'88 bucking and rough idle (long)

[bigrubberjeep]

At times I think this BBS has saved me $$$ in advise from others.

My wrench must hate this.

[bill3667]

The Cyl. Head Temp Sensor is in front of Cyl. # 3, visable from the INSIDE the left rear wheelwell above the exhaust.

2 things, do a search on the forum on "cyl head sensor", there is much info already written on it including Guest Tech. Article "Cylinder Head Temp. Sensor - Upgrade" that explains everything you need to know and check for. Also get yourself the Bentley Porsche 911 Carrera Service Manual for about $85 (or therabouts). The Bentley is both loved and hated for assorted errors but overall, in my opinion, worth the money.

By the way, that isn't a stupid question, it's a very good one. I would have never thought the sensor was where it is. In addiition I've asked ALOT stupider (wink-wink) ones in the past and am sure I do it again.

Hope this helps,
Bill W.

[Lorenfb]

You need to check a number of things:

1. Hopefully you don't have a performance chip, if so replace with the stock Porsche
chip. You have the DME selector switch set to the base position (fully CCW).
2. You've checked the fuel pressure, (36 to 40 psi)
and MONITORED it while driving.
3. You've checked the CO at 2000 and the problem point,
S/B about 1.5% before the CAT w/o the O2 sensor.
4. You've disconnected the O2 sensor and tested the car.
5. You've checked for no binding areas in the AFM, i.e.
the flapper is not sticking.
6. You've checked the temp sensor for proper values,
visit www.systemsc.com on the Diagnostics page for values.
You can bypass the temp sensor with a jumper once the engine is hot.
7. You've checked for an adequate spark, at least 20-25 mm from
coil wire. Also check the distributor cap & rotor.
8. You've checked for proper voltage to the DME unit when
the problem occurs.
9. You've cleaned the speed and reference sensors.
10 You've cleaned & tightened all ground connections related to
the fuel injection and ignition systems.

[bill3667]

Loren is notorious for for slamming aftermarket chips. I, one of many on this board, love my Steve Wong chip and rue the times I've reverted to the stock chip. Steve stands behind his work, sent me another (alt mapped) chip for me to test (without me even asking for it) and sent me several off list emails suggesting things to check/test to get my problem resolved. Steve W.'s chip WAS NOT the cause of any of the problems I had on my car! I will keep one of his chips in my car unless I have to revert to the stock chip for some unknown reason.

Bill W.

[fitz]

Bill and Loren,
Thanks for the information I'll start checking thing over this weekend. Yesterday was my first day I drove my car with the new ignition cables and for the beginning of the drive is seemed a little better. Today the care seemed the same nice sounding engine noise then bum.....bum....bum...then nice sounding.

So I'll start testing things out, thank again Ron