My 95 xj6 has a problem staying started. It fires up after a few tries, but won't idle unless you hold the throttle down for a bit. After a few seconds it will maintain an idle. It doesn't seem to matter if the engineis hot or cold. Any ideas where to look would be helpful.

Thanks

Todd
95 xj6

 

Tod, First things first.

You a NEW, so WELCOME, fun is about to begin.

I would remove the intake bellows, and with a solvent (petrol if nothing else) soaked rag, manually open the throttle disc (engine OFF obviously) and wipe all that black goo out of there, and keep going until it is nice a new looking.

This MAY NOT be your issue, but it is where I always start with any car that has idling issues. My V12's a mongrels for that goo, and idle is waaaaay off until both bodies are cleaned, then as sweet as.

 

Thanks Grant, for both the welcome and the advice. I will be taking the intake system apart today and going at it.

Todd
95 xj6

 

So I have cleaned out the intake, used a MAF cleaner, etc. No go. Still fires and immediately dies. Holding my foot on the gas for a few seconds to keep it from dying will allow it to settle in and idle and then it will run normally. Turn it off and the cycle starts all over. Strange.


Todd
95 xj6

 

Todd,

Bugga.

OK, you are in the USA, and your market gets an EGR system (exhaust gas recirculating), and we dont. I have read somewhere??? that the EGR valve? and its associated pipes etc reeks havoc with idle, and a simple clean out fixes the issues.

Hopefully someone in your market will post up with it real soon. Whilst waiting, perhaps look in the search area of THIS forum and you might stumble accros the posts.

 

Since having cleaned out the intake, it is clear that the hard start situation has changed. If it is warm, it states right up as normal. If it is cold, it still is a hard start situation. Is there a cold start valve or something that performs that type of function on these cars?

Thanks
Todd
95 xj6

 

Todd:
I add my welcome also.- There is no cold start injector on these cars- the function is performed by software in the ECU.

Grant's point about checking the EGR is a good start. Thats the metal can looking thing sticking up from the intake manifold. Usually they stick closed and throw a code, but yours could be sticking open. Remove and clean around the port and the thing that works into the port, which I think is called a pintle.

The idle speed function is set by the ISSC, which is a steppe motor that meters air around the throttle plate and works fom engine speed. The ISSC closes to full closed each time the car is shut off, but re-opens to the number of steps open that it learned from the last correct idle operation. It sounds like your ISSC is probably working correctly, since the idle comes under control once its running. The idle control depends on the TPS working correctly, since it must know your throttle plat is completely closed before it begins controlling. That is the basis for the recommendation to clean the throttle plate. Your TPS MIGHT be acting up, but it is expensive and hard to replace and many times requires a dealer software recalibration adfter replacement, and other things need to be checked first.

Since the car responds to temperature, I recommend you check the input air and engine temperature sensors, The best way is a OBD scanner that displays operating paramaters, although you can probably find the temp to resistance calibration chart in the JTIS manual. If the temperature is not sensed right, the ECU cannot properly compensate for temperature, right?

Iidle control, in general, can be a PITA on there cars. It took me a yar to finally sort mine, which turned out to be the TPS. but mine was the classic high idle. The good outcome was that I learned a whole bunch about the engine control strategy while I was running it down!

 

Ross has given you enough to keep you all warm and fuzzy until Christmas hahaha.

Cold start on the AJ16 CAN be other things also.

My short time with this piece of very technology advanced system (as compared to ALL my other Jags), is that the following may be giving you heartache:

1) The cam angle sensor (that whizzy thing where a distributor lived in a previous life) may NOT be timed "just right", and that will give long cranking times until Mr Nippon Denso sorts out what you want to do, um START.
2) The spark plugs may be gapped too large, and/or they are getting tired and need renewing.
3) The fuel pump (in the tank) may NOT be supplying that initial "squirt" of fuel when the ignition is turned ON, So get a mate/wife/whatever, and put them in the boot, and have them put their ear up against the tank panel (LH side) and listen for a distinctive WHIR when you turn on the ignition. Probably NOT an issue, but just for giggles eliminate it from the plot.
4) The fuel filter is waaaaaaay past replacement time. Cheap enough to renew, again, just to eliminate it.
5) In the RH under bonnet fuse box is a BLUE relay. This is an ignition relay (one of many), and this one supplies the juice to the Crank Angle Sensor, and they are known to get hissy from time to time. Simply pull it apart and give the contacts inside a careful clean, or simply replace it??.

If I think of more I will post back.

 

I had a similar issue, only mine would not only start and die sometimes, but it would also have a high idle issue and shut off when coming to a stop. I replaced the IACV, EGR, and TPS and calibrated the mechanical screw that controls the butterfly opening and after much calibration the car is now like new! Starts right up every time and i have yet to have any issue! The tps on these cars does alot for the computer and if it isnt working correctly then the other sensors and valves that rely on it wont function correctly either. IN the end i think i only needed to change my TPS, but since i already bought the other parts first since they are cheaper i decided not to return them and just keep them, hope this helps. Also check for vacuum leaks on the air tube elbow, this can cause havoc too!

 

Awesome, guys !
Your insight has given me some things to look into. I will report back

Thanks
Todd
95 xj6

 

Thanks dudes for your replies, I appreciate that
I am looking forward to seeing good news Crosst

 

So, did you solve the problem? If so, what was the solution?

 

Thanks guys, time to have a look at this car again since I'm now back from holiday. I think I will start off taking the EGR valve off and clean it up, and probably won't look at replacing the TPS since it is a $400 item

The plugs were replaced right away when this problem started

Thanks
Todd
99 xj6