98 3.8L Hard starting when hot

[bkimbel]

My 1998 Windstar has 252,000 miles, and within the past year has developed a problem starting when the engine is hot.

For example, when I start the car in the morning - no problem. Drive 8-9 miles to work, and no problem again. Shutdown and let it cool all day, again no problem when I start in the evening. If I stop on the way home, shut down for 15-20 minutes, then restart, the engine runs very rough, and sometimes stalls. Once I get it running and moving, it will smooth out and run normally, and will continue to run normally until the next time I stop for 15-20 minutes while the engine is hot.

Any thoughts?

Bill Kimbel
Tallahassee, FL

[12Ounce]

Under the hood, where things get hot, are the relays for the power train. I would replace the "PCM power" and "fuel pump" relays as starters.

Then check fuel pressure duing a no-start event ... fuel pump may be failing.

[bkimbel]

I will check the relays - appreciate the tip.

I saw a Chevy response that suggested the rough start was due to the fuel regulator allowing a load of fuel in the cylinders which evaporates as the engine cools down. No big puff of smoke, but I do see a fair amount of soot in the tailpipe.

Is your suggestion about too much fuel during the restart, or too little?

Bill Kimbel
Tallahassee, FL

[12Ounce]

Too little ....

You could easily check the fuel pressure at the fuel rail Schraeder valve. A shop rag wrapped around a small screwdriver will do the trick ... just be careful!!!! Expect quite a "squirt" even with the engine "off".....

The pressure regulator is also a possibility ... but after the relays on my list.

[bkimbel]

This relates to my 1998 Windstar with (now) 280,000 miles.

Sorry for the delay. I was also reading a thread about Warm or Hot Soak Start, and took some ideas to my mechanic for investigation.

He agrees there is a lean condition, but so far, cannot identify it.

As I was reading the other threads, there was a pointer to the IMRC issue, and we worked that and found a one with a defective diaphragm, so both were replaced, and found some vacuum leaks which were repaired by replacing the tubing all the way from the PCV valve to the intake manifold.

I've also replaced all of the plugs and wires, the fuel cap, fuel pump, and MAF, and cleaned the IAC and Air Temp Sensor. The pressure on the fuel rail is constant after turning off the engine for at least a half hour, so no indication of bleed down through a dirty injector. The EGR ports have been cleaned. The front oxygen (O2) sensors in the exhaust pipes have been replaced (Just because - no CEL there, either).

SO NOW! The Warm/Hot Soak problem continues at a lower level, and with the improved vacuum situation, I'm starting to see (or maybe just notice) a couple of new symptoms:

1. The shift from 1 to 2 is what my transmission mechanic has characterized as a "Slide - Thump". It's a hard shift with a bit of a slippage just before the shift. He is the guy who rebuilt the transmissikon at 235,000, and thinks there is a spring that can be replaced with a lighter spring to control the shift. I can soft pedal during the shift and it isn't as harsh. He will be investigating that in the coming weeks.

2. When driving along the interstate at around 70 MPH with the cruise engaged, or on manual with a light throttle, as I start up a rolling hill, I will feel a series of thumps, that sometimes feel like misses, but no CEL is illuminated. Looking at the Scan Gauge II, I see the RPMs jump up by 100-200 RPM, then settle back and repeat. This is at around 2100-2250 RPM, and is to be discussed as well at the transmission place.

3. In my neighborhood, when going up a hill, RPMs are around 1000-1200, and I get the same sensation. Easing up on the accelerator doesn't make it stop bobbling, but stepping on it will. It almost feels like it is locked in too high a gear, and the engine is lugging. Easing down on the gas causes a downshift and the thumps stop, but then I'm going too fast for the neighborhood.

4. When using a drive through carwash, I sometimes get a P0302 code which points at a sparkplug or wire or an ignition coil, but I can clear the code with the ScanGauge II immediately after I exit the carwash. The ignition coils are original.

