engine cuts out. - Page 2

Fl Ted · 04-07-2005, 12:01 PM

Re; clutch work.
05/31/2001 @ 61548mi the following were replaced:
2ea 911 606 215 01 sensor, ref mark
1ea 915 116 911 01 clutch kit
1ea 930 102 033 01 flywheel
Odometer now reads 65244 = 3696 mi on clutch components.
Which means??

Thanks for the quick response

Ted

kqw · 04-07-2005, 12:28 PM

I am assuming you have your work order available...

What exactly was done at clutch time.

Clutch kit to me only suggests the pressure plate, T/O bearing and Disc. Was this in your kit?

Also, what about: pilot bearing, guide tube, release bearing fork, 9 Pressure plate bolts, 9 Flywheel bolts etc. These are generally not included in a "clutch" kit.

What shop did the work or did you DIY?

Fl Ted · 04-07-2005, 12:29 PM

Chris:
Thanks for the tip

Located plug easily and now I have an idea where the CHT is lurking!

Measured probe to ground, got 2.2K

I'll get a resistor and try what you said, probably won't drive it till tomorrow, as we're about to get hit with some bad thunderstorms shortly

Thanks, Ted

Fl Ted · 04-07-2005, 12:36 PM

KQW:
Work done @ Eibell Performance Inc, Clearwater, Fl, 2 owners previous to me. Nothing else pertaining to the clutch is listed. Shop supplies is listed @ $96.96. Could be a percentage of total bill, or charge for misc parts.
Why are you looking at the clutch???
Ted

kqw · 04-07-2005, 01:39 PM

Quote:

Originally posted by Fl Ted

Why are you looking at the clutch???
Ted

It's the prominent bucking when the clutch is engaged yet smooth rev'ing when dis-engaged.

A quick test on the CHT: With the engine running, pull the plug on the CHT (in the engine compartment next to the # 3 cylinder. It should be the TOP plug) and your engine should begin to race at higher RPM's. Reconnect and it should smooth out.

kqw · 04-07-2005, 02:08 PM

A good clutch job would include:

Guide tube - $85.00
Pilot Bearing - $35.00
Fly wheel bolts - $20.00
Pressure Plate bolts - $12.00
Rear Main seal - $25.00
Release bearing fork - $80.00
Main shaft seal - $15.00

or approximately $272.00 in additional parts. This is not taking into consideration the cable, clevis pin etc.

If you are close, have your mechanic drive the car (there shouldn't be any charge to do this) and they should be able to quickly diagnose a clutch issue.

Fl Ted · 03:16 PM

KQW:
I appreciate your interest and input.
My problem is not clutch related. (other than when clutch is depressed while engine is "cutting out" it "unloads" the engine and lets it run normally)
The "cutting-out" is like turning the ignition on and off, or turning the fuel on and off.
I was sure it was fuel, untill I "unloaded" the engine by disengaging the clutch while in motion, and seeing the engine run normally. Usually this would indicate an ignition problem, as an engine under load has higher
cylinder pressures (BMEP) than one running with no load. The higher pressures make it harder for the spark to jump the plug gap, which increases the resistance in the ignition system to the point where the ign high voltage will jump to ground wherever it finds the path of least resistance, and the cyl fails to fire,commonly called a "miss". However a coil or condensor in the ign system can break-down, usually with heat, and cut off spark to all plugs, causing the type of "cutting-out" that I am experiencing.
BUT (there's always a BUT) usually when that happens, fuel is still being delivered to all cyl's, and when the ign system comes back to life in an intermittent failure scenario, it ignites the unburned fuel that has been accumulating while the ign system was napping, causing loud "backfireing" and FLAMES out the tailpipe!!! As teens, we used to do this deliberatly by turning the ign key off for a few seconds, then back on!! Great fun we thought, untill we had to buy new mufflers!!
As my car"bucks", there is no backfiring, but the engine is starting and stopping just as if you were turning the fuel on and off rapidly and randomly.
If it were the clutch releasing and catching rapidly, I would expect to see the tach jump up when it released, and go back down when it grabbed. It doesn't do that. When it cuts out, the car slows rapidly, throwing you forward in the seat,, even with the seat belt on and tight, and the tach drops. Have you ever had gunk in the fuel tank/line/filter that would stop fuel flow as the flow drew the gunk towards the orifice of the tank, etc, and the engine starves and quits, which stops the fuel flow, which lets the gunk float away from the orifice, and all of a sudden your under power again, then the scenario repeats it self over and over until you take every thing apart and clean out the gunk. Well, thats what its like, EXCEPT that usually when the above happens, applying additional throttle makes it worse but sometimes you can "nurse" it along with partial throttle.
Of course a Porsche wouldn't do anything so mundane! When mine cuts-out, I can give it max throttle and it takes off like a goosed goose!! When I back off the throttle, the "cutting-out" returns.
Remember, this whole scenario only occurs after approx 10 mi of driving. Could be related to eng temp affecting some sensor, or temp affecting some electronic controlling device (DME).
Thats my story, and I'm stickin to it!!
Ted

smcdermaid · 04-07-2005, 03:14 PM

Have all the basics been covered? I had identical symptoms in an early 944, turned out to be bad dist. cap and rotor. Microscopic(almost) carbon tracking on rotor and on one side of inner cap, wouldn't exhibit symptoms until warm and under load, very intermittent. New cap and rotor fixed it completely. Just a thought. I wasted a lot of time and resources checking other things until this was discoverd. Good luck,

Fl Ted · 04-07-2005, 03:19 PM

smcdermaid:
Did you have a "miss" or "cut-out"?
Did you have "backfiring"?
Ted

kqw · 04-07-2005, 05:42 PM

Ted...Thanks for the clarification.

