308 QV Popping at low RPM

Very possibly could be from an ignition system that is putting out weak spark due to the battery being low from sitting for a few months. Once you raise the revs the problem will go away due to the alternator current taking over as the power source for the ignition. My guess is the problem goes away above 2000 RPM.
Try charging the battery or replacing it if it is old already.

My .02.

John
P.S. I had this problem with my 308 QV. I think they only have 75 amp charging systems!

 

My 328 always has a red light on until I blip the throttle. That is normal. Mine has done it for 18 years.

 

A glowing alternator light is almost always a bad diod in the alternator. It's a cheap repair of less than a hundred bucks including R&R at any good auto electric shop.

 

My early '88's 328 alternator doesn't "kick in" until 2000 rpm or so. Having the alt lamp on until you rev it is normal. The QV is probably similar.

I had a fresh Red Top Optima installed in my 328 in September. In mid November, it got too cold for the S03s, and I parked the 328 in the garage. In mid Feb, the battery was not only dead, but wouldn't hold a charge, even with zero load.

Apparently, the recent Optimas don't take to sitting very well.

In 30 years, I've only had one bad experience with Sears Die-Hard batteries. (The one sitting a foot from the Celica's glowing turbo collapsed internally.) The decades old battery in the Alfa fired it right up after sitting for five months. I think I might see how a Die Hard (with a battery tender) does in the 328.

Rich when cold only might point to the aux air valve, which is mounted on the bottom of the coolent reservoir. Did you, by any chance, leave the connector off?

 

Just to confirm the info posted by the 328 guys... My 1985 308 QV has the red light on at start up as well. I've owned mine for a year now and it has done it consistently on every start up. Blip the throttle a little backing out of the driveway and it goes off.

Scott
'85 308 QV
'71 DeTomaso Pantera

 

Driving may clear it. I'd suggest adding a container of Chevron Techron fuel injection cleaner concentrate to about a 1/2 full tank of gas & driving until at least 1/4 of a tank has been used before filling up. Takes care of most fuel system related problems.

BTW, how old was the gas in the car when you took it off of the road? Could also be that the gas has gotten stale.

The regulator circuit in the 308/328 BOSCH alternators holds off charging until an RPM threshold of ~1500-1800 RPM is reached. This is documented in either the OM, or the FSM.

So getting the alt. light on just after startup is normal. Once the oil pressure is fully up, just blip the accelerator to get the alternator to kick in.

 

If it is popping through the intake, that indicates a lean condition. Can be caused by fuel system problem or a simple vacuum leak. I know another QV owner who spent much money tracking it down only to find it was a bad ground on the fuel system ECU. I used to own a QV that had bad gaskets under the plenum which caused the symptoms you mentioned.

DAve

 

Not in this particular case. It is well known that ALL 308's, 328's and Mondials will have the alternator light glow/on after initial start up. It will go out once you blip the throttle over 2k rpm, or start off.

 

Typically you will hear the popping the loudest from the right side air intake. Also, the popping is probably accompanied by a circuit breaker going on and off in the footwell which is very audible. Exhaust backfires are very loud.

Dave

 

Checking for vacuum leaks and tightening grounds on the fuel system electronics is free and therefore wise to elimianate first. The FI meters fuel according to how much air is going by the airflow meter. If addtional air gets in downstream, then you end up lean.

Dave

 

Lean conditions will certainly make it pop. Ask any carb 308 guy. Mine was popping like crazy because the idle jets were too lean for the exhaust system. I went up a size on idle jet and it was like a new car.

With a carb car you can take the top of the airbox off and see the fuel mist shoot out the top of a carb when it pops. The pop is caused by incomplete combustion because the mix is too lean to support a proper burn.

It sounds like this could be happening to you. I'm no expert on Kjets but I would bet it's just a clogged injector or something simple like that. First thing is do what Verell says and put some techron through it. The stuff DOES clean injectors and it won't hurt your car. If that doesn't work, pull the injectors and soak them in carb cleaner overnight, blow them out and visually inspect.

Birdman

 

I had the same problem with my 85 QV after it sat for 8 months. Had the injectors cleaned by Bosch for $76.00. She runs like new now. As for the red light on startup, have had my 308 for 6 years, comes on every start and goes away with a quick flick of the throttle.

 

The updated brass ones are: 04 37 502 047

You will also need replacement rubber o-rings....do a look up for a 77 VW Rabbit, order the black ones (not the green). Not sure why, but those are the ones I was told to use, and worked fine.

Too bad, the injectors used to be $21 a year ago....

I noticed my 328 ran better above 5,000 rpm with the new injectors. My technician tested my old ones for kicks, and found two leaking, and two with poor spray patterns.

Dave

 

Six of the eight plugs look good but two are pretty black and one of them fouled to the point of not firing at all till I replaced it (and the rest). It ran great after that but I've been checking those cylinders and they sure look different then the others. It seems to me that either the spark is weak to those two and thus not fully burning (it's missing a bit at low RPM) or perhaps the intake valves are not seating and are letting in too much. Am I thinking right? It's a carburetted car so if it was set too rich all the plugs should show it I think. Is it time to buy a Leakdown tester or could it be a Wire?
TIA....Clark

 

Hello - I have the same problem with my 308 - started after the ferrari service did a major service - now they could figure wtf they did or was causing - but this is exactly my proble m as described above in this thread. I got the car back today becuas ethay had for a month and it was like dealing with a bb in a rainbarrel. No clue and just excuses and maybe this. None of which did anything - I am starting to trouble shoot myself this weekend with info ffrom you guys. Thank you

Any other advice?

John