I have a 98 XJ8 with 137,000 miles that runs perfectly....once it starts. Nine out of ten times it will take 5-6 times cranking the engine for 15-20 seconds each time for the car to finally start. This happens mostly in the morning and the car starts just fine the rest of the day as long as it doesn't sit for more than 3 or 4 hours. The average temp in the garage is 55 degrees F. I've checked the mass air sensor, the aux air valve, the injector sensor, all electrical connections including the multitude of relays in the cold-start loop. When it does start in the morning it is nearly instantaneous. At all times, on the first start, the engine idles a little high (1200 rpm) for about 5-6 seconds, and then stumbles down to around 500 rpm and the levels out smoothly at about 800 when cold, later when it is warmer it idles about 650 rpm. My mechanic and I are at our wits end. Any ideas?

 

I am not an expert on the '98s, but your symptoms seem to mirror loss of compression experienced with some Nicasil engines. The nicasil cylinder lining gets eroded over time by gasoline with sulpher content. After sitting a while, the oil drains off the cylinder walls causing loss of compression. Once oil gets splashed back on the cylinder walls during cranking, enough compression is restored for the engine to fire and run.

Again, I am not an expert. I am sure they will chime in soon. It could also be a fuel pump issue.

 

Test the fuel pressure at the Shrader valve on the fuel rail. Failing fuel pump or clogged fuel filter.

 

We also check the fuel pump and it is fine. How can I narrow down the possibility of the cylinder liners being the issue. Thanks a ton for your help so far. Jagpg

 

I am hoping that someone more knowledgeable chimes in, but you may want to do a compression test on each cylinder when stone cold. Then test each cylinder again after injecting a small amount of oil into the cylinder. If the compression increases significantly, it may indicate a problem.


There is a procedure documented on this forum to diagnose failing Nicasil. I apologise for not being able to direct you to it. Try searching on Nicasil.

 

How did you test the fuel pump? I'm asking because your symptoms sound a lot like a fuel issue. How old is the fuel filter? A plugged fuel filter may allow normal pressure at start up, but not enough flow. I'm thinking that if you were getting fuel, then by the time you cranked it 5 times for 20 seconds the motor would be flooded if it didn't start. Does it smell gassy before it starts? Is it trying at all while cranking?

A handy test I've used to diagnose a fuel issue is to put a little bit of gas or starting fluid in at the throttle body. Disconnect the air intake, put a little bit of fluid in, reconnect the intake and turn it over as usual. If it immediately fires you have a fuel problem. All the ECU is doing when it is cold starting is shooting a lot of fuel into it while cranking. Most of the sensors aren't being used and the situation isn't all that unlike the old carbureted motors. Once it is running, the other sensors come in to play, but it is still basics: fuel, spark, and compression.

I just went through a hard starting issue on an X308 XJR that was the fuel pumps. You car is prime age for a fuel pump failure if it is still on the original.

-Mike

 

Well, I'm giving it up. I'll put the Jag up for sale. It would be a great project for someone. Other than the hard start its a beautiful car. Thanks to all who supplies info. Jagpg

 

Giving up doesn't help. Try changing the temperature sensor on the cross over pipe. If it has failed, the ECU thinks the car is warm and doesn't enrich. Fuel filter is also an occasional problem. Might try cleaning the injectors with some gas treatment (I like Gumout's SEAFOAM look alike). How old are the plugs?

 

It could be just the (common on the early models) bore wash issue.

 

Bore wash only occurs when the car doesn't start immediately or when the engine is shut off shortly after starting.
My '97 has never failed to start immediately.

 

You need a leakdown test, although a compression test would eliminate to cylinder wash issue.


Although your symptoms are not typical for a bore wash I would not rule it out altogether. I've seen it many times in cars that come to the shop on a hook with atypical complaints.


Get a competent shop to do a leakdown. Won't cost much. You can do a quick, cold compression check yourself when the problem occurs. Then you can either rule out the nikasil and the wash, or have a solid diag.