I just bought this 1988 NA convertible with 75,000 miles, and it's running rich at idle. It runs fine, and gets reasonable mileage (18 city, 23 hwy), but at a stop light it fumes you pretty bad with that rich gas smell.

I have the Haynes manual, but it has about 20 different things to check in that throttle body system. I'm clueless about fuel injection. Anybody got some ideas for easy checks to track this down?

Thanks,
E.

 

Join the club.
Stock exhaust system or aftermarket?

 

It's bone stock. The car has been somebody's baby for a lot of years, sitting in a garage and being driven only about 5k miles/year. It was pretty sluggish when I got it, but after a few weeks of standing on its throat from time to time, it seems to enjoy revving and is fairly sprightly (still a drag that my wife's Acura CL 3.0 will kick its butt, tho).

I'm embarrassed to admit I haven't done anything except check the oil and buy the manual, thus far. Haven't even done the easy stuff like plugs, air filter, etc. I had a couple of 1st gen RX's way back when, and I don't remember this problem. They were coupes, though and presumably tighter.

I found a few things in the archive, but they seemed to be talking about Turbo cars. Don't see anything in Haynes at all that is about mixtures and the like - only "drop dead" tests for components. I guess I can go thru all that, but if there is a common failure mode, I figured you guys would know about it!

Thx,
E.

 

Other than smelling rich, how does it idle?

 

A little low (about 700 rpm), but otherwise fine. When starting from cold, it revs to 2500+ for a few seconds, but I'm told that is normal.

To be honest, it may be running rich all the time, but when I'm moving, the smell just gets blown away! Certainly, on that initial overrun on a cold start, it stinks then too.

BTW, after posting that last message, I did go open up what must be the Fort Knox of air filter holders (8 cap screws? Come on!) and the filter was fine - nearly new.

 

you might try cleaning the engine bay, with one of those spray on cleaners, I useually get the cheapest one like a buck or two, use the entire can after prepairing the engine bay. spray the **** on a Warm engine let it sit for a few minutes spary it off with the hose and take your car for a spin to burn off the rest.

 

I don't understand how cleaning the engine bay will help, unless your looking for leaks. I'd say change the plugs & oil, then check to make sure the 6 ports are not stuck open. With that kind of gas mileage they're probably not stuck open, but it's worth a look. Could be a failing exhaust system, too.
Good luck!

 

If it's an eye-watering rich smell you're experiencing, my money would be on a failed catalytic convertor.
You can check them without disassembling the exhaust or doing an emissions test - with an infra-red pyrometer you measure the inlet and outlet pipe temps. The outlet should be hotter if it's burning off the excess HC's.

 

I had thought of that, without knowing how to test it, because it would make sense that the most expensive single part would be the one! "Eye-watering rich smell" is a very precise description of what I'm experiencing.

Now, where can I find an infra-red pyrometer?

Also, since it takes some temp to fire off a cat, do all RX's do the eye-watering thing when starting from cold?

 

i'd change the plugs and check the timing for starters...cheap and easy to do.

john