I Searched, But nothing Quite Fits.(Long)

Ive been through this board, Turbo Ford and even Foxtbird cougars looking for a solution to my problem, but no dice. Here we go:

1988 TC manual, Cone on the VAM, Gillis at 18, FRESH Motorcraft Tuneup (Plugs, Wires, Cap,Rotor,) New ECT Sensor. Fuel Pressure is correct at Idle, and at cruise/under boost. TPS is set to .94V, IAC is a NOS Motorcraft part. Timing (Ignition) Is dead on at 10* Spout out. Cam Timing hasnt been verified. Pulled codes, Memory code 42 is the only one Ive EVER come up with. Fresh motorcraft Ignition coil.


Okay here's the problem. When I first start it up in the morning, or afternoon (Engine Cold) It misses a bit for about 20-30 seconds and catches correct, Idles up a bit till it gets warm, and the idle settles back to 1000rpms. Now, the car can be completely warm, or just barely warm, and I will have varying vac readings at idle. sometimes I look and it will be at 15-16, sometimes 18-19. It doesnt fluctuate quickly at all, and Ive never actually caught it moving one way or the other. At Idle I get a strong miss for a split second at least once or twice every minute or so. It seems like the ignition is cutting out, but I havnt been able to fuiger out if that is the case. At WOT it misses a bit, not much but enough to notice a lack of power for a sec. It also looses Most of its power at full boost and about 4K RPMs. It drives around town fine, but everysooften, I seem to catch it miss VERY VERY slightly, so slight in fact I question if its really happening. Like I said, the ony code is a memory code 42, and it seems to come back up every so often after i clear the codes. FPR hose is dry, no fuel inside, just the very slight smell. The injectors are also sealed tight with no leaks, and all have been professionaly cleaned in the last 6 months. Could it be possible that the cam timing is off one tooth and cause this?? I'm only getting between 17 and 21MPG lately also. I'm just sick of the miss.
My 87TC seemed to pull a lot harder with just a cone and a bypassed BCS. And that motor had 278K on the clock as opposed to under 100K like this one does. any help would be apreciated.

I would check the cam timing just to be sure. Is the VAM functioning properly? When you say it looses most of its power, does it fall flat on its face and miss and sputter, or does it just seem to plateau or level off at about 4k?

Have you tried this yet:

http://www.turbotbird.com/techinfo/Idle-...e2005.html

Also, may be the stator(or PIP),or TFI, or wire harness connectors. And I'm kind of leaning towards the PIP with the symptoms you describe. Try this to verify and let us know.


Step 1:
Engine should be cold at this point. Unplug the spout connector, located by the TFI used for timing. Using a volt meter connect the negative lead to the distributor base. Then start the engine, using the positive lead of the volt meter, measure the battery voltage (positive terminal) at 1200-1500 rpm. Then, using the positive lead of the volt meter, measure the voltage on the TFI module side of the spout plug at 1200-1500 rpm. (remember this voltage for step 3 if necessary) If voltage from spout is greater than 40% of battery voltage replace the stator assy.

Step 2:
If not try this; with the neg. lead still connected to the dist. base and the positive lead on the TFI module side of the spout plug, measure voltage at 1200 rpm and at aprox. 4000 rpm. If the voltage at 4000 rpm is less than 90% of the voltage at 1200 rpm replace the stator.

Step 3:
If not try this; warm the engine up to normal operating temp. With the neg lead still connected to the dist. base, use the positive lead to measure the voltage on the TFI module side of the spout connector at 1200-1500 rpm. Now using the voltage from the 1st test, engine "cold" neg lead on dist base and positive on TFI side of the spout plug. Is that voltage from test 1 less than 90% of the voltage you just took with the engine warm? If so replace the stator. If not stator is probably fine.

James

Just to add to the confusion.

I recently had to swap a lot of injectors. After finally getting a set that doesnt appear to leak (knock on wood) I forgot to tighten the IC clamps. I was really surprised how ridiculusly smooth my idle was....

Guess what happend when I tightend the clamps, back to a similar drop every minute or so, only for a moment when at idle.

For me it points to the VAM possibly having a small dead spot... or this is just the idle that these cars have... your problem, I got nothin... sry.

I would point to the TFI.....

If you want...take the whole distributor from the other car and install....see what happens...

Travis

Well, this is all great info, but I'm thinking vam mabey too. Actually Its plateau ing around 3500rpms. and at Idle, the vac is variable. Anybody have an explination for that??

My vote is for TFI - PIP problems, leaning towards PIP. If you have a spare disty it's pretty quick to change it out.

Keep us informed, please.

The problem with that is my spare is about 3 hours north of here. I just noticed that my knock sensor is still connected.....Now in my 87 I had a serious problem with the ecu pulling timing because of that little gem, and I remember having the same pleateau ing (SP) problem...that solved that. It was pulling some serious timing because of normal engine noise, most notably cycling injectors. So I'm going to try that as well. Wouldnt the TFI PIP set a code if it was bad enough to cause a misfire/pleateauing Joe?

You can try pulling the knock sensor, and that may help the plateauing issue, but the intermittent miss when cold is another issue. I would still vote for either the TFI plug, the TFI, or the PIP (and still leaning towards the PIP). The voltage test is a real quick easy way to check the PIP without just changing parts, especially when your spare is 3 hrs away. If it was in your garage that may be a quick way to check it as long as you know that your spare is good.

It's my understanding that a failing TFI or PIP sensor doesn't necessarily throw codes; you might not get any.

Hmm. Okay. I will check out the readings off the test that James threw up there for me. I'll let you know what I come up with. I'm also running a tank of 92 Octane+Lucas Injector cleaner, just in case an injector is clogged up for some reason. I'll post my results when I get them! Thanks so far everyone!