Lizard928

If the Temp II reads one then nothing is getting through meaning a broken circuit.

Dont bother checking pin to pin, just pin to Temp Ii housing.

Tom. M

Injection labs...but it's been in there for a while...maybe 3 years max but ran fine that whole time..?

Leaning towards temp II..I'll update once I check..and then replace it..

Lizard928

A bad MAF will normally make a lean, not rich condition.

It is possible to be the LH, but the temp II has shown a fault already.

Tom. M

just checked cold and still no continuity (reading 1)..so I'll be getting the temp II sensor and hope that will take care of it..

WallyP

"If the Temp II reads one then nothing is getting through meaning a broken circuit.

Dont bother checking pin to pin, just pin to Temp Ii housing. "

An Ohmmeter will normally read zero if there is no resistance, meaning a shorted circuit, not a broken one. The meaning of a reading of "1" depends upon the range set/shown on the Ohmmeter/multimeter, but is meaningless in this test in any case. If you touch the meter probes together, you can see what zero resistance will read on your meter. When the probes aren't touching anything, you can see what an open circuit will read on your meter.

Testing resistance from pin to housing might not show the problem, although it will show a faulty sensor. There have been cases where powder coating the intake electrically isolated the intake (and therefore the sensor) from the block/chassis ground. You need to test from each pin to a good ground.

Tom. M

Yep, touching ends together reads 0. when disconnected it reads 1. Tried each pin to ground (several areas including the base of the sender, the bolts to the cross brace, several spots on the engine, the fuel rail etc..no change. Also tried every range on the resistance scale..and no change... All signs point to the Temp II.. I'll swap it out and report back...

Tom. M

User = 1D10T ...

I went to check PET for the part number of the Temp II sender..and sent it out for price quote. Rog came back with "that's the inside temp gauge sender"..here's the one you want...
Crap LOL... leaning over the passenger side of the car..the Temp II was totally obscured by the strut brace. I was testing the wrong sender the whole time.

Went home at lunch to test the proper Temp II .. Readings were within spec; however, as Sean suggested, I checked the connector too. The wires were exposed and frayed in a couple of spots so it's possible they were touching together. I will replace the connector and ensure there are no other spots touching and hopefully see if she runs right..

JoeTaylor

Vacuum leak?

Lizard928

PEBFAC! (Problem Exists Between Floor And Car)

Tom. M

so..put on the new connector to the temp II and made sure no other wires were frayed etc...

Fired it up and it ran great........

for about a minute. After that the idle became erratic, up down up down...and started belching black smoke..enough to leave a black streak on the garage floor..

was able to rev through the rough running and it started running smoother, but the idle was all over the place. As the temp got up to normal, it revved to about 1300 and just stayed there. When I stepped on the gas pedal, it would hesitate for a sec..and then rev... very odd...

Listened for air leaks or any unusual noises up front and nothing was out of the ordinary...

Probably going to disconnect the MAF tomorrow (neighbors have probably had enough of the revving today)..and see if it anything changes...

thoughts?..

Lizard928

My vote is for the LH in that instance.

AO

Hate to point out the obvious, but stock injectors for your car are 19# not 24#, so it's going to run rich (unless you've sharktuned it), but the O2 sensor will try and compensate. If the O2 cannot compensate (maybe because it's bad), you will end up running rich... way rich.

Three things I would try at this point.

1. Test the Temp II points on the LH connector. Should get approximately the same reading as you got at the sensor itself. Will tell you if there is any shorting of the leads. Test points can be found in the links in my signature.

2. Battery disconnect so the LH can re-adapt. (A bit of a long shot, but might help)

3. Test the O2 sensor to see if it's working properly. While the car is running the O2 sensor should put out between 0 and 1v. Again, test procedure is in my signature link (LH diagnostics)

Tom. M

24's have been in the car for years. The LH usually can handle them during warmup (open loop) ..but when it goes to WOT..it'll be much richer than the 19's of course. Had 30's in there for a while and even with dialed back fuel pressure (adj. fuel pressure regulator), it wouldn't run right at start up ..but once warmed up it was fine (open loop vs. closed loop thing).

The richness currently is only when it's running rough (like it's missing)..when I get it to clear, it doesn't belch black...but the idle is jumping all over.

I'll add the temp II points at the brain and the O2 sensor test to the list...

thanks for the tips...

AO

Well black smoke is unburnt fuel. So either you've got WAY too much fuel or bad spark.

If it used to run fine, then I'd look at the O2 sensor after you verify the Temp II. Because its the O2 sensor's function to tell the LH how far to lean things out to bring it to stoich. If the O2 is broken it will revert to the stock mapping with no adjustment for the increased injector size = rich.

After that, Look at spark.

Tom. M

Borrowed a spare LH brain (even an 89 version) and plugged it in the 928. Fired it up and the stumble/miss from before was gone. Let it warm up and the idle started to jump wildly again. Seems to happen when the car is almost warmed up. It was really odd...up down up down...then it stayed at around 2k... figured I would pull it into the garage..and then poof..it died.
Fired it back up and it ran perfect. Smooth idle and even idled a bit lower than before (this brain was from a 89 AT...) but I am still running my ezk and my coding plug... Does the 89 AT brain chip lower the idle?

I shut it off and started several time and it ran great and started great every time. I'll drive it around some more over the weekend to see if that up/down idle was just the brain learning the car?..