3.8L Starting Issue

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3.8L Starting Issue

October 29, 2007, 03:09:07 PM

Hello,

I'm new to this forum, but have been lurking on occasion...seems to be a lot of knowledgable people on here! I went through the previous posts and did not find a question such as mine, so here goes:

I have a '87 Cougar with 3.8L V6 (CFI). Engine short block (rebuilt) has about 120K on it, the rest of the car has 204K. Recently, upon start-up, it no longer goes on high idle. This happened pretty much all-of-a-sudden. However, it does seem to correlate (quite well) with our recent weather change (days in the lo 60s, nights in the upper 30s). Coincidence??? My car stays garaged (unheated, but attached) at night, but sits out during the day at work.

The engine fires off right away just fine, but then desn't ever go into a higher speed...although, it generally won't stall, just slowly gets going. I've looked at the exhaust right after I start it, and the engine does not appear to be loading up (no black exhaust). And after a minute or two, it runs good. I have noticed a bit more of a rough idle at all times, however.

I admit to not having done a lot of underhood checking, but since this happened all-of-a-sudden, I'm wondering what failed quickly? No, I've not tried to pull any codes off, yet.

I have a set of new plugs that I need to install (there's a set of Bosch Platinums in with about 90K miles), the cap and rotor are about a year old, and plug wires were replaced with the Bosch plugs a while ago.

I tend to think this is something other than just tune-up items, but thought I'd give as much info as I can think of up front for you all to ponder...

Oh, the engine has always run better with the EGR vacuum line disconnected, so I have that line plugged off and a cap on the EGR valve side.

Isn't there some sort of barometric or ambient temperature sensor on these cars? Could that be malfunctioning?

Thanks in advance!

Greg

3.8L Starting Issue

Reply #1 – October 29, 2007, 03:12:57 PM

Quote from: bike70ride;185234

No, I've not tried to pull any codes off, yet.

Let me know when you do...

3.8L Starting Issue

Reply #2 – October 31, 2007, 06:38:03 AM

The idle control motor assembly is on the driver side front of the CFI. When you start up the engine, the plunger is suppose to extend out a certain amount,, engine warms on high idle, then the idle speed motor control plunger retracts and allows the trottle linkage to come at full rest there abouts.

The 4 wire connector for the ISC is within 5 inches away , inspect that connector. Turn on your key and fiddle around with it and you should hear a funny noise form the ISC if there is an intermittant connection. If you have never touched its adjustment, thats great, just leave it alone cause its likely right where it should be.

The motor itself is just a two wire assembly where the windings appear at the eec (yellow/black and white/light blue). The motor will rotate cw and ccw based fully on the eec deciding the polairity reverse or forward.
Furthermore, the direction in which the motor turns to extend the plunger or retract the plunger is governed by the second two wires connected to the idle tracking switch inside the ISC (black white from the MAP sensor and light green/white to the eec).

so,,,,,if the map sensor is not sending a signal (black white) to the idle tracking switch to the eec (light green/white), the the motor will not power either forward or reverse extending or retracting the plunger.

Below is the evtm page 56 that applies.

Advance still sells the ISC but check for intermittant connection first. After that, the trouble shooting is a little more detailed so reply back.

as for the egr,, on the 3.8 it happens to be fairly functional but has a flaw. On the rear driver side there is a gold elbow fitting that ties in your pcv system. If you unbolt the CFI and look under it, you will see carbon buildup. That area is a port that leads up to the base of the egr. Also, when you remove the egr, there is a port down in there under the egr spacer that gets carbon'd up as well. If the EGR holds vac and stays sucked in , this is a good thing cause the EVP sensor on top is able to interpert information back to the map sensor and the EEC.

I would get the egr back in the game. The green vac line that hooks to the egr as well as the tan, orange, black and red all lead to a solenoid bank behnd the coolant fill tank. The red line is the main feeder for the whole bank and is connected eventually to a long white distribution tube. When applicable, each solenoid with actuate and deliver vac suction to each component on the far end,,ie- egr solenoid will activate and allow suction along the green vac line to the egr,, egr diapharm moves ,,, diaphram sucks up and moves the spring loaded rod which is a part of the evp sensor,, evp sensor is a variable resistor that interperts a voltage drop to the map and eec.

I have no idea what happens with the signal on the map end cause its just magic. Altitude plays a role on the map more than barometric presure. My diy link has info on that as well if your interested.

3.8L Starting Issue

Reply #3 – November 01, 2007, 11:23:23 AM

You may also check your fuel pressure regulator and set your air/fuel ratio.

3.8L Starting Issue

Reply #4 – November 01, 2007, 02:01:07 PM

Thanks to everyone who replied. Sounds like I have some troubleshooting to do! jcassity, I really appreciate the detailed explanation! I plan to try and work on it this weekend, but the wife and I re-finished the 1/2 bath downstairs, and I've got some paint touchups as well as hardware and toilet WC to re-install. Then, we've got our Nephew's b-day party at noon on Sunday followed by the Chiefs/Packers game! (I'm a transplanted Cheesehead in KC.) Lots going on and (unfortunately) the Cougar is taking a bit of a back seat lately.

I'll keep you all posted...

