Set Ignition timing to 6 deg BTDC (which it was when I started !). Re-connect Blue Temp Sender - observe timing advances significantly. Disconnect Blue Temp Sender again - just to check it returns to 6 deg BTDC. So it's working in principle, but my basic timing light can't tell me how much the significant advance was (should be 30 deg BTDC + or - 3 deg). Next to check are the vacuum hoses - especially to the PFR. After that - what else should I look at please ? Really appreciate your help rubjonny. Andy
I'd just replace all the vacuum hose, but make sure you get good quality stuff, I bought some off ebay and after a few months it was cracked & pourus! VW will charge you about 6 for 5 meters Once you've replaced the vac hose reset the idle & CO as a pourus vac hose will have thrown off the mixture readings, I got a digital CO meter off ebay for about 30 The haynes procedure is mostly right, but you need to rev the engine over 3k 3 times, not 2.5k or whatever it says. You could try replacing is the MAF, (Mass Air Flow, the metal thing on the back of the airbox) the tracks can get a bit worn with age. I believe ones from digifant 2.0 8v engines from the MK3 or Passat are the same part and more likly to be lower milage... Tho on my 160k old digi I swapped this twice and didnt really notice any improvement! Another thing worth checking is the knock sensor if the wire to it is cracked or damaged, they seem to be that way on most digi mk2s now. AFAIK they're all the same apart from the wire lengths differ, I used one off an Audi on mine and it made no difference to the car so I assume there was nothing wrong with my original. The thing to remember is that it must be torqued up exactly right or it will either be damaged or not work properly!
rubjonny - Thanks for all your help and advice, I'm starting to feel a bit more comfortable (and reading lots from Haynes !). I'll post up as I go along. Andy
Yeah this digifant system is a steep learning curve, it took months of hard work to get mine running properly
After lots of tweaking of mine I found out my CO readings were sky high and without being able to check with a gas analyser I was lost. I have bought one now and check that any changes I make also result in a tweak of the CO screw if required. MKone, where are you based? Someone local might be able to help out with a gas meter.
Hello Calimori, I'm in Tring so "someone local" might be you But seriously, you make a good point and I've been thinking it's time to buy a gas analyser anyway. What make/model tester did you buy ? Many Thanks Andy
dont get the green gunson one! its total rubbish! im going to write a letter to them as it want it changed for one that works! edit: colour ture plug can be a cheap way to check.
hmm I have the green gunsuns one, seems to work fine? Its a bit of a pain since it takes a few minutes to calibrate and for any readings to settle...
I have the green gunsun one as well. Not great in windy weather and takes a while to settle but it does the job and a double check on a far more expensive bit of kit says it was reasonably accurate. More than willing to meet up and let you have a play with it so you know what you get for your money. I have been thinking of buying a snap-on kit which a large number of MOT centres use, they are over 1k to buy but were given as a deal to MOT centers at the end of last year so a lot appeared on ebay for half that price. We have a Herts club meet which is just starting up, next one is on the 5th of april at Bourne End. Link
