# 9A CIS-E won't idle without vac leak



## cra2y86 (Nov 27, 2004)

Here's a picture of the area in question: 









The blue T fitting was improvised by a PO, and that vacuum line travels to a tube-like thing mounted on the firewall by the ecu... 

Anyways, to the left of the improvised T is the hole that I'm talking about. I guess that's what's left of the original T. If I cover the hole, the idle gets rough and dies. 

Currently the idle is choppy, between 1k and 1.3k rpm. 

What does this suggest?


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## cuppie (May 4, 2005)

That (to me) suggests that somebody "tuned" it to cover up the intake leak(s), a faulty 02 sensor, or other issues. It's more common that you'd think.  

CIS 101: 
fix the obvious, make sure everything is how it should be. 
What I would do: 
- get a bunch of new small (2.5mm) vacuum hose 
- get a new set of injector O-rings. 
- get whatever you feel needed to repair/replace the broken part. 

Pull the injectors, and check them for proper spray pattern, leakage, and volume difference. Since they're out, install new O-rings (which they probably need anyways.) 
OK here now? Replace (don't 'check' - just replace!) all of the small vacuum hose in the bay. While nice & abrasion resistant, the cloth-covered hose hides cracks from view. st 
While you have the intake boot off (since it's off for the injector checks), carefully and meticulously inspect it for cracks; replace if needed. 
Replace o-ring on idle screw (should be able to find one at the hardware store.) To 'baseline' the adjustment: turn it all the way in, counting turns - this is your base adjustment. Then, remove, replace o-ring, and reinstall & adjust. 

Have Bentley? Now that we've fixed a bunch of stuff, you're probably going to need to do a 'baseline setting' of the fuel distributor. Sensor plate rest position and freeplay in spec (this should allow it to run again - because, it might not otherwise.) 

Get it running, verify that O2 sensor is functional (best is checking it with an oscilloscope; next is analog voltmeter; digital voltmeter is third choice (low-end DVOMs just aren't fast enough.) 
If the sensor is lazy, stuck, or just plain dead, replace it. 

Should be running now, and able to perform a proper mixture adjustment. 
Reminder: because everything inter-relates... always make sure that idle speed is correct, ignition timing is correct, and the throttle switches work. Correct as needed (and, recorrect as needed during adjustment.) 


Finally.... if you don't have a Bentley for the car, you should get one! Just for this one issue alone, it'll be invaluable (fault charts, specs, pictures, etc.) 
It will be far more help than you'd think.


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## cra2y86 (Nov 27, 2004)

cuppie said:


> That (to me) suggests that somebody "tuned" it to cover up the intake leak(s), a faulty 02 sensor, or other issues. It's more common that you'd think.
> 
> CIS 101:
> fix the obvious, make sure everything is how it should be.
> ...


 First, thank you for taking the time to reply. 

Seems like I have some work to do. I do have a bentley. I guess it's worth noting that 6 months ago I swapped the car to 5 speed and tried to do some regular maintenance in the process. This included both injector o-rings and the shrouds, along with a new o2 sensor. 

I've been trying to avoid hard-resetting the fuel system, but it sounds like that's what I need to do!


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## cra2y86 (Nov 27, 2004)

Checking in here:

Replaced all of the vacuum lines as well as replaced that broken fitting on the brake booster hose. That seemed to smooth the idle out, but it was still all over the rev range.

Fuel mileage was horrible, to the tune of 10 mpg. Raw fuel was basically dumping out of the exhaust. I read up on tuning the fuel mixture with a DPR test harness, so that's what I set out to do. Much to my chagrin, the tamper-proof plug had already been drilled out of the fuel distributor. 

After a few days of messing with that, I just decided to swap in a virgin distributor and a spare ECU. The idle is rock solid now, right around 850 rpm. Much improved driveability. The jury's out on fuel mileage, but I'm optimistic.


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## cra2y86 (Nov 27, 2004)

255 miles on 8.5 gallons in mixed city/highway driving. That's more like it!


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