Car is now at the shop for two weeks while they hunt this issue down. There something causing the fuel injector to not inject.

It's not an issue with the injector, something is telling it to not inject fuel.

I handed them a spare ECU I kept from my old car hoping it could be a quick fix.

Apparently they are telling me that the diagnostic computers have ruled out the CPS. I know they have a functioning PDU, not sure how they can tell, but I guess that's why I took it to the shop.

Just wished I had tried swapping out ECUs before I took it over there...

 

Sorry to hear you are still having problems.

There are 3 fuel related relay in the trunk. Have those been checked??

 

Thanks for the consideration. Would a relay have any bearing on the fact that a particular cylinder is being told not to inject fuel?

It only occurs at cylinder 4...

The shop is confident that it is a short causing the problem. I will post back when I get a final determination.

I was hoping that my spare ECU might come in handy here.

 

Apparently it was just lazy oxygen sensors?

 

So I finally picked my car back up from the shop.

I have six new coils installed. Apparently 4 of them were going bad.
All four oxygen sensors have been replaced.
An EGR valve was replaced.
The TPS and IACV were also replaced.

The car was reset on a PDU.

After all that, the car's idle still occasionally dips a bit when at a stop light. This was an initial issue when I brought the car in, except that it would occasionally stall. The dip is much less pronounced, but the tach will drop to below 500 for a brief second.

I suppose I may have to drive around for a little while to give it a chance?

 

Drove it this morning and it stalled out.

Ugh.

So much for the Jaguar Specialist...

 

Vee,

Sorry to hear you've still got the elusive problem. If the garage were sure that it was a short on cylinder 4 that was causing the problem, what was it that they did to the wiring to cure that short?

Paul

 

I believe they chalked that up to a failing coil. They essentially ended up writing all of the coils off. They allegedly tested them.

I'm kind of pissed at these guys since they had the car at the shop for three weeks and although the rough idle is gone, I don't know why it took them so long to diagnose the oxygen sensors. They're supposed to be the experts.

Anyways, I will probably clean off the crankshaft sensor today and see if anything improves.

I hate to throw parts at this problem but I am running out of possibilities?

A. Crankshaft sensor
B. MAF Sensor
C. Coolant Temp Sensor

Anything else?

 

Vee,

If the car starts fine and the rough idling is generally gone, just leaving a tendency to stall, then I guess you might start to look for problems which only happen with a hot engine. Perhaps areas like:

- vacuum pipes softening or leaking
- momentary fuel starvation - filters or pipes
- breakdown in wiring integrity through heat - anything from coil wires to 02 wires etc
- electrical components overheating
- slight air leaks on the inlet side - manifold joint, pipe joints etc

I feel for you. Those type of inconsistent problems are a pain to solve and spoil the enjoyment of running the car.

Good luck as always

Paul

 

I feel your pain, Vee. Must have spent a small fortune on this problem. My 96 was stalling and a new TPS cured it. After a year of perfect idling it now has started to rev about 700 rpm instead of the 600 it should be turning. Not stalling though.
Luck, RagJag

 

I appreciate this list.

I have done the best job I could do hunting down vacuum leaks. I've gone through two cans of carb cleaner and fixed anything I could find.

I was contemplating checking into the fuel pressure regulator, because a slight starvation of fuel could be it.

Wiring would be an absolute last option as it could be impossible to find.

The car drives great, it just does't seem able to idle reliably.

 

I would love to know more about your issues before the TPS replacement. I installed a TPS that I inherited with a lot of other parts. It sure looked new...but I don't believe it altered my problem in any way. I've had it for years, so I'm wondering if it was just a super-old part that might have gone bad?

My car does idle at the right numbers...580rpm when hot and in gear. If I shift to neutral, the revs go a bit higher, perhaps to 700rpm.

I'll have to keep driving and figure out what else could be at fault.

 

I feel bad about ripping the Jag specialist. the car is fixed. the problem was that there was a hose that was not reconnected at the intake elbow.

I broke that when I was disconnecting the hose and I glued it back into place. they must have re-broken it. I re-glued it and the car runs as smooth as ever.

funny that the car never threw a code even when there was as large a vacuum leak as there was!

 

Vee, been there done that with the pain of paying specialists big money, long periods without your car, and when you finally get it back - problem pops up again!!! Frustrating to say the least.

Now I always keep a couple of vehicles in the stable so it's no big deal. They're cheap enough now to buy yourself a twin!

 

I can't say that this hasn't been a learning experience!

I hate it say this, but just about everything that goes wrong on this car has been replaced.

6 new Japanese coils, EGR, air pump, IACV....what else can fail. I guess the starter and the fuel pump.

Wish me luck!

 

Luck, Vee. A starter is pretty cheap and not too difficult to replace. The pump may be a bit more.
RagJag