1996 3.5L Vision TSI (LH) - Occassional Hard Starting

Enlist a helper to stand at the back of the car and watch the exhaust pipe as you try to start it. (perhaps, since the pipe is on the driver's side, you can hang out the driver's door and watch the pipe while you crank the engine).

If you see black smoke in any amount when the engine finally catches and as it's running rough, suspect one or more leaky fuel injectors.

Your fuel delivery system is fine at least up to the fuel rail, unless you have high-speed/high-load running problems you haven't mentioned. Even a filthy fuel filter and/or weak fuel pump will usually supply enough fuel to start and idle the engine. When fuel demand goes up, *that's* when the a substandard pump or partly clogged filter show themselves.

Not only do you have extended crank times, but also rough running once it does start. A bad fuel pump outlet check valve (for instance) that would cause the pressure to drain down would cause extended crank times but not the rough running.

On the other hand, if the system's pressure is draining down through a few leaky fuel injectors, all that raw gas would be in the cylinders -- you'd have your extended crank time to repressurize the system, your extended crank time to clear the overly-rich mixture out of the cylinders, and your rough running thereafter. Another test you can do: Next time it gets cranky, push the accelerator about halfway down while continuing to crank; see if that shortens the crank time.

If a crank or cam sensor is getting wonky, or the MAP sensor is headed South, this can also cause these kinds of problems, often without setting a code. An easy check for the MAP sensor is simply to unplug it. The computer will then not see it and will substitute fixed values. If the black-smoke test is negative, you might try this to see if the car starts more easily.

-Stern

Dan,

Thanks for the thoughts and suggestions here. Your note leads me in a different direction than I was originally leaning (fuel delivery) and is exactly why I posted my request for other ideas.

The fact that this only happens occasionally (maybe 1 in 50-60 starts and generally when I am not driving it), requires the vehicle to have been sitting for some time unused, and is not repeatable with any frequency makes it difficult to diagnose. Nonetheless, I will do my best to try to have someone else watch the exhaust or turn the key for me so I can see what is happening at the exhaust myself.

I'll also keep in mind that it could be a sensor and that I can try to unplug the MAP sensor but once again, the unpredictability makes this difficult to do much here. Based on what you've said, I am now leaning towards leaking fuel injector(s). Let's hope I can confirm this by visual examination of the exhaust. That said, is there any way to easily diagnose which one(s) are leaking or is a total replacement of all 6 the best approach given the vehicle mileage and the cost of diagnosis by a good mechanic?

Bob

You can pull the whole fuel rail assembly and leave it connected to the fuel supply, put a twist of paper towel around the bottom of each injector and a plastic bag over that, leave it sit for awhile and then remove and see which paper twists smell of fuel...donno how "easy" that is...

Dan,

Sounds like a plan. I'll try to remember to post the outcome when I get around to looking at this. As I indicated, it happens infrequently and is basically an annoyance, but I would like to fix this before winter cause I expect it might become a real problem then.

Bob

Bob, On my 94' LHS there was one time that it wouldn't start at all. It was the crank position sensor. That sensor supplies all timing to the rest of the system and won't set a code when it is acting up.

Steve m..

My granddaughters '97 Intrepid ES has the 3.5 but it has 2 throttle bodies on it..so I don't have a clue how you would check the injectors ..Did those early 3.5's come with port injection?

Occasionally she used to experience this problem, but DS recommended turning the key off and on for some one else on a different vehicle to troubleshoot a problem and this "cured" her trouble completely, we have not pursued the problem further as this has worked so well,, it is just a habit now,, key on wait for the pump to stop,, key off, key on wait again, then crank.. Lights up instantly.. She doesn't use the vehicle much anymore and will wait for the real problem to manifest itself and fix it then.

DS also stated you can only do this twice in so many seconds,, he said there is some kind of timer in the circuit that only lets you do it so often in so much time...unfortunately I didn't save the post so I don't know how much time. I learned my lesson and save the stuff that has good info in it now.

Overall once we got the intake manifold gasket and water pump taken care of, this engine has been just about as bullet proof as you can get... 125000 and counting smooth and very powerful for it's size.

