My engine has never idled perfectly. It was horrible when I first got it but a quick replacement of the FPR fixed that. It used to idle around 1500-2000rpms but at some point in the last few months it has went down and now it idles around 900-1000rpms. (Which is a pretty normal idle as far as I know) It still lopes though. The engine doesn't keep a constant rpm and continually fluctuates while idleing. It still runs fine and I'm not that picky so I've just ignored it. A few days ago it became worse. Now my idle is fluctuating all over the place. (estimate 800-1100). When you listen to the exhaust it sounds like its going to die at any moment. I put a vacuum guage (T) between a red vacuum line and the vacuum tree. It fluctuates from 18-20hg at idle and is consistant with the rpms. Hah.. I ran the guage hose out through the top of the hood and taped (mounted) the guage in front of the winshield. I closed the hood and went for a ride. The first time I monitored the EGR. I tested it earlier and the valve works but I couldn't check if the EGR was getting vacuum to open it. On the road it started getting vacuum. Anytime I would let off the gas it would jump to 1hg but it didn't seem to hold. That seems really low but I'm not familiar with whats normal for an EGR. Also this was just 25-35 mph driving and I'm under the impression they do more out on the highway. I pulled over and switched it to the red line I referred to earlier. Just cruising the vacuum held around 20hg. When I would press the accelerator it would go down to around 15hg and when I floored the pedal it would jump down below 5hg. Is this normal activity and how should I go about my idle issue? Visually checking the hoses and spraying some wd-40 here and there didn't reveal much.
You should have 15" or more at idle. It should go to 0" at wide open throttle and be everywhere in between when driving.
yup, I wouldnt expect too great of a idle anyway, my old Original motor didnt idle super smooth, it bounced around in a 200 rpm range. (1000-1200 rpms) and my new turbo motor does the same.. 4 cyls just dont idle good. Your vac looks good though, i get from about 20" at idle in a nice smooth arc till i hit 15psi boost, when decell. i pull about 23" Dr.
Your model year isn't posted, but if you have an IAC valve, that's probably your problem with idle variation. Clean it or replace it.