Greg

3.8L Starting Issue

Reply #5 – November 29, 2007, 09:51:05 AM

Well, finally got around to working on the car last night. Did a cap & rotor change and plugs (went back with the basic Bosch Platinums...they seemed to do me well enough last time).

Anyway, I discovered that the connector for the ISC is in pretty rough shape...2 of the wires have insulation that pulled back about 1/2" from the connector, and one has craked insulation. I made a mental note of this awhile ago, but never did anything about fixing it

It definitely appears that the two bared wires did come in contact and ther was some arcing. I moved the connector around, and made it sit as best as possible to not touch. Turned on the ignition, and the ISC DID still work, but it sure doesn't sound good! I started the engine, and it does go on high idle like it should, and the ISC pulls back fairly normally. However, when I shut the engine off, you hear the ISC running strangely, before it finally shuts off.

I know I need a new ISC... jcassity says theu're still available at Advance...maybe other places, too? Anyone rebuild the connector? I was thinking of checking out Rad Shack to see if I can get pins to re-do all the connections on the wiring harness connector. Unfortunately, the side that comes with the ISC is in much better shape than the wiring harness connection... :(

Considering the likely arcing issue, does anyone think I may have damaged something else besides the ISC???

Thanks!

Greg

Oh, I had to change out a water pump 2 weeks ago before I got to this issue! When it rains, it pours!

3.8L Starting Issue

Reply #6 – November 29, 2007, 11:54:51 AM

Quote from: bike70ride;185765

....the Chiefs/Packers game! (I'm a transplanted Cheesehead in KC.)Greg

Oh noes...a GB fan lol j/k Welcome to the board, and Missouri

Hope ya get your engine sorted soon.

3.8L Starting Issue

Reply #7 – November 29, 2007, 12:00:13 PM

Quote from: FordTruckFreeek;190171

Oh noes...a GB fan lol j/k Welcome to the board, and Missouri
Hope ya get your engine sorted soon.

Hey now! There's ALWAYS room in the world for another Cheesehead! Although I'm sure if you have your way, I'll have to convert to the Chiefs before it's over...wonder if Favre will ever forgive me if that happened, lol?

3.8L Starting Issue

Reply #8 – November 29, 2007, 12:49:08 PM

my lack of high idle was bad temp sensor. I think there are 2 if i remember correctly. it stopped the control motor from working correctly until it warmed up

3.8L Starting Issue

Reply #9 – November 29, 2007, 02:19:56 PM

Actually, I live in Olathe...but, thanks for the Welcome! I'll always be a Cheesehead...should be an interesting game tonight!

I do have some temperature fluctuations going on, but I think that may just be a sticky thermostat (which I should have replaced when I was doing the waterpump, I know...).

I know the ISC is on its way out, so I'm hoping I can still find one new...

3.8L Starting Issue

Reply #10 – November 29, 2007, 02:56:43 PM

I bought an ISC for a CFI 3.8 at Advance Auto this past spring for around $70. They're still available.

3.8L Starting Issue

Reply #11 – November 29, 2007, 03:22:00 PM

I use "liquid electrical tape" to reseal wires where the insulation has come off.
The brand I have is Star brite and I got it at a hardware store.

3.8L Starting Issue

Reply #12 – November 30, 2007, 05:47:06 PM

My Advance didn't have one, but Auto Zone did...about $70 as you said.

Hmmm, I may need to look in to that liquid electrical tape. In this case, though, the wires have been exposed long enough that there's significant corrosion, so I'd prefer to re-do the whole connection if possible.

3.8L Starting Issue

Reply #13 – December 01, 2007, 03:28:48 AM

You do not need a new ISC. Your description of each event matches the theory of operation.

key on cold motor,, you hear a click and a bunch of>>> ..BUzzzzzz(ISC plunger is extending to slightly open the trottle plate and also increase the voltage on the TPS green wire to signal the eec to deliver proper fuel pulse)

While in start / warm up, the isc will extend then the ACT sensor will signal it to back off when warm. This is when your allowed to change the idle to suit you.

There is a little tiny throttle stop screw that can be adjusted with nothing less than needle nose but i wouldnt touch it. Thats what the flat plate bumps into so your throttle plates inside the cfi do not bind.

when key is off, you will hear click and a bunch of>>>,,BUzzzzzz (ISC is retracting to the rest position and getting itself in the "latest and greatest" spot according to the performance gathered on the last run cycle.)

Yes the iSC is noisy but keep in mind, it is a tiny motor. They are noisy new as well.

all normal,, all well.

save your money cause it aint broke.

do what softouch says on the wires. I cant figure out why but my harness insulation was pulled back as well. I dont think the insulation is non-halogen rated so it probably shrinks with heat/cooling.

Pull your codes and if you do not see a "current" ISC code, your good. There may be an ISC code in memory but that will go away in 40 warm up cycles give or take a few.

3.8L Starting Issue

Reply #14 – December 01, 2007, 07:59:06 AM

I agree, check the codes first before checking or replacing anything. you'll drive yourself insane if you don't.
My harness insulation pulled back too. i had bare wires for the longest time . i'll have to see how i fixed mine. I like the liquid electrical tape idea
jcassity--are there codes listed in your diy fix it link?