Hello again, friends. Searched and found a few mildly similar issues, but nothing exactly like what I'm experiencing.

Here's the dealio: When my 99 TL (160K miles) sits overnight, it takes maybe 3-4 seconds of cranking the ignition before it will turn over. The cranking of the engine is good and strong (Interstate 72 month battery with 12 months on it/H2O levels good), but the engine is noticeably slow to engage. When it does finally engage, it revs to nearly 3000 rpm (no foot on accelerator) and slows to idle at about 1500 rpm like you would expect a cold engine to do. The actual temp outside is not a factor, but the car sitting overnight is. After the first start of the day, all subsequent starts are without effort, even if it sits for 6 - 8 hours.

It's not throwing any codes. I have had a intermittent P0420, but that was diagnosed as the cat and not the downstream O2 sensor. Living in Indiana allows me to ignore that for the time being. The only notable event was that the symptom began maybe 100 miles after Seafoaming the fuel tank only (1 can: 8 gals @ 93 octane). Nothing other than some suspension/drivetrain work done recently. EGR ports and TB cleaned 20K miles ago. NGK Iridium plugs about 30K miles ago. Doesn't seem to me to be a charging issue as the cranking is strong.

Ideas?

 

Hey Mrcombs, as you already probably know.....'99 TL's had problems with their ignition switches going bad. Also, is your immobilizer light flashing when attempting to start ? You may want to have the electrical charging system load tested at a local parts store. There's also a possibility that a relay or the fuel regulator may be on the edge.

The 3000 rpm revving is a concern at start-up......is it really getting cold overnight ?.... maybe a sensor or the idle speed control valve ? Is the P0420 code the only one coming up with the CEL ? Clear it and recheck on a cold morning when experiencing the problem.

 

3.2 - I'm not sure about the immobilizer light. I'll check on that. The outside temp doesn't seem relevant as it behaves the same whether it's 75 degrees or 40 degrees overnight. The P0420 is the only code and I reset it a couple hundred miles ago with the clock fuse to see if I could get something new to pop up. Nothing. The P0420 shows up from time-to-time, but I'm assured it is the cat by 2 separate diagnostics I trust. I'll do a load test again, but I just replaced the battery 12 months ago. Maybe it's got a bad cell. Seems to me if the charging system were at fault, it would labor to crank. With the revving, it's almost like it's injecting too much fuel before it finally ignites. Does that make sense?

If the immobilizer light is flashing, what does that tell you? Ignition switch or replace the immobilizer?

 

means its working!

how was the cat diagnosed, flow rate? temp? pressure?
it doesnt matter where you live- a bad cat effects how the engine runs
say its clogged- so there is excess backpressure = bad things happen upstream!

charging may be suspect--never hurts to test system live
its not H2o in the batt= or you have real problems!

cleaned throttle body and IACV = idle air control valve- inside bottem of TB assembly?
very likely suspects
my 01 cold idles about 1200 for a short time then 1000 and drive off
yours normally is 1500? wow

ck PCV valve just to make sure it works fully, source of many recent problems

 

As always, thanks for the tips. I wasn't aware the cat effected starting and engine performance. Everything I've been told by master techs is that not replacing it only effects the content of emissions - "Bottom line is that you'll kill maybe one more tree per year," they say. Indiana doesn't require annual emissions inspection, so I held off. Seems odd that they would pass up a chance to sell me a repair. Don't know whether I'm comforted by that or not.

The only time the immobilizer is flasing is when the ignition is turned to the off position. I know this is normal behavior.

I'll dig into the rest of these suspects and report back. Thanks

 

when the cat is bad the rear sensor constantly tells the ecu something is wrong, which alters the fuel profile and timing to try and fix it

ck with our sponsor josh at exelerate he is the cat master provider
any price and performance range you want

 

Aside from the battery, plugs etc.. It may be a fuel pressure regulator issue. The injectors may not be getting the required pressure right away.

 

isnt that a bit of a stretch Kris? FP regulator failure?
what do you suggest--seafoam the gas to clean lines and injectors??

was it the FP relay on some cars with hard hot start a few months ago?

 

Turned out not to be a zebra after all... faulty battery. Sorry, I should have checked out the no-brainer stuff before sounding the alarm. These Interstate batteries are supposed to be the moneyball, but this is the second "75-month-er" I've had to replace in less than 40 months. ~sigh~

 

I had the same issue battery means its on its way out my did the same.thing slow crank in the morning good after driven

 

Maybe your alternator is next ?

 

That's what I was thinking, but the Interstate battery dudes say the rest of the charging system checked out a-okay. I gave 'em every chance to blame their product's poor performance on bad cables, dying alternator or some other issue, but they assured me it was just the battery... again. Go figure.

 

Our TL's do require their fair share of power to support all of the added features.
It's good to know that they stand behind the product with no pressure !