So what's the bottom line? My interim goal is to go to 300,000 miles and beyond, if possible, but I'm not sure what is causing the engine bobbling, or the hard shifting. Is there a pointer to one or more items that could cause all of these problems?

Thanks for the guidance!

Bill Kimbel

[tempfixit]

Bill has the camshaft sensor and snycronizer every inspected or changed?? Could it be that the syncronizer is a little sloopy and causing a out of timing under load???

Just a thought

[12Ounce]

I reads as though you are getting an intermittent miss-fire. I would pull the plugs and inspect to see if any show oil or other indications of miss-fire. While the plugs are out I would conduct a compression test to see if any valve-burning is evident.

If the compression on all cyls is "even" ... I would be suspicious of some spark issue. The coil, the crank pos sensor, the cam pos sensor, etc, etc...

[bkimbel]

Is the inspection of the camshaft sensor and crank sensor a simple thing?

Also, based on work I did with a 69 Mustang, are the cam and crank syncronized together with a timing belt? And could that be a culprit at 280,000 miles?

[12Ounce]

Any of these sensors can act up when aged, especially the crank sensor which is low to the ground and catches a lot of stuff off the roadway.

[bkimbel]

More Data - IAC re-cleaned - better drivability...

I followed the procedure for cleaning the Idle Air Control by removing the IAC, hosing out the loose debris with WD-40, then up ending the IAC and filling the two holes with WD-40.

After 15 minutes, I drained out the remaing WD-40, and used a brush to rub all of the available surfaces.

After that, I rinsed the IAC again with WD-40, then swabbed it out with the corner of a shop towel, rinsed it again, shook out all of the loose WD-40. and let it drain into a shop towel for about another 15 minutes, then reassembled it to the engine.

It "feels" better when I drive it!

Fewer bobbles, but still some. The first couple of days were fairly cool, and no warm soak episodes or issues, but then yesterday, I did have some more hard starting, but it cleared fairly fast.

Question on the IAC - If cleaning it makes a positive change (subjectively), is this an indication that I should replace the IAC with a new one?

Regards,

Bill

[12Ounce]

Yes, its an "indication" ... but not much else. The IAC could be trying to compensate for something else totally. Too pricey just to experiment with a new one.

[bkimbel]

Electro-mechanical items that can be cleaned are great, but I'm always suspicious of things that can fail at a high mileage, like my fuel pump did.

What are the symptoms of an IAC with a problem? When will I know for sure that it needs replacement?

[scubacat]

I don't know if this is morally sound or not but if I'm being honest, I'd pick one up at an auto parts store and just try it. If the problem persists, simply return it.

[perrytime]

I tried most everything to try and fix a hot soak, rough idle issue. the one thing that would smooth out the idle was pulling the vacuum from the fuel pressure regulator. So I purchased a solenoid and electronic timer used on alarm systems mainly. So now on every start, my FPR has vacuum bled off for 90 seconds, then returns to normal operation. So far it has been a couple years and still no issues hot soak and rough idle. for less $30 in parts i am happy, wish I could have fixed root cause, but I had spend hundreds and lots of hours trying to fix it.

[bkimbel]

Update on the saga. I'm now at 282,600 miles. I ordered a new IAC valve and installed it, then went on a 400 (or so) mile trip over the weekend.

The bobbles/surges seem to have settled down to being gone after 900 total miles post replacement, but this is also in some cooler weather.

I still have the hard 1 > 2 shifting and the hot soak misfires when starting.

This post from Perryman is the first glimmer of hope. Is there a parts list and instructions for the following fix available?

Also, did you try replacing the fuel pressure regulator?

"Perryman: I tried most everything to try and fix a hot soak, rough idle issue. the one thing that would smooth out the idle was pulling the vacuum from the fuel pressure regulator. So I purchased a solenoid and electronic timer used on alarm systems mainly. So now on every start, my FPR has vacuum bled off for 90 seconds, then returns to normal operation. "