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83 Rabbit GTI Backfires When Hot

Hello all, I have a backfiring problem with an 83 GTI -- only happens when hot. The problem came on fairly recently. It either backfires or cuts out suddenly when it gets hot, and usually won't restart until it gets cold (lately it just cuts out without warning!). If I try to restart when hot, it will just backfire every now and then, but usually won't start. I'm assuming it's a timing problem, but I don't know how to check the timing. There appears to be a port on the transmission-side of the engine - I'm not sure if that's the timing port. If it IS the timing port, will there be markers in there to help me avoid parallax error? ( I learned that term in chemistry in the

80's!) Even more importantly, how do I adjust the timing? It was easy on my Toyota, but I'm not sure what to do on this one. I don't think I've ever adjusted timing on a car with fuel injection, so let me know if the technique is entirely different. I'm guessing that another possibility is the fuel mixture/supply. I have a hole in the gas tank, so the fuel filter may be clogged with rust. Or maybe that's just a whole 'nother problem .... Any info would be greatly appreciated!! Thanks, Fred
Reply to
Fred Mann
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Your timing isn't computer controlled so thtat's easy. Timing mark is located under the big plastic screw on top of the gearbox between the two big mounting bolts. Unscrew it and you'll find the '0' mark on the flywheel. Backfires are also caused by very lean mixtures...

SFC

"Fred Mann" schreef in bericht news:6WEUe.121$ snipped-for-privacy@bignews4.bellsouth.net...

Reply to
SFC

Thanks!! Now for the stupid question: How do I adjust the timing? On my Toyota, it was easy. There were two bolts on either side of the distributor. I don't see anything like that on my Rabbit. Also, should I adjust it when hot? Do I need to pull any tubes/wires first? Finally, what is the ideal setting? Thanks again, Fred

Reply to
Fred Mann

It sounds like you have a lot of problems. A messed up fuel filter and a hole in the gas tank seem like they should be dealt with immediately. If the car's been backfiring its very possible the catalytic converter and oxygen sensor are damaged at this point. A backfire means that unburnt fuel is getting dumped into your exhaust and is igniting because of the heat of the exhaust. Obviously this can greatly accellerate damage for anything in the exhaust.

Setting the timing is quite simple. Assuming you have a manual transmission there is a green plastic plug in the bellhousing of the transmission. There is also a clear plastic plug in the green one. You must remove the green plug. If its loose you can do it by hand, otherwise you'll most likely need a special tool. To adjust the timing you unbolt the holddown bracket on the distributor (I think its a 10mm head, but it might be a 13) and then rotate it until you get the desired timing.

If you look in the bellhousing you will see the flywheel. There are two marks on the flywheel. A small dimple shaped mark and a larger diamond shaped mark. The dimple is at TDC, the diamond is at 6 degrees BTDC. There is also a > shaped mark on the side of the hole. The desired mark on the flywheel should be aligned with the > shaped mark on the bellhousing. The engine should be set for 6 degrees BTDC +/- 2 degrees at idle.

I don't know the impact temperature has on the engine, but generally speaking its probably better to set it when hot. Two things to keep in mind before doing this:

1) I've never seen *ANYONE* do this correctly without having someone point out what the marks are. They always get confused. It might behoove you to rotate the crank by hand and observe the entire flywheel so you are more sure what you are looking at. Some people put a little dab of paint on the right spot so its more obvious. 2) Even in 1983, the ignition was electronic (although timing wasn't). Short of problems with the advance mechanism your timing shouldn't wander. I've never seen the base timing change over time, ever.
Reply to
not_I

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