Serious road construction in my area has prompted me to beach my 2014 Camaro SS and drive the less than pristine Jag. (Funny, is it bad that I think I actually enjoy driving the Jag more than my brand new 426 hp car?)

Anyway, some issues have arisen. (BTW we are talking about my 1988 xjs here)

1st: The idle of the car once warmed up is rough and vibrates through the steering wheel. It seems like it is set too low (700 rpm in park and 500 rpm in drive) but no adjustment of the idle set screw yields any change. It stumbles and gives you the impression that it's about to break down.

2nd: When you "stab it", or give it more than 50% throttle, it just loads up for a while and then starts accelerating.

3rd: Finally, to the title of this post, driving down the street with the window rolled down because the climate control in non-op, I smell this sulfur/rotten egg smell. I'm guessing this is raw/unburnt fuel but WTH causes this?

4th: On cold start, it loads up and dies when you give it any gas at all and you have to repeat this process several times before it starts running fine all of the sudden and then I'm off the work and all is well.

I have already replaced both ignition coils, the TPS, and the amplifier so aside from the plugs and distributor, the ignition components are new.

I know how smooth these engine are supposed to be and something is definitely not right but I just can't think of where to look next for the problem. She's a good running car but these are serious annoyances while driving.

Thanks in advance!

 

Back in the days when both leaded and unleaded cars shared the road, accidentally putting leaded gas in an unleaded car would make a rotten egg smell from the catalytic converter. The lead damages the cat and will plug it up.

Based on some of the other problems you report I think you might have a plugged/damaged cat.

 

Thanks for the quick response Safari but the PO had just had new high efficiency cats installed prior to me buying the car. The rotten egg smell definitely seems to correspond with the other issues though. I wonder if I have a misfiring issue which would explain the rough idle/unburnt fuel smell? The car seems to run way too well for this to be the case however..

 

Are your sure...
check for a leaking injector... or two... check the pulses at the pipes at the back of the car to see is each bank is smoothly running... if not check the bank that is missing...

Newbie Jonathan

 

As soon as read "rotten egg smell" my first and only thought was Cats.

 

that is definitely from a fuel/ignition issue. The extra fuel gets stored in the cat and released as hydrogen sulfide.

so it would load up and then accelerate because its dumping fuel and then regulating. So the question is whether it is dumping too much fuel, maybe an o2 issue, or if it is just not getting burned properly.

I would check voltage at the dizzy and if it is out of spec, head back from there.

 

Ok so I felt the exhaust on both sides and they both feel like they are misfiring. Both have a steady rhythm but it is interrupted by one large pulse, the idle drops for a split second and then the cycle continues.

The PO had aftermarket cats installed and welded into the exhaust system. Maybe they weren't up to the task?
Maybe I could pull the injectors and have them tested and cleaned?
With the cold start issue I always had the feeling that the engine was flooded. Bad regulator?

 

You can check fuel pressure and quality of vacuum at the regulator, but it usually tends to fail in such a way as to not let enough pressure through. I guess it could always be letting too much in, but that should affect all of the cylinders, not just a few.

I'm still leaning towards ignition issues

 

I definitely remember the Jaglover forums days - sulfur / rotten egg smell is always fuel / catalytic converter related. If you don't have emissions testing:

1. remedy the problem
2. lose the cats


ooh - you'e in Cali - just fix the problem then.

 

My experience with rotten egg smell is that it's caused by rich mixture/over-fueling and/or unburned fuel going thru the converters. (see Sidescrollin's post above).

The odor wouldn't occur were it not for the converters....but it's not that the converters are faulty. It's just the chemical reaction that occurs.

Cheers
DD

 

New cats always stink for at least 500 miles or more. I just put a new converter on my sons car and it stunk for a couple of weeks...

 

missing both sides hmmm... black soot on the exhaust pipe(s)? (running rich ie unburnt from the missing)
make sure your spark plugs are in good order and the SP wires also... make sure they are all connected to the correct places ....

Though I am leaning toward a leaking injector...

 

Can the XJS injectors be disassembled for rebuild or soaked to clean then? I have never had them off the car..

 

UPDATE: The car does not rev past 4500 rpm. It surges violently. I think it's being starved for fuel. Seems like I might have more than one problem here.

Here's my plan to shotgun the issue. Tell me how this sounds:
1. Pull fuel rail, have injectors tested and professionally cleaned, replace injector hoses, replace fuel filter
2. Change spark plugs and wires
3. replace the distributor cap and rotor
4. See where this gets me

 

don't confuse starving for fuel with starving for air. If you already have an overfueling/ lack of ignition issue, its probably flooding.

if it were so lean it couldn't run at 4500 it would be overheating. My recommendation is due some diagnostic work, because you may be unhappy throwing money at the car with parts and still have to do the problem solving anyways. These ARE probably items that need to be done if they haven't been anyway, but I would do some testing around the dizzy and coils to see if its doing what it should be

 

Nothing wrong with doing all that stuff, but .....

*Begin* with the fuel filter. Remove it and empty the contents into a clean contatiner. What you see might very well dictate your next steps.

Cheers
DD

 

It may be worth checking TPS setup.

 

Visiter opines:


My 69 Toyota FJ40 did not have a cat. But, at times, it would develop that "rotten egg smell. Hydrogen sulfide!!


Black tail pipes mean little or nothing in this day of unleaded methanol laced fuel.


The uneven pulses certainly indicate a mis fire in one or more cylinders.


Caveat, over fueling and the resultant raw fuel will kill the cats!! $$$$ Don't ask!


Carl

 

One other thing to check. I had an alternator problem on mine which was cooking the battery.
May want to check amps and stage of the battery..

 

I just read an article by a local auto tech instructor. The subject was the interesting uses of an infra red thermometer. According to him, a cat can be tested. The temps after should be decidedly cooler than before, if it is clear and functioning.


And, reading temps at the exhaust manifold adjacent to each cylinder. Seeking one or more that are cooler denoting not firing evenly if at all.


I have one from HF. Gotta play with it some more.


Carl