JE928Sx4.

I finally got my nagging electrical issue resolved on the $5K 88 S4 in time to get it in for it's emisions and state inspections. Now the stalling problem that plauged the PO and made him decide to sell is back. YIKES! The results of the emissions test is scary. HC ppm are in the 740's when the should be in the 110's. CO% is over 11% when it should be about .65%. NO ppm was wayyyy under the limit. and everythig else passed. Bummer.

Thanks to Doc Mohr who was in the area last night buying interior parts for giving me a LH brain to test. I'm figuring that it's got to be a sensor or brain failure at this spoint. We shall see.

It's always something with these cars.

SharkSkin

Wow, that's running awfully rich...

JE928Sx4.

Yep, I'm hoping that swapping the brain will cure it and the stalling. Things are never that easy on these cars though.

jamesld

Have you checked the CO2 sensor? If it is not functioning correctly or missing it will affect the emission gas levels under acceleration. I am in the Landmark area if you need any help.

Bryan

The usual suspects for rich running like this are dripping/leaking injector(s), and failed fuel pressure regulator/dampers. Or a broken/unhooked vacuum line to the fuel pressure regulator.

When does it stall?

Bryan

JE928Sx4.

It just started doing it and I haven't taken any substantial drive in it since the emmisions testing station is on the next block. However, it stalls when I cold start it. It also stalls when warm and I rev it and let my foot off the gas. This condition drove the PO to sell the car (though mostly siting as I restored the interior since I got it) and had been running very nice for the last 4 months when I have started it. The intermittentcy of the condition makes me suspect it's something electronic (Brain, MAF or O2 sensor).

Regards,
John

JE928Sx4.

The O2 sensor is on the list, But I can easily swap out a brain or the MAF first before I go to the O2. I've been told you can put a meter on it, but I don't know what reading to look for to tell if it's gone bad. However, I've also heard that an O2 gone bad wouldn't produce the drastic rich condition my car has. I'm no expert in this area. Any help properly diagnosing would be appreciated.

Regards,
JE

Thaddeus

JE, that car is just too much trouble. Drive it on up to Minnesota and I'll give you 5K for it... just as a friend you understand.

Garth S

JE,
Have you been driving the car, or just moving it around the yard (eg., awaiting tags/registration)? if the former, any idea of mpg/ fuel consumption? Does it idle smoothly at ~ 750 rpm, pull hard without missing?
In your restoration, have you visited all the basics? - air filter, wires, plugs, caps/rotors, and so on.
If these sorts of things were done, sorry for bringing it up: if not, a little ground work can only help as the suspicion turns to MAF/ECU/ ...
The O2 sensor output (direct and disconnected - plug in fuse panel area) on an eng. at operating temp is in the 0.2 - 0.8v range: rich mixture = low O2= 0.8+v.However, an O2 sensor will neither cause nor cure a condition that rich.
Bryan covered the most likely causes from the fuel side. Its reasonably easy to remove the fuel rail and check. The MAF can also be suspected - somewhere, either by way of false signal (MAF?), of mechanical failure (excessive fuel pressure, faulty injectors, ...) way too much fuel is obviously getting in.
BTW, if the emissions station is next door, the current wisdom will have you taking a 30+ mile "shortcut" before any visit - a good run and a hot engine are a plus.