85 Carrera Idle Question

[SPIKES]

HI
1) my car idles a little rough. it idles at about 600-700 rpm.

When i brige the socket to override the idle stab.unit ..the idle goes up to about 850 and is stable.
i have tried to up it but about 10 seconds after i take the bridge wire off it drops back again and idles lumpy.

- do you think it is the idle stab.unit?

2) i have done seaches about setting the co. as the unit is upside down does clockwise adjustment (turning screw out) make the mixture leaner?

your responses are appreciated

thanks

[Kurt B]

You have to drill it, and the factory won't support it for emissions. Best to leave it. Most problems can be solved by cleaning the injectors with something.
the 84 to 89 Carreras have a lot of reported problems that I never see or hear about except that they are reported, like rod bolts and valve guides, but the fact is, they have idle problems for sure.
I replaced the idle stabilizer for that reason, didn't help much. I think it was working OK.
The idle goes up when you bridge it. You bridge it, adjust it higher than you think you want it, then it settles, then 2 days later when your car is back to running normal, it's bouncing off at 1500. (I assume you're talking about the Haynes manual adjustment technique).
Once again, check your air box as per Bentley Manual, but mainly just change the fuel filter, air filter, run some techron through it, check the plugs and plug wires, the injector connectors etc and evaluate it from there. Chances are it's that and not a bad unit--coming from someone who changed all that stuff out for exactly that reason.
Also, you could have screwed up injectors...

[jmohn]

Is your TPS adjusted correctly?

Jerry M
'78 SC

[SPIKES]

Originally posted by jmohn
Is your TPS adjusted correctly?

Jerry M
'78 SC

excuse my ignorance...what is a tps?

also i drove the car this morning...it really battles to rev clean while warming up..splutters a bit ...not undrivable though.

i remember from my sc that there was a auxillary air valve that aids cold running?

thanks

[SPIKES]

Originally posted by Kurt B
Also, you could have screwed up injectors...

THANKS KURT

if i pull of the injectors ....how can i check the spray pattern or clean them other than running cleaner through the tank?

i suppose i could somehow bridge the fuel pump and get it to spray.

thanks

[ChrisBennet]

You can't easily test the electronic fuel injectors ('84-on). They are opened electrically. If you just apply a voltage across them you can get them to open - until the the selenoid burns out. (Translation: Don't do that.)
-Chris

[ChrisBennet]

Make sure your off idle switch is working. With the motor off, pull up on the throttle lever. You should hear a faint click - like a ballpoint pen. This little switch lets the DME know that it should switch to the idle mode. If the throttle linkage is too tight, the throttle may not be returning all the way. Try pushing the throttle lever closed by hand or try pulling the gas pedal up with your toe.
-Chris

[BGCarrera32]

I agree with Chris. I'd check the idle switch first...mine had fallen loose and the idle was hunting all over. It is on the drivers side back of the throttle body...tough to see.

As for what is being reffered to as the TPS (throttle position switch), that little black box switch on the passenger side of throttle body is actually a wide open throttle switch (looks like a modern day TPS). When the linkage is full open throttle, that switch rotates and engages a contact for full fuel enrichment. It is not a resistive type TPS like the later 911's have and what many cars are equipped with today.

-BG

[jmohn]

TPS = "Throttle Position Sensor". If it's misadjusted it can cause an erratic idle (among other things). Rather than trying hit-or-miss adjustments (especially the fuel mixture, what you call CO) you should do the entire Motec check. It's not difficult once you have the procedure and all you need is a fuel pressure gauge and a volt\ohm meter. The procedure will discuss checking fuel pressure and delivery, the "TPS", the idle air valve, the mass air flow sensor, the air temp sensor, etc. These items must work together, adjusting one without checking the others may be part of the problem.

Jerry M
'78 SC

[SPIKES]

thanks for the replies

[BGCarrera32]

jmohn is correct on the TPS, my point was that an 85 Carrera doesn't have one. That function is controlled by the air vane meter, the much larger box right off the air filter box.

