Hello all, Usually I can figure things out for myself and be on my merry way, but this funky idle issue with my 1980 GTBi is starting to annoy me. Below are the details; I'm open to suggestions: Symptoms: - When the car gets hot (either sitting at idle for a long time, or driving on a hot day), the idle drops very low and the exhaust gets very, very, very (like eye-burning) rich. - If I sit and just let it idle until it happens, it begins in an instant as a very slight change, and then deteriorates gradually until the car is barely idling. In other words, it will be idling perfectly, there will be a sudden but slight drop and change in the rhythm of the idle, and then it gets progressively worse. - For it to happen while sitting idling, it always happens after the fans are on (i.e. hot). If I leave it idling long enough, it will eventually recover and go back to idling normal, almost as gradually as it deteriorated. - Doesn't happen when I drive the car on a cool night; always happens on a warm day. Has been getting progressively more frequent/common/easy to happen over time. - At first I thought it was one bank of cylinders dropping out, so I did all of those remedies (see below), but just now when it was doing it, pulling either coil wire caused it to not run. So I no longer think it's that. Here are some things I've done and checked: - I've tested and switched both coils and Digiplexes. Doesn't make a difference - I've replaced all three references sensors with new Marelli 8D sensors from Superformance. I had to carefully modify the mounting plate and change the connectors. I soldered the connections for putting the old connectors on the end and kept the wires the same length as original. - I replaced the spark plugs and extenders (just as a matter of course). - I measured a voltage drop associated with the idle drop. It would go as low as 12 volts while running (checked at battery, alternator, and coils all the same). At first I thought the fans (which are aftermarket SPAL) were doing it, but it also happens when I come off a freeway ramp and the engine is cool from getting lots of wind, no fans running. (So I'm not sure which came first chicken/egg idle drop or voltage drop. All is fine at speed.) - I thought I had a bad voltage regulator back then, and I replaced it. The voltage regulator I got from Superformance allowed something like 15 volts, and it shorted one of my Digiplexes (bastard). I bought two perfect Digiplexes from a 11k mile wrecked GTSi and played the swapping game again -- no difference. - I have a 10-gauge ground wire going from the body of each Digiplex (mounting stud) to the mounting tabs at the rear of the shelf (as the front ones are just in fiberglass and not connected to the frame). No detectable resistance from those ground wires to any other ground point on the car. Is there some other place to put the wires other than the body (mounting stud/nut) of the Digiplex? - The wires coming from the wiring loom with the digiplex plugs are also looped onto the mounting studs for the digiplexes. Is this correct? - I removed the cold/high idle crap. The wires going to the switch on the coolant tank are jumped so I have no yellow light at startup. The vacuum-operated valve to the right of the plenum (about 2:00) is removed and the redundant line is plugged. I did this because when the idle would get low, that thing would start to fluctuate open/closed and cause the idle to surge. Now the idle just gets low steadily, lol. - Car has Birdman's fuse blocks. I'm going to replace the spark plug wires this week just because they're old and it's time. So, getting back to the symptoms, what can cause this? It's almost like something turns off or on or a switch or relay is flipped when it begins. And the fact that it gets better after a while?!?!? I know this is not a totally uncommon problem, as I've talked to a couple other injected 308 owners over the years who had a similar issue (and never resolved it). So, I'm really not sure at this point if it is an ignition system problem or an injection system problem. Are there any other common "old 2vi" remedies (like the ground wires) that I missed or did wrong? Anyone else had this problem? Where should I go next? What other information can I give to get a better answer from you knowledgeable folk? Thanks, Tony
I've got a problem with similarities to yours. My '80i develops a sputter or misfire in the 3-4k range but only after the car is really warm (20 plus minutes). Like you i've replaced the extenders/plugs and added the digiplex grounds and replaced the plug wires. Mine is so predictable that like you i feel like a sensor or switch is coming on and adding vaccum or adjusting the air/fuel mixture wrongly and causing the sputter. Currently i'm waiting on a new distributor dust cap spring as one of mine was really rusty and a loop actually feel off. Beyond this i don't know where to go except to replace the engine and alternator grounds. I feel your pain.
Toni, Needless to say there are many possibilities---------------------- here is a tale from the north woods. I had decided to take the plunge and buy a 308 (first item on the bucket list) after 40 yrs. of English iron. I missed a couple and then found what I was looking for and made the trip with trailer on hand. The guy I bought the 82 GTSi from let me drive it and the idle was as you described rough and heavy with raw fuel. I took the car out and after warm up redlined the motor and it ran perfectly. At an idle the car was terrible and I decided to buy it and then sought it out since it ran so well at high RPM. This is getting to be a novel so I'll get to the point. Whomever did the last valve adj. (have a receipt from a dealer, YIKES!!!) got the math wrong and all the ex valves were way under stated clearances. So bad in fact that #7 was -.020mm and was not sealing , the other 7 were less than .020mm. At speed the valves are moving so fast that a complete seal is not affected as much as at idle. I am in the process of reassembly now (takes much longer to get all the hoses changed and the engine bay detailed than it did to pull the mill and diagnos the problem. In closing I simply suggest you do a valve clearance check and a leak-down. I hope this helps. lostbowl
