First, this place rocks. I finally signed up after five years watching from the sidelines and stealing everybody’s thunder. Now I’m here to beg for help on everything I can’t figure out. Which is a lot… the following is lifted from my first post that I threw up in the new members’ section. Now it’s in the right place, I’m confident someone can understand my pain.

Here's The Big Problem: Start the motor from cold; it purrs like a kitten. Run it 20 minutes/10 miles. Park it while hot. Go to restart 10 minutes later and it shakes like San Andreas, smokes out the tailpipes, revs bog down below 500 rpm often to the point of stalling out completely. Alternatively, it'll start reasonably well; but then you push the brake, shift to reverse and the revs bottom out to the point of stalling. This now happens 50% of the time. BTW, car now has 167,000 on the odo. (Bought in 2018 w/119,000) There is no check engine light even when stalling out and only code showing on Advanced Auto's reader is (a patronizingly insulting) P1111. Yeah, right. All systems go my ***.

Note: it's only while hot that it does this. It also threatens to stall when coming to a complete stop at intersections and redights when the motor is hot. It hates multiple short trips on the same day. Driving in town is now nerve-racking. It has progressed to the point where it can't be driven further than 8-10 miles without threatening to stall at a standstill or on restarting. The most frustrating thing is that, when the car's in motion, it runs exceptionally well with great response and pep right up through the rev range. It only gets an attitude when you take your foot off the gas, cruise to a stop and sit at idle. Then it acts like it's full of unburned fuel and choking itself to death. (I can smell fuel in the cabin after each episode.) My cats must be filthy by now.

Here's some history of recent repairs/issues: 4 years ago, had transmission refurbished by ZF-experienced indy. It was floating for a heartbeat before kicking me up the butt away from standstill. 36 months ago, replaced part load breather hose (cracked) and intake mani. gasket (leaking) plus valve cover gaskets and front crank oil seal. Fuel trim dropped from +20% at idle to 5%. Noticeable rise in power/throttle response; drop in smoking at tailpipe on startup/kickdown. 24 months ago, sudden coil failure cyl 4; replaced all 4 original coils in that bank (with cheaper STI coils for government-related reasons) plus all 8 plugs (NGK Platinum). Misfire cured. Sluggishness at low rpm persisted but not too bad. Idle has always been kinda rough/vibey (Engine mounts known to be "shot" - can't afford labor to replace). This winter, battery died flat after extreme cold snap when it sat for four days. It was a decade old. Replaced with same rated battery (higher cold-cranking). 4 weeks ago, another gradual coil failure on opposite bank; replaced remaining 4 coils with STI and all 8 plugs with NGK again. Replaced fuel filter same time. Misfire cured but noted remaining sluggishness at low rpm under load. Then (after doing a full-on emergency stop to avoid T-boning yet another white Lexus) developed random misfire with no code while idling but not when driving or under load. Tore out another fistful of hair. Down to three or four fistfuls left.

2 weeks ago took it to local indy and asked him to read all current codes and check trims at idle. No f***ing codes. Trims still at 5% with closed throttle, zero vacuum issues. He asked me about coils; I told him they were all new. He said, "New don't equal good. Are they OEM?" I 'fessed up. They're STI from AutohausAZ. His opinion was it's shitty coils, given the heat-related dropout when first applying load and no other readable problems. So I bit the bullet, said so-long to a kidney and bought 8 Denso coils from SNG Barratt and another 8 NGK plugs. Fitted them four days ago. Idle misfire completely disappeared. Pickup fantastic under load. I started hunting for the fistful of hair in the footwell thinking I might still be able to save it. Then I pulled up to a redlight 15 miles away and it almost f***ing stalled out!! AAAARGH. Hot stalling problem persists and is, if anything, worse than ever.