When you mentioned "bucking Wildly" and not a shut off/Turn on/engine miss situation, it led me to a mechanical diag. rather than an ignition issue.

Keep me posted....

smcdermaid · 04-08-2005, 06:51 AM

Fl Ted,

I'd call it hard bucking, complete momentary cut-out. Not missing. I don't remember backfiring but it would certainly be possible. I was surprised at how much bucking occured once the cause was determined. Carbon tracking can be tough to ID especially if the components are old or dirty. You can clean them with spray electronic cleaner or just plain Isopropyl alcohal to get a better look. However, from your description there should be clear evidence if this is indeed the problem. As others have said check for obvious ground connections, loosness etc. but the bucking sounds just like intermittent HT ign. failure. JMHO

ausdilecce · ausdilecce's Garage

Sorry to come in late with another possible cause..

My 87 targa was bucking just like you describe
.. bucking when warm only
.. will NOT buck if I accel at WOT
.. bucked madly at *exactly* the same rpm range each time 2650-2900

Now, since my car is in aus and a ROW.. that rpm range equated to the range that the engine would run at 90% of the time ( at 100 kph in 5th, at 80 kph in 4th, at 60 kph in 3rd etc )

I looked into the Air Flow Meter (AFM ) the motronic carreras have. The AFM (stock) is a 'barn door' type. When air is entering the engine, the barn door will be forced open a certain amount. The barn door is directly connected to a 'potentiometer' ( like a volume control on a stereo ). This potentiometer is a thin film carbon type. As the car ages, the 'wipers' of the potentiometer cut thru the thin fim carbon track ( where the wipers would be most of the time ). When this happens, the AFM will send bogus values of air entering the engine and erratic engine perfomance is the result..

My carbon track was cut all the way thru in several places !. I moved my wiper assembly and all is great now..

There is a 'home mechanic' way of checking for this possibility AND a 'home mechanic' way of fixing the AFM for $0.. There used to be a web page devoted to it but it was taken down approx 2 months ago..

the site's address is in the first post of this thread
Free HP Increase for your 3.2
Dont know why this very valuable resource went away, but...

this is also a good thread to read reagarding possible issues
'88 bucking and rough idle (long)

Good luck

Fl Ted · 04-08-2005, 09:22 PM

Drove around local "test track" tonight, started cutting-out on third lap. Pulled over, jumperd CHT input plug with 270 ohm resistor. Three more laps thrashing it petty hard, ran perfect!!

But i've got to be pessimistic at this point. One good run is only that!

I'm going to do a few more things in the AM, drive it again in the PM(after a trip to the bank for gas money!

)
I'll post results afterward.
And give out the appropriate kudos!!

Ted

ChrisBennet · ChrisBennet's Garage

Any more news?

Fl Ted · 04-12-2005, 11:37 AM

I don't believe it!! I just spent an hour typing my reply, only to get a message saying I used too many images in my message! and no way to get back to it: SON OF A BITC!!
Anyway, Chris, the 270 ohm (RS was out of 330's) did the trick! After 3 drives it's running great! I just have to order a new one. Mine was the single wire version.
thanks to all who responded I was able to resolve this problem and fix a few others "while I was in there" !!!
Chris, if you ever get to Fl west coast, I'l buy the beer!!!
Thanks again,
Ted

ChrisBennet · ChrisBennet's Garage

Glad to hear it worked out! I need to think of a reason to come to Florida now...

-Chris

McLovin · 04-18-2011, 11:50 AM

Quote:

Originally Posted by ChrisBennet

My vote is for the CHT. Because it is intermittent, a DMM isn't going to help you. The CHT is the white connector on the left side of the motor. There should be a group of 3 connectors near the heater blower motor. The top one is CHT (usually).

The CHT should read approximately 3500 ohms cold, and approx 300 ohms hot. You can "fake out" the computer by substituting a resistor for the sensor.

Go to Radio Shack and get a 330 ohm 1/2 watt resistor (or a selection).

Once the motor is warmed up:
1. remove the CHT connector,
2. bend the ends of the resistor leads over on themselves
3. shove the ends of the resistor leads into the female connector for the CHT and use some masking tape to hold it in place.

Now you should be able to drive around as long as the motor is warm. If you still get bucking, it's not the head temp sensor.

If this doesn't make sense I can take pictures.
-Chris

resurrecting an old post for a great idea.

I want to set up a resistor like described above, for emergency use. That description is for a 1 wire CHT.

For a 2 wire CHT, since the second wire is simply a ground, would you just put plug the resistor in, one side to the ground line, and one to the other, on the CHT wire? Seems like that would be the way, anyone think differently?

1989G50 · 08-14-2011, 07:09 PM

Hello,
I have a 1989 3.2 with the exact same problem you describe!!! I too had the DME relay changed. Plugs and wires didn't fix it. Fuel pump didn't fix it either. Although I can say it made the bucking feel less severe when the problem did arise. The only difference i would say is that I have to drive 45 minutes or so before it occurs to my car. I read everything that was posted but am curious to know what exactly ended up being the cause/fix to this problem. Any help would be greatly appreciated! Thanks!!