-BG

[SPIKES]

Originally posted by ChrisBennet
Make sure your off idle switch is working. With the motor off, pull up on the throttle lever. You should hear a faint click - like a ballpoint pen. This little switch lets the DME know that it should switch to the idle mode. If the throttle linkage is too tight, the throttle may not be returning all the way. Try pushing the throttle lever closed by hand or try pulling the gas pedal up with your toe.
-Chris

I can hear the click...i checked the tps on right hand side of the throttle body...it is the adjustable one.it has a plug with 3 connectors going into it although only 2 are wired. according to the bosch book i should have o resistance at idle and then again 0 at fully open.

i only get 0 at fully open......????
IS this ONLY A FULL THROTTLE SWITCH?
IS it supposed to be O AT IDLE?
i have tried to adjust it but it wont...

(1985 carrera 3.2)

THANKS

[BGCarrera32]

Like I said in my post above, that IS NOT a tps (but it does look like one!!). It is a "wide open throttle" switch only, and has nothing to do with your idle problems. I thought the same things you did when I was having similar problems on my 84 Carrera, this is how I know with confidence. You should have no continuity through those 2 active pins until you pull the throttle lever all the way open (back towards you) and then your meter should sweep or beep or whatever. When you floor the car, that switch engages at the end of its rotation, and tells the DME computer to make the injectors go like nuts for max fuel flow. Your Bosch book is most likely giving you info for the '90 and on cars. Get a manual (like the Bentley sold on this site or find one at a bookstore) and start going through the fuel pressure checks. Could be you have fuel pressure bouncing around too and causing a fluctuation.

[SPIKES]

Originally posted by BGCarrera32
jmohn is correct on the TPS, my point was that an 85 Carrera doesn't have one. That function is controlled by the air vane meter, the much larger box right off the air filter box.

-BG

thanks BG.

I misread your earlier post. i thought that it did not have the micro switch!

i found it behind the linkage on the left as i traced the wire from smaller black plug from front?
yip you are right the one is full throttle only and the other plug is for micro switch.... ONLY works for idling.
that seems to work ok.

i am trying new plugs tonight as precaution. i pulled one and it seems old. no harm dto do it.
thanks

[SPIKES]

question about idle positioner?

i read prev. post that resistance should be 40 with 2 outside pins (mine is 58) and 20 between middle and outside pins (mine is 25 and 30)

is this o.k?

i did plugs last night...not real improvement...checked resistance between plug wire ends and cap end. the highest was 309 and lowest was 288. (not sure how to use meter... but it was ohms)
is there a book to learn these analysers?

what should they be?

(btw: i have ordered WAYNES book and also service manual by bentley)

your replies are appreciated..
thanks.

[nhromyak]

My '85 idles on the low side of 600 too.

But, mine doesn't idle rough.

Perhaps you have an intake leak?
I hear this is common on these cars to become hard and sometimes crack causing leaks.

I keep checking mine, and found I had to retighten them about every other year.

Good luck.

[SPIKES]

Originally posted by nhromyak
My '85 idles on the low side of 600 too.

But, mine doesn't idle rough.

Perhaps you have an intake leak?
I hear this is common on these cars to become hard and sometimes crack causing leaks.

I keep checking mine, and found I had to retighten them about every other year.

Good luck.

if it leaks air won't it idle higher?

[SPIKES]

Originally posted by SPIKES
question about idle positioner?

i read prev. post that resistance should be 40 with 2 outside pins (mine is 58) and 20 between middle and outside pins (mine is 25 and 30)

is this o.k?

i did plugs last night...not real improvement...checked resistance between plug wire ends and cap end. the highest was 309 and lowest was 288. (not sure how to use meter... but it was ohms)
is there a book to learn these analysers?

what should they be?

your replies are appreciated..
thanks.

[nhromyak]

Hmm I am not sure, I know it would on a GM TBI car.

But when I take off my oil cap (air leak) it stumbles and drops the RPMs for a moment. Then the Idle circuit does it thing and brings RPMS back up. I can't really tell if it's idling roughly at that point or not.

Good luck.

Hopefully someone else who is more familiar with the 3.2 will respond.

[SPIKES]

Originally posted by nhromyak
when I take off my oil cap (air leak) it stumbles and drops the RPMs

yip i think you are right.
i will check again for air leaks.

ANYBODY with comments about the values i posted earlier....