328 gts poor idle

Hi ! I have a 1988 328 gts in the shop today, it idles slow with virtually no throttle response and a rough uneven idle. I've cleaned the throttle body which was quite nasty looking. the plugs are slightly black but not completely fouled . depressing the air valve just slightly picks up the rpm but the throttle response is still not there till past 3000 rpm. any ideas ? the car has about 20000 miles with the same owner since virtually new.

 

I went through this same issue with my 328 this year. Idle at 500RPM, no response at all with throttle (embarassing crawling through the red line).

Here is what I had:

nunber 7 cylider dead due to a bad plug extender (measured infinite ohms)
Number 1 wire hardened to stone: 20 years old wire sitting next to the exhaust header will do that
1 cracked dizzy cap (although I am not sure that was the actual cause)

My remedy: 8 new cheap copper plugs (they will try to sell you the $40 ones, forget that). One set of wires I made up with supplies bought from Kingsborne. This is good for DIY but the shop mechanic will not spend time making wires up, it costs the same as buying a set.
One dizzy cap from Ricambi

Then it is now happy again ... until this week when the passenger door sticks a bit and the driver door jolts loose over big bumps. Life is never ending with Ferraris.

 

I had a similar situation with a Mondial QV that I owned. It had run fine, then started idling at 500 rpm and no power. Turned out that the front bank had dropped out on me, bad plug wires. I changed all the wires, front and rear and coil wires, as well as the plugs and extenders, and the car went back to running like a charm.

IMHO, rather than plain old copper plugs, I'd go for the NGK Iridium plugs. I'm running them in my '86 328 and they work great!

BTW, it was easy to check with an inductive timing light. The rear bank was firing just fine. The front bank wasn't even there at all.

 

I had no problem paying $4-$5 a plug, but the Iridium plug was north of $25 each. Of course, they are "meant" to last 100,000 miles. Well, a new set of copper plugs every year is fine with me.

 

At $25 each, I wouldn't use NGK EIX either -- I get mine for ~$7 each from my local autoparts store.

 

The good old days: gas was $1, a can of oil was $1, a spark plug was $1, and a radio (not stereo) has the DIN standard opening.

 

Have you checked the operation of the frequency valve? What you're describing sounds pretty similar to what happened when mine stopped working. All it needed was a jiggle at the relay to get it going again.

It should be vibrating or buzzing when operating, which you can check by putting a finger on it.

 

Ok great, where is this frequency valve and what exactly does it do ?

 

Ditto. In fact, sometimes Pep Boys or Strauss Auto around here has them on sale for about $5/ea. I never heard of them being $25, at least not the NGK's.

 

I have an '87 Mondial, so I'm assuming they are the same which is usually a mistake.

If you are standing behind the car and looking at the fuel distributor, it is at about 10.30 on the clock. That is, it is directly between the air intake hose and the top (front) of the fuel distributor. It has a wiring connection toward the back of the car, and a single hard formed line coming out the top. There has to be a photo of one here somewhere, I'll look in a minute.

It controls fuel metering, I believe related to idle/emissions controls, but I'm not much clearer than that. I believe they are frequently a problem, though.

OK, here's a diagram. It's part #26. That's an exploded view, so it's really behind the fuel distributor if you were looking at it from this angle. I have no idea where the relay that controls it is mounted in a 328--it's in the trunk of a Mondial.
Image Unavailable, Please Login

 

The good old days involved a rectangular opening and two 3/8 holes for knobs for a radio, thanks for all your help everyone !

 

So have you solved it?

 

Clogged intake screen on the WUR.

 

I vote for bad relay (protection relay) for frequency valve. Mine would do it intermittently. Nearly drove me nuts until the relay dropped out altogether. Then I found it when I noticed the FV was not vibrating.

 

Great diagram.
Thanks

 

Same here - new wires, extenders, plugs, caps, fuel injector cleaner, etc. Relay in the right lower trunk, replaced and good to go. All the other changes made the car a little better once the real problem was solved.

The OP said it idles slow with virtually no throttle response. A bad wire, plug, or extender doesn't seem to create this much disturbance, unless a bunch failed at the same time. The bad frequency valve condition is obvious at low RPMs and is more masked at higher RPMs (but still there), so I would go with the frequency valve relay, which is a bigger effect on idle and performance.

 

"The good old days: gas was $1"

Those were the mediocre old days! In the REAL good old days (60's Muscle car era until the Arab oil embargo in '73) it was 33c a gallon for premium unless there was a gas war going on between service stations, then it was 26-28c for premium and they gave away free drinking glasses with a fillup.

I never filled up because no self respecting street racer would EVER have more than 1/4 tank of gas in the car.

 

I had this same experience: intermittent problem with the frequency valve not buzzing, the car running like crap, and it drove me nuts, too. Never did find a failed component, but just working through the system seemed to fix it temporarily, several times.
I finally concluded that it must be a loose or oxidized plug fitting somewhere; those tinned pins are only good for so many plug-unplug cycles, and the mating surfaces tend to oxidize over time.
So I applied a small dab of Krytox contact grease (Loctite Dupont Krytox RFE PFPE Lubricant 2oz 29710; Ebay, $18) to all the engine harness and ECU plug pins, to prevent oxidation. Since then, I have had no more problems in 1000+ miles.

 

I had a similar situation way back in '77 with - of all cars - a 1973 Triumph Spitfire! Couldn't accelerate. It was a cracked distributor cap...just as you have eluded to. Not saying that the ugly British electrics of that day were anything like Ferrari's electrics a decade or so later, but maybe the same situation has occured here?

 

Absolute first time finger to phone. Very interesting to read the various responses. Now my 1986 built 328 aust delivered rhd us stats goes like it's running late so it goes and stops in a hurry but when I go to put it at any angle (other than level) to park it at very low revs, OH NO it SAYS, i want
to stall. I'm sure it's telling me it's in charge, a bit like my partner.
I'm going to check the voltage from the freq valve relay thanks to the comments on FC. Anyone had this issue.
Reg dunnowhatdunno
Regar

 

Philip, start a different Frequency Valve thread.