Oh wow, I forgot about the shake (whole point of thread, duh). lol

When I started the car it had just been reset, so it always runs funny until the computer learns idle. I didn't really think about it. I did all the test driving after that first start-up. I guess I'll find out the next time I start the car whether or not the shake has been eliminated.

My wife and I have a date-night tonight. I'll report afterwards... about the CAR that is, not the date.

 

So I didn't notice a terrible shake when I started the car. Does it run as smooth as it does at operating temperature? No. Was it all jumpy like before? No. But, that's one start up. Well, two because when we left to come home it started up pretty smooth. But, it was still pretty warm.

The trims still do unpleasant stuff when coasting. I sprayed the EGR valve with ether when I got home and it still spikes negative fuel trims if I hit it just right. I guess eventually I'm in the market for a new EGR valve. I already have all new gaskets in a box on my shelf. I just have to come up with $250 in disposable income.

If anyone has a high quality used one they'd like to sell pretty cheap, PM me.

 

The only thing I can figure is that the valve closes when 12V is applied. According to the EMS manual, the valve is controlled by a pulsed signal (similar to the signals that control the fuel injectors).

Otherwise, great news, Jeff!!!

Cheers,

Don

 

Newest development:

I removed the EGR valve again. I tried to see if the unit would hold a vacuum, it will not. I did a smoke test on just the valve; it leaks out of the electrical connection! Inside the electrical connection all around the base of the prongs smoke pours out.

Don't know what to make of that....

 

The only openings inside the electrical connection are right around the prongs themselves. The plug goes in flush to the bottom so I'm at a loss as to how to seal those prong holes.

Forgive the fuzzy picture, but you can see I have to somehow seal those openings without compromising the electrical prong itself and still allowing the plug to slide all the way flush into the connector receptacle.

I started to use a pick with RTV on the tip. It just didn't seem to work without gunking everything up inside.

Buying a new one is just not an option right now.

 

does the egr block off route not appeal to you?

you might try plugging the whole thing together
then wrapping the two connectors in self sealing
tape. don't forget that the smoke will also push
past the harness connector to the entry point of
the wires to the connector.

 

Jeff,

Is there a rubber seal inside the electrical connector around the pins? If so, could you use a pick or needle to pry the seal out, inject some RTV sealant as far down the terminal pins as you can, replace the seal to push the RTV further down the pins and hopefully seal all the openings, then use Q-tip swabs (cotton buds to our U.K. friends) to clean any residual RTV off the pins?

Just thinking out loud.

Cheers,

Don

 

I tried working some RTV in there, but when I smoke tested it again it made very little difference.

I tried the self-sealing tape like plums recommended, I have always liked that stuff. I wrapped from the EGR valve all the way down to the sheathed line from the engine harness. It appeared to make a perfect seal over the electrical connection, I was very optimistic.

Same fuel trims, in fact they seem slightly worse. I sprayed carb cleaner on the body of the EGR and still got a negative trim spike. That valve is hopelessly leaky. What a complete waste of time today was...

 

Ok, so I broke my own rule. I'm going outside of my discretionary car budget. I ordered the new EGR valve.

I will update at the end of the week after it has arrived and been installed.

Thanks for your patience guys...

 

I installed a new Denso EGR valve yesterday morning. I have removed mine so many times that from hood up to hood down was only a little over an hour. Not bad for an amateur.

Sixty mile round trip to work with absolutely no change in fuel trims. They are identical to the readings from the day before, with the old EGR valve.

I decided to just live with it. Then, on the way home I had a restricted performance code and had to pull over. The only pending code was P1121 and when I restarted the car it ran and drove fine.

I will re-check all of my connections, but a failing TPS would also explain my idle issues. Maybe this fault code is a blessing in disguise?

 

That really sucks dude. I'm not second guessing you here, I just want to make sure since it's easy to skip stuff when you've done a million times You did a hard reset, and let the engine idle for the x minutes required to establish accurate new idle lt trims, and then again at 1500 rpm? (I don't remember the precise amount since it's been a while the I messed with this stuff)

Does the carb cleaner still raise the idle?

Idle and start quality?

 

Hard reset and 10 minute idle, yes.

I drove at sustained 1,500 and 2,000 rpm speeds, but didn't do that at idle.

Carb cleaner is like before. I can spray like crazy and see no change, but about 1 out of 25 times I spray the EGR valve it will go crazy negative. I can spray the same spot again 10 seconds later and... nothing.

Car starts great, and stumble is mild before it smooths out but it is still there. Honestly the small stumble and slightly irregular fuel trims have both improved enough that I am happy to live with them, now I just have to address the P1121 issue.

I turned off the cruise control and have had no more problems with the P1121. I miss my cruise control though....

 

I tried to do some more diagnosing today. I cleaned all three of the electrical connections to the throttle body and I loosened my throttle cable just a 1/4 turn (it was a bit too tight). When I started it back up the fuel trims were awful! I slowly traced every possible leaking point and sprayed cab cleaner with my live fuel trim readings in my hand. NO leaks. Everything is tight, even the EGR valve.

I discovered that the car randomly goes bottom-out negative for a few seconds every now and then. What I thought was a random EGR leak was, I think, just a coincidence. If I watch the trims while it's idling long enough it eventually drops to -25 or more for 10 to 20 seconds and then goes back up. It does this all on it's own.

I switched the MAF out with my loaner again and the readings are identical. I bent the pins in the MAF up a little, then down a little...no change. I thoroughly cleaned the MAF connector from the wiring harness, no change.

Now, after two hours of diagnostic work, the trims are almost twice as bad as they were and I have no idea what's going on.

