[Vintre]

Hello All,

I have been experiencing some hesitation in lower RPM's. The car will hesitate then, jump, until higher RPM's are reached. If I keep the RPM's high all the time, no hesitations. Almost feels like there is no fuel, then, fuel is supplied. Hope you understand what I am trying to explain.

I pulled the plugs and found all 4 to be the same. White electrodes.

I think this means I'm running Lean.

I should say that I installed the Squadra Chip about 2 years ago, but I thought the chip makes you run rich.

Any thoughts are appreciated.

Sincerely,

Vin

 

[60sRacer]

Which car? It's easier to diagnose if you pull back the green curtain a bit.

Robert

 

[Vintre]

Sorry about that.

1991 Spider Veloce.

Running NGK BP7ES's installed 3 years and 6,000 miles ago or so.

Vin

 

[Vintre]

I've done some reading so, here some additional information.

O2 sensor replaced in '08 to pass emissions
Intake runners replaced in '09 and no obvious air leaks
Fuel injectors serviced by Cruzin Performance in '09
Head gasket changed in '10
Temp runs between 175 and 190
Idles fine
Did my first compression test both Dry and Wet and seems fine

Not sure if the CAT is working. Will borrow my friends temp guage and see if the CAT is working. As I understand, the back of the CAT should be around 50 degrees hotter than the front. Won't be able to test that until Tuesday or Wednesday though.

Hope that rules out some things off the bat.

Vin

 

[howndog]

Sounds like its running lean. I know my car is different, but when I had a similar problem i advanced the timing , and all was good. FTR, my problem was that from idle to about 2000 rpm there was little power, once it reached 2-3k rpm(i don't recall) the car ran great. Not sure if thats what you're experiencing.
FWIW my car was carbed with a points dizzy..

 

[Vintre]

Hi Howndog,

Thanks for the reply.

I have an S4, so EFI with timing controlled by the ECU.

Also, I have installed the Squadra Chip which as I understand, adviances the timing, so the chip is doing that.

Thanks for chiming in.

Vin

 

[bianchi2]

a bad cat won't make you car run lean, as the o2 sensor is upstream of the cat...that chip..poss. your injectors are not providing enough fuel to the motor.. these cars on stock injectors are allways running close to lean.. this was to pass smog from the factory,,ther are a few injectors that would send more fuel to your car..i know of a few..

 

[RandallM]

I do not know about the Squadra Chip, but anytime you put a chip in to add power they always run the engine leaner. The leaner you run the engine the more horsepower you produce. The problem is the leaner the burn the hotter the piston temperature, the whiter the plugs.

More power is always better, but you'll reduce engine life. It's the old saying, a candle that burns twice as bright only last half as long.

NGK makes a BP5ES that operates at a higher temperature.

 

[Gubi]

I do not know about the Squadra Chip, but anytime you put a chip in to add power they always run the engine leaner. The leaner you run the engine the more horsepower you produce.

That is incorrect. Max power is actually slightly rich of stoichiometric. The standard graph is in the link below.

File:Ideal-stoichiometry.jpg - Wikipedia, the free encyclopedia

AFAIK the Squadra chip advances the timing and adjusts the mixture map, probably making it a bit richer. I don't know if it also disables the check engine light, but it might. If that were the case you wouldn't get visual feedback if your mixture were out of spec.

Maybe try writing Squadra to see if they have any suggestions. When I was having trouble with a chip a while back they were reasonably responsive.

 

[RandallM]

Personally, I do not believe it. lowering the air to fuel ration will just load the engine up with fuel and reduce horsepower. I guess it's the miracle chip or the Alfa engineers totally missed the mark.

 

[howndog]

I've always believed and I thought I read in the alfa bible that richer means more HP

 

[Gubi]

Well Randall, it's your opinion versus a hundred years of combustion science. Personally I'm gonna go with science here.

On top of that, your advice to go to a BP5 is completely wrong. That's a hotter plug, meaning the electrode has a smaller heat conduction path and thus causes higher electrode temperatures at the same engine conditions. This is exactly the opposite of what you'd want to do if the car had overly white electrodes.

Vin, in thinking about this, how'd you read the plugs? Supposedly to really read them right you need to drive the car hard, shut it down and coast to a stop, and then pull the plugs and check color. If it idled at all that'll mess up your read.

Anyway, I don't remember the electrodes on my Spider ever being very dark when I've pulled them. You may have some other problem besides the mixture. Have you checked everywhere for air leaks, especially the accordion section of the intake tube and the four intake runners?

 

[jc96]

Just for giggles...white (not ashen grey) could be an indication of water entering the combustion chamebers as well. ciao

 

[Elio Comello]

Ciao Vincenzo,
It looks like you have 2 symptoms:
Hesitation....
Could be a hardened/unresponsive diaphragm in the fuel rail pressure regulator.
Another possible cause is a "spot" on the resistor slide/wiper of the AFM.
VVT circuit working good?
Lean?....
Though "new" the Oxy sensor could be toast,
You could have false air leaks at the injector seals of the intake manifold, or air leaks at the throttle shaft bushings. Or other "uncommon" locations downstream of the AFM. One contributing factor can be the OVS, if the internals are toast (contact me if you want to rebuild the OVS).

Aside, I have good results in going to the Iridium version of the NGK BP7ES (EIX suffix), got a set of 4 for less than $30 delivered on eBay). Have you tried to see if you can ascertain any difference when you go back to the OE chip?

Ciao for now Elio

 

[ghnl]

How about a photo of the plugs being discussed so we can actually see what you are seeing? EFI engines & today's gasolines run very clean and thus the spark plugs will be very light tan/almost white even after being driven many miles.

Spark Plug Diagnosis

Normal Light brown, tan or grey firing end.

 

[60sRacer]

If you changed the chip for more power, it's possible that the plugs are too hot for the set-up. Easy step is to get a set of cooler plugs.

But the first thing I'd try is to put the stock chip back. I'll even bet you won't see any loss in power. Most of these chips just push the stock set-up to the edge of its envelope. They set everything as if the intake air is under 65 degrees F (cold air) and push the advance a few degrees up, giving you a few HP if the air actually is cold. But you get too hot otherwise. Never saw a "chip" that was worth the hype.

Robert

 

[Vintre]

How about a photo of the plugs being discussed so we can actually see what you are seeing?

Absolutely correct. Sorry I didnt post right away.

Here are a couple of pictures. I took them against a dark brown background and with the flash off.

So they are not exactly white. I called my 16 year old daughter over and asked her what colour they were since I think woman describe colours better than men .

She says grey.

So, all of this for not?

Vin

 

[spiderserie4]

look ok to me...nice and even at least. Put them back in with a spot of coppereaze grease on the threads, as the lower threads look pretty dry - and you are dealing with an aluminium head

 

[60sRacer]

Doesn't look like the plugs are your problem, 'though I'd try a cooler plug anyway. Try putting the original chip back. See if you can make some real OBJECTIVE test of the car's power before and after. Like I said, chips rarely do more than a few HP and then only in a few circumstances.

Robert

 

[Vintre]

Thanks to everyone.

Sorry to have bothered all, but I did learn so it's not a total loss.

Still have the hesitation issue and a squealing belt, but that's another thread .

Vin