Don't mention tie rods though,, ..... anyone know if there is a "permanent" fix for these out there..?? On the 4th set, well 3rd not counting the original.. {:-(

Thanks

Ted

Ted,

Thanks. Sounds like your granddaughter's vehicle may have a bad check valve in the fuel pump. This is initially what I thought my problem may be as well before Dan pointed out the rough idle after it finally started most likely being due to raw gasoline leaking from my injectors into the cylinders/combustion chambers.

I've done the water pump and timing belt thing twice on this vehicle already. The second time was not really the water pump, but was due to corrosion around the O-ring in the water pump housing that bolts to the engine block.

I've had no problems with the intake gasket.

I've replaced one set of tie rods and the infamous sway bar links as well so can relate to your comments here as well. I wish they had placed grease fittings on the front end since this would probably have lasted a lot longer.

Otherwise, I can't complain as it still drives like it did when it was new. I'm preparing to hand it down to my oldest son so want to get everything squared away before then so he does not have any problems.

Bob

troubleshoot

"permanent"

Steve M,

Thanks for the reply. I presume your crank sensor failing caused a "hard" failure. That is, the vehicle would not start at all once this sensor failed. This is not the case with my vehicle since it starts normally the majority of the time and only occasionally exhibits this "rough start" condition. Even after it does happen, it might be a week or a month before it reoccurs. I just have not really noticed any pattern to it other than the engine has not been running for a period of many hours. I've had it happen when the weather was sub-zero and most recently when the temperature is in the mid-80's.

Bob

All the '93-'97 3.5s had the same induction system.

Well, no, this isn't a "cure". All you're doing there is pressure-priming the system (which in your case is probably leaking down via a bad fuel pump outlet check valve) so that the engine will start quickly. Nothing really wrong with it, won't hurt anything, but it hasn't cured the problem. I sometimes use the same "double prime" technique on my '89 D100 in cold weather. Sort of the modern equivalent of giving the accelerator two pumps instead of one before initially cranking the engine. Also don't think the on-off-on-off-on deal will get you diagnostic codes on your '97 as it will on earlier cars, but I could be wrong about that.

Again, you won't hurt anything, but the fuel pump will only run twice on initial key-on within a certain time period, so additional key flicks won't do anything.

-Stern

Assuming the same OBD-II diagnostics were in place on '97s as they were in my '96, the keycode method does work.

--Geoff

For future reference, the really good news is that you don't have to save *anything* posted here, and yet you will always be able to find it.

This and several thousand other news groups are archived on Google for posterity. Go to google and hit the "Groups" link just above the key word box. Then drill down to find the particular group that you want to search (in this case rec.autos.makes.chrysler). Then type in some keywords that you remember from a previous post or thread, or that you suspect might be in a thread that you're not even sure exists on the subject of interest. Then check the box that says "Search only in rec.autos.makers.chrysler" (or whatever ng you identifed), and hit "Search". Notice that you don't have to search a particular group - once you hit "Groups" and some keywords, and check the box to "Search only in...", it will search any or all groups that you have narrowed it down to (i.e., if you only drill down to the "rec." part, it will search all ng's that start with "rec."; if you don't drill down at all within groups, it will check *all* groups for those key words).

Notice that after a search is performed, you can tell it to sort what it found by date (upper right). And when you click on a particular found post, you can tell it to show the whole thread (again - upper right of window).

You can also hit the "Advanced Groups Search" to narrow the search down to dates (anytime, within the last 24 hours, week, month, 3 weeks, 6 months, or between...and...), specific author, and/or more complex key word combinations.

Anyway - take a look at the archives search on Google, play around with it, and you'll figure it out. Comes in *very* handy when you know an answer to a certain problem was given but you can't remember what that answer was. Takes the pain out of having to decide what to save to your hard drive and what not to - because the answer is: Don't save anything

- *always* go to Google.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Thanks,,, this is the "one" I will save then !!!

I had a bad crank sensor on my wife's 93 3.5 that was intermittent before failing hard. It would "stumble" at highway speed, and would stall at idle.

Weirdness at starting sounds more like a fuel injector (or lower O-ring more likely) leak, or just a drain-down of fuel system pressure. You might try cycling the ignition 3-4 times (spaced apart by about 2 seconds) to cause the fuel pump to run longer than its normal one burst of operation prior to cranking, just to see if its a loss of pressure. (Or better yet, use a fuel pressure guage.... ;-)