I drove to Walmart to return a garden hose that I just bought and only used twice because the plastic connector broke (buying from Lowes from now on) and during the drive it hesitated once during acceleration from a stop. It idled poorly sometimes and smoothly sometimes. It goes from good trims to bad trims, back and forth. No codes anymore though, just running a bit poorly.

I've spent $400 on an EGR valve and purge valve, plus gaskets, with no real improvement. I've been told I'm getting a company car in a couple of weeks. If that happens I may have to seriously contemplate selling the XJR. I love it, but until I retire I just don't know if I have the time to maintain it.

My next reflex would be the throttle body re-build, but I just can't look my family in the face right now and say I'm spending more money on the XJR. If I keep the car (which I really want to do) I'll consider sending the throttle body off sometime in late September for re-build and drive it as little as possible between now and then. The car has so much that is RIGHT about it. The transmission and brakes are flawless, the engine is very strong except for the sporadic fuel/air issues. The fuel pumps are new, the front adaptive shocks and mounts are new...it's so close to being perfect! But, it seems that last mile is the longest...

 

I used the cheaper aftermarket valve cover gaskets a few months ago. I have read on here that the brand I bought has proven problematic.

My question:

Is it possible that all this time it has been a valve cover leak that is variable and intermittent? A leak that does not show up with carb cleaner at idle and also does not show up under a positive pressure smoke test?

Thanks in advance...

 

When it's running/idling right then crack the oil cap loose and see if it reacts like it does when it's running wrong.

 

Or, pull up the dip stick. Either way, you will be able to tell if it is leak if there is no change.

 

Thanks for continuing to follow this guys.

I spent a couple more hours (3 actually) attempting to diagnose today. I already had the intake and all off when I saw your posts, but here's what all I did.

I closed off the throttle body and the full load breather opening and did a higher pressure smoke test attempting to eliminate anything but the intake components. I kept blowing the plastic wrap off of the throttle body, but I finally used enough rubber bands and got everything to stay on. Absolutely nothing is leaking. At the highest pressure (the plastic on the throttle body was blowing up like a balloon) the only thing that would leak at all was the dipstick tube. I went to the store and bought a new O-ring for it, even though I doubt the vacuum is ever strong enough to over come the O-ring that was already there. However, after I put on the new O-ring it would not leak at ALL, ANYWHERE. Not even the dipstick tube.

I put the intake back on and tested again. Slight smoke where the plastic intake mounts on the rubber gasket to the throttle body, again with high pressure. I used some self sealing silicone tape and improved the seal at the throttle body; no more leak there. The freaking car is tight!

Started it all back up, LTFT = +12 on bank 1 and +19 on bank 2... even after yet another hard reset and extended idle. STFT stay around 0. It was the same before and after the reset. Went through another full can of carb cleaner.... nothing is leaking.

When I drive the car under load the trims are pretty good, all between 0 and +9. When I accelerate they all go close to zero. When I coast the STFT either skyrocked to +12 to +22 or the dive to -25 to -40. No rhyme or reason. Sometimes they go up, sometimes they go down.

It's like there is a leak that is there most of the time but occasionally it goes away all together. If I drove in stop-and-go traffic long enough I think I would probably get a lean code. If I drive at 75 to 80 miles per hour all my trims are between 0 and +5.

There is absolutely no smoke at start-up. There is no trace of oil in the coolant and no trace of coolant in the oil. The coolant temperature is always between 187 F and 199 F. This is a 2003 so I can hopefully rule out a head gasket problem.

 

In addition, I just removed the intake and sealed both ends for a smoke test. The plastic intake assembly does not leak either, at all.

 

Although I agree that your symptoms are still pointing to a vacuum leak, did you consider that the cause of the problem might be something completely different?
You did sooo much to eliminate leaks, it almost can't be causing this any more, otherwise each and every one of us should have the same problems.

Your description of the regular bottom-out should make me take a step back and consider other causes (fuel supply, injectors, ECU, whatever).
Just a thought.

 

Eric my friend, I agree that thinking outside the box (air box in this case) is called for.

I will keep an open mind certainly. I checked the fuel pressure a few weeks ago and it was fine, both pumps and the filter are new. That doesn't mean something didn't happen in the interim though. Perhaps I should check the fuel pressure again. I have run two cans of BG 44k through the engine in the last 5 weeks or so, plus a can of seafoam and a can of techron. None of those treatments were consecutive, just spread out over several weeks.

Tonight I hooked up a vacuum gauge and got 18" HG at idle, which I think is pretty normal?

I also noticed it was pretty low on gas and I have to be at work in the morning, so I went to fill the tank. I chose a station with Amoco premium rather than the Sheetz premium I usually buy (because it's convenient). The car runs very good and is VERY fast, it doesn't act like there is a problem, except for the stumbling idle which has become more common. During the drive home the trims were perfect all zeros anytime I had the throttle 1/2 way down or more. When I coast though the trims went crazy positive....at first. As I got closer to home the trims went crazy negative when I coasted. By the time I got in my garage the idle reading was about +12 LTFT and -12 STFT. I thought "great, they are canceling each other out!".

I let it idle for over ten minutes, and the LTFT never adapted. It stayed right around +12 LTFT and -12 STFT. I don't know what that means. I have a sixty mile round trip to work tomorrow, maybe the system will "learn" better values than I've been seeing today.

My fallback concern is the throttle body, since I got that p1121 code a few days ago. The code has not come back though. Does anyone know if a failing TPS would actually throw the fuel trims off at idle and coasting, but NOT under acceleration?

By the way.. I haven't said this in a very long time but I really do appreciate this forum and all of you folks who get involved with peoples threads.