Hi any help would be greatly appreciated.
Newbie member but I have read posts in the past and found they are great help. I am driving a 2001 S-type with a 3.0L engine. I have had it for a year and a half and drive 700 miles a week. The style and ride are great with this car but I am afraid it may be near its end.

A couple of weeks ago, I got an error code with lean bank 1 and 2 PO171 and 174 but also the dreaded P1587. I cleaned the throttle body and the MAF (with CRC mass air flow cleaner), the 1587 code has not returned but the lean codes return. Looking at the fuel trim codes, it appears to be an air leak. ST trim goes negative when accelerated to 2500 rpm. LT trim holding at 44%.

Engine in park idles at 1500 rpm and then drops to 700 and returns fast again.

For a long time, I have had a periodic oil burning smell but then it goes away. Getting off the highway will smell for a couple seconds at the end of the ramp. I just assumed a small leak that would have a drop onto the exhaust.

Yesterday, it really went crazy on me. I drove about 20 miles and stopped for gas. When I left, it would not accelerate past 10MPH. After a short time of starting and stopping engine worked fine. Then it acted a little strange on the highway, so I pulled off. it did the same thing again. I ended up having to drive about a mile at 10 MPH on a 55MPH road at rush hour. It would periodically stutter but would keep going. Again after clearing codes, and restarting a few times, it drove again. I drove home at up to 75 MPH without a problem.

I can hear a significant hiss coming from the rear center of the engine.

As far as I can tell none of the hoses are cracked.

Based on this, I was suspicious of the IMT leaking. I checked by spraying them with carb cleaner and cannot tell a difference in engine running. I then tried spraying down all the likely spots and could not detect a change.

I switched to a water bottle (hot engine) and repeated the attempts. There may be a problem at the upper manifold for cylinder 3 (passenger side closest to firewall) but it was not obvious. It seemed to choke down a little but tough to say. Tried carb cleaner there and again only a slight change. Hard to tell with engine revving up and down on its own in idle.

I can replace the upper intake gaskets and IMT gaskets but I don't want to take the engine apart only to find it is something more drastic.

I replaced the battery when I got the car and have not had any issues with it.

It needs a few other things too so if throttle body, intakes, tires, and possible suspension are all needed I think it becomes cost prohibitive to fix it.

Any ideas on how to debug this one???

thanks again

 

Firstly welcome to the forum. Plese do an intro in the "New members area" when time permits.

Under the LOWER inlet manifold is a 90deg vent hose, the split, they are a PITA to change. They "hiss" and the idle is crap, the trims are crap, due to "unmetered air" entering the system.

At the very rear of the engine, LH side, is a rubber elbow thingy, and that splits also.

Mine did that, both of them, so I blocked off the vac source.

Car LUVS me again.

PLEASE note, this is not permitted in some markets, your car your choice. I will sort this on both my cars when I get a 2 day stretch where the arthritis is not so savage, untill then, it stays as it is.

The snap shows the blanking cap on the throttle body vac spigot, with my finger pointing out for those unfamiliar with my words.

 

Your V-6 has a list of very well know problems. No need to get rid of the car but you do need to do some maintenance.

At this point you should plan.
Replace coils, plugs , vacuum lines, vacuum elbows , leaking IMT O-rings and this will require removing the intake manifold so the best idea is to just do it all at once.

The good thing is all of this is not very expensive and we have several GREAT write ups on how to do it. So you can fix this yourself without too much effort. It will be expensive if done at a commercial shop.

So do all of the above before messing with replacing the throttle body. That's a bit expensive!

Please think about getting the transmission serviced too. The fluid is not life time.
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Thanks to Mr. Grant Francis, I had not thought of plugging the ports. If nothing else, it will be a great way to debug exactly where the problem is located. I can plug one at a time to see if the hissing and/or lean codes go away. That way I can do a short term and a long term fix.

Clubairth1, those sound like excellent ideas. thank you. I really don't want to keep throwing money at it until I am confident of a solution. Those ideas should not be too bad. The vacuum lines seemed a little pricey. I did a quick search and it looked like about two hundred dollars off PartsGeek. I saw some cheap coils for $50 off Amazon. I will research the site to see if the cheap ones work on Jags.

Has anyone every experienced the maximum 10MPH issue? I do not think it is the throttle body losing the TPS sensor as the engine would rev up to 2500 rpm. That speed limit plus the clunking has scared me into thinking a trans or rear axle issue.

 

Motorman, the following link is what you need to repair your vehicle. Please pay close attention to the "jagrepair" link in the first paragraph. Fellow member Gus has graciously provided a detailed and pictured DIY on the elbow under the lower intake manifold that is your problem! You cannot see it without removing the plenum and lower intake.

I repeat do not concern yourself with anything else until you replace the rubber elbow, that is your problem. Very well documented here on this site. You might want to drop the $200.00 on the assorted vacuum lines as well. They are very brittle at this point. I know I would just as good insurance.

Follow this link: https://www.jaguarforums.com/forum/s...ics-faq-52720/

 

I had a delay doing the repairs. It ended up not being too bad a job. I will post a more detailed explanation with photos. I replaced the IMT oring seals, the plugs, the infamous elbow and another vacuum connection on the back of the engine, as well as both the intake gaskets and a valve cover gasket. It seems to have fixed everything, I have driven about 1000 miles.