Known remaining issues with car: EVAP purge valve seized. Has been since 2019. Advised it was "ancillary" and wouldn't affect performance. Now I'm not so sure. ABS light and traction control lights are on. I've never driven anything with ABS or trac.con. before. I don't notice their absence. I've noticed blowby oil in both full- and part-load breather hoses. It's a 24-yr-old motor with Nikasil coatings - hardly surprising it might have compression issues but never had it tested yet (can't face it). Also have the right-rear turn signal failing under braking because of poor ground issue.

Question: WTF is going on with my car? Will any of the above as-yet unfixed issues add up to a hot stalling problem? It feels electrical to me but also acts like a breathing problem at zero throttle. TPS? My indy says his computer thingy would have spotted any discrepancy between throttle angle, trim, and TPS. Should I believe him? I plan to clean part load breather and replace MAFS (cleaned regularly with CRC MAFS cleaner) as well as purge valve at earliest opportunity. What else should I try?

I'd appreciate any response from anyone who has limped this far down the freakin' page. Thanks in advance, Mark.

 

TSBs and Recalls.
Throttle bodies can cause issues.

When I worked at the dealer we used WDS or IDS to look for Throttle Failure Activation to determine faulty throttle body assys.
A failure indicated a replacement was required.

 

Motorcarman, thanks for chipping in. I know the TB was pulled and replaced years before I owned it. I've been leaning that way in my head as a mechanical/electrical cause. It's above my paygrade to diagnose, though. Back to my indy if I want that checked out.

Thanks again!

 

First, I would take a hard look at that purge valve and all of its plumbing. If/when it is stuck open, it will constantly suck fuel fumes from the charcoal canisters and dump them in the intake, making the mixture super rich, especially at idle. The purge valve is supposed to be driven on/off 1 min every 2 min I believe. Some hear that ticking sound from the driver side wheel well. To my knowledge, there are codes for purge valve-related issues. The purge valve has evolved through the years with various hoses and associated part#. Some even require additional "coding" in the ECM. Normally, the purge valve plumbing has an access point for a smoke machine to check for leaks, etc. It is typically a shrader valve with a green cap.

Not sure how likely, but fuel injectors also sometimes get stuck open. Might be worth checking on your engine oil for fuel smells. IOW, you need to get to the bottom of that fuel smell. Check the fuel rail and pressure regulator too.

I would also have a look at the ABS error. The ABS module serves as the termination point for the CAN bus. A failed circuit board (as is very common) could also crash the CAN bus. These failures are known to be temporary and the source of a lot of frustration, but there is a lot of accumulated knowledge on those in this forum. FWIW, the other end of the CAN bus is the instrument cluster, itself with its list of TSBs.

As a last resort, check the condition of the ECM itself. Maybe the circuit board has damage from leaked capacitors, etc. It is not uncommon for the earlier car, not sure if it extends to a '99 like yours.

Best of luck, keep us posted.

 

fmertz, exactly the kind of wisdom I was hoping for. The purge valve nags me, knowing it has had an issue for so long. I found a replacement low-mileage one with all associated hoses/lines for under $100. Since I already know mine to be seized (open vs. closed, I have no idea), I'm leaning towards pulling it and replacing it ASAP. It gave a CEL with attendant emissions code when it first failed. Since clearing that code years ago it never reappeared, but the problems persisted. Excess fuel vapor on a constant basis might go some way to explaining the frequent odor (saturated cats, maybe), and the fact the purge valve affects fueling at idle sounds like it’s up there on the “likely culprit” list. I often feel, when idling in D at lights, a sudden drop in revs as if something cyclical just kicked in and starved it of air/fuel for a full second. A failed purge valve actuation each drive cycle would prob. feel like that.

luckily I just transitioned to working at home. The Jag appreciates no longer commuting every day, and I finally have some time to devote to curing it.

Really appreciate your pointers! I’ll update when I have any progress.

 

once the issue gets sorted, find a way to give the car frequent and regular usage. They don’t age well when sitting unused. A seldom used X-100 develops more issues than the daily driver.

Z