Irradic idle

[Rodney McDaniel]

Hi guys , 16 new injectors (fic ) new gm coils, new plug wires , seems somewhat better, still have irradic idle when idle is coming down. From higher rpm. Any suggestions

[DRM500RUBYZR-1]

What year?

Original Chip?

:cheers:
Marty

[Paul Workman]

One never should assume a replaced part, being "new', is therefore exempt from suspicion. Bad, bad, bad mistake! (In fact, the period in a device's life when it is MOST LIKELY TO FAIL is when it is first put into service: statisticians call it "infant mortality".)

A good place to start is with an OBD-I scan, with particular attention to Throttle Body voltage, BLM and INTEGRATOR values, O2 readings and dwell time (left vs. right), etc. Are the plugs new, and if so, what are they and what gap are they set at? I (we) might assume it is closed loop when the issue is present, but is it?

All things to know before attempting to throw more parts at the problem... :icon_scra

[tccrab]

And he needs to exactly define what the "erratic idle" is that he is wondering about.
If it's the emissions hesitation from ~1200rpms then down to idle at 700rpms a few seconds later, then it's a condition and not a symptom.

'Crabs

[Paul Workman]

And he needs to exactly define what the "erratic idle" is that he is wondering about.
If it's the emissions hesitation from ~1200rpms then down to idle at 700rpms a few seconds later, then it's a condition and not a symptom.

'Crabs

Yeah. Very good point!:thumbsup: Just what zackly R we talkin' about here, Rodney?

[Rodney McDaniel]

Hi, that was pretty vague. It's a 91, stock chip that I know of, Watson long tube headers, 3 inch B&B exhaust no cats. The original problem was varying idle speed about 500 to 1500 rpms, car started good, after a couple min. warm up about a mile from my house it would start bucking , missing like it ran out of gas. This is in the 2 to 3 thousand rpm range, 20 - 30 mph, push in the clutch turn the power key off, motor not running let the clutch out and it would chug back to life then run fine. Installed new fuel filter, new fic injectors, all new viton orings, car has 2 new fuel pumps. So while I was under the plenum I installed new gm coils,& wires. Testing fuel pressure 50 psi. Car has only cut off once since, that time the power key was off. Still has varying idle speeds + sometimes it idles at 2- 3 grand. Sometimes it idles fine ???

[dredgeguy]

Hi Rodney, great meeting you at Hunt Valley cars and coffee yesterday. Sure that our forum brothers can get this sorted out for you and hopefully we can have a Wazoo maintenance day soon as well.

[Rodney McDaniel]

Yeah. Hi Charles, it was nice meeting you and your daughter yesterday. Looking forward to meeting more members, and hanging out at a Wazoo maintenance day.Thanks.

[Paul Workman]

I wouldn't (ever) throw parts at a problem. Not only is it expensive and time consuming, but often frustrating when you guess wrong (new part didn't fix it). AND, then there's always the how was the old part performing vs. how the new part is (now) performing? (The most failure prone period in a part's service life is when it is first installed [and now that so much stuff is out of China where QC is often vague at best, so much the worse for infant mortality]. And, this fact often complicates troubleshooting as it may introduce ANOTHER problem - compounding the whole attempt to fix an issue!)

Scanning is going to be your best bet to zero in on what is/isn't working. In particular I'd want to know what the O2 sensors (left and right) are doing, the BLMs and INTEGRATOR and IAC counts and % throttle was doing.

Beings your in WAZOO land, your in good hands, as Charlie said!

[XfireZ51]

How many miles on motor? May want to pull IAC and clean the pintle and the TB opening where it fits.

[Rodney McDaniel]

Hi guys, car has 84,000 miles. Car has seen setting a lot since 2012, it was the original injectors, one of the coils had been replaced (so I replaced all with AcDelco parts) I try to use name brand quality parts. I cleaned the Iac valve,(intake system very dirty ) seemed to help. When idle is varying now it's between 1100 and 800 rpm, sometimes it's steady about 750 rpm. We'll see next time I take it out. Maybe it just needs some run time. I have a Matco obd 1 but truthfully I don't know anything about it.

[tccrab]

Sounds like a vacuum leak.
If your Z is a '90, see the following link.
Had the exact same problem on mine.

http://www.zr1.net/forum/showthread.php?t=32275


'Crabs

[Rodney McDaniel]

Hi guys, replaced the iac valve , new intake air sensor seems to be running much much better and a better quality idle. Thanks to all for there input.