'91 Testarossa won't idle

My 86 TR did this recently. I had to blip the throttle a bit at each red light to keep it reved up but after it caught itself up it would be ok on it's on. My mechanic instantly recognized the problem and readjusted the idle and the problem went away. I can't remember what the exact cause was but it was a minute adjustment. Easily fixable. Good luck with it.

 

Andy -- Do you have a KE-Jet with lambda (i.e., with O2 sensors) TR, or is it a simple K-jet without lambda TR?

 

How can you tell which system is on the car? Will the manual reveal such information? TIA

 

Yes, the corresponding year/version TR OM will state whether it's K-Jetronic or KE-Jetronic, and there's usually a good illustration showing the injection system components and their locations (although I've noted that there can be errors -- e.g., the US TR OM still showing a "By-Pass Valve" when this component is not actually used on the US version TRs).

There are three TR injection/exhaust configurations that I've come across in the technical manuals:

K-Jetronic without catalytic converters
KE-Jetronic without catalytic converters
KE-Jetronic with catalytic converters and O2 sensors (US, CH, etc.)

The easiest way to differentiate K from KE is the presence (K) or absence (KE) of separate Warm-up Regulators. On KE, the Electromagnetic Pressure Actuator performs the Warm-up Regulator duties. I'll post pics of each in a second.

 

This is K-Jetronic TR engine with the separate Warm-up Regulators below the upper intake manifolds:

 

This is a KE-Jetronic TR engine:

 

Had the same situation occur with mine as well -- an '85 Euro TR with K-Jetronic. IIRC, it occurred during cold weather conditions. Problem mysteriously went away and hasn't occurred since. Sorry not to be of much help though...

 

Andy -- I know that a mis-adjusted or non-working throttle microswitch will cause your exact reported symptom on a US TR (KE-Jet with O2 sensors). I'm not sure that a KE-Jet without O2 sensors would respond in the same way to the same fault (and I'm still not sure exactly which KE-Jet you've got), but it's a fairly easy thing to check/readjust so wouldn't hurt to verify regardless of which KE-Jet set-up you have.

Loosen the two small screws that hold the slotted ears on the throttle microswitch body and gently rotate the microswitch body fully CCW (as viewed when standing outside the RH rear wing and facing the throttle microswitch). You don't want to cause the throttle plate to be lifted of it's idle rest, but you want the microswitch to be fully at that end of its travel simultaneously when the throttle plate is on its physical idle rest. The functional test (ignition key "off") is to unplug one of the injection ecus and measure the DC resistance between pin 1 and pin 13 in the harness connector end:

when the throttle plates are at their idle position, the resistance from pin 1 to pin 13 should measure 0 ohms (say 10 ohms or less -- I just measured mine at 7.4 ohms).

when the throttle plates are slightly opened, the resistance from pin 1 to pin 13 should be either ~140 ohms (cold) or infinite ohms (warm) -- mine measured 145 ohms (cold).

The injection ecu connector pin numbers are shown in the TR OM if you're not familiar with those. No gaurentee that this for sure is your problem, but it's worth a quick look IMO. Give a shout back either way.

 

I think Steve in going down the correct avenue with his advice. After seeing his last post I now recall my mechanic describing this proceedure to cure my problem. The right side throttle ear was slightly out of place at idle. It only took a tiny adjustment to get it right.

 

(Just reposting the picture so I can refer someone to this thread)

This is a KE-Jetronic TR:
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(Just reposting the picture so I can refer someone to this thread)

This is a KE-Jetronic TR:This is K-Jetronic TR engine with the separate Warm-up Regulators below the upper intake manifolds:
Image Unavailable, Please Login

 

I had a similar problem on my 328 recently - turned out to be a combination of idle adjustment AND a very dirty throttle body which was covered in crap on the inside which was preventing the butterfly from closing properly - thereby screwing up the results of trying to adjust the idle.

I.