Power Transistor & CAS & TPS - Hesitation

[juiceman]

I have been having some hesitation while driving and just tried the hesitation procedures listed on twinturbo.net. I decided to check out all the sensors I could. The throttle bodies were dirty but no too bad. Cleaned them anyway.

I could not get continuity between ground and any of the pins on the power transistor and the polarity of the probes for the pin to pin check was reversed, black terminal vs red terminal on the meter. I have read about a recall on the power transistor but I think if this was going bad I would be having stalling problems? Any comments? Jsut seems weird to not get any readings and I did triple check everthing.

Upon checking the Closed TPs I found that there was no continuity when released but continuity when the pedal was pressed. Is this a typo in the manual? Should I replace the TPS unit?

I checked all electrical connectors and found them clean but just cleaned them anyway to be sure.

I checked my timing and some times I will hear a noise coming from the CAS. I did not check the CAS voltage because I did not want to pull it from the engine. Not real sure and did not have the daylight to play. If a CAS starts to go will it cause the hesitation?

Thanks for any input. Decided to get dirty this weekend and really get to know my car. A lot of fun and I feel really good.

Thanks

[Q451990]

I've noticed that the transistor packs check "backwards" from the manual too. I talked to my dad about this, and he said there may be differences in the way my multi-meter works compared to the one they used when writing the book. I wouldn't worry about that too much.

You could be on to something with the CAS noise. Q45Tech has mentioned that the bearing will wear out and leave a rust-colored reddish powder which interferes with the operation of the CAS. I think I'd focus my attention there... having a timing problem will definately cause hesitation!

Heath

[Q45tech]

The V8 CAS has 360 tiny slots, think of it as a clock ticking once every 2 degrees of crank rotation [1 per degree of cam rotation]........the SUB MASTER CLOCK for the whole ecu........there is a xtal time base for real time in microseconds so the two together create the rpm. Where the Revs and the minute get created into RPM

Since a complete brand new cycle starts every 90 degrees with a V8 [ 120 V6/I6....180 for I4]........timing is very important a 2,3,4 degree error in the start of injection or when a plug fires will not create a perfect balance of equal power pulses.

The valves and piston motion are pretty well controlled via the timing chain belt and repeatable from rpm to rpm [except initial power on and sudden power off when chain/belt slack creates tiny errors momentarily.

The CAS 360 pulse are backed up on the Q with a redundant circuit providing an every 90 degree pulse from a different disk.........the 4 slots are different widths as is the 0 slot in the 360 disk so the ecu KNOWS where the number one pistion is. 8 cycles then start again.

One needs to examine the pulse train from both circuits to see that the pulse are uniform height and duration at a steady rpm with an oscilloscope.

Background not necessarily like the Q:http://www.donet.com/~jsg/efi332crank.h ... icokit.htm

Still you always [ALWAYS] start by measuring the fuel pressure at idle, upon acceleration [in gear driving on road] at at WOT at 4,000 and 6,000